Apparatus and method for coupling to multi-conductor cables

Abstract

An apparatus and method for coupling to a multi-core steel wire armored cable or multi-core cable are described. The apparatus may include one or more magnets and one or more magnetic field sensors, and / or may include two or more arrays of one or more sensors that allow twisting of the multiple conductors or cores. The apparatus is configured such that when the apparatus is coupled to the multi-core steel wire armored cable, a magnetic field corresponding to the one or more magnets is applied to a region of the multi-core steel wire armored cable. The apparatus is oriented such that when the apparatus is coupled to the multi-core steel wire armored cable, each magnetic field sensor detects a component of the magnetic field emanating from the region of the multi-core steel wire armored cable.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for non-contact measurement of current in a multi-core cable. In some instances, the multi-core cable may be armored. In some instances, the multi-core cable may be used to supply net current. [Background technology]

[0002] A magnetically permeable shell around a current-carrying cable reduces the surrounding magnetic field due to the current in the cable, making it impractical for measuring anything more than the net current in the cable flowing through the center of the cable, which is measured by a conventional current transformer or Rogowski coil placed around the cable. Thus, information about the external magnetic field relative to (among other things) the differential current and the placement of the conductors in the cable is lost.

[0003] Prior art related to the present invention WO 2013 / 068360 A1 (2013) discloses a device for measuring currents in conductors of a covered cable in a multiphase network. The device comprises at least six magnetic field sensors arranged around a central hole. The cable to be measured passes through the central hole, and the number of conductors in the cable must be less than the number of magnetic field sensors. The device also includes a calculation device and a library of matrices that relate the measured fields to the currents in the conductors when the conductor configuration is known. Procedures for selecting the optimal matrix, optimizing it, and adapting it to the set of conductors being tested are described. WO 2013 / 068360 A1 offers important advantages over documents such as EP 0 874 244 B1: the total current is not limited to zero, the number of sensors is not constrained to be equal to the number of conductors minus one, and, with some limitations, it can adapt to unexpected configurations of conductors.

[0004] Thus, deriving current in unarmoured multicore cables from magnetic fields is known in the art, an example being disclosed in patent application WO2013 / 068360A1.

[0005] The invention disclosed herein addresses a need for measuring current flow in steel wire armored multi-conductor cables that is not addressed by the prior art.

[0006] Single-conductor current sensors based on Gauss's law and the magnetic field from electrical current, such as current transformers and Rogowski coil units, have been the mainstay of electrical measurement. They rely on Faraday's law, require sensors to be placed around each conductor, and provide accurate readings of the enclosed net current, regardless of the material used in the cable (magnetic or otherwise).

[0007] Systems have been demonstrated to simultaneously measure multiple conductors in the same cable, but traditionally this has required isolating each conductor and measuring the current with a separate CT, Rogowski, shunt, etc. Sensing current in multiple conductors in the same cable without separating the conductors is discussed in US5473244A, US7755347B1 and EP0874244A2. Summary of the Invention

[0008] This specification relates, in part, to methods and apparatus for applying a magnetic field to saturate the magnetically permeable shell of an armored multi-core cable, reducing its effective magnetic permeability and allowing magnetic fields resulting from the current distribution within the cable to reach the exterior. In this way, techniques can be employed to calculate the internal current distribution from external field measurements.

[0009] A typical armored cable uses steel wire wrapped around the conductor, providing a partially magnetically permeable shell that attenuates and distorts the fields due to the current distribution within the cable. Magnetically saturating the steel wire, as described herein, reduces (or effectively eliminates) this effect, allowing for accurate and repeatable measurements of the fields due to the current distribution within the cable. Based on the magnetic field, calculations of the current distribution can be performed, resulting in derived parameters such as, but not limited to, conductor current, differential current, phase, harmonics, time-domain current in one or more individual cores, and the number and / or shape of cores in a multi-core steel-wire armored cable and / or a multi-core cable without armor.

[0010] According to a first aspect of the present invention, there is provided an apparatus for coupling to a multi-core steel wire armored cable. The apparatus includes one or more magnets and one or more magnetic field sensors. The apparatus is configured such that when the apparatus is coupled to the multi-core steel wire armored cable, a magnetic field corresponding to the one or more magnets is applied to a region of the multi-core steel wire armored cable. The apparatus is oriented such that when the apparatus is coupled to the multi-core steel wire armored cable, each magnetic field sensor detects a component of the magnetic field emanating from the region of the multi-core steel wire armored cable.

[0011] The magnets may be rare earth magnets such as samarium cobalt (SmCo) and / or neodymium (NdFeB), and / or other non-rare earth magnets.

[0012] Magnets may be fragile and require protection from mechanical shock or impact. The magnets may be coated with rubber or other polymers. The magnet(s) may be overmolded with a polymer or assembled with hard polymer or metal (magnetic or non-magnetic) cover(s) that protect the surface of the magnet(s) exposed to impact.

[0013] In this way, the magnetic field from one or more magnets saturates or at least partially saturates the steel wire sheath (usually in the form of wires wrapped around the outer periphery of the multi-core cable). As a result, the magnetic permeability of the steel wire sheath is reduced, allowing a greater portion of the magnetic field generated by the current in the cable's core to couple to the magnetic field sensor(s). This can improve the accuracy and reliability of measured magnetic fields caused by differential current flow between two or more cores (or conductors) of a multi-core steel wire sheath cable. As a result, derived quantities calculated based on the measured magnetic fields can also be improved. Examples of derived quantities may include (but are not limited to) current, differential current, phase, harmonics, time-domain current in one or more individual cores, and the number and / or shape of cores in a multi-core steel wire sheath cable.

[0014] Each magnetic field sensor can be oriented to detect a component of a magnetic field resulting from current flowing through one or more of the cores in a region of the multi-core steel wire armored cable to which a magnetic field corresponding to one or more magnets is applied. The magnetic field sensors can be configured to measure a magnetic field resulting from a differential current flow between two or more cores of the multi-core steel wire armored cable.

[0015] Multicore cables are also sometimes called multi-conductor cables (these terms should be interpreted interchangeably).

[0016] The magnetic field corresponding to one or more magnets corresponds to the superposition of the magnetic fields generated by each of the one or more magnets.

[0017] The coupling may include a mechanical coupling and / or a mechanical connection. The coupling may include coupling the magnetic fields generated by or within a multi-core steel wire armored cable and / or its core. The coupling does not include a galvanic connection.

[0018] When the device is coupled to a multi-core steel wire armored cable, within the region, the magnetic field corresponding to the one or more magnets may include a component parallel to the axis of the multi-core steel wire armored cable. The component parallel to the axis of the multi-core steel wire armored cable may be the largest component of the magnetic field at each point within the region. The component parallel to the axis of the multi-core steel wire armored cable may be the largest overall component of the magnetic field.

[0019] At least one of the one or more magnets may include or take the form of a permanent magnet, two or more of the magnets may include or take the form of a permanent magnet, or all of the one or more magnets may include or take the form of a permanent magnet.

[0020] At least one of the one or more magnets may include or take the form of an electromagnet; two or more of the magnets may include or take the form of an electromagnet; or all of the one or more magnets may include or take the form of an electromagnet.

[0021] At least one of the one or more magnetic field sensors may include or take the form of a coil. Two or more of the magnetic field sensors may include or take the form of respective coils. All of the one or more magnets may include or take the form of respective coils. The coils may be prefabricated with the cable inserted, wrapped around the cable in the field, connected around the cable in the field, or placed around the cable in the field. The coils may be mounted radially, tangentially, or in other axes relative to the longitudinal axis of the sensor. Combinations of coil orientations, including but not limited to radial and tangential orientations, may be used within a single sensor. The coils may be wound around a core of magnetically permeable material. The coils may be so-called "air-core" coils that do not include a core of magnetically permeable material. "Air-core" coils may be wound around a support structure in the form of a non-magnetically permeable material, such as plastic, glass, etc.

[0022] At least one of the one or more magnetic field sensors may include or take the form of a solid-state magnetic field sensor device. Each solid-state magnetic field sensor may sense magnetic fields in one, two, three, or more axes. The solid-state magnetic field sensor device may include or take the form of a semiconductor-type magnetic sensor, a magnetoresistive sensor, a giant magnetoresistive sensor, or an anisotropic magnetoresistive sensor. The solid-state magnetic field sensor device may include or take the form of a giant magnetoimpedance (GMI) sensor. The solid-state magnetic field sensor device may include or take the form of a superconducting quantum interference detector (SQUID). The solid-state magnetic field sensor device may include or take the form of a magneto-optical sensor. The solid-state magnetic field sensor device may include or take the form of a fluxgate. The solid-state magnetic field sensor device may include or take the form of a chip or integrated circuit. The solid-state magnetic field sensor device may include or take the form of a Hall sensor.

[0023] The two or more magnetic field sensors may include or take the form of respective solid-state magnetic field sensor devices (of any type described herein). All of the one or more magnetic field sensors may include or take the form of respective solid-state magnetic field sensor devices (of any type described herein).

[0024] The magnetic field corresponding to the one or more magnets may have a magnitude of at least 5 mT within the region. The magnetic field corresponding to the one or more magnets may have a magnitude of at least 12 mT within the region. The magnetic field corresponding to the one or more magnets may have a magnitude of at least 50 mT within the region.

[0025] The magnetic field corresponding to one or more magnets may be time-varying. The time-varying magnetic field may correspond to at least some of the one or more magnets in the form of electromagnets. At least some of the electromagnets may be driven with alternating current. At least some of the electromagnets may be energized during operating periods and de-energized during idle periods. The device may be configured to compare measurements of the magnetic field during operating periods with measurements of the magnetic field during idle periods to identify and preferably compensate for residual screening effects of the steel wire sheath. The operating and idle periods may be sequenced according to a predetermined schedule. Additionally or alternatively, the device may be configured to energize at least some of the electromagnets in response to a trigger condition, a received signal, or the like.

[0026] The device may be configured so that the magnetic field corresponding to one or more magnets is constant. Constant means that the magnetic field does not change over time when powered and operating correctly. The constant magnetic field may be provided by permanent magnets, electromagnets energized by direct current, or a combination of both.

[0027] The device may be configured to mechanically couple to the multi-core steel wire armored cable using magnetic forces resulting from applying a magnetic field to the steel wire armor. The one or more magnets may be primarily configured to apply a magnetic field to the region to at least partially saturate the steel wire armor. However, this always results in some magnetic force between the device and the multi-core steel wire armored cable. With appropriate design choices, this magnetic force can also be used to secure the device and the coupled multi-core steel wire armored cable relative to one another. For example, the device may be designed to have a weight that is less than the magnetic force generated when the multi-core steel wire armored cable is received within the region.

[0028] The device may also include a structure supporting one or more magnets and one or more magnetic field sensors. The structure may include a channel configured to receive the multi-core steel wire armored cable. That is, the structure may be a channel-defining structure. The cross-section of the channel may have a circular or arc shape. The cross-section of the channel may be non-circular and have a shape that does not correspond to an arc. The channel may be open to receive the multi-core steel wire armored cable. The structure may define the cross-section of the channel to be C-shaped or U-shaped. The cross-section may be taken in a plane perpendicular to a direction corresponding to an axial direction of the channel through which the multi-core steel wire armored cable is received when coupled to the device.

[0029] The channel may be defined by a first part and a second part of the structure and configured to close around the multi-core steel wire armored cable when received within the channel. The first part and the second part may be biased toward one another by a spring. The first part and the second part may be biased toward closing around the multi-core steel wire armored cable by the magnetic force of at least some of the one or more magnets. The first and second parts of the structure may provide a clamp. Once closed around the multi-core steel wire armored cable, the first and second parts may be secured to one another by a latch, catch, or similar fastening means.

[0030] The structure may include or take the form of two or more components configured to close or wrap around the multi-core steel wire armored cable to define a channel. The two or more components may be biased together by a spring. Once closed around the multi-core steel wire armored cable, the two or more components may be secured together by one or more latches, one or more catches, or one or more similar fastening means.

[0031] The device may also include a net current sensor configured to measure a net current through the multi-core steel wire armored cable when the device is coupled to the multi-core steel wire armored cable. The net current sensor may include or take the form of a Rogowski coil. The net current sensor may include or take the form of a current transformer. The one or more magnetic field sensors may be disposed within a current transformer coil of the current transformer.

[0032] At least one of the one or more magnetic field sensors may include or take the form of a coil. Each coil may be wrapped around a sensing pole piece. Two or more of the magnetic field sensors may be provided by respective coils. Two or more coils providing a magnetic field sensor may be wrapped around respective portions of a single sensing pole piece. Alternatively, two or more coils providing a magnetic field sensor may be wrapped around each of the individual sensing pole pieces.

[0033] A circumferential sensing pole piece may extend around all or part of the circumference surrounding the multi-core steel wire armored cable when received and may include two or more inward radial projections, and a coil providing a magnetic field sensor may be wound around each inward radial projection.

[0034] At least one of the one or more magnets may include or take the form of an electromagnet. Each electromagnet may be wrapped around a pole piece. Two or more of the magnets may be provided by electromagnets. Two or more electromagnets may be wrapped around respective portions of a single pole piece. Alternatively, two or more coils providing the magnetic field sensor may be wrapped around each of the individual pole pieces.

[0035] The device may include a common pole piece with one or more coils providing magnetic field sensors wrapped around respective portions and one or more electromagnets wrapped around other portions.

[0036] The device may include two or more magnetic field sensors. The device may include three or more magnetic field sensors. The device may include four or more magnetic field sensors. The device may include five or more magnetic field sensors. The device may include six or more magnetic field sensors. The device may include ten or more magnetic field sensors.

[0037] The magnetic field sensors may be equiangularly positioned around a channel that receives the multi-core steel wire armored cable.

[0038] The one or more magnets may include or take the form of a first group including a plurality of first magnets and a second group including a plurality of second magnets. The first and second groups may be disposed on opposite sides of the one or more magnetic field sensors along a direction corresponding to the axial direction of the multi-core steel wire armored cable when coupled to the device. That is, the first and second groups of magnets may group or sandwich the magnetic field sensors along the length of the coupled / accepted multi-core steel wire armored cable.

[0039] The device may include a pair of magnets corresponding to each magnetic field sensor. Each pair of magnets may be positioned on either side of the corresponding magnetic field sensor along a direction corresponding to the axial direction of the multi-core steel wire armored cable when coupled to the device. That is, each pair of magnets may bracket or sandwich the corresponding magnetic field sensor along the length of the coupled / accepted multi-core steel wire armored cable.

[0040] The one or more magnetic field sensors may include a first set of first magnetic field sensors and a second set of second magnetic field sensors, the first and second sets being spaced apart along an axial direction of the multi-core steel wire armored cable when the multi-core steel wire armored cable is coupled to the device.

[0041] In this way, the difference between the magnetic field measurements made using the first and second sets can be used to compensate for different twist rates between different multi-core cables, as further described with respect to the apparatus of the third aspect.

[0042] The sensor may include the device of the first aspect and a controller. The controller may be connected to one or more magnetic field sensors and configured to calculate one or more derived quantities based on magnetic field components measured by the magnetic field sensors for some or all of the cores of the multi-core steel wire armored cable.

[0043] The one or more derived quantities may include (but are not limited to) current in an individual core, core current which may be AC ​​or DC difference current between cores, phase between cores, harmonics, time domain current in one or more individual cores, number and / or shape of cores in a multi-core steel wire armored cable, or cores / conductors in a soft magnetic conduit or pipe or cable tray, etc.

[0044] At least a portion of the device, including the at least one sensor, may be movable relative to the core or conductor of interest to provide additional data and enable improved determination of derived quantities. The at least one sensor may be movable between two defined positions relative to the conductor of interest to provide additional magnetic field data and enable determination of the geometry and other derived quantities of the current-carrying conductor.

[0045] Two or more rings of the magnetic field sensor may be axially spaced apart. Additionally or alternatively, one or more of the rings may be offset from the central axis of the sensor assembly, thereby providing additional magnetic field data for determining the geometry of the current-carrying conductor / core and other derived quantities.

[0046] The array of magnetic sensors may be arranged in any predetermined shape during measurement, such as a ring, two clamp or clamshell shape, or any shape used in a conventional single current probe, or a fixed or open rectangular shape (suitable for use with conductors placed in rectangular duct or cable tray sections), or in an oval shape (fixed or open), or a shape with an open, such as a "C" or "U", or a shape that returns on itself. The relative positions of the sensors must not change during the measurement process.

[0047] The described apparatus and methods may also be applied to cores, cables, or conductors that are grouped together, but not necessarily housed in a single multi-core cable.

[0048] Steel-armored multi-core cables are a subset of multi-core cables.

[0049] The described device and method can be used to partially saturate partially magnetically permeable steel or soft magnetically soft conductor containing conduits or pipes or cables.

[0050] The one or more magnets and the one or more magnetic field sensors can be mounted within a soft magnetic housing or within a soft magnetic channel-defining structure that provides magnetic immunity to carry external current to an external current-carrying conductor near or adjacent to the device.

[0051] The channel-defining structure may be formed from a non-magnetic (i.e., non-magnetically permeable) material if magnets are not used. The channel-defining structure may be formed from a non-magnetic (i.e., non-magnetically permeable) material if magnets are used. The channel-defining structure may be formed from a magnetic (i.e., magnetically permeable) material if magnets are used.

[0052] Magnetic immunity can be achieved using magnetic field sensors, for example, using known relative positions and orientations of magnetic field sensors to distinguish magnetic field sources internal to a multi-core cable from external magnetic field sources.

[0053] The controller may include one or more digital electronic processors communicatively coupled to a memory. The controller may include storage for holding computer program code that, when executed by the one or more digital electronic processors, causing the controller to obtain magnetic field measurements using one or more magnetic field sensors; having a controller control the energization state of one or more electromagnets; causing the controller to do one or more of the following: calculate one or more derived quantities;

[0054] The computer program may be an algorithm or a range of algorithms. The computer program may operate on the same principles as the cited prior art and / or may use the range of principles developed. making the derived quantities insensitive to external magnetic fields (e.g., external magnetic fields caused by adjacent current-carrying conductors external to the sensor); and / or The calculation of the derived amount may be made insensitive to core twist associated with multi-core cables.

[0055] The sensor may include the device of the first aspect. The device may be further configured to generate one or more signals based on the output of the one or more magnetic field sensors. Each signal may be proportional to a differential current between cores of a multi-core steel wire armored cable when the multi-core steel wire armored cable is coupled to the device. Each signal may be proportional to an individual core current in an individual core of the multi-core cable. The sensor may also include a link corresponding to each signal for connection to a control system and / or a measurement system.

[0056] Some or all of the links may take the form of wired links. Some or all of the links may take the form of low power wireless links, for example Bluetooth, RFID, etc.

[0057] Any of the sensors may also include one or more voltage sensors, and the one or more derived quantities may include one or more power values, which may include the power supplied by each core and / or the total power supplied by the multi-core steel wire armored cable.

[0058] The system may include any sensor coupled to provide input to a measuring device. The measuring device may receive one or more derived quantities from the sensor. The measuring device may receive one or more signals based on the output of one or more magnetic field sensors.

[0059] The measurement device may be a power quality analyzer, which may sometimes be referred to as a "power quality monitor."

[0060] The measurement device may be a power quality logging device, which may take the form of a power logger or an energy logger.

[0061] According to a second aspect of the present invention, there is provided a method comprising coupling an apparatus according to the first aspect to a multi-core steel wire armored cable, or coupling an apparatus incorporating a sensor or system to a multi-core steel wire armored cable, such that a magnetic field corresponding to one or more magnets is applied to a region of the multi-core steel wire armored cable, The method also comprises measuring components of the magnetic field emanating from the region of the multi-core steel wire armored cable using one or more magnetic field sensors.

[0062] The magnetic field corresponding to the one or more magnets may saturate the magnetic field of the steel wire sheath in the region. The magnetic field corresponding to the one or more magnets may magnetically saturate (wholly or partially) the steel wire sheath in the region.

[0063] The permeability of a magnetic material, such as a steel wire sheath, can be defined as the gradient of the magnetic flux relative to the magnetic field, i.e.,

number

[0064] The magnetic field within the steel wire sheath may be considered saturated when the magnetic permeability μ is less than or equal to 20% of its peak value. The magnetic field within the steel wire sheath may be considered saturated when the magnetic permeability μ is less than or equal to 15% of its peak value. The magnetic field within the steel wire sheath may be considered saturated when the magnetic permeability μ is less than or equal to 10% of its peak value. The magnetic field within the steel wire sheath may be considered saturated when the magnetic permeability μ is less than or equal to 5% of its peak value.

[0065] Alternatively, when the same current is supplied to each cable core, the magnetic field within the steel wire sheath can be considered saturated if the magnetic field measured by one or more magnetic field sensors attenuates by 10% or less compared to a multi-core cable identical to the multi-core steel wire sheath cable except for the steel wire sheath.

[0066] The method may also include calculating one or more derived quantities based on the magnetic field components measured by the magnetic field sensors for some or all of the cores of the multi-core steel wire armored cable. The one or more derived quantities may include (but are not limited to) current through individual cores, differential current between cores, high frequency, time domain current through one or more individual cores, the number and / or shape of cores in the multi-core steel wire armored cable, etc.

[0067] The method may include features corresponding to any feature of the apparatus of the first aspect and / or a sensor or system comprising the apparatus of the first aspect (and / or a feature of the first aspect). Definitions applicable to features corresponding to any feature of the apparatus of the first aspect and / or a sensor or system comprising the apparatus of the first aspect (and / or a feature of the first aspect) are equally applicable to the method of the second aspect (and / or a feature of the second aspect).

[0068] According to a third aspect of the present invention, there is provided an apparatus for coupling to a multi-core cable. The apparatus includes a first set of one or more first magnetic field sensors. The apparatus also includes a second set of one or more second magnetic field sensors. When the apparatus is coupled to the multi-core cable, each of the first magnetic field sensors is oriented to detect a magnetic field component emanating from a first region of the multi-core cable. When the apparatus is coupled to the multi-core cable, each of the second magnetic field sensors is oriented to detect a magnetic field component emanating from a second region of the multi-core cable. When the apparatus is coupled to the multi-core cable, the apparatus is configured such that the first region is spaced apart from the second region along the length of the multi-core cable.

[0069] The apparatus of the third aspect may include features corresponding to any of the features of the apparatus of the first aspect and / or the method of the second aspect (and / or features of these aspects). Definitions applicable to the apparatus of the first aspect and / or the method of the second aspect (and / or features of these aspects) may equally be applied to the apparatus of the third aspect (and / or features of the third aspect).

[0070] When coupled to a multi-core cable, the number and arrangement of the first magnetic field sensors relative to the multi-core cable may be the same as the number and arrangement of the second magnetic field sensors relative to the multi-core cable.

[0071] The individual cores of a multi-core cable are typically twisted relative to one another to increase the overall cable's mechanical compliance and facilitate easier routing, winding, and the like. When measurements of the magnetic fields generated by the cores are used to estimate the currents in the cores and / or the relative phases between the cores, certain assumptions must be made about the relative positions and twisting speeds of the cores. However, when measuring an unknown cable, such geometric factors cannot be utilized without disassembling the cable and defeating the purpose of non-invasive measurements. Using the device of the third aspect, the relative positions of each core are varied between the first and second sets of magnetic field sensors, while the currents are preserved between the first and second regions. In this way, the difference between the magnetic field measurements made using the first and second sets can be used to compensate for different twisting speeds between different multi-core cables. For example, the measured rotational speed of the magnetic field detected by the magnetic field sensors may be related to the twisting / rotational speed of the cores of the multi-core cable.

[0072] The device of the third aspect may also include one or more magnets arranged such that when the device is coupled to the multi-core cable, magnetic fields corresponding to the one or more magnets are applied to the first and second regions of the multi-core cable.

[0073] The magnetic field corresponding to the one or more magnets may be applied substantially uniformly to the first and second regions of the multi-core cable. Substantially uniform may mean that the magnetic fields in the first and second regions are approximately symmetrical about a mirror plane that is equidistant between the first and second regions and oriented perpendicular to the axial direction of the multi-core cable when combined. Approximately symmetrical may mean that the magnetic field components (e.g., x, y, z components) at any point in the first region differ by 10% or less from a reflection point in the second region.

[0074] According to a fourth aspect of the present invention, there is provided an apparatus for coupling to a multi-core cable, the apparatus including a current transformer coil and one or more magnetic field sensors. The apparatus is configured such that when the apparatus is coupled to the multi-core cable, a region of the multi-core cable passes through the current transformer coil. The apparatus is configured such that when the apparatus is coupled to the multi-core cable, one or more magnetic field sensors are disposed at least partially between a core of the current transformer coil and the multi-core cable. At least one of the magnetic field sensors is oriented to detect a component of the magnetic field emanating from the region of the multi-core cable.

[0075] The current transformer coil may also be referred to as a "CT" coil. The current transformer coil may be configured to measure the net current flowing through the multi-core cable. The one or more magnetic field sensors may be configured to measure one or more derived quantities for some or all cores of the multi-core cable based on magnetic field components measured by the magnetic field sensors. The derived quantities may include any or all of the derived quantities specified in connection with the apparatus according to the first aspect and / or the method according to the second aspect.

[0076] The apparatus according to the fourth aspect may include features corresponding to any features of the apparatus(es) according to the first and / or third aspect. Definitions applicable to the apparatus(es) according to the first and / or third aspect (or features of those aspects) may be equally applicable to the apparatus (or features thereof) of the fourth aspect.

[0077] The current transformer coil may be short-circuited through a resistor, which may also be called a "shunt resistor," "load resistor," or "burden resistor." The resistance may be between 0.1 Ω and 100 Ω. Preferably, the resistance is between 1 Ω and 10 Ω. The voltage measured across the "burden resistor" is proportional to the net current in the multi-core conductor passing through the current transformer coil.

[0078] The one or more magnetic field sensors may be disposed at least partially within an inner diameter of the current transformer coil.

[0079] The core of the current transformer coil may include or take the form of a magnetically permeable material. The magnetically permeable material may be soft iron. The current transformer coil may be wound directly around the core of magnetically permeable material. The current transformer coil may be wound around a bobbin (or similar support), and one or more regions of magnetically permeable material may be received within the bobbin (or similar support). For example, the current transformer coil may be wound around a bobbin having a through hole, and the core of magnetically permeable material may be inserted into the through hole so as to be disposed within the current transformer coil.

[0080] The bobbin may be flexible and / or may have a segmented structure. In this manner, the current transformer coil may be wound around the bobbin in a flat configuration, and the bobbin may then be curved and / or folded to form a toroidal shape (or a portion of a toroidal shape).

[0081] A current transformer coil may include or take the form of two or more sub-coils. Two or more sub-coils may be connected to each other. Two, a subset, or all of the sub-coils may be connected in series. Two, a subset, or all of the sub-coils may be connected in parallel.

[0082] The device may be configured such that a region of the multi-core cable received through the current transformer coil is axially oriented. The current transformer coil may extend axially on either side of the one or more magnetic field sensors. Cores of the current transformer coil may extend axially on either side of the one or more magnetic field sensors.

[0083] The current transformer coil may extend axially a length equal to or greater than half the inner diameter of the current transformer coil. The current transformer coil may extend axially a length equal to or greater than the inner diameter of the current transformer coil. The current transformer coil may extend axially a length equal to or greater than twice the inner diameter of the current transformer coil. One or more magnetic field sensors may be positioned axially at a position equal to or greater than half the length of the current transformer coil.

[0084] At least one of the one or more magnetic field sensors may include or take the form of a sensor coil. Each sensor coil may be wound around a sensing pole piece. Each sensor coil may be wound around a portion or protrusion of the core of the current transformer coil. Two or more of the magnetic field sensors may include or take the form of a respective sensor coil. All of the one or more magnetic field sensors may include or take the form of a respective sensor coil. The sensor coils may be prefabricated with the multi-core cable inserted, or may be wound around the multi-core cable in the field, or may be connected around the multi-core cable in the field, or may be placed around the multi-core cable in the field. The sensor coils may be mounted radially, tangentially, or on other axes relative to the longitudinal axis of the device (along which the multi-core cable is configured to be received). Combined sensor coil orientations may be used, including but not limited to radial and tangential orientations within a single device. The sensor coils may be wound around a core of magnetically permeable material. The sensor coils may be so-called "air-core" coils that do not include a core of magnetically permeable material. An "air core" sensor coil may be wound around a support structure in the form of a non-magnetically permeable material such as plastic, glass, etc. The sensor coil may be wound around a bobbin, which may be common with the current transformer coil.

[0085] At least one of the one or more magnetic field sensors may include or take the form of a solid-state magnetic field sensor device. Each solid-state magnetic field sensor may sense a magnetic field in one, two, three, or more axes. The solid-state magnetic field sensor device may include or take the form of a semiconductor-type magnetic sensor, a magnetoresistive sensor, a giant magnetoresistive sensor, or an anisotropic magnetoresistive sensor. The solid-state magnetic field sensor device may include or take the form of a giant magnetoimpedance (GMI) sensor. The solid-state magnetic field sensor device may include or take the form of a superconducting quantum interference detector (SQUID). The solid-state magnetic field sensor device may include or take the form of a magneto-optical sensor. The solid-state magnetic field sensor device may include or take the form of a fluxgate. The solid-state magnetic field sensor device may include or take the form of a chip or integrated circuit. The solid-state magnetic field sensor device may include or take the form of a Hall sensor.

[0086] The two or more magnetic field sensors may include or take the form of respective solid-state magnetic field sensor devices (of any type described herein). All of the one or more magnetic field sensors may include or take the form of respective solid-state magnetic field sensor devices (of any type described herein).

[0087] The device may include a structure supporting a current transformer coil and one or more magnetic field sensors. The structure may include or take the form of a bobbin on which the current transformer coil and / or one or more sensor coils are wound. If one or more magnets are included in the device, the structure may also support the one or more magnets.

[0088] The structure may include a channel configured to receive the multi-core cable, i.e., the structure may be a channel-defining structure.

[0089] The cross section of the channel may have a circular or arc shape.

[0090] The cross section of the channel may be non-circular and have a shape that does not correspond to an arc of a circle.

[0091] The channel may be open. The open channel may receive a multi-core cable. The structure may be defined such that in cross section the channel folds back on itself. The structure may be defined such that the channel has a C- or U-shaped cross section. The cross section may be taken in a plane perpendicular to a direction corresponding to the axial direction of the channel in which the multi-core cable is received when coupled to the device.

[0092] The channel may be defined by a first part and a second part of the structure and configured to close around the multi-conductor cable when received within the channel. The first part and the second part may be biased toward one another by a spring. The first and second parts of the structure may provide a clamp. Once closed around the multi-conductor cable, the first and second parts may be secured to one another by a latch, catch, or similar fastening means.

[0093] The structure may include two or more components configured to close or wrap around the multi-core cable to define a channel. The two or more components may be biased together by a spring. Once closed around the multi-core cable, the two or more components may be secured together by one or more latches, one or more catches, or one or more similar fastening means. The structure may be a split structure with two or more components joined together by a flexible material, or may use axially aligned hinges.

[0094] The device may include two or more magnetic field sensors.

[0095] The device may also include one or more magnets. The device may be configured such that when the device is coupled to the multi-core cable, a magnetic field corresponding to the one or more magnets is applied to a region of the multi-core cable passing through the current transformer coil.

[0096] In this way, the device according to the fourth aspect can be applied to steel wire armored multi-core cables in the same way as the device according to the first aspect, with the same effects and advantages.

[0097] The one or more magnetic field sensors may include a first set of first magnetic field sensors and a second set of second magnetic field sensors, and the first and second sets of magnetic field sensors may be spaced apart along an axial direction of the multi-core cable when the multi-core cable is coupled to the device.

[0098] The sensor may include the device according to the fourth aspect. The sensor may also include a controller connected to the one or more magnetic field sensors. The controller may be configured to calculate one or more derived quantities based on the magnetic field components measured by the magnetic field sensors for some or all of the cores of the multi-core cable.

[0099] The controller may be further configured to calculate a net current through the multi-core cable based on measurements using the current transformer coils.

[0100] The one or more derived quantities may include (but are not limited to) current in an individual core, core current which may be AC ​​or DC difference current between cores, phase between cores, harmonics, time domain current in one or more individual cores, number and / or shape of cores in a multi-core cable, or cores / conductors in a soft magnetic conduit or pipe or cable tray, etc.

[0101] The sensor may include a device according to the fourth aspect. The device may be further configured to generate one or more signals based on the output of one or more magnetic field sensors. Each signal may be proportional to a differential current between cores of a multi-core cable when the multi-core cable is coupled to the device. Alternatively, each signal may be proportional to an individual core current in an individual core of the multi-core cable. The sensor may also include a link corresponding to each signal for connection to a control system and / or a measurement system. The device incorporated in the sensor may be further configured to generate a net current signal based on the output from the current transformer coil.

[0102] The sensor may also include one or more voltage sensors. The one or more derived quantities may include one or more power values. The sensor may be configured to correctly assign phases to cores of a multi-core cable using the one or more voltage sensors.

[0103] Using a current transformer coil, the sensor may be powered by the net current flowing through the multi-core cable.

[0104] The system may include a sensor as described herein coupled to provide input to a measurement device. The measurement device may be a power quality analyzer. The measurement device may be a power quality logging device. The measurement device may be an energy meter. The measurement device may be an electricity meter.

[0105] According to a fifth aspect of the present invention, there is provided a method comprising coupling an apparatus according to the fourth aspect (or a sensor / system incorporating the apparatus) to a multi-core cable, a region of the multi-core cable passing through a current transformer coil, and measuring components of a magnetic field emanating from the region of the multi-core cable using one or more magnetic field sensors.

[0106] The method according to the fifth aspect may include features corresponding to any features of the apparatus(es) according to the first, third and / or fourth aspects. Definitions applicable to the apparatus(es) according to the first, third and / or fourth aspects may be equally applicable to the method (or features thereof) according to the fifth aspect.

[0107] The method may also include measuring a net current passing through the multi-conductor cable using a current transformer coil.

[0108] According to a sixth aspect of the present invention, there is provided an apparatus for coupling to a multi-core cable, the apparatus including a Rogowski coil and one or more magnetic field sensors. The apparatus is configured such that when the apparatus is coupled to the multi-core cable, a region of the multi-core cable passes through the Rogowski coil or the Rogowski coil is wrapped around the region of the multi-core cable. At least one of the magnetic field sensors is positioned adjacent to the Rogowski coil and oriented to detect components of the magnetic field emanating from the region of the multi-core cable.

[0109] At least one of the one or more magnetic field sensors may be located inside the inner diameter of the Rogowski coil or at least partially inside the Rogowski coil, i.e., between the Rogowski coil and the multi-core cable in use. At least one of the one or more magnetic field sensors may be located outside the Rogowski coil, i.e., separated from the multi-core cable by the Rogowski coil. At least one of the one or more magnetic field sensors may be located axially adjacent to the Rogowski coil.

[0110] The apparatus according to the sixth aspect may include features corresponding to any features of the apparatus(es) according to the first, third and / or fourth aspect. Definitions applicable to the apparatus(es) according to the first, third and / or fourth aspect (or features of those aspects) may be equally applicable to the apparatus (or features thereof) according to the sixth aspect.

[0111] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0112] [Figure 1] FIG. 3 is a three-quarter cross-sectional view of a sensor assembly including two magnet arrays, an array of semiconductor-type magnetic sensors, a housing channel-defining structure, and associated electronics, connections, and outputs, with the armored multi-core cable shown at length for illustrative purposes. [Figure 2] FIG. 1 is a three-quarter cross-sectional view of a sensor assembly including two magnets, an array of semiconductor-type magnetic sensors, and a housing channel-defining structure, with the armored multi-core cable shown in cross-section for illustrative purposes. [Figure 3] 1 is a cross-sectional view of a sensor assembly including a housing, two magnet arrays, an array of semiconductor-type magnetic sensors attached to a soft magnetic mounting ring, and a channel-defining structure in the housing. [Figure 4] FIG. 1 is a three-quarter cross-sectional view of a sensor assembly including a housing, two magnet arrays, an array of tangential coil magnetic sensors, a housing channel-defining structure, and associated electronics and output. [Figure 5] FIG. 1 is a three-quarter cross-sectional view of a sensor array including a soft magnetic ring and several axial sensor coils and their associated outputs. [Figure 6] FIG. 1 is an isometric view of a sensor assembly configured specifically as a polyphase electricity meter, including the sensor assembly, an associated electronics enclosure with a display and service port, a load to be measured, phase connections from the electronics enclosure to the load to be measured, and a multi-core cable shown in length for illustrative purposes. [Figure 7] FIG. 1 is an isometric view of a sensor assembly specifically configured as a power quality analyzer, including the sensor assembly, a power meter, phase connections to the device being measured, and a set of three Rogowski coils, to illustrate an alternative method; the armored multi-core cable being measured is not shown. [Figure 8A]FIG. 1 is an isometric axial cross-sectional view of a sensor assembly including two magnet arrays, an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring, and a housing channel-defining structure. [Figure 8B] FIG. 1 is an isometric cross-sectional view of a sensor assembly including two magnet arrays, an array of radial coil-type magnetic sensors mounted on a soft magnetic mounting ring, and a housing channel-defining structure. [Figure 9A] FIG. 1 is an isometric axial cross-sectional view of a sensor assembly including two magnet arrays, an array of radial and tangential coil magnetic sensors mounted on a soft magnetic mounting ring, and a housing channel-defining structure. [Figure 9B] FIG. 1 is an isometric cross-sectional view of a sensor assembly including two magnet arrays, an array of radial and tangential coil magnetic sensors mounted on a soft magnetic mounting ring, and a housing channel-defining structure. [Figure 10A] FIG. 1 is an isometric axial cross-sectional view of a sensor assembly including two magnet arrays, an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring, and a housing channel-defining structure with two additional radial coils on either side of the soft magnetic mounting ring. [Figure 10B] FIG. 1 is an isometric cross-sectional view of a sensor assembly including two magnet arrays, an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring, and a housing channel-defining structure with two additional radial coils on either side of the soft magnetic mounting ring. [Figure 11] FIG. 1 is an isometric cross-sectional view of a sensor assembly including two magnet arrays, two arrays of radial coil-type magnetic sensors mounted on respective soft magnetic mounting rings, and a housing channel-defining structure. [Figure 12A] FIG. 1 is an isometric axial cross-sectional view of an open sensor assembly including two magnet arrays, an array of radial coil magnetic sensors mounted on a soft magnetic mounting ring, a mounting channel-defining structure, and a housing with armored multi-core cables arranged in a planar configuration, shown at length for illustrative purposes. [Figure 12B] FIG. 1 is a side view of an open sensor assembly including two magnet arrays, an array of radial coil magnetic sensors mounted on a soft magnetic mounting ring, a mounting channel-defining structure, and a housing with armored multi-core cables arranged on a flat surface, shown at lengths for illustrative purposes. [Figure 12C] FIG. 1 is an isometric cross-sectional view of an open sensor assembly including two magnet arrays, an array of radial coil magnetic sensors mounted on a soft magnetic mounting ring, a mounting channel-defining structure, and a housing with armored multi-core cables arranged in a planar configuration, shown at lengths for illustrative purposes. [Figure 13A] FIG. 1 is an isometric cutaway (open) view of a “spring clamp” type sensor assembly including two magnet arrays, an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring, a mounting channel defining structure, and a housing assembly with a spring, with armored multi-core cable shown in length for illustrative purposes. [Figure 13B] FIG. 1 is an isometric (closed) view of a "spring clamp" type sensor assembly including two magnet arrays, an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring, a mounting channel defining structure, and a housing assembly with a spring, with an armored multi-core cable shown in length for illustrative purposes. [Figure 13C] FIG. 1 is an isometric cross-sectional (open) view of a "spring clamp" type sensor assembly including two magnet arrays, an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring, a mounting channel defining structure, and a housing assembly with a spring, with an armored multi-core cable shown in length for illustrative purposes. [Figure 14A] FIG. 1 is an isometric cross-sectional view of a sensor assembly including two magnets, a radial sensor coil, a soft magnetic substrate piece, and wire connections, with an armored multi-core cable shown in length for illustrative purposes. [Figure 14B]FIG. 1 is a top cutaway view of a sensor assembly including two magnets, a radial sensor coil, a soft magnetic substrate piece, and wire connections, with armored multi-core cable shown in lengths for illustrative purposes. [Figure 14C] FIG. 1 is an isometric view of a sensor assembly including two magnets, a radial sensor coil, a soft magnetic substrate piece, and wire connections, with an armored multi-core cable shown in length for illustrative purposes. [Figure 15A] FIG. 1 is an isometric (open) view of a multiple unit sensor assembly, each of whose individual units includes two magnets, a radial sensor coil, a soft magnetic substrate, a hinge element, and a movement-limiting element, with an armored multi-core cable shown in length for illustrative purposes. [Figure 15B] FIG. 1 is an isometric (closed) view of a multiple unit sensor assembly, each of whose individual units includes two magnets, a radial sensor coil, a soft magnetic substrate, a hinge element, and a movement-limiting element, with an armored multi-core cable shown in length for illustrative purposes. [Figure 15C] FIG. 1 is a side (closed) view of a multiple unit sensor assembly, each of whose individual units includes two magnets, a radial sensor coil, a soft magnetic substrate, a hinge element, and a movement-limiting element, with an armored multi-core cable shown in length for illustrative purposes. [Figure 15D] FIG. 1 is an isometric axial cross-sectional (closed) view of a multiple unit sensor assembly, each of whose individual units includes two magnets, a radial sensor coil, a soft magnetic substrate, a hinge element, and a movement-limiting element, with an armored multi-core cable shown in length for illustrative purposes. [Figure 15E] FIG. 1 is an isometric cross-sectional view of a multiple unit sensor assembly, each of whose individual units includes two magnets, a radial sensor coil, a soft magnetic substrate, a hinge element, and a movement-limiting element, with an armored multi-core cable shown in length for illustrative purposes. [Figure 16A]FIG. 1 is an isometric view of a sensor assembly including a soft magnetic cylindrical sensor body, an electromagnetic coil, and an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring. [Figure 16B] FIG. 1 is an isometric cross-sectional view of a sensor assembly including a soft magnetic cylindrical sensor body, an electromagnetic coil, and an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring. [Figure 16C] FIG. 1 is an isometric axial cross-sectional view of a sensor assembly including a soft magnetic cylindrical sensor body, an electromagnetic coil, and an array of radial coil type magnetic sensors mounted on a soft magnetic mounting ring. [Figure 17A] FIG. 1 is an isometric view of a sensor assembly including an electromagnetic coil, a soft magnetic armature, a hinged and / or clip-on housing, and an array of radial coil-type magnetic sensors, with an armored multi-core cable shown in length for illustrative purposes. [Figure 17B] FIG. 1 is an axial cross-sectional view of a sensor assembly including an electromagnetic coil, a soft magnetic armature, a hinged and / or clip-on housing, and an array of radial coil-type magnetic sensors, with an armored multi-core cable shown in length for illustrative purposes. [Figure 17C] FIG. 1 is a cross-sectional view of a sensor assembly including an electromagnetic coil, a soft magnetic armature, a hinged and / or clip-on housing, and an array of radial coil-type magnetic sensors, with an armored multi-core cable shown in length for illustrative purposes. [Figure 18A] FIG. 1 is an isometric cross-sectional view of a sensor assembly including one magnet, a radial sensor coil, a soft magnetic substrate piece, and wire connections, with armored multi-core cable shown in length for illustrative purposes. [Figure 18B] FIG. 1 is a top cutaway view of a sensor assembly including one magnet, radial sensor coil, soft magnetic substrate piece, and wire connections, with armored multi-core cable shown in lengths for illustrative purposes. [Figure 18C]FIG. 1 is an isometric view of a sensor assembly including one magnet, a radial sensor coil, soft magnetic substrate pieces, and wire connections, with armored multi-core cable shown in length for illustrative purposes. [Figure 19] 8A and 8B show experimentally measured current in a three-conductor multicore cable using the sensor assembly shown in FIGS. 8A and 8B, compared to measurements made using a conventional current clamp probe with one of the conductors isolated. [Figure 20] The error obtained from the analysis of the data shown in FIG. 19 is shown for a range of applied currents. [Figure 21] Equivalent data is shown in FIG. 19 for a current signal with harmonic content up to the 11th harmonic. [Figure 22] Equivalent data is shown in FIG. 19 for a current signal with harmonic content up to the 11th harmonic. [Figure 23] 19 shows experimentally determined currents obtained using the same arrangement as in FIG. 19 for a current signal containing a superposition of sine waves at the fundamental frequency and its 31st harmonic. [Figure 24A] 9B is an isometric axial cross-sectional view of a sensor assembly that is a variation of the sensor assembly shown in FIG. 9A. [Figure 24B] FIG. 9C is an isometric cross-sectional view of a sensor assembly that is a variation of the sensor assembly shown in FIG. 9B. [Figure 25A] 1 is an isometric view of a sensor assembly including two channel-defining structures that together form a ring, with an array of solid-state magnetic field sensors disposed around the inner surface of the ring. [Figure 25B] 1 is an axial cutaway view of a sensor assembly including two channel-defining structures that together form a ring, with an array of solid-state magnetic field sensors disposed around the inner surface of the ring. [Figure 26A] FIG. 1 shows an axial cutaway view of a sensor assembly including a set of radial sensor coils disposed within two semi-cylindrical channel-defining structures of magnetically permeable material. Magnet(s) arrays are included at either end, with end caps of magnetically permeable material serving to complete the magnetic circuit outside the sensing volume. [Figure 26B] 1 shows an axial side view of a sensor assembly including a set of radial sensor coils disposed within two semi-cylindrical channel-defining structures of magnetically permeable material. Magnet(s) arrays are included at either end, with end caps of magnetically permeable material serving to complete the magnetic circuit outside the sensing volume. [Figure 26C] 1 shows an isometric view of a sensor assembly including a set of radial sensor coils disposed within two semi-cylindrical channel-defining structures of magnetically permeable material. Magnet(s) arrays are included at each end, with end caps of magnetically permeable material serving to complete the magnetic circuit outside the sensing volume. [Figure 26D] 1 shows a top view of a sensor assembly including a set of radial sensor coils disposed within two semi-cylindrical channel-defining structures of magnetically permeable material. Magnet(s) arrays are included at either end, with end caps of magnetically permeable material serving to complete the magnetic circuit outside the sensing volume. [Figure 27A] FIG. 26B shows a plan view of a bobbin arrangement used in the sensor assembly of FIGS. 26A to 26D. [Figure 27B] FIG. 26B shows an axial side view of a bobbin arrangement used in the sensor assembly of FIGS. 26A to 26D. [Figure 27C] FIG. 26B shows an isometric view of the bobbin arrangement used in the sensor assembly of FIGS. 26A to 26D. [Figure 28A] FIG. 26B shows a plan view of a magnet used in the sensor assembly of FIGS. 26A to 26D. [Figure 28B] FIG. 26B shows an axial side view of a magnet used in the sensor assembly of FIGS. 26A to 26D. [Figure 28C] FIG. 26B shows an isometric view of the magnet used in the sensor assembly of FIGS. 26A to 26D. [Figure 29A] FIG. 26B shows a plan view of an outer core used in the sensor assembly of FIGS. 26A to 26D. [Figure 29B] FIG. 26B shows an axial side view of an outer core used in the sensor assembly of FIGS. 26A to 26D. [Figure 29C] FIG. 26B shows an isometric view of an outer core used in the sensor assembly of FIGS. 26A to 26D. [Figure 30A] FIG. 26B shows a plan view of an end cap used in the sensor assembly of FIGS. 26A to 26D. [Figure 30B] FIG. 26B shows an axial side view of an end cap used in the sensor assembly of FIGS. 26A to 26D. [Figure 30C] FIG. 26B shows an isometric view of an end cap used in the sensor assembly of FIGS. 26A-26D. [Figure 31A] FIG. 1 shows an isometric axial cross-section of a sensor assembly including two magnet arrays and an array of tangential coil type magnetic sensors mounted on a channel-defining structure. [Figure 31B] FIG. 1 shows an axial cutaway view of a sensor assembly including two magnet arrays and an array of tangential coil type magnetic sensors mounted on a channel-defining structure. [Figure 32A] 1 is an isometric view of a closed sensor array, which includes an array of tangential coil-type magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 32B] 1 is an isometric view of an open sensor array that includes an array of tangential coil-type magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 32C] 1 is a plan view of a closed sensor array, which includes an array of tangential coil-type magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 32D] 1 is a plan view of a closed sensor array, which includes an array of tangential coil-type magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 33A] 1 is an isometric view of a closed sensor array, which includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 33B]1 is an isometric view of an open sensor array, which includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 33C] 1 is a plan view of a closed sensor array, which includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 33D] 1 is a plan view of a closed sensor array, which includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section. [Figure 34A] 1 shows an isometric view of a sensor assembly including two magnet arrays and an array of radial coil type magnetic sensors supported within a magnetically permeable core of a current transformer, the radial coil type magnetic sensors being positioned around the protrusions of the current transformer core. [Figure 34B] 1 shows an isometric axial cross-sectional view of a sensor assembly including two magnet arrays and an array of radial coil type magnetic sensors supported within a magnetically permeable core of a current transformer, the radial coil type magnetic sensors being positioned around the protrusions of the current transformer core. [Figure 34C] 1 shows an axial cutaway view of a sensor assembly including two magnet arrays and an array of radial coil magnetic sensors supported within a magnetically permeable core of a current transformer, the radial coil magnetic sensors being positioned around the protrusions of the current transformer core. [Figure 34D] 1 shows a plan view of a sensor assembly including two magnet arrays and an array of radial coil magnetic sensors supported within a magnetically permeable core of a current transformer, the radial coil magnetic sensors being positioned around the protrusions of the current transformer core. [Figure 34E] 1 shows a plan cross-sectional view of a sensor assembly including two magnet arrays and an array of radial coil type magnetic sensors supported within a magnetically permeable core of a current transformer, the radial coil type magnetic sensors being positioned around the protrusions of the current transformer core. [Figure 35A] 1 shows an isometric axial cross-sectional view of a sensor assembly including two magnet arrays and an array of radial coil magnetic sensors supported within a magnetically permeable core of a current transformer. The radial coil magnetic sensors are air-cored. [Figure 35B] 1 shows a top cross-sectional view of a sensor assembly including two magnet arrays and an array of radial coil magnetic sensors supported within a magnetically permeable core of a current transformer, the radial coil magnetic sensors being air-cored. [Figure 36A] FIG. 1 shows an isometric view of a flat bobbin assembly. [Figure 36B] 1 shows an isometric view of the same bobbin assembly rearranged into a curved configuration. [Figure 36C] 10 shows an isometric view of a semi-cylindrical core section for threading a bobbin assembly in a curved configuration. [Figure 37A] FIG. 1 shows a plan view of a sensor assembly having an array of solid-state magnetic sensors positioned immediately inside a current transformer coil wrapped around a ring-shaped core of magnetically permeable material. [Figure 37B] FIG. 1 shows an isometric view of a sensor assembly having an array of solid-state magnetic sensors positioned immediately inside a current transformer coil wrapped around a ring-shaped core of magnetically permeable material. [Figure 38A] FIG. 1 shows a plan view of a sensor assembly having an array of solid-state magnetic sensors disposed inside the windings of a current transformer coil wrapped around a ring-shaped core of magnetically permeable material. [Figure 38B] FIG. 1 shows an isometric view of a sensor assembly having an array of solid-state magnetic sensors disposed inside the windings of a current transformer coil wrapped around a ring-shaped core of magnetically permeable material. [Figure 39A] FIG. 1 is an isometric view of a closed sensor array including an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section, the channel-defining structures being formed from a magnetically permeable material and serving as the cores of the current transformer coils. [Figure 39B] FIG. 1 is an isometric view of an open sensor array that includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section and are formed from a magnetically permeable material and serve as the cores of current transformer coils. [Figure 39C]1 is a plan view of a closed sensor array, which includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section, the channel-defining structures being formed from a magnetically permeable material and serving as the cores of the current transformer coils. [Figure 39D] 1 is a plan view of a closed sensor array, which includes an array of solid-state magnetic sensors attached to a pair of channel-defining structures that form an oval cross section, the channel-defining structures being formed from a magnetically permeable material and serving as the cores of the current transformer coils. [Figure 40A] 1 shows an isometric view of a sensor array that receives a multi-core cable and includes a Rogowski coil adjacent to an array of radial coil magnetic sensors. [Figure 40B] 1 shows an axial side view of a sensor array that receives a multi-core cable, the sensor array including a Rogowski coil adjacent to an array of radial coil magnetic sensors. DETAILED DESCRIPTION OF THE INVENTION

[0113] In the following, identical parts are designated by the same reference numerals.

[0114] FIG. 1 shows a first sensor assembly I with a “channel-defining structure” 1, which is a soft magnetic housing made from laminated steel, sintered or bonded metal powder, or any other suitable material, partially or totally surrounding an armored multi-core cable 6 to be measured.

[0115] The first sensor assembly I is a device for coupling to a multi-core steel-wire armored cable, although unarmored multi-core cables can also be used. The first sensor assembly I is formed from one, two, or more soft-magnetic "channel-defining structure" sections of a housing and may be hinged laterally along an axis parallel to the longitudinal axis of the first sensor assembly I to allow the sensor to open and close around the multi-core steel-wire armored cable 6. The armored multi-core cable 6 or armored multi-conductor cable to be measured has three-phase AC carrying wires 8, 9, and 10 armored by a "cage" of multiple metallic, non-current-carrying soft-magnetic wires 7 embedded in the outer section of the multi-core cable 6. The first sensor assembly I closes around the multi-core cable 6, partially or completely enclosing the multi-core cable 6 to be measured. Each end of the channel-defining structure 1 has one or more magnets 2 and 3 or (or an array of magnets). One end of the magnet(s) 2 is polarized with a north pole, with all north poles facing inward from the array, toward the multi-core cable 6 being measured. At the opposite end, all magnet(s) 3 (e.g., forming a magnetic array) are polarized with a south pole, with all poles also facing toward the multi-core cable 6 being measured. These magnets 2 and 3 are concentric with the multi-core cable 6 being measured and generate a magnetic field that extends from north pole to south pole along the multi-core cable 6 being measured (see also FIG. 3 , item 107), which in turn saturates the area of ​​the steel sheath 7 of the section of the multi-core cable 6 where the first sensor assembly I is located. The magnetic field can also be generated in part or in whole by an electromagnetic coil installed together with or in place of the permanent magnets 2, 3.

[0116] Mounted within the channel of the channel-defining structure 1, and positioned between both the magnetic arrays 2 and 3, is a magnetic field sensor array 4. The magnetic field sensor array consists of several magnetic field sensors 5 aligned on the same axis. The magnetic field sensors 5 are all oriented inward toward the armored multi-core cable 6 being measured, concentric with the multi-core cable 6, forming a ring of magnetic field sensors 5 around it. The first sensor assembly I uses solid-state or semiconductor-type sensors, such as Hall sensors or giant magnetoresistive sensors, mounted on a flexible printed circuit board or flexi-board in close proximity to the housing 1 (or "channel-defining structure"). The magnetic field sensors 5 are positioned relative to, adjacent to, or abutting the soft magnetic housing 1. The position of the magnetic field sensors 5 allows them to measure the magnetic field(s) generated by currents in the cores 8, 9, and 10 of the multi-core cable 6 in the region of the cable saturated by the magnets 2 and 3.

[0117] Processing of the signals from the magnetic field sensor 5 is performed by a processor (or controller) 12 which may be integrated with the first sensor assembly I or wired 11 individually to the first sensor assembly I. The processor takes the form of an electronics enclosure which includes the controller 12 which is electrically connected to the first sensor assembly I. The controller 12 processes the data to generate three different current signal outputs, one for each of the three discrete phases 13, 14, 15 of the multi-core cable 6 under test. An apparatus in the form of a first sensor assembly I may be used with two, three, four, five, six or more core cables. The number of outputs 13, 14, 15 may be arranged as appropriate.

[0118] The electronics unit 12 (or "controller") may also include one or more connectors 16 in the form of USB or similar for power, data, updates, and other utilities.

[0119] This first sensor assembly may also be used with non-steel multi-core cables, for example cables with a copper wire "sheath" that can also be used as a neutral or earth, or cables with no "sheath", i.e. just a conductive core within a plastic sheath.

[0120] FIG. 2 illustrates a second sensor assembly II, which is similar in design and operation to the first sensor assembly I described in connection with FIG. 1. The second sensor assembly II also includes one or more soft magnetic "channel-defining structure" sections 21 with a sensor array 25 having one or more magnetic field sensors 24 surrounding an armor strand 27 of a multi-core cable 26, the multi-core cable 26 having cores 28a, 28b, and 28c to be measured. In this case, instead of an array of magnets 2, 3, each end of the channel-defining structure 21 includes an axially magnetized ring magnet or ring magnet section 20 and 23. The magnets 20 and 23 are positioned at opposite ends of the channel-defining structure 21. The magnets 20 and 23 are oriented in the same direction, with their north poles oriented in the same direction along the axis of the multi-core cable 26 to be measured. Thus, the sides of the two magnets 20, 23 facing each other in the second sensor assembly II are magnetically opposite. These create a magnetic pole 22 extending from north to south pole, which in turn saturates the area of ​​the steel sheath 27 of the section of the armored multi-core cable 26 to be measured in which the second sensor assembly II is located.

[0121] Figure 3 shows a cross-sectional view of a third sensor assembly III, which is similar to the first sensor assembly I described in connection with Figure 1, with the channel-defining structures 102 and 103 including magnets 105, 110, 109, and 104, with magnetic poles oriented north 105, 110 (facing radially outward) and south 104, 109 (facing radially outward), generating magnetic fields 107, 108.

[0122] The third sensor assembly III differs in that it has semiconductor or solid-state magnetic sensors 106 and 111 mounted on a flexi or printed circuit board 112, and others mounted on a ring 101 (shown interspersed between 106 and 111 in FIG. 3 ) made from axially or radially stacked / wound laminated steel or other soft magnetic material. Ring 101 may alternatively be made from ferrite, pressed, sintered, or composite magnetic material. Ring 101 may be wide enough to accommodate magnetic sensors 106, 111 with individual components housing magnets or arrays 105, 110, 109, and 104 at each end of channel-defining structure 102, or ring 101 may be wide enough to form the entire channel, eliminating the need for channel-defining structures 102 and 103.

[0123] FIG. 4 illustrates a fourth sensor assembly IV similar to the first sensor assembly I described in connection with FIG. 1 , including a channel-defining structure 1 including magnets (or arrays of magnets) 49a, 49b with north- and south-oriented poles at opposite ends for generating a magnetic field in the armored multi-core cable 6 being measured. As detailed in FIG. 1 , processing of signals from the magnetic sensors 41, 42, 43, 44, 45, 46, 47, 48 is performed by a controller 50 that is either integrated with the fourth sensor assembly IV or individually wired to the fourth sensor assembly IV. The controller 50 may provide three different outputs 51, 52, and 53, one for each of the cores 8, 9, and 10 in the multi-core cable 6 being measured (not shown in FIG. 4 for clarity). The controller 50 may include one or more connectors in the form of a USB or the like 54 for power, data, updates, and other utilities.

[0124] The fourth sensor assembly IV differs from the first sensor assembly I in that it uses several magnetic sensors in the form of sensor coils 41, 42, 43, 44, 45, 46, 47 and 48 mounted in a ring tangential to the multi-core cable 6 to be measured. The sensor coils 41, 42, 43, 44, 45, 46, 47 and 48 are mounted between magnets (or arrays of magnets) 49a and 49b. The sensor coils 41, 42, 43, 44, 45, 46, 47 and 48 can be replaced by solid state magnetic field sensors in a sensor on flex / printed circuit board material.

[0125] FIG. 5 shows a fifth sensor assembly V similar to the third sensor assembly III shown in FIG. 3, but with the semiconductor-type sensor 111 on a flex / printed circuit board material 112 replaced with several sensor coils 62 mounted in a ring shape radially around the armored multi-core cable 6 to be measured (not shown in FIG. 5) and positioned between magnet arrays (e.g., as shown at 104, 105, 109, and 110 in FIG. 3). The sensor coils 62 are read using connections 63, which may be twisted wire pairs as shown or coaxial cables (or similar) to improve interference signal rejection. The sensor coils 62 may include pole pieces 61 made from a soft magnetic material or an air core, which may be mounted on a support such as a plastic bobbin. The sensor coils 62 may be mounted on a soft magnetic ring 60 made of radially laminated / wound laminated steel or ferrite magnetic material, pressed magnetic material, sintered magnetic material, or composite magnetic material. Alternatively, the fifth sensor array V may be mounted directly within the channels formed by the channel-defining structures of a similar sensor assembly (not shown) (as in FIG. 1).

[0126] FIG. 6 shows a sixth sensor assembly VI in the form of an electricity meter. While any version of the first through fifth sensor assemblies I through V described above may be used, one may be specifically configured as a polyphase electricity meter, particularly with the advantage of non-invasive installation. This can be achieved by combining magnetic sensor assembly data obtained from sensor assemblies 72 and 73 (provided, as shown, with half of first sensor assembly 72 and half of second sensor assembly 73 secured around the multi-core cable 79 being measured) with additional monitoring of phase voltages u, v, and w (indicated by indicators 71 in FIG. 6). This may include magnets and sensor assemblies 72 and 73 attached to the armored multi-core cable 79 being measured and connections 75 to a meter 74. Sensor assemblies 72 and 73 may be similar to (or the same as) any of the first through fifth sensor assemblies I through V described and shown in the previous figures (FIGS. 1 through 5) or variations using alternative sensors, magnets, and magnetic materials. The meter 74 includes a display for displaying measurements and other relevant information 82. Flying leads 81 allow voltage input from phases u, v, and w to the meter 74. The flying leads 81 include three wires 80, each connected to an exposed portion 76 of a respective core 77 extending into the housing 70. The armor strands 78 are stripped to allow connection of the flying leads 81. The voltage input from the phases u, v, and w can help correctly assign measured current from the armored multi-core cable 79 being measured to the correct core of the cable 79. The meter 74 may include one or more connectors in the form of a USB or the like 83 for power, data, updates, and other utilities.

[0127] 7 shows a seventh sensor assembly VII in the form of a power quality analyzer. The sensor assembly magnetic sensor 87 is attached to the armored multi-core cable 6 to be measured (not shown in FIG. 7) and may be used in combination with a power meter 91 as the power quality analyzer VII. Three flying leads 88, 89, and 90 are connected to the respective phases at the connection point to the load (e.g., exposed portion 76 shown in FIG. 6) and input the voltage of each phase (u, v, w) to the power quality analyzer VII.

[0128] This solution may be a lower cost and easier to install alternative to using a set of three Rogowski coils 84, 85, or 86 (shown for illustrative purposes, but not necessarily required when using sensor 87). Using Rogowski coils 84, 85, 86 would require that the armored multi-core cable 6 being measured have its three phases (e.g., cores 8, 9, 10) split from the armor (e.g., wire 7) and separated to provide sufficient space for each Rogowski coil 84, 85, 86, thus increasing component cost and installation complexity that could be avoided by using sensor assembly 87.

[0129] In a seventh variation of sensor assembly VII (not shown), the output of magnetic sensor assembly 87 can be split into three outputs that mimic the outputs of three current transformers or three Rogowski coils (similar to 84, 85, 86) applied to the individual cores 8, 9, 10 (when split from a multi-core cable). In this manner, these three outputs (not shown) of magnetic sensor assembly 87 can be connected to an existing power meter or power quality analyzer designed for inputs from three Rogowski coils (similar to 84, 85, 86) or three current transformers.

[0130] 8A and 8B show an eighth sensor assembly VIII. The eighth sensor assembly VIII is similar to the sensor assemblies I and V shown in FIGS. 1 and 5, but in more detail, instead of semiconductor magnetic sensors with printed circuit boards / flexi mounted between magnet arrays 117a and 117b, it shows several radial field coils 115 (magnetic sensors) attached to rings 114 made from axially or radially stacked / wound laminated steel. Rings 114 can alternatively be made from ferrite, pressed, sintered, or composite magnetic materials. Rings 114 may extend to the center of each radial field coil 115 to form pole pieces 116, or rings 114 may be flush with the rear ends of the coils 115 (i.e., tubular). In other words, coils 115 may have an air core and a ring of magnetic material 114 behind them. Alternatively, the radial field coils 115 may be attached to the channel-defining structure 113 without the addition of a magnetic material mounting ring.

[0131] 9A and 9B show a ninth sensor assembly IX. The ninth sensor assembly IX has several radial and tangential sensor coils 121 and 122 arranged in a ring around the multicore cable 6 to be measured (not shown in FIGS. 9A and 9B) and positioned between magnets 120a and 120b. The sensor coils 121, 122 and the magnet arrays 120a, 120b are supported by a channel-defining structure 118. The sensor coils are arranged in the same line as the tangential and radial coils 122 and 121, possibly alternating, or in any other pattern, such as two tangential coils and one radial coil, or vice versa. They may have air coils, as shown in FIG. 9A, with individual pole pieces (not shown), or may be integrated into a magnetic material ring 119 that is a combination of an air core (not shown) and integrated / separate magnetic poles (not shown) (the ring 119 having radially extending protrusions to provide the pole pieces / pole cores).

[0132] 10A and 10B show a tenth sensor assembly X. The tenth sensor assembly X is comprised of either magnet 128a or magnet 128b (or array), a sensor coil 124, and a soft magnetic material 127 similar to some configurations described in the previous assemblies, but adds one or two additional magnetic sensors 125, 126 (or arrays) on either side of the primary sensor array 124. These additional sensors 125 and / or 126 are used to detect the amount of physical twist in the multi-core cable 6 being measured (not shown in FIGS. 10A and 10B). If the cable being measured does not have a soft magnetic sheath or armor, the magnets 128a and 128b are not required. The ring of soft magnetic material 127 is axially sandwiched by a channel-defining structure 123, and the magnets 128a, 128b and the additional magnetic sensors 125, 126 are supported by the channel-defining structure 123. The magnetic sensor 124 is supported by (or is integrally formed with) a ring of soft magnetic material 127 .

[0133] 11 illustrates an eleventh sensor assembly XI. The eleventh sensor assembly XI is comprised of any of the magnets 131 a, 131 b and material configurations described herein, but includes a secondary (or second) sensor array 130 in addition to the primary (or first) sensor array 129. Many features may be similar to sensor assembly VIII, but in this case includes an additional ring of sensors 130. The use of two axially spaced rings of magnetic field sensors 129 and 130 is used to detect the amount of physical twist in the three phase wires (e.g., cores 8, 9, 10) in the armored multi-core cable 6 being measured, or in any multi-core cable, including unarmored multi-core cables.

[0134] 12A, 12B, and 12C show a twelfth sensor assembly XII. The twelfth sensor assembly XII consists of any of the magnets 132a, 132b, magnetic sensors 133, and soft magnetic material 137 configurations described herein, but the array of measurements (magnetic sensors 133) and magnets 132a, 132b forms an open or U-shape, or an equivalent shape that returns to itself without forming a closed loop. The open shape of the twelfth sensor assembly XII allows for insertion and measurement of a conductor (e.g., a multi-core cable 6) when an armored or unarmored multi-core cable 135 to be measured is attached against or adjacent to the flat surface 134. This can take the form of a handheld device 136 for rapid deployment applications or a permanent or semi-permanent device.

[0135] 13A, 13B, and 13C show a thirteenth sensor assembly XIII. The thirteenth sensor assembly XIII is comprised of magnets 138a, 138b (or array), a magnetic sensor 139, and any of the configurations of soft magnetic material (channel-defining structures) 140 described herein, but in the form of a clamp-on device for quick attachment and easy transfer from one armored or unarmored multi-core cable 141 to be measured to another. The thirteenth sensor assembly XIII includes two channel-defining structures 142, 143 with magnets 138a, 138b and magnetic sensor 139 mounted in double-handled “spring clamp” housings 145, 146, with one or more springs 144, compression, torsion, or any other suitable type, arranged to hold the sensor arrays (i.e., channel-defining structures 142, 143) closed when not opened by squeezing the handles 145, 146 together. The one or more springs 144 may supplement, substitute for, or be used in addition to, catches (not shown) at the open ends of the sensors (i.e., channel-defining structures 142, 143) to ensure that the thirteenth sensor assembly XIII is fully closed when in use.

[0136] Figures 14A, 14B, and 14C show a fourteenth sensor assembly XIV. The fourteenth sensor assembly XIV uses the same technology detailed for the first sensor assembly I shown in Figure 1, but is comprised of a pair of magnets 150, 151 (or, alternatively, a single magnet and a member made of a flexible material) attached to a soft magnetic substrate piece 147 (or "structure") and one or more magnetic sensors 152. The fourteenth sensor assembly XIV can be comprised of any of the magnet / sensor / material configurations described herein, but could also be in the form of a simplified single sensor / coil / magnet configuration for a low-cost, easy-to-install variation, or temporarily fixed or pressed against the armored multi-core cable 149 to be measured.

[0137] The fourteenth sensor assembly XIV may be connected by wiring 148 for connection to sensing, monitoring, data logging, or other equipment and / or may include some or all of the data processing electronics, either built-in or remote wired / wireless.

[0138] 15A, 15B, 15C, 15D, and 15E show a fifteenth sensor assembly XV. The fifteenth sensor array XV is made from individual simplified sensors 153 similar to or described in the fourteenth sensor assembly XIV shown in FIGS. 14A through 14C, but the individual simplified sensors 153 (e.g., the fourteenth sensor assembly XIV) are connected to the flexible assembly using integrated or individual hinges, clips, or other flexible joining elements 155 to provide more coverage around the armored multi-core cable 154 to be measured, thereby providing monitoring performance closer to the first sensor assembly I and variations shown in FIG. 1. Each simplified sensor 153 includes magnets 157, 158 and a magnetic sensor 159. The fifteenth sensor assembly XV (or array) can be spring-loaded to facilitate rapid installation and can have a stop that naturally springs closed to form a circle 156 to facilitate minimizing errors due to misalignment.

[0139] To optimize the internal diameter (ID) of the sensor, some sensor modules 153 (simple sensors) can be added or removed as required.

[0140] Similar to the fourteenth sensor assembly XIV detailed in Figure 14, each sensor can be hardwired for connection to sensing, monitoring, data logging, or other equipment (item 148 in Figure 14B) and / or can include some or all data processing electronics, either on-board or remote, wired or wireless. Alternatively, the individual sensor outputs can be combined into a single electronics housing (item 12 in Figure 1) to process data from all sensors 153 in the fifteenth sensor array XV.

[0141] In variations (not shown), the fifteenth sensor assembly XV (or array) can include more or fewer than the six simple sensors 153 illustrated in FIGS. 15A through 15E . Furthermore, a modified fifteenth sensor assembly XV (or array) can be configured to use only additional or fewer segments, and can use as many simple sensors 153 as needed to wrap around a given multi-core cable 154. In some implementations of such a modified fifteenth sensor assembly XV (or array), an operator can specify the number of simple sensors 153 to use, for example, by providing an input to a controller (not shown) or by activating a switch or similar element on each individual simple sensor 153. Additionally or alternatively, the controller (not shown) can automatically determine the number of active simple sensors 153, for example, by analyzing the signals received from each simple sensor. Inactive (or excess) simple sensors 153 can continue to be wrapped around the cable 154 or can be left hanging away and ignored. The relative angle of each simple sensor 153 is easily derived from the number of active sensors.

[0142] In a further variation, the simple sensors 153 may be connectable / disconnectable to one another, for example, using clips, connectors, etc. for mechanical and / or electrical connections between the simple sensors 153. In this way, an operator can easily add or remove simple sensors 153 to obtain the appropriate size. The number of simple sensors 153 connected together can be automatically detected, in a particularly simple example, by adding additional connections with resistors in series with each simple sensor 153, and the total resistance value can be used to automatically determine the number of simple sensors 153 in use. The relative angle of each simple sensor 153 is easily derived from the number of active sensors.

[0143] 16A, 16B, and 16C show a sixteenth sensor assembly XVI. The sixteenth sensor assembly XVI is a simplified, low-cost version of the first sensor assembly I shown in FIG. 1 and / or other variations described above. The sixteenth sensor assembly XVI is a one-piece sensor consisting of a cylindrical body 161 (channel-defining structure) made of a soft magnetic material with an electromagnetic coil wound around the outside of magnetic poles 162, and an array of magnetic sensors 163 forming a ring. The magnetic sensors 163 can be radial coils (as shown) or tangential coils or semiconductor or solid-state types, and can be attached to a separate soft magnetic ring (see reference numeral 101 in FIG. 3) or directly to the cylindrical body 161, with or without individual magnetic poles, or with or without extensions from the ring or cylindrical body 161 forming the magnetic poles. The armored or unarmored multi-core cable 160 to be measured is designed to be screwed in as a single unit. The electronics may be integrated with or separate from the sixteenth sensor assembly XVI, which may include an additional magnet (not shown) if armored cables are to be evaluated.

[0144] Figures 17A, 17B, and 17C show a seventeenth sensor assembly, XVII. Similar in operation to sensor assemblies I, II, and VIII detailed in Figures 1, 2, and 8, this assembly uses an offset electromagnetic coil 165 to provide a magnetic field that saturates or substantially saturates the steel armor of the armored multi-core cable 170 being measured. The magnetic field is induced around the armored multi-core cable being measured by a soft magnetic armature 167 to which the electromagnetic coil 165 is axially attached (or directly wrapped). The armature 167 extends toward and loops around the armored multi-core cable 170 being measured on both sides of the sensor array, and is housed in a hinged 168 and / or clip-on 169 housing to fit around the armored multi-core cable 170 being measured.

[0145] The magnetic sensor can be of any of the types described, such as the axial or tangential coil 166 shown, or of the semiconductor type, with or without a magnetic backing, and with or without a pole piece.

[0146] 18A, 18B, and 18C illustrate an eighteenth sensor assembly XVIII. The eighteenth sensor assembly XVIII is a simplified sensor similar to the fourteenth sensor assembly XIV detailed in connection with FIGS. 14A-14C, but is comprised of a single magnet or magnetic field source 174 and a magnetic sensor 175. The eighteenth sensor assembly XVIII can be configured with any of the magnet / sensor / material configurations described herein, but in this example, a permanent magnet and sensor coil on a soft magnetic backing plate / mount 173 (or "structure") is used. The eighteenth sensor assembly XVIII can be pressed against, held, or coupled to the armored or unarmored multi-core cable 171 to be measured (e.g., if the multi-core 171 is armored with steel, it can be held in place by a magnet or magnetic field 174).

[0147] This low-cost variation (eighteenth sensor assembly XVIII) may be connected to sensing, monitoring, data logging, or other equipment by a wired connection 172 and / or may include some or all of the data processing electronics, either built-in or remote wired / wireless.

[0148] The linearity of the sensor assembly described herein was evaluated with reference to Figures 19 and 20. An example of the eighth sensor assembly VIII was applied to a 30 mm diameter, three-core, steel-wire-sheathed multi-core cable. The inner diameter of the channel of the eighth sensor assembly VIII was 42 mm. Figure 19 shows the current measured for each of the three cores (solid, dashed, and chain lines) using the example of the eighth sensor assembly VIII. The dotted line shows the current measured using a conventional current clamp applied directly to a second core separated from the multi-core cable and steel wire sheath at a point offset from the example of the eighth sensor assembly VIII. Despite the presence of the steel wire sheath, a very accurate match can be observed.

[0149] The current range of the eighth sensor assembly VIII used was from about 40 mA to 500 A. The eighth sensor assembly VIII was tested from 25 mA to 80 A, and the measured % error is plotted in FIG.

[0150] Referring also to Figures 21 and 22, similar data to Figure 20 are shown for signals with higher harmonic content. Specifically, a square wave was applied to Core 1, and a triangular wave was applied to Cores 2 and 3. All waveforms contained components up to the 11th harmonic. The solid, dashed, and chain lines represent the first, second, and third core currents measured using the eighth example of Sensor Assembly VIII. In Figure 21, the dotted line represents measurements obtained using a conventional current clamp probe applied to Core 2 when separated from the multi-core cable and steel wire armor at an offset from the eighth example of Sensor Assembly VIII. Figure 22 is the same, except that the conventional current clamp probe was applied to Core 1 instead of Core 2. In both Figures 21 and 22, good agreement is obtained between the eighth example of Sensor Assembly VIII and conventional measurements (which required physical disassembly of the multi-core cable components), even through the steel wire armor.

[0151] Referring also to Figure 23, data similar to Figures 20, 21, and 22 are shown for a three-phase current with a fundamental sine wave of amplitude 20 A superimposed on the 31st harmonic of amplitude 2 A. In this case, the dotted line representing the conventional current clamp measurement was obtained from core 2. Even for the 31st harmonic, good agreement was obtained with the conventional measurement method (which has the disadvantage of requiring physical disassembly of the multi-core cable) using the eighth sensor assembly VIII as an example.

[0152] 24A and 24B illustrate a nineteenth sensor assembly XIX. The nineteenth sensor assembly XIX is identical to the ninth sensor assembly IX, except that the ring of magnetic material 119b and the tangential sensor coil 122b are reconfigured in a manner that may improve efficiency. In particular, the tangential sensor coils 122 of the ninth sensor assembly IX are positioned entirely within the inner radius of the channel-defining structure 118. To accommodate this, the ring of magnetic material 119 of the ninth sensor assembly IX includes a "twist" corresponding to each of the tangential sensor coils 122, in which the ring 119 turns radially inward to pass through the windings of the tangential sensor coils 122. This may be disadvantageous with respect to the turning of the magnetic flux path within the ring 119. In comparison, in the nineteenth sensor assembly XIX, the ring of magnetic material 119b has a simpler shape without a "twist." The tangential sensor coil 122b is wound partially around the ring 119b, with the coil being positioned partially inside and partially outside the channel-defining structure 118. In this way, the tangential magnetic flux can follow an uninterrupted circular path around the ring 119b. The radial sensor coil 121 remains wound on the radially inner protrusion of the ring 119b, as in the ninth sensor assembly IX, and may be wound directly on the protrusion or on a bobbin received over the protrusion.

[0153] 25A and 25B illustrate a twentieth sensor assembly XX. The twentieth sensor assembly XX is similar to the first through third sensor assemblies I, II, and III, except that the twentieth sensor assembly XX is formed to be substantially more compact along the length of the multi-core cable, which may be an armored or unarmored multi-core cable 160. The twentieth sensor assembly XX includes a first channel-defining structure 180 and a second channel-defining structure 181 coupled to one another around the armored or unarmored multi-core cable 160. The first channel-defining structure 180 and the second channel-defining structure 181 may, but need not, be formed of a magnetic material (e.g., magnetic steel). The inner surfaces of the channel-defining structures 180 and 181 support a solid-state magnetic sensor 182, either directly or via a flex or printed circuit board. Both longitudinal ends of the channel-defining structures 180, 181 include respective lips 183a, 183b, 184a, 184b that extend radially inward a distance at least equal to the height of the solid-state magnetic sensors 182. The twentieth sensor assembly XX is shown with six solid-state magnetic sensors 182 spaced circumferentially at 60 degree intervals to form a hexagonal arrangement, although more or fewer solid-state magnetic sensors 182 may be used and / or the angular spacing may be different or irregular.

[0154] The twentieth sensor assembly XX can be used with an unarmored multi-core cable 160 as shown. When used with an armored multi-core cable 6, a magnet (not shown in FIGS. 25A and 25B) must be added. This can be discrete or annular and can be received on the inner surface of the channel-defining structures 180, 181 and / or lips 183a, 183b, 184a, 184b. In some embodiments, the lips 183a, 183b, 184a, 184b can be formed using a ring-shaped magnet.

[0155] 26A through 30C, a twenty-first sensor assembly XXI is shown. The twenty-first sensor assembly XXI is similar to the eighth sensor assembly VIII, with components specifically designed for compact, efficient, and cost-effective manufacturing.

[0156] Figures 26A-26D show the assembled twenty-first sensor assembly XXI. Figures 27A-27C show a bobbin arrangement 185 with a semicircular support 186 from which three bobbins 187 extend radially inward. Preferably, the bobbins 187 are integrally formed with the semicircular support 186 using injection-molded plastic. Alternatively, the bobbins 187 may be formed separately and attached to the semicircular support 186. The bobbins 187 are spaced 60 degrees apart around the semicircular support 186 (approximately 30 degrees apart on either end). Each half of the twenty-first sensor assembly XXI includes a bobbin arrangement 185, which together form a ring around the multi-core cable 6, 160. A radial sensor coil 188 is wound around each bobbin 187. For example, each radial sensor coil 189 is formed from 300 turns of 0.25 mm diameter enameled copper wire. Although shown as air coils in Figures 26A-26D, in some embodiments, a magnetic core material may be inserted into the through-hole of each bobbin 187 (either before or after winding the sensor coil 188).

[0157] The bobbin arrangement 185, on which the windings of the sensor coil 188 are formed, is received in a first outer core 189a and a second outer core 189b (shown separately in Figures 29A-29C). Each outer core 189a, 189b is a semi-cylinder of magnetic material suitable for current transformers, such as wound magnetic steel tape. The first outer core 189a and the second outer core 189b are preferably formed by splitting a wound magnetic steel tape cylinder in half. A pair of magnets 190a, 190b is also received in each outer core half 189a, 189b. A single magnet 190 is shown in Figures 28A-28C. The magnets 190a, 190b may be, for example, grade C5 magnetized ferrite, as used in speakers. The magnets 190a, 190b may be magnetized to provide a magnetic field substantially along the longitudinal axis, as in the second sensor assembly II, or may have opposite radial polarities, as in the first sensor assembly I. Each outer core 189a, 189b is terminated at both ends with identical end caps 191, formed, for example, using magnetic steel (or other material suitable for current transformer cores). Each end cap 190 has a semicircular shape, with the diameter of the semicircular cutout defining the maximum size of the multi-core cable 6, 160 that can be accommodated.

[0158] The two halves of the twenty-first sensor assembly XXI are positioned together around the multi-core cable 6, 160 and secured to one another. For example, the two halves may be hinged on one side and provided with a latch or similar securing mechanism on the other side.

[0159] When intended for use with armored multi-core cables, magnets 190a, 190b may be omitted.

[0160] 31A and 31B, a twenty-second sensor assembly XXII is shown. The twenty-second sensor assembly XXII is the same as the fourth sensor assembly IV, except that a specific design of tangential sensor coils 41b-48b is shown instead of the generally cylindrical sensor coils 41-48 shown in FIG. 4. The tangential sensor coils 41b-48b are wound on respective bobbins and supported within the channel-defining structure 1. The tangential sensor coils 41b-48b may be air-core or may have magnetic material inserted into the coils before or after winding. The specific shape shown for the tangential sensor coils 41b-48b, being radially flattened and elongated along the longitudinal axis (rounded rectangle), can help increase the total area of ​​the sensor coils 41b-48b without reducing the diameter of the cable 6 that can be accommodated (compared to a cylindrical sensor coil).

[0161] When intended for use with armored multi-core cables, magnets 49a, 49b may be omitted.

[0162] Whether the channel is designed to close around the multi-core cable or remains open, the first through twentieth sensor assemblies I through XXII are illustrated as defining a circular channel (or a portion of a channel). However, the present invention is not limited to sensor assemblies having a circular (or a portion of a circle) cross-section (perpendicular to the longitudinal axis of the received multi-core cable).

[0163] 32A-32D, a twenty-third sensor assembly XXIII is shown. The twenty-third sensor assembly XXIII is similar to the twentieth sensor assembly XX, except that the lips 183, 184 are omitted, a tangential sensor coil 192 is used instead of the solid-state magnetic field sensor 182, and the first and second channel-defining structures 180b, 181b are not semicircular. Instead, each channel-defining structure 180b, 181b defines a half-oval (or "egg shape") in cross-section (or end view).

[0164] 33A-33D, a twenty-fourth sensor assembly XXIV is shown. The twenty-fourth sensor assembly XXVI is identical to the twenty-third sensor assembly XXIII, except that a solid-state magnetic field sensor 182 is used instead of the tangential sensor coil 192. The twenty-fourth sensor assembly XXVI can alternatively be considered to be the same as the twentieth sensor assembly XX, except that the lips 183, 184 are omitted and a first semi-ovular channel-defining structure 180b and a second semi-ovular channel-defining structure 181b are used.

[0165] In a similar manner, any of the first sensor assembly I through the twentieth sensor assembly XXII can be modified to have a non-circular shape in cross section (or end view).

[0166] Sensor assembly incorporating a current transformer When measurements are made from multi-core cables, whether armored or unarmored, the net current flowing through the multi-core cable can saturate the magnetic field sensor and / or components of any channel-defining structure(s) containing magnetically permeable material.

[0167] As will be discussed later, such problems can be reduced (or even avoided) by installing sensors on current transformers (CTs) with an internal opening large enough to accommodate the multi-core cable (armored or unarmored) and with a current rating appropriate for the net or zero-sequence currents expected in the multi-core cable.

[0168] 34A-34E, a twenty-fifth sensor assembly XXV is shown. The twenty-fifth sensor assembly XXV is similar to the eighth sensor assembly VIII, except that instead of having a separate ring 114 and channel-defining structure 113, the twenty-fifth sensor assembly XXV has a channel-defining structure 193 in the form of a single piece (or preferably two half pieces) of magnetically permeable material that also provides a core for the winding of a current transformer coil 194. The current transformer coil 194 is provided in the form of eight sub-windings 194a-194h that are connected together and arranged in series with a burden resistor 195.

[0169] The core 193 of the current transformer coil 194 includes a radially inwardly extending protrusion 196 on which the radial sensor coil 115 is wound or received (e.g., pre-wound on a plastic bobbin). The core 193 of the current transformer coil 194 is preferably made of a material suitable for current transformers, such as magnetic steel.

[0170] Magnets 117a, 117b may be included if it is desired to measure armored or unarmored multi-core cables, although magnets 117a, 117b may be omitted if sensor assembly XXV is intended for use only with unarmored multi-core cables. When magnets 117a, 117b are included (as shown in FIGS. 34A-34E), core 193 of current transformer coil 194 may also include end or "lip" projections 197a, 197b at both ends along the longitudinal axis that coincide with magnets 117a, 117b. End projections 197a, 197b serve to connect the return flux path between magnets 117a and 117b.

[0171] The twenty-fifth sensor assembly XXV may be formed in two halves to provide a clamp-on sensor, or may be of the thread-through type (ie, a multi-core cable threaded through the current transformer coil 194).

[0172] The radial magnetic field entering the core 193 of the current transformer coil 194 is measured by the radial sensor coil 115. A solid-state magnetic field sensor and / or a tangential sensor coil may be used in addition to or instead of the radial sensor coil 115. The magnetic field sensor, whether a radial / tangential sensor coil, a solid-state magnetic field sensor, or other magnetic field sensor suitable for sensing dipole moments generated by unbalanced currents (or symmetrical or antisymmetrical currents) in a multi-core cable, may be disposed between the core of the current transformer coil and the multi-core cable, or the core 193 of the current transformer coil 194 may be positioned so that the core of the current transformer coil is between the magnetic field sensor and the multi-core cable. Preferably, the magnetic field sensor (such as the illustrated radial sensor coil 115 or equivalent) is disposed at least partially within the core 193 to provide shielding from external magnetic fields, as described below. However, whether the magnetic field sensor is positioned between the core of the current transformer coil and the multi-core cable, or whether the core of the current transformer coil is positioned between the magnetic field sensor and the multi-core cable, other effects can be obtained, such as preventing the core 193 of the current transformer coil from being saturated by the net current of the multi-core cable.

[0173] The current transformer coil 194 and core 193 provide four functions:

[0174] 1) Measurement of the net current, or common mode current, or zero sequence current in a cable (from the voltage across the burden resistor).

[0175] 2) Partial magnetic shielding of the dipole-sensing magnetic sensor (radial sensor coil 115 as shown) by the current transformer core 193 from magnetic fields due to cable currents (or other magnetic field sources) that do not pass through the sensor. The degree of shielding is largely determined by the aspect ratio of the core 193. A long core 193 (relative to its inner diameter) can be expected to provide more effective shielding than a short core 193 with a large inner diameter.

[0176] 3) The current transformer core 193 improves the sensitivity of the dipole-sensing magnetic sensor (radial sensor coil 115 as shown) by providing a low reluctance magnetic flux path for the outer portion of the dipole-field-sensing magnetic circuit.

[0177] 4) Preventing core 193 from being saturated by the net current of the multi-core cable.

[0178] It is important to note that the use of the current transformer coil 194 for functions 2) and 3) is preferable over a simple tube of magnetically permeable material (e.g., a core 23 without a secondary winding 194). This is because the windings of the current transformer coil 194, combined with its approximate short circuit provided by the burden resistor 195, provide a balancing current to the net current in the multi-core cable. This prevents the net current in the multi-core cable from saturating the core 193 (function 4), which could otherwise easily occur with the high-permeability core 193 required for most effective shielding from external magnetic fields. This results in the core 193 heating up, causing voltage steps in the net current in the multi-core cable as the core 193 saturates, modulating the sensitivity of the dipole-field-sensing magnetic sensor (radial sensor coil 115 as shown), and inducing interference in the dipole-sensing magnetic sensor (radial sensor coil 115 as shown) due to different portions of the core 193 saturating at different times.

[0179] The level of shielding provided by a long core 193 is roughly the permeability of the core 193 times the thickness / diameter of the core 193. For example, this can result in a 1000-fold improvement for a core 193 that is 10 mm thick, has an outer diameter of 100 mm (and therefore an inner diameter of 80 mm), and has a relative permeability of 10,000. Such a large core 193 will saturate at a net current of 50 A through the sensor (2 Tesla). For shorter, high-permeability cores 193, the shielding improvement is limited by the geometry (related to length / inner diameter).

[0180] Although the twenty-fifth sensor assembly XXV is illustrated using radial sensing coils 115, these may be replaced with any other magnetic field sensors suitable for sensing dipole components, such as, for example, tangential sensor coils and / or solid-state magnetic field sensors described herein, or combinations thereof.

[0181] Magnets 117a, 117b may be omitted if measurements from armored multi-core cable 6 are not required. If magnets 117a, 117b are omitted, protrusions 197a, 197b may be omitted or may be retained to help define an opening / channel for receiving the multi-core cable.

[0182] Except where expressly incompatible, any feature, modification and / or application of the first sensor assembly I through the twenty-fourth sensor assembly XXIV is equally applicable to the twenty-fifth sensor assembly XXV.

[0183] Any of the first through twenty-fourth sensor assemblies I through XXIV described herein above can be modified to include a current transformer coil 24, for example, by replacing the respective channel-defining structures with appropriately shaped cores and then adding windings of the current transformer coil 24. The degree of shielding obtained depends on the aspect ratio (length to diameter), as explained, and can be improved by changing this aspect ratio. When modified to include the current transformer coil 24 in this manner, the included magnet can be omitted in any of the first through twenty-fourth sensor assemblies XIV if measurements of armored multi-core cables are not required. Such modified first through twenty-fourth sensor assemblies I through XXIV can still obtain, to varying degrees, the advantages / functions 1), 2), and 3) described in connection with the twenty-fifth sensor assembly XXV.

[0184] 35A and 35B, a twenty-sixth sensor assembly XXVI is shown, which is the same as the twenty-fifth sensor assembly XXV, except that the core 23 does not include the protrusion 196 and the radial sensor coil 115 is air-core.

[0185] If the end projections 197a, 197b are also omitted, the twenty-sixth sensor assembly XXVI can be manufactured in a particularly simple manner, as will be explained also with reference to Figures 36A to 36C.

[0186] 35A shows a bobbin assembly 198 for forming the sensor coil 115 and the current transformer coil 194 of the 26th sensor assembly XXVI. The bobbin assembly 198 includes a first tangential bobbin 199 sandwiched between a second radial bobbin 200. The radial bobbins 200 extend perpendicular to (and are integrally formed with) a support plate 201. The tangential bobbins 199 and the support plate 201 are connected by a thin, flexible joint 202. Each tangential bobbin 199 includes a respective rectangular through-hole 203, and each radial bobbin 200 includes a respective rectangular through-hole 204.

[0187] The radial sensor coil 115 is fabricated on a radial bobbin 200 (shown in FIG. 36A) with the pair of first and second bobbin assemblies 198 in a flat state. Four sub-windings 194a to 194d of the current transformer coil 194 are fabricated on the tangential bobbin 199 of the first bobbin assembly 198, and the remaining sub-windings 194e to 194h are fabricated on the tangential bobbin 199 of the second bobbin assembly 198.

[0188] 36B , each of the first and second bobbin assemblies 198 is curved as shown by bending the flexible joints 202, and the semi-cylindrical core portion 205 is inserted into the through-hole 203 of the tangential bobbin 199. Once this is done for both halves, magnets 117a, 117b are added, along with any end caps (not shown), as needed, and the halves are assembled to complete the 26th sensor assembly XXVI (e.g., the halves may be hinged on one side and lockable on the other side with a latch or equivalent mechanism(s)).

[0189] If it is desired that the sensing coil 115 have a magnetically permeable core, a suitably shaped piece of magnetically permeable material can be inserted into the radial bobbin through-hole 204 either before or after winding the radial sensor coil 115.

[0190] The bobbin assembly 198 can be modified to accommodate a solid state magnetic field sensor that can be attached directly to the support plate 201 or via a flexi / printed circuit board before bending the bobbin assembly 198 and inserting the semi-cylindrical core portion 205. Similarly, the orientation of the second bobbin 200 can be changed from radial to tangential (or vice versa) to allow other magnetic field sensor configurations to be formed.

[0191] 37A and 37B, a 27th sensor assembly XXVI is shown. The 27th sensor assembly XXVII includes an annular current transformer core 206 wound with a continuous helical current transformer coil 207. Ends 208 of the current transformer coil are connected via burden resistors (not shown in FIGS. 36A and 36B) to form a current transformer. Twelve (or a variable number of) solid-state magnetic field sensors 209 are supported on a substrate 210, such as a flex / printed circuit board, positioned exactly on the inner diameter of the current transformer coil 207.

[0192] The 27th sensor assembly XXVII functions in a similar manner as already described in connection with the 25th sensor assembly XXV and / or the 26th sensor assembly XXVI, except that the 27th sensor assembly XXVII has a shorter length parallel to the longitudinal direction for receiving the multi-core cable, resulting in relatively reduced shielding.

[0193] To use an armored multi-core cable, a magnet can be added to the twenty-seventh sensor assembly XXVII.

[0194] 38A and 38B, a twenty-eighth sensor assembly XXVI is shown. The twenty-eighth sensor assembly XXVIII is the same as the twenty-seventh sensor assembly XXVII, except that the substrate 210 is supported on the inner diameter of the annular core 206, and the solid-state magnetic field sensor 209 is housed within the coils of the continuous helical current transformer coil 207.

[0195] To use an armored multi-core cable, a magnet can be added to the twenty-eighth sensor assembly XXVIII.

[0196] Furthermore, the cross-sectional / end shape of the sensor assembly including the current transformer is not limited to a circular shape. For example, referring to Figures 39A to 39D, a 29th sensor assembly XXIX is shown.

[0197] The twenty-ninth sensor assembly XXIX is similar to the twenty-fourth sensor assembly XXIV, but adds current transformer coil sub-windings 211 associated with the first channel-defining structure 180b and the second channel-defining structure 181b, which are also formed of a magnetically permeable material and form cores for current transformer coils realized by connecting the current transformer coil sub-windings 211 together. The current transformer coil sub-windings 211 are also connected in series with a burden resistor (not shown) to form a current transformer. The first channel-defining structure 180b and the second channel-defining structure 181b are hinged on one side to accommodate a multi-core cable through the current transformer coil formed by connecting the sub-windings 211, and the opposite side is closed, preferably secured by, for example, a latch or equivalent mechanism. Alternatively, a spring or similar biasing means may be included to bias the unhinged ends of the first channel-defining structure 180b and the second channel-defining structure 181b together.

[0198] To use an armored multi-core cable, a magnet can be added to the twenty-ninth sensor assembly XXIX.

[0199] 40A and 40B, a thirtieth sensor assembly XXX is shown. The thirtieth sensor assembly XXX includes a Rogowski coil 212 and several magnetic field sensors 213. For purposes of illustration in FIGS. 40A and 40B, the magnetic field sensors 213 are shown as radial sensor coils with air cores, but any type of magnetic sensor described herein may be used, including, but not limited to, solid-state magnetic field sensors. These include radial sensor coils (with air cores or cores of magnetically permeable material), tangential sensor coils (with air cores or cores of magnetically permeable material), and the like.

[0200] The Rogowski coil 212 and several magnetic field sensors 213 are supported by a channel-defining structure, which is not shown in Figures 40A and 40B but can be configured as described in connection with the sensor assembly earlier in this specification.

[0201] The thirtieth sensor assembly XXX is configured such that when the device is coupled to a multi-core cable 214 (e.g., three cores as shown), a region of the multi-core cable 214 passes through the Rogowski coil 212. At least one of the magnetic field sensors 213 is positioned adjacent to the Rogowski coil and oriented to detect components of the magnetic field emanating from the region of the multi-core cable 214. Preferably, the magnetic field sensor 213 surrounds the multi-core cable 214 and enables sensing of dipole magnetic fields and measurement of derived quantities, as previously described herein in connection with the first through twenty-ninth sensor assemblies I through XXIX. The Rogowski coil 212 is used to measure net current.

[0202] Alternatively, in some examples, the Rogowski coil 212 may be flexible (so that it can be wrapped around a region of the multi-core cable 214), in which case the Rogowski coil 212 and magnetic field sensor 213 may be supported by a flexible or bonded structure.

[0203] The placement of the Rogowski coil 212 and the magnetic field sensor 213 in close proximity to one another allows measurements to be directly compared. For example, the net current measurement from the Rogowski coil 212 can be used as a check on the individual core currents inferred using the magnetic field sensor 213.

[0204] 40A and 40B, the magnetic field sensor 213 may be positioned adjacent to the Rogowski coil 212 along the axial direction of the multi-core cable 214 (in use). For example, at least one of the one or more magnetic field sensors 213 may be positioned inside or at least partially inside the Rogowski coil 212, i.e., between the Rogowski coil 212 and the multi-core cable 214 (in use). Alternatively, at least one of the one or more magnetic field sensors may be positioned outside the Rogowski coil 212, i.e., separated from the multi-core cable 214 by the Rogowski coil 212.

[0205] The illustrated multi-conductor cable 214 is not armored, but a magnet can be added to the thirtieth sensor assembly XXX for use with armored multi-conductor cables.

[0206] Modification It will be understood that the above-described embodiments may be modified in various ways, including by incorporating equivalent and other features already known in the design, manufacture, and use of electrical power test and measurement equipment and / or its component parts, which may be used instead of or in addition to features already described herein. Features of one embodiment may be replaced or supplemented by features of another embodiment.

[0207] Although the claims in this application have been set forth in terms of particular combinations of features, it will be understood that the scope of the present disclosure also includes any novel feature or any novel combination of features or any generalization thereof disclosed herein, either explicitly or implicitly, whether or not they relate to the same invention as presently claimed in any claim, and whether or not they alleviate any or all of the same technical problems that the present invention alleviates. Applicants are hereby notified that they may formulate new claims to such features and / or combinations of features during the prosecution of this application or any further application derived therefrom.

Claims

1. 1. A device for coupling to a multi-core steel wire armored cable, comprising: one or more magnets; one or more magnetic field sensors; The device, when coupled to a multi-core steel wire armored cable, a magnetic field corresponding to the one or more magnets is applied to a region of the multi-core steel wire armored cable; The apparatus, wherein each magnetic field sensor is oriented to detect a component of a magnetic field emanating from the region of the multi-core steel wire armored cable.

2. The apparatus of claim 1 , wherein at least one of the one or more magnets comprises a permanent magnet.

3. The apparatus of claim 1 or 2, wherein at least one of the one or more magnets comprises an electromagnet.

4. The apparatus of any one of claims 1 to 3, wherein at least one of the one or more magnetic field sensors comprises a coil.

5. The apparatus of any one of claims 1 to 4, wherein at least one of the one or more magnetic field sensors comprises a solid state magnetic field sensor device.

6. The apparatus of any one of claims 1 to 5, wherein the magnetic field corresponding to the one or more magnets has a magnitude of at least 5 mT in the region.

7. The apparatus of any one of claims 1 to 6, wherein the magnetic field corresponding to the one or more magnets is configured to be time-varying.

8. The apparatus of any one of claims 1 to 6, configured so that the magnetic field corresponding to the one or more magnets is constant.

9. 9. The apparatus of claim 1, wherein the apparatus is configured to mechanically couple to the multi-core steel wire armored cable using magnetic forces resulting from applying the magnetic field to the steel wire armor.

10. An apparatus according to any preceding claim, comprising a structure supporting the one or more magnets and the one or more magnetic field sensors.

11. The apparatus of claim 10 , wherein the structure comprises a channel configured to receive the multi-core steel wire armored cable.

12. The device of claim 11 , wherein the cross section of the channel has a circular or arc shape.

13. The apparatus of claim 12 , wherein the cross section of the channel is non-circular and has a shape that does not correspond to an arc of a circle.

14. The device according to any one of claims 11 to 13, wherein the channel is open.

15. 14. The apparatus of any one of claims 11 to 13, wherein the channel is defined by first and second parts of the structure and is configured to close around the multi-core steel wire armored cable when received within the channel.

16. 14. The apparatus of any one of claims 11 to 13, wherein the structure includes two or more parts configured to close or wrap around the multi-core steel wire armored cable to define the channel.

17. 17. The apparatus of any one of claims 1 to 16, further comprising a net current sensor configured to measure a net current through the multi-core steel wire armored cable when the apparatus is coupled to the multi-core steel wire armored cable.

18. 18. The apparatus of any preceding claim, wherein at least one of the one or more magnetic field sensors comprises a coil, each coil being wound around a magnetic pole sensing piece.

19. 19. The apparatus of any preceding claim, wherein at least one of the one or more magnets comprises an electromagnet, each electromagnet wrapped around a pole piece.

20. An apparatus according to any preceding claim, comprising two or more magnetic field sensors.

21. the one or more magnetic field sensors include a first set of first magnetic field sensors and a second set of second magnetic field sensors; 21. The apparatus of claim 1, wherein the first and second sets are spaced apart along an axial direction of the multi-core steel wire armored cable when the multi-core steel wire armored cable is coupled to the apparatus.

22. A device according to any one of claims 1 to 21; a controller connected to the one or more magnetic field sensors and configured to calculate one or more derived quantities based on magnetic field components measured by the magnetic field sensors for some or all of the cores of a multi-core steel wire armored cable.

23. 22. The apparatus of claim 1, further configured to generate one or more signals based on the output of the one or more magnetic field sensors, each signal being proportional to a differential current between cores of the multi-core steel wire armored cable when the multi-core steel wire armored cable is coupled to the apparatus; and and a link corresponding to each signal for connection to a control system and / or a measurement system.

24. 24. The sensor of claim 22 or 23, further comprising one or more voltage sensors, and wherein the one or more derived quantities include one or more power values.

25. A system comprising a sensor according to any one of claims 22 to 24 coupled to provide an input to a measurement device.

26. 26. The system of claim 25, wherein the measurement device is a power quality analyzer.

27. 26. The system of claim 25, wherein the measurement device is a power quality logging device.

28. coupling an apparatus according to any one of claims 1 to 21 to a multi-core steel wire armored cable, or coupling the apparatus of a sensor according to claims 22 to 24 or the apparatus of a system according to claims 25 to 27 to the multi-core steel wire armored cable, such that a magnetic field corresponding to the one or more magnets is applied to a region of the multi-core steel wire armored cable; and using the one or more magnetic field sensors to measure components of a magnetic field emanating from the region of the multi-core steel wire armored cable.

29. 30. The method of claim 28, wherein the magnetic field corresponding to the one or more magnets saturates the steel wire sheath in the region.

30. 30. The method of claim 28 or 29, further comprising calculating one or more derived quantities based on the magnetic field components measured by the magnetic field sensors for some or all of the cores of a multi-core steel wire armored cable.

31. 1. A device for coupling to a multi-conductor cable, comprising: a first set of one or more first magnetic field sensors; a second set of one or more second magnetic field sensors; The device may be configured such that, when the device is coupled to a multi-core cable, each first magnetic field sensor oriented to detect a component of a magnetic field emanating from a first region of the multi-core cable; each second magnetic field sensor configured to be oriented to detect a component of a magnetic field emanating from a second region of the multi-core cable; The apparatus, wherein the first region is spaced from the second region along the length of the multi-conductor cable.

32. 32. The device of claim 31 , further comprising one or more magnets positioned such that when the device is coupled to the multi-core cable, a magnetic field corresponding to the one or more magnets is applied to the first and second regions of the multi-core cable.

33. 1. A device for coupling to a multi-conductor cable, comprising: a current transformer coil; one or more magnetic field sensors; The device may be configured such that, when the device is coupled to a multi-core cable, a region of the multi-core cable passing through the current transformer coil; the one or more magnetic field sensors are configured to be at least partially disposed between a core of the current transformer coil and the multi-core cable, and at least one of the magnetic field sensors is oriented to detect a component of a magnetic field emanating from the region of the multi-core cable.

34. 35. Apparatus according to claim 33 or 34, wherein the core of the current transformer coil comprises a magnetically permeable material.

35. 35. Apparatus according to claim 33 or 34, wherein the current transformer coil comprises two or more sub-coils.

36. the device is configured such that the region of the multi-core cable received through the current transformer coil is axially oriented; 36. Apparatus according to any one of claims 33 to 35, wherein the current transformer coils extend in the axial direction on either side of the one or more magnetic field sensors.

37. 37. The apparatus of claim 36, wherein the current transformer coil extends in the axial direction a length greater than or equal to half of an inner diameter of the current transformer coil.

38. 38. Apparatus according to any one of claims 33 to 37, wherein at least one of the one or more magnetic field sensors comprises a sensor coil.

39. 39. Apparatus according to any one of claims 33 to 38, wherein at least one of the one or more magnetic field sensors comprises a solid state magnetic field sensor device.

40. 40. Apparatus according to any one of claims 33 to 39, comprising a structure supporting the current transformer coil and the one or more magnetic field sensors.

41. 41. The apparatus of claim 40, wherein the structure comprises a channel configured to receive the multi-conductor cable.

42. 42. The device of claim 41, wherein the cross section of the channel has a circular or arc shape.

43. 42. The apparatus of claim 41, wherein the cross section of the channel is non-circular and has a shape that does not correspond to an arc of a circle.

44. 44. The device of any one of claims 41 to 43, wherein the channel is open.

45. 45. The apparatus of any one of claims 41 to 44, wherein the channel is defined by first and second parts of the structure and is configured to close around the multi-core cable when received within the channel.

46. 45. Apparatus according to any one of claims 41 to 44, wherein the structure comprises two or more parts configured to close or wrap around the multi-core cable to define the channel.

47. An apparatus according to any one of claims 33 to 46, comprising two or more magnetic field sensors.

48. further comprising one or more magnets; 48. The apparatus of any one of claims 33 to 47, wherein the apparatus is configured such that when the apparatus is coupled to the multi-core cable, a magnetic field corresponding to the one or more magnets is applied to the region of the multi-core cable passing through the current transformer coil.

49. the one or more magnetic field sensors comprising a first set of first magnetic field sensors and a second set of second magnetic field sensors; 49. The apparatus of any one of claims 33 to 48, wherein the first and second sets are spaced apart along the axial direction of the multi-core cable when the multi-core cable is coupled to the apparatus.

50. An apparatus according to any one of claims 33 to 49; a controller coupled to the one or more magnetic field sensors; The sensor, wherein the controller is configured to calculate one or more derived quantities based on the magnetic field components measured by the magnetic field sensors for some or all of the cores of a multi-core cable.

51. 51. The sensor of claim 50, wherein the controller is further configured to calculate a net current through the multi-conductor cable based on measurements using the current transformer coil.

52. 50. An apparatus according to any one of claims 33 to 49, further configured to generate one or more signals based on the output of the one or more magnetic field sensors, each signal being proportional to a differential current between cores of the multi-core cable when the multi-core cable is coupled to the apparatus; and and a link corresponding to each signal for connection to a control system and / or a measurement system.

53. 53. The sensor of claim 52, wherein the device is further configured to generate a net current signal based on an output from the current transformer coil.

54. 54. A sensor according to any one of claims 50 to 53, further comprising one or more voltage sensors, and wherein the one or more derived quantities include one or more power values.

55. 55. The sensor of claim 54, configured to use the one or more voltage sensors to correctly assign phases to the cores of the multi-conductor cable.

56. A system comprising a sensor according to any one of claims 50 to 55 coupled to provide an input to a measurement device.

57. Coupling an apparatus according to any one of claims 33 to 49 to a multicore cable, or coupling the apparatus of a sensor according to claims 50 to 55 or the apparatus of a system according to claim 56 to the multicore cable so that the region of the multicore coil passes through the current transformer coil; and using the one or more magnetic field sensors to measure components of a magnetic field emanating from the region of the multi-core cable.

58. 58. The method of claim 57, further comprising measuring a net current passing through the multi-conductor cable using the current transformer coil.

59. 1. A device for coupling to a multi-conductor cable, comprising: Rogowski coil and one or more magnetic field sensors; The device may be configured such that, when the device is coupled to a multi-core cable, a region of the multi-core cable passing through the Rogowski coil or the Rogowski coil wrapping around the region of the multi-core cable; The apparatus, wherein at least one of the magnetic field sensors is positioned adjacent to the Rogowski coil and is configured to detect a component of a magnetic field emanating from the region of the multi-core cable.

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