Non-contact current measurement system

Abstract

The present invention is entitled "Non-contact current measurement system." The present invention provides systems and methods that provide a non-contact current measurement system for measuring alternating current flowing through an insulated wire without requiring electrical contact with the insulated wire current. The measurement system can include a magnetic field sensor that can be selectively positioned proximate to an insulated wire to be measured. The magnetic field sensor, in operation, detects a magnetic field generated by the current flowing in the insulated wire. By using an adjustable clamping assembly, the measurement system provides control over the mechanical positioning of the insulated wire relative to the magnetic field sensor to ensure consistent measurements. The non-contact current measurement system can determine information related to the physical dimensions (e.g., diameter) of the insulated wire. By using the detected magnetic field, known mechanical positioning, and the determined information related to the physical dimensions of the insulated wire, the measurement system accurately determines the magnitude of the current flowing through the insulated wire without current contact.

Description

[0001] This application is a divisional application, the parent application of which has the title "Non-contact current measurement system", filed on November 10, 2017, and has the application number 201711104974.4. BACKGROUND TECHNICAL FIELD

[0003] The present disclosure relates generally to the measurement of electrical properties, and more particularly, to non-contact measurement of alternating current (AC) in electrical circuits.

[0004] Description of the Related Art

[0005] Ammeters are instruments used to measure current in electronic circuits. Instruments that measure more than one electrical property are called multimeters or digital multimeters (DMMs), and are used to measure many parameters typically required for service, troubleshooting, and maintenance applications. Such parameters typically include alternating current (AC) voltage and current, direct current (DC) voltage and current, and resistance or conductance. Other parameters such as power characteristics, frequency, capacitance, and temperature can also be measured to meet the requirements of specific applications.

[0006] To measure current with a general purpose multimeter, an internal current shunt with a known resistance must be inserted in the current path, requiring the load carrying conductor to be disconnected. The voltage drop across the current shunt is then measured to determine the current in the current path. The measurable current with a general purpose multimeter employing an internal current shunt is very limited, typically no more than a few amperes, due to the load carrying capability of the multimeter test leads and the circuit. In addition, for both safety reasons and to prevent damage to the multimeter, the multimeter must typically be protected with an internal fuse to prevent excessive current from flowing through the multimeter.

[0007] For conventional ammeters or multimeters that measure AC current, it can be necessary to make electrical contact with the conductor current with at least one measurement electrode or probe, which typically requires disconnecting the circuit and / or cutting away a portion of the insulation of the insulated wire, or providing a measurement terminal in advance. In addition to the need for exposed wires or terminals for current contact, the step of contacting the probe to the stripped wire or terminal can be quite dangerous due to the risk of electric shock or electrocution. SUMMARY

[0008] A non-contact current measurement system can be summarized as including an adjustable clamping assembly that selectively clamps an insulated wire and can position the wire in a defined position; a position feedback sensor that in operation generates a position feedback sensor signal indicative of a diameter of the insulated wire clamped in the adjustable clamping assembly; a magnetic field sensor positioned proximate the adjustable clamping assembly, wherein the magnetic field sensor in operation generates a magnetic field sensor signal indicative of at least one characteristic of a current flowing through the insulated wire clamped in the adjustable clamping assembly; and at least one processor communicatively coupled to the position feedback sensor and the magnetic field sensor, wherein the at least one processor in operation: receives the position feedback sensor signal from the position feedback sensor; receives the magnetic field sensor signal from the magnetic field sensor; and determines at least one characteristic of the current flowing through the insulated wire based at least in part on the received position feedback sensor signal and the magnetic field sensor signal.

[0009] The adjustable clamping assembly can include a first clamping surface and a second clamping surface, the second clamping surface can face the first clamping surface, and at least one of the first clamping surface and the second clamping surface (e.g., a "jaw") can be movable in a direction toward and away from the other of the first clamping surface and the second clamping surface to selectively clamp the insulated wire at a defined location between the first clamping surface and the second clamping surface. The first clamping surface can comprise a front end surface of a front end of a housing of the non-contact current measurement system, and the second clamping surface can be disposed on a clamping member that is selectively movable relative to the front end surface. The magnetic field sensor can be positioned proximate the front end surface of the housing front end. The adjustable clamping assembly can comprise a slider clamping assembly, and the position feedback sensor can comprise a linear position feedback sensor that generates a position feedback signal indicative of a linear position of the slider clamping assembly. The adjustable clamping assembly can comprise a first clamping portion having a first clamping surface and a second clamping portion having a second clamping surface facing the first clamping surface, and a biasing member can bias the first clamping portion toward the second clamping portion. The non-contact current measurement system can further comprise a user interface operatively coupled to the at least one processor, wherein the at least one processor, in operation, causes the user interface to display at least one characteristic of the determined current flowing through the insulated wire. The at least one characteristic of the current flowing through the insulated wire can comprise a magnitude of the current flowing through the insulated wire. The position feedback sensor can comprise a resistive sensor, a magneto resistive sensor, a Hall effect sensor, or an optical sensor. The non-contact current measurement system can further comprise a voltage reference signal type sensor that, in operation, senses a reference signal in the insulated wire without contact with the insulated wire current, wherein the at least one processor receives the reference signal and determines at least one characteristic of the current flowing through the insulated wire driven by the reference voltage based at least in part on the received reference signal. The at least one processor can further determine at least one physical dimension of the conductor inside the insulated wire based at least in part on the received reference signal. The at least one processor can further determine at least one physical dimension of the conductor inside the insulated wire based at least in part on the received reference signal and a received position feedback sensor signal that provides an outer diameter of the conductor of the insulated wire.

[0010] A method of measuring current in an insulated wire without contact with the conductor current in the insulated wire can be summarized as including clamping the insulated wire between a first clamping surface and a second clamping surface via an adjustable clamping assembly; determining a clamping distance between the first clamping surface and the second clamping surface, wherein the clamping distance is indicative of a diameter of the insulated wire clamped between the first clamping surface and the second clamping surface; sensing, via a magnetic field sensor positioned proximate the insulated wire clamped between the first clamping surface and the second clamping surface, a magnetic field generated by a current flowing through the insulated wire; and determining, via at least one processor, at least one characteristic of the current flowing through the insulated wire based at least in part on the determined clamping distance and the sensed magnetic field generated by the current flowing through the insulated wire.

[0011] The first clamping surface can include a front end surface of a front end of a housing, and the second clamping surface can include a surface of a clamping member of the adjustable clamping assembly, the surface being movable relative to the front end surface, and clamping the insulated wire between the first clamping surface and the second clamping surface can include clamping the insulated wire between the front end surface and the surface of the clamping member. Sensing the magnetic field generated by the current flowing through the insulated wire can include sensing the magnetic field via the magnetic field sensor, and the magnetic field sensor can be positioned proximate the front end surface of the front end of the housing. Clamping the insulated wire between the first clamping surface and the second clamping surface can include clamping the insulated wire between the first clamping surface and the second clamping surface of a slider clamping assembly, and determining the clamping distance can include determining a linear position of the slider clamping assembly. Any other clamping mechanism other than a slider can also be used to provide a position. Another example is a clothespin style clamp where the wire diameter is proportional to the opening angle of the rotating clamp. The first clamping surface can be positioned on a first clamping portion, and the second clamping surface can be positioned on a second clamping portion, and the method can further include biasing the first clamping portion toward the second clamping portion. The method can further include displaying, via a user interface, the determined at least one characteristic of the current flowing through the insulated wire. Determining the at least one characteristic of the current flowing through the insulated wire can include determining a magnitude of the current flowing through the insulated wire. The method as claimed in the claims can further include sensing, via a reference signal type sensor positioned in the housing, a reference signal in the insulated wire without contact with the insulated wire current; and determining, via the at least one processor, the at least one characteristic of the current flowing through the insulated wire based at least in part on the sensed reference signal. The method can further include determining, via the at least one processor, at least one physical dimension of an inner conductor of the insulated wire based at least in part on the received reference signal. The method can further include determining, via the at least one processor, at least one physical dimension of an inner conductor of the insulated wire based at least in part on the received reference signal and the received position feedback sensor signal. The reference method can also provide a position of the wire, and both the mechanical clamping or reference signal methods can be used separately or together to determine the wire diameter.

[0012] A non-contact current measurement system can be summarized as including a housing including a front end portion having a front end surface; a clamping member having a clamping member surface facing the front end surface, wherein the clamping member is movable relative to the front end surface to selectively clamp an insulated wire between the front end surface and the clamping member surface; a position feedback sensor generating a position feedback sensor signal indicative of a position of the clamping member; a current sensor positioned proximate the front end surface of the housing, wherein the current sensor, in operation, generates a current sensor signal indicative of at least one characteristic of a current flowing through the insulated wire clamped between the front end surface and the clamping member surface; and at least one processor communicatively coupled to the position feedback sensor and the current sensor, wherein the at least one processor, in operation: receives the position feedback sensor signal from the position feedback sensor; receives the current sensor signal from the current sensor; and determines, based at least in part on the received position feedback signal and the current sensor signal, the at least one characteristic of the current flowing through the insulated wire.

[0013] The current sensor can include a magnetic field sensor. The non-contact current measurement system can further include a display operatively coupled to the at least one processor, wherein the at least one processor, in operation, causes the display to present a magnitude of the current flowing through the insulated wire. The position feedback sensor can include a resistive sensor, a magneto resistive sensor, a Hall effect sensor, a capacitive sensor, an inductive sensor, or an optical sensor. BRIEF DESCRIPTION OF DRAWINGS

[0014] In the drawings, like reference numerals indicate similar elements or acts throughout the several views. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes and angles of various elements can have been exaggerated or distorted to improve the visibility of the drawings. Moreover, the specific shapes of the elements as drawn are not intended to convey any information regarding the actual shape of the particular element, and can have been selected solely for ease of recognition in the drawings.

[0015] Figure 1 is a schematic diagram of an environment in which an operator can use a non-contact current measurement system to measure an AC current present in an insulated wire without requiring contact with the insulated wire current, in accordance with one illustrated implementation.

[0016] Figure 2A is a front elevation view of a non-contact current measurement system including an adjustable clamping assembly, with the clamping member of the adjustable clamping assembly shown spaced apart from an insulated wire.

[0017] Figure 2B is Figure 2Ais a front elevation view of a non-contact current measurement system of the'1 1 1 patent, showing an insulated wire being clamped by a clamping member of an adjustable clamping assembly.

[0018] Figure 3 is a front elevation view of another implementation of a non-contact current measurement system according to an example implementation.

[0019] Figure 4 is a front elevation view of another implementation of a non-contact current measurement system according to an example implementation.

[0020] Figure 5 is a front elevation view of another implementation of a non-contact current measurement system according to an example implementation.

[0021] Figure 6 is a schematic block diagram of a non-contact current measurement system according to an example implementation.

[0022] Figure 7A is a schematic diagram of an environment in which an operator can measure the insulation thickness of an insulated wire using a non-contact measurement system including a reference signal type sensor without requiring contact with the wire current, according to an example implementation.

[0023] Figure 7B is a schematic diagram of a non-contact measurement system according to an example implementation. Figure 7A is a top view of a non-contact measurement system showing the coupling capacitance formed between an insulated wire and a conductive sensor of the non-contact measurement system, the insulated conductor current component, and the body capacitance between the non-contact measurement system and an operator.

[0024] Figure 8 is a schematic diagram of various internal components of a non-contact measurement system according to an example implementation.

[0025] Figure 9 is a block diagram showing various signal processing components of a non-contact measurement system according to an example implementation.

[0026] Figure 10 is a schematic diagram of a non-contact measurement system implementing a fast Fourier transform (FFT) according to an example implementation.

[0027] Figure 11 is a block diagram of a non-contact measurement system implementing an analog electronic filter according to another example of signal and reference signal separation.

[0028] Figure 12 is a schematic circuit diagram of a non-contact measurement system according to an example implementation.

[0029] Figure 13A is a schematic diagram of a non-contact measurement system showing various leakage and stray capacitances according to one illustrated implementation.

[0030] Figure 13B is a schematic diagram of a non-contact measurement system showing various leakage and stray capacitances according to one illustrated implementation, and including compensation for a reference current signal.

[0031] Figure 13C shows an exemplary sensor arrangement of the system of Figure 7B

[0032] Figure 14 is a schematic circuit diagram of a non-contact measurement system showing capacitance between a sensor of the non-contact measurement system and an external ground terminal according to one illustrated implementation.

[0033] Figure 15A is a schematic circuit diagram of a non-contact measurement system showing capacitance between an internal ground guard of the non-contact measurement system and an external ground terminal according to one illustrated implementation.

[0034] Figure 15B is a schematic circuit diagram of a non-contact measurement system showing capacitance between an internal ground guard of the non-contact measurement system and an external ground terminal according to one illustrated implementation.

[0035] Figure 16 is a perspective view of a sensor and internal ground guard assembly of a non-contact measurement system according to one illustrated implementation.

[0036] Figure 17 is a cross-sectional view of a "U" or "V" shaped sensor front end of a non-contact measurement system according to one illustrated implementation.

[0037] Figure 18 is a front view of an arcuate sensor front end of a non-contact measurement system according to one illustrated implementation.

[0038] Figure 19 is a perspective view of a cylindrical sensor front end of a non-contact measurement system according to one illustrated implementation.

[0039] Figure 20A is a top view of a sensor front end of a non-contact measurement system according to one illustrated implementation, with a protection ring clamp of an internal ground guard in a closed position.

[0040] Figure 20B shows an exemplary sensor arrangement of the system of Figure 20A ​A top view of the front end of the non-contact measurement system shown with the protection ring clamp of the internal ground protection in an open position.

[0041] Figure 21 is a perspective view of a portion of the sensor front end of Figure 20A DETAILED DESCRIPTION

[0042] The systems and methods disclosed herein provide a non-contact current measurement system that measures current flowing through an insulated wire without requiring electrical contact with the conductor of the insulated wire. In at least some implementations, the non-contact current measurement system includes a magnetic field sensor that is selectively positionable proximate (e.g., adjacent) to the insulated wire under test. Non-limiting examples of magnetic field sensors include anisotropic magnetoresistive (AMR) sensors, giant magnetoresistive (GMR) sensors, fluxgate sensors, superconducting quantum interference sensors, fiber optic sensors, optical pump sensors, nuclear processing sensors, search coil sensors, magnetically sensitive transistor sensors, magnetically sensitive diode sensors, magneto-optic sensors, Hall effect sensors, Rogowski coils, current transformers, or other types of magnetic field sensors. The magnetic field sensor detects a magnetic field generated by the current flowing in the insulated wire. The magnitude of the magnetic field around the conductor of the insulated wire is related to (e.g., proportional to) the magnitude of the current flowing through the conductor of the insulated wire.

[0043] In addition to detecting the magnetic field around the conductor, at least some implementations of the present disclosure utilize an adjustable clamping assembly to provide control over the mechanical positioning of the insulated wire relative to the magnetic field sensor. Further, in at least some implementations, the non-contact current measurement system determines information related to at least one physical dimension of the insulated wire under test, such as the outer diameter or wire diameter of the conductor inside the insulation of the insulated wire. Using the detected magnetic field, the controlled mechanical positioning, and the determined physical dimension information, the non-contact current measurement system accurately determines the magnitude of the current flowing through the conductor of the insulated wire.

[0044] In the following description, certain specific details are set forth in order to provide a thorough understanding of the various specific implementations disclosed herein. However, one skilled in the relevant art will recognize that these implementations can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with computer systems, server computers, and / or communication networks have not been described in detail to avoid unnecessarily obscuring the descriptions of these specific implementations.

[0045] ​Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "coupled" or "coupling" refer to any connection or coupling, either direct or indirect, between or among two or more elements, whether or not it is the exclusive connection or coupling between the two elements. Likewise, the term "operatively coupled" or "operatively coupling" refers to any coupling or connection between or among two or more elements in which the coupled or connecting elements function together to produce a desired result.

[0046] Reference throughout this specification to "one implementation" or "an implementation" means that a particular feature, structure, or characteristic described in connection with the implementation is included in at least one implementation. Thus, the appearances of the phrases "in one implementation" or "in an implementation" in various places throughout this specification are not necessarily all referring to the same implementation. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more implementations.

[0047] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its sense including "and / or" unless the context clearly dictates otherwise. Furthermore, the headings and Abstract of the Disclosure provided herein are provided herein solely for convenience and should not be interpreted as limiting the scope or meaning of the implementations.

[0048] Figure 1 is a schematic illustration of an environment 100 in which a technician 104 can use a non-contact current measurement system 102 to measure an AC current present in an insulated wire 106 without requiring galvanic contact between the non-contact current measurement system and the insulated wire 106. Figure 2A and Figure 2B An enlarged view of the non-contact current measurement system 102 is shown.

[0049] The non-contact current measurement system 102 includes a housing or body 108 that includes a grip portion or end 110 and a front or end 112 opposite the grip portion. The housing 108 can also include a user interface 114 that facilitates user interaction with the non-contact current measurement system 102. The user interface 114 can include any number of inputs (e.g., buttons, dials, switches, touch sensors) and any number of outputs (e.g., displays, LEDs, speakers, buzzers). The non-contact current measurement system 102 can also include one or more wired and / or wireless communication interfaces (e.g., USB, Wi-Fi ® , Bluetooth ® ).

[0050] As Figure 2A and Figure 2BAs shown in the middle, a magnetic field sensor 116 (e.g., an anisotropic magnetoresistive (AMR) sensor, a giant magnetoresistive (GMR) sensor, a fluxgate sensor, etc.) is positioned below a top surface 118 of the front end 112. The magnetic field sensor 116 is used to detect a magnetic field generated by a current flowing in an insulated wire 106, which includes a conductor 122 surrounded by one or more layers of insulation 124. The magnitude of the magnetic field around the conductor 122 is related to (e.g., proportional to) the magnitude of the current flowing through the conductor. In general, the magnitude of the current flowing in the conductor 122 can be accurately determined by the magnetic field sensor 116 when two parameters are satisfied. The first parameter is control over the mechanical positioning of the insulated wire 106 relative to the magnetic field sensor 116, which is controlled by an adjustable clamping assembly 126 in at least some implementations. The second parameter is physical dimension information of the insulated wire 106, such as its outer diameter or the diameter of the conductor inside the insulation of the insulated wire (i.e., the wire diameter), which can be determined or estimated by a position feedback sensor 128 operatively coupled to the adjustable clamping assembly 126. The adjustable clamping assembly 126 and the position feedback sensor 128 are discussed further below.

[0051] In addition, in at least some implementations, the physical dimension information regarding the wire diameter of the insulated wire 106 can additionally or alternatively be obtained with one or more reference signal sensors that detect a reference signal (e.g., a reference current signal) generated between the sensor and the insulated wire 106. Various exemplary non-contact measurement systems implementing such “reference signal” methods for detecting physical dimension information of an insulated wire are discussed below with reference to Figures 7A-21 For example, in at least some implementations, the total diameter of the insulated wire can be determined using the adjustable clamping assembly and the position feedback sensor, and the thickness of the insulation of the insulated wire can be determined using the reference signal method. Using the determined total diameter of the insulated wire and the determined thickness of the insulation, the non-contact current measurement system can automatically determine or estimate the diameter of the conductor inside the insulation of the insulated wire (e.g., the diameter of the conductor equals the total diameter of the insulated wire minus twice the thickness of the insulation). The determined conductor diameter can then be used together with the detected magnetic field to accurately determine the magnitude of the current flowing through the insulated wire.

[0052] In the illustrated specific implementation, the mechanical positioning of the insulated wire 106 is provided by an adjustable clamp or “slider” holding assembly 126 that ensures the insulated conductor is properly aligned (e.g., adjacent) with the magnetic field sensor 116 during measurement. The adjustable clamping assembly 126 includes a clamping member 130 coupled to the housing 108 and selectively movable toward and away from the front end 112. The clamping member 130 may be referred to herein as a first clamping portion, and the front end 112 may be referred to herein as a second clamping portion. The clamping member 130 includes a clamping surface 132 facing the front end 112 and generally parallel to it. The clamping surface 132 and the top surface 118 together define a variable-sized clamping opening 134, the size and dimensions of which are designed to receive a portion of the insulated wire 106 therein. In the illustrated example, the clamping member 130 can be selectively moved between a first position P1 where the clamping opening 134 is relatively large and a second position P2 where the clamping opening is relatively small.

[0053] like Figure 2A As shown, when the clamping surface 132 of the clamping member 130 is spaced from the top surface 118 of the front end 112 by an amount sufficient to easily allow the insulated wire to be moved into the clamp opening, the user can position the insulated wire 106 within the clamp opening 134. Then, as... Figure 2B As shown, the user can move the clamping member 130 downward to a third position P3 to "clamp" the insulated wire 106 between the top surface 118 and the clamping surface 132 of the front end 112, such that the top surface and the clamping surface are in contact with the insulation layer of the insulated wire on opposite sides. As used herein, the term "clamp" refers to the insulated wire 106 being in contact with the top surface 118 and the clamping surface 132 on opposite sides of the insulated wire to maintain the position of the wire relative to the magnetic field sensor 116. That is, the term does not indicate that the top surface 118 or the clamping surface 132 must apply any specific amount of force to the insulated wire 106.

[0054] The position feedback sensor 128 is used to sense a position (e.g., a linear position) of the clamping member 130 and generate a position feedback sensor signal (e.g., a linear position feedback sensor signal) indicative of this position. This position feedback signal can be, for example, a digital or analog signal. The sensed position of the clamping member 130 can be used to determine or estimate the diameter or wire size of the insulated wire 106 when the insulated wire 106 is clamped between the clamping surface 132 and the top surface 118 of the front end 112. For example, the position feedback sensor 128 can provide a position feedback sensor signal that is proportional to the extension of the clamping member 130. The position feedback sensor 128 can be any suitable sensor for sensing the extension of the clamping member 130 and determining the diameter of the insulated wire 106. For example, the position feedback sensor 128 can include a resistive sensor, a magneto-resistive sensor, a Hall effect sensor, an optical sensor, etc. As discussed further below, in at least some implementations, a "reference signal" approach can additionally or alternatively be used to determine the diameter or size of the inner conductor of the insulated wire 106, which can further allow the system 102 to provide accurate current measurements.

[0055] In at least some implementations, the clamping member 130 can be biased toward the second position P2 by a suitable biasing member 136. For example, the clamping member 130 can be biased toward the second position P2 by a spring that is coupled between the clamping member and a portion of the housing 108. Advantageously, biasing the clamping member 130 can allow the clamping assembly 126 to better retain the insulated wire 106 in the clamp opening 134 while also providing a more uniform measurement of the diameter of the insulated wire 106.

[0056] Due to the orthogonal relationship between magnetic flux density and current (e.g., the "right-hand rule" for magnetic flux around a current-carrying conductor), the mechanical positioning of the insulated wire 106 relative to the magnetic field sensor 116 can be important. In addition, the physical size information provided by the position feedback sensor 128 can be important because, for the same current, the magnetic flux density that is tangential to the conductor circumference is higher in a conductor with a smaller diameter than in a conductor with a larger diameter. Thus, by knowing at least an estimate of the diameter of the insulated wire, the non-contact current measurement system 102 can more accurately determine the current flowing through the insulated wire by accounting for the effect of the diameter of the wire on the relationship between the sensed magnetic field and the current flowing in the wire.

[0057] As discussed below with reference to FIGS. 4-6, the non-contact current measurement system 102 can be used to determine the diameter of the inner conductor of the insulated wire 106. In at least some implementations, the non-contact current measurement system 102 can be used to determine the diameter of the inner conductor of the insulated wire 106 by using a "reference signal" approach. In this approach, the diameter of the inner conductor of the insulated wire 106 is determined by comparing the magnetic field sensed by the magnetic field sensor 116 to a reference signal that is generated by the position feedback sensor 128. The reference signal can be generated by the position feedback sensor 128 in response to the clamping member 130 being moved between the first position P1 and the second position P2. For example, the position feedback sensor 128 can generate a reference signal that is proportional to the extension of the clamping member 130. The reference signal can be generated by the position feedback sensor 128 in response to the clamping member 130 being moved between the first position P1 and the second position P2. For example, the position feedback sensor 128 can generate a reference signal that is proportional to the extension of the clamping member 130. The reference signal can be generated by the position feedback sensor 128 in response to the clamping member 130 being moved between the first position P1 and the second position P2. For example, the position feedback sensor 128 can generate a reference signal that is proportional to the extension of the clamping member 130. Figure 6As further discussed, using data from the magnetic field sensor 116 and diameter or wire diameter data from the position feedback sensor 128 and / or the reference signal sensor, at least one processor of the non-contact current measurement system 102 can accurately determine at least one characteristic (e.g., magnitude, frequency) of the current flowing through the insulated wire 106. Such information is stored in a non-transitory processor-readable storage medium of the non-contact current measurement system, can be presented to a user via a display of the user interface 114 and / or transmitted to a separate device through a wired or wireless communication interface.

[0058] While the illustrated non-contact current measurement system 102 includes a magnetic field sensor 116, it should be understood that in other implementations, the non-contact current measurement system can include various other types of magnetic field sensors (e.g., Hall effect sensors, Rogowski coils, current transformers, etc.) that are capable of sensing a magnetic field produced by a current without requiring contact with the wire current being measured.

[0059] As further discussed below, in at least some implementations, the non-contact measurement system 102 can utilize a body capacitance (Cbody) between the operator 104 and the ground node 128 during current measurement. B While the term “ground node” is used for the node 128, this node is not necessarily the earth / ground, but can be connected to any other reference potential in a galvanically isolated manner through a capacitive coupling.

[0060] Figure 3 A front elevation view of a non-contact current measurement system 300 having a different form factor than the non-contact current measurement system 102 is shown. The non-contact current measurement system 300 can be similar or identical to the non-contact current measurement system 102 discussed above in many respects. Accordingly, some or all of the above discussion regarding features of the non-contact current measurement system 102 can also apply to the non-contact current measurement system 300.

[0061] The non-contact current measurement system 300 includes a housing 302 having a front end 304 and a gripping portion or end 306 opposite the front end. The housing 302 includes a user interface 308 (e.g., display, buttons) positioned on a surface of the housing. The front end 304 includes a current sensor 312 (e.g., magnetic field sensor), an optional reference signal sensor 313, and a retractable jaw or gripping member 314 for grasping an insulated wire (e.g., insulated wire 106) of Figure 1 、 Figure 2A and Figure 2B Figures 7A-21 ​The operation of various reference signal sensors is further discussed. Front end 304 includes a front end surface 316 adjacent to current sensor 312, and clamping member 314 includes a clamping surface 318 opposite to front end surface 316. To further improve current measurement accuracy, a second magnetic field sensor can be used in clamping member 314. The average signal between current sensor 312 and the additional sensor located in clamping member 314 can be used for current calculation. Additionally, the difference exceeding a limit between the two sensors can be used to identify unreliable conditions caused by external stray currents or incorrectly positioned wires clamped between clamping members 314 and 316. In use, an insulated wire can be clamped between front end surface 316 and clamping surface 318 to position the insulated wire adjacent to current sensor 312. Clamping member 314, as well as other clamping members of this disclosure, can be permanently attached to housing 302 or selectively detached from housing. The non-contact current measurement system 300 also includes a position feedback sensor 320 and optionally includes a biasing member 322 to bias the clamping member 314 toward the housing 302 to clamp the insulated wire between the front end surface 316 and the clamping surface 318. About Figure 6 Further discussion is provided on implementation schemes for current sensors and position feedback sensors suitable for a non-contact current measurement system 300.

[0062] Figure 4 A front view of a non-contact current measurement system 400, having a different form factor than the non-contact current measurement system 102, is shown. The non-contact current measurement system 400 may be similar to or identical in many respects to the non-contact current measurement system discussed above. Therefore, some or all of the above discussion regarding the characteristics of the aforementioned non-contact current measurement system may also apply to the non-contact current measurement system 400.

[0063] The non-contact current measurement system 400 includes a housing 402 having a front end 404 and a gripping portion or end 406 opposite to the front end. The housing 402 includes a user interface 408 (e.g., a display, button, dial) positioned on the surface of the housing. The front end 404 includes a current sensor 412 (e.g., a magnetic field sensor), an optional reference signal sensor 413, and a gripping mechanism for holding an insulated wire (e.g., [missing information]). Figure 1 , Figure 2A and Figure 2Bretractable hook or clamping member 414 of the insulated wire 106). The front end 404 includes a front end surface 416 adjacent the current sensor 412, and the clamping member 414 includes a clamping surface 418 opposite the front end surface 416. In use, the insulated wire can be clamped between the front end surface 416 and the clamping surface 418 to position the insulated wire adjacent the current sensor 412. The clamping member 414 can be permanently attached to the housing 402, or can be selectively detached from the housing. The non-contact current measurement system 400 also includes a position feedback sensor 420, and optionally a biasing member 422 to bias the clamping member 414 toward the housing 402 to clamp the insulated wire between the front end surface 416 and the clamping surface 418. See Figure 6 Suitable embodiments of current sensors and position feedback sensors that can be used in the non-contact current measurement system 400 are provided.

[0064] Figure 5 A front elevation view of a non-contact current measurement system 500 having a different form factor than the non-contact current measurement system 102 is shown. The non-contact current measurement system 500 can be similar or identical to the non-contact current measurement systems discussed above in many respects. Thus, some or all of the above discussion regarding features of the non-contact current measurement systems described above can also apply to the non-contact current measurement system 500.

[0065] The non-contact current measurement system 500 includes a housing 502 having a front end 504 and a grip portion or end 506 opposite the front end. The housing 502 includes a user interface 508 (e.g., display, buttons, dials) positioned on a surface of the housing. The front end 504 includes a current sensor 512 (e.g., magnetic field sensor), an optional reference signal sensor 513, and a retractable hook or clamping member 514 for gripping an insulated wire (e.g., Figure 1 , Figure 2A and Figure 2B the insulated wire 106). The front end 504 includes a front end surface 516 adjacent the current sensor 512, and the clamping member 514 includes a clamping surface 518 opposite the front end surface 516. In use, the insulated wire can be clamped between the front end surface 516 and the clamping surface 518 to position the insulated wire adjacent the current sensor 512. The clamping member 514 can be permanently attached to the housing 502, or can be selectively detached from the housing. The non-contact current measurement system 500 also includes a position feedback sensor 520, and optionally a biasing member 522 to bias the clamping member 514 toward the housing 502 to clamp the insulated wire between the front end surface 516 and the clamping surface 518. See Figure 6Additional discussion of embodiments of current sensors and position feedback sensors suitable for use in a non-contact current measurement system 500 is provided.

[0066] Figure 6 is a schematic block diagram of a non-contact current measurement system or instrument 600 that provides non-contact current measurement functionality. The non-contact current measurement system 600 can be similar or identical to any of the non-contact current measurement systems discussed herein.

[0067] The non-contact current measurement system 600 includes a current sensor 602 (e.g., a magnetic field sensor) communicatively coupled to a processor 604. The non-contact current measurement system 600 also includes an adjustable clamping assembly 606 and a position feedback sensor 608 operatively coupled to the adjustable clamping assembly and the processor 604. As discussed above, the position feedback sensor 608 generates a position feedback sensor signal indicative of a position of the adjustable clamping assembly 606, and determines a diameter of an insulated wire clamped in the adjustable clamping assembly 606 from the detected position. The processor 604 receives the position feedback sensor signal from the position feedback sensor 608.

[0068] The current sensor 602 can be any suitable non-contact current sensor, such as a magnetic field sensor, a Hall effect sensor, etc. The current sensor 602, in operation, generates a current sensor signal indicative of at least one characteristic of a current flowing through an insulated wire clamped in the adjustable clamping assembly 606. For example, the at least one characteristic can include a magnitude of the current or a frequency of the current. In the particular implementation where the current sensor 602 is a magnetic field sensor, the current sensor can generate a magnetic field sensor signal indicative of a magnetic field generated by the current flowing through the insulated wire, which can be analyzed by the processor 604 to determine the at least one characteristic of the current flowing through the insulated wire.

[0069] The adjustable clamping assembly 606 can be similar or identical to any of the adjustable clamping assemblies discussed herein. The position feedback sensor 608 is used to generate a position feedback sensor signal indicative of a clamped position of the adjustable clamping assembly 606, which in turn is indicative of a diameter of an insulated wire clamped by the adjustable clamping assembly. The position feedback sensor 608 can be any suitable position sensor, including but not limited to a resistive sensor, a magneto-resistive sensor, a Hall effect sensor, an optical sensor, etc.

[0070] The processor 604 can include one or more logic processing units, such as one or more central processing units (CPUs), microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microcontrollers, other programmable circuits, combinations of the foregoing, or the like. Generally, the processor 604 can serve as the computational hub of the non-contact current measurement system 600 by supporting the execution of instructions and the reading and writing of data to one or more memory devices, I / O interfaces, and communication systems.

[0071] The non-contact current measurement system 600 can also include a memory 610 communicatively coupled to the processor 604 storing at least one of instructions or data thereon. The memory 610 can include one or more solid state memories, such as a flash memory or a solid state drive (SSD), that provide non-volatile storage of computer-readable instructions, data structures, program modules, and other data for the non-contact current measurement system 600. Although not shown, the non-contact current measurement system 600 can employ other non-transitory computer or processor-readable media, such as a hard disk drive, an optical disk drive, or a memory card media drive.

[0072] The non-contact current measurement system 600 can include a user interface 612, which can include any number of inputs 613 (e.g., buttons, dials, switches, touch sensors, touchscreens, trigger switches, selectors, rotary switches) and any number of outputs 614 (e.g., displays, LEDs, speakers, buzzers). Non-limiting examples of display devices include liquid crystal display (LCD) devices, light emitting diode (LED) devices, and / or organic light emitting diode (OLED) devices. The user interface 612 can include a touchscreen, which can be any type of touchscreen currently known or later developed. For example, the touchscreen can be a capacitive device, an infrared device, a resistive device, or a surface acoustic wave (SAW) device. In implementations of the non-contact current measurement system 600 that include a display, the display can present readings and / or waveforms indicative of at least one characteristic (e.g., magnitude, frequency) of the current flowing through the insulated wire under test.

[0073] In operation, the processor 604 receives sensor signals from the position feedback sensor 608 and the current sensor 602, respectively, to obtain the clamp position and current measurements. As described above, the clamp position measurement is indicative of the diameter of the insulated wire under test, and the current sensor signal can be indicative of at least one characteristic (e.g., magnitude) of the current flowing through the insulated wire. As described above, the processor 604 can utilize such measurements to determine at least one characteristic of the current flowing through the insulated wire under test, such as the magnitude and / or frequency of the current flowing through the insulated wire.

[0074] The processor 604 can provide a reading of one or more of the measured or determined characteristics (e.g., current magnitude, current frequency, diameter of the insulated wire), and can provide a graphical representation of one or more of the characteristics. Such graphical representations can include waveforms, harmonic bar graphs, etc.

[0075] To communicate with one or more processor-based external devices, the non-contact current measurement system 600 can include one or more wired and / or wireless communication interfaces 616. Non-limiting examples of wireless communication interfaces include Wi-Fi ® , Bluetooth ® , Bluetooth ® Low Energy, ZigBee ® , 6L0WPAN ® , Optical IR, Wireless HART, etc. Non-limiting examples of wired communication interfaces include USB ® , Ethernet, PLC, HART, MODBUS, FireWire ® , Thunderbolt ® , etc.

[0076] In addition to sending data to external devices, in at least some implementations, the non-contact current measurement system 600 can receive at least one of data or instructions (e.g., control instructions) from external devices via the wired and / or wireless communication interfaces 616.

[0077] In at least some implementations, the non-contact current measurement system 600 can not include a display, and can instead be used as a sensor to remotely monitor electrical equipment via a processor-based external device. Such processor-based devices can include various types of devices, such as smartphones, tablets, laptops, wearable computers, servers, cloud computers, etc. The processor-based external device can include a display to present data acquired by the non-contact current measurement system 600 over a period of time (e.g., minutes, hours, days, weeks).

[0078] In at least some implementations, the non-contact current measurement system can include one or more additional electrical sensors 618 communicatively coupled to the processor 604. Such electrical sensors 618 can include voltage sensors capable of sensing voltage, resistance sensors capable of sensing resistance, capacitance sensors capable of sensing capacitance, etc. In such implementations including one or more additional sensors 618, the non-contact current measurement system 600 can function as a multimeter providing multiple electrical characteristics (e.g., current, voltage, power, resistance, capacitance).

[0079] In at least some implementations, the electrical sensor 618 can include a reference signal sensor for detecting the thickness of the insulator of the insulated wire under test. Reference is made to FIG. 7 below for further discussion of various example reference signal sensors. Figure 21 Various example reference signal sensors are further discussed below. In such implementations, the adjustable clamping assembly 606 and the position feedback sensor 608 can be used to determine the overall diameter of the insulated wire, and the reference signal sensor 618 can utilize a reference signal method discussed further below to determine the thickness of the insulator of the insulated wire. Using the overall diameter of the insulated wire determined by the adjustable clamping assembly 606 and the position feedback sensor 608, and the determined insulator thickness determined by the reference signal sensor 618, the non-contact current measurement system can automatically determine the diameter of the conductor of the insulated wire, which is equal to the overall diameter of the insulated wire minus twice the thickness of the insulator. The determined conductor diameter can then be used with the detected magnetic field to determine the magnitude of the current flowing through the insulated wire.

[0080] The discussion below provides examples of systems and methods that utilize a "reference signal" approach for measuring at least one physical dimension of an insulated wire (e.g., the thickness of the insulator) without requiring an electrical connection between the conductor of the insulated wire and a sensor or electrode ("reference signal sensor"). As noted above, in at least some implementations, a non-contact current measurement system can utilize a reference signal approach (with or without mechanical position feedback) to determine or estimate one or more physical dimensions of an insulated wire (e.g., the diameter of the conductor). As discussed below, the reference signal approach can additionally or alternatively be used to measure an alternating current (AC) voltage of an insulated conductor or uninsulated bare conductor (e.g., an insulated wire) without requiring an electrical connection between the conductor and a test electrode or probe. The implementations disclosed below can be referred to herein as "reference signal type" sensors or systems.

[0081] Figure 7A is a schematic illustration of an environment 700 in which a non-contact measurement system 702 including a reference signal type voltage sensor or system can be used by an operator 704 to measure an AC current present in an insulated wire 706 without requiring an electrical contact between the non-contact measurement system and the wire 706. The non-contact measurement 702 can include some or all of the components and functionality of the non-contact current measurement systems discussed above. Figure 7B is Figure 7AA top view of a non-contact measurement system 702 illustrates various electrical characteristics during operation. The non-contact measurement system 702 includes a housing or body 708 comprising a grip portion or end 710 and a probe portion or end 712 (also referred to herein as a front end) opposite the grip portion. The housing 708 may also include a user interface 714 facilitating user interaction with the non-contact measurement system 702. The user interface 714 may include any number of input elements (e.g., buttons, dials, switches, touch sensors) and any number of output elements (e.g., displays, LEDs, speakers, buzzers). The non-contact measurement system 702 may also include one or more wired and / or wireless communication interfaces (e.g., USB, Wi-Fi). ® Bluetooth ® ).

[0082] In at least some specific implementations, such as Figure 7B As best shown, probe portion 712 may include a recess 716 defined by a first extension portion and second extension portions 718 and 720. Recess 716 receives insulating wire 706 (see [reference]). Figure 7A The insulated wire 706 includes a conductor 722 and an insulator 724 surrounding the conductor 722. When the insulated wire is located within a recess 716 of the non-contact measurement system 702, the recess 716 may include a reference signal sensor or electrode 726 adjacent to the insulator 724 of the insulated wire 706. Although not shown for clarity, the sensor 726 may be disposed inside the housing 708 to prevent physical and electrical contact between the sensor and other objects.

[0083] like Figure 7A As shown, in use, the operator 704 can grasp the grip portion 710 of the housing 708 and position the probe portion 712 close to the insulated wire 706, allowing the non-contact measurement system 702 to accurately measure the current present in the wire, as described above. Although the probe tip 712 is shown as having a recess 716, in other embodiments, the probe portion 712 may be configured differently. For example, in at least some embodiments, the probe portion 712 may include a selectively movable clamp, hook, a flat or arcuate surface including the sensor, or other types of interfaces that allow the sensor of the non-contact measurement system 702 to be positioned close to the insulated wire 706. (Refer to above) Figures 1-6 Examples of various adjustable clamping components and position feedback sensors are discussed below. (See below for reference.) Figures 16-21 Examples of various probe components and sensors are discussed.

[0084] In certain specific implementations, the operator's body may serve as a ground / ground reference. The non-contact measurement capabilities discussed herein are not limited to applications measuring only relative to the Earth. An external reference can be capacitively coupled to any other potential. For example, if an external reference is capacitively coupled to another phase in a three-phase system, the phase-to-phase voltage is measured. In general, the concepts discussed herein are not limited to using only body capacitive coupling connected to a reference voltage and any other reference potential as a reference relative to the Earth.

[0085] As discussed further below, in at least some specific implementations, the non-contact measurement system 702 can utilize the volume capacitance (C) between the operator 704 and the grounding terminal 728 during measurement. B Although the term "ground terminal" is used for node 728, this node is not necessarily earth / ground, but can be connected to any other reference potential in a current-isolated manner via capacitive coupling.

[0086] The following is for reference. Figures 8-21 The specific systems and methods used in the non-contact measurement system 702 are discussed.

[0087] Figure 8 It shows in Figure 7A and Figure 7B The diagram also shows a schematic of the various internal components of the non-contact measurement system 702. In this example, the conductive sensor 726 of the non-contact measurement system 702 is generally "V-shaped" and is positioned close to the insulating wire 706 to be measured and capacitively coupled to the conductor 722 of the insulating wire 706, thereby forming a sensor coupling capacitor (C). O The operator 704 who operates the non-contact measurement system 702 has a capacitance to ground (C). B Therefore, as Figure 7B and Figure 8 As shown, the AC voltage signal (V) in line 722 O ) through series-connected coupling capacitors (C O ) and volume capacitance (C B ) generates an insulated conductor current component or "signal current" (I O In some specific implementations, the bulk capacitance (C) B It may also include test leads that generate current isolation from ground or any other reference potential.

[0088] The AC voltage (V) in line 722 to be measured O The non-contact measurement system 702 has a connection to an external grounding terminal 728 (e.g., neutral wire). The non-contact measurement system 702 itself also has a capacitance to the grounding terminal 728, which is primarily supplied by the operator 704 when the user... Figure 7A The volume capacitance (C) when holding a non-contact measurement system in one's hand BComposed of: Capacitor C O and C B The two form a conductive loop, and the voltage in this loop generates a signal current (I). O Signal current (I) O The AC voltage signal (V) is capacitively coupled to the conductive sensor 726. O The data is generated and transmitted through the housing 708 of the non-contact measurement system and the body capacitor (C) to the ground terminal 728. B Return to external ground terminal 728. Current signal (I) O The distance between the conductive sensor 726 and the insulating wire 706 under test in the non-contact measurement system 702, the specific shape of the conductive sensor 726, and the size and voltage level (V) of the conductor 722 depend on the distance between them. O ).

[0089] To compensate for the direct impact on the signal current (I) O The distance variance and the resulting coupling capacitance (C) O The variance of the non-contact measurement system 702 includes a common-mode reference voltage source 730, which generates a reference frequency (f) that is different from the signal voltage frequency (fo). R AC reference voltage (V) R ).

[0090] To reduce or avoid stray currents, at least a portion of the non-contact measurement system 702 may be surrounded by a conductive internal grounding protection element or screen 732, which allows most of the current to flow through a coupling capacitor (C) formed with the conductor 722 of the insulated wire 706. O The conductive sensor 726. The internal grounding protection element 732 may be formed of any suitable conductive material (e.g., copper) and may be solid (e.g., foil) or have one or more openings (e.g., mesh).

[0091] Furthermore, to prevent current from flowing between the internal grounding protection 732 and the external grounding terminal 728, the non-contact measurement system 702 includes a conductive reference shield 734. The reference shield 734 can be formed of any suitable conductive material (e.g., copper) and can be solid (e.g., foil) or have one or more openings (e.g., mesh). A common-mode reference voltage source 730 is electrically coupled between the reference shield 734 and the internal grounding protection 732, generating a reference voltage (V) for the non-contact measurement system 702. R ) and reference frequency (f R The common-mode voltage of this type of AC reference voltage (V). R ) drive additional reference current (I R ) through coupling capacitor (C O) and body capacitor (C B ).

[0092] The internal ground guard 732 around at least a portion of the conductive sensor 726 protects the conductive sensor from the direct influence of the AC reference voltage (V R ) that would cause an unwanted shift in the reference current (I R ) between the conductive sensor 726 and the reference shield 734. As noted above, the internal ground guard 732 is an internal electronic ground 738 for the non-contact measurement system 702. In at least some implementations, the internal ground guard 732 also surrounds some or all of the electronics of the non-contact measurement system 702 to avoid coupling of the AC reference voltage (V R ) into the electronics.

[0093] As noted above, the reference shield 734 is used to inject the reference signal onto the input AC voltage signal (V O ) and, as a second function, to minimize the capacitance of the guard 732 to the ground 728. In at least some implementations, the reference shield 734 surrounds some or all of the housing 708 of the non-contact measurement system 702. In such implementations, some or all of the electronics see a reference common mode signal that also generates the reference current (I R ) between the conductive sensor 726 and the conductor 722 in the insulated wire 706. In at least some implementations, the only gap in the reference shield 734 can be an opening for the conductive sensor 726 that allows the conductive sensor to be positioned in proximity to the insulated wire 706 during operation of the non-contact measurement system 702.

[0094] The internal ground guard 732 and the reference shield 734 can provide a double layer of shielding around the housing 708 (see Figure 7A and Figure 7B ) of the non-contact measurement system 702. The reference shield 734 can be disposed on the outer surface of the housing 708 and the internal ground guard 732 can act as an internal shield or guard. The conductive sensor 726 is shielded from the reference shield 734 by the guard 732 so that any reference current is generated by the coupling capacitor (C O ) between the conductive sensor 726 and the conductor 722 under test.

[0095] The guard 732 around the sensor 726 also reduces the stray influence of adjacent wires in proximity to the sensor.

[0096] As Figure 8As shown, the non-contact measurement system 702 can include an input amplifier 736 operating as an inverting current-to-voltage converter. The input amplifier 736 has a non-inverting terminal that is electrically coupled to an internal ground guard 732 that serves as an internal ground terminal 738 of the non-contact measurement system 702. The inverting terminal of the input amplifier 736 can be electrically coupled to the conductive sensor 726. A feedback circuit 737 (e.g., a feedback resistor) can also be coupled between the inverting terminal and an output terminal of the input amplifier 736 to provide feedback and appropriate gain for input signal conditioning.

[0097] The input amplifier 736 receives a signal current (I O ) and a reference current (I R ) from the conductive sensor 726 and converts the received currents into a sensor current voltage signal indicative of the conductive sensor current at the output terminal of the input amplifier. The sensor current voltage signal can be, for example, an analog voltage. The analog voltage can be fed to a signal processing module 740, as discussed further below, that processes the sensor current voltage signal to estimate or determine the thickness of the insulating layer 724 of the insulated wire 706 and / or determine the AC voltage (V O ) in the conductor 722 of the insulated wire 706. As noted above, the determined thickness of the insulating layer 724 of the insulated wire 706 can be used, at least in part, to estimate or determine at least one physical dimension (e.g., diameter) of the conductor 722 that can be used with the magnetic field measurement to determine the current flowing through the conductor 722 of the insulated wire. The signal processing module 740 can include any combination of digital and / or analog circuitry.

[0098] The non-contact measurement system 702 can also include a user interface 742 (e.g., a display) communicatively coupled to the signal processing module 740 to present the determined current and / or the determined voltage (V O ) or to communicate with the operator 704 of the non-contact measurement system through the interface.

[0099] Figure 9 is a block diagram of a non-contact measurement system 900 illustrating various signal processing components of the non-contact measurement system. Figure 10 is a more detailed diagram of the non-contact measurement system 900 of Figure 9 .

[0100] The non-contact measurement system 900 can be similar or identical to the non-contact measurement system 702 described above. Accordingly, similar or identical components are marked with the same reference numbers. As shown, the input amplifier 736 receives an input current (I O + I R) into a sensor current voltage signal indicative of the input current. An analog-to-digital converter (ADC) 902 is used to convert the sensor current voltage signal into digital form.

[0101] The AC voltage (V O ) in the wire 722 is related to the AC reference voltage (V R ) as in equation (1):

[0102]

[0103] where (I O ) is the signal current through the conductive sensor 726 due to the AC voltage (V O ) in the conductor 722, (I R ) is the reference current through the conductive sensor 726 due to the AC reference voltage (V R ), (f O ) is the frequency of the AC voltage (V O ) being measured, and (f R ) is the frequency of the reference AC voltage (V R ).

[0104] The signal labeled“O” related to the AC voltage (V O ) has different characteristics, such as frequency, than the signal labeled“R” related to the common mode reference voltage source 730. In Figure 10 embodiments, digital processing such as circuitry implementing a fast Fourier transform (FFT) algorithm 906 can be used to separate the signal magnitudes having different frequencies. In the embodiments of Figure 11 discussed below, analog electronic filters can also be used to separate the“O” signal characteristics (e.g., magnitude, frequency) from the“R” signal characteristics.

[0105] The currents (I O ) and (I R ) depend on the frequencies (f O ) and (f R ), respectively, due to the coupling capacitor (C O ). The currents flowing through the coupling capacitor (C O ) and the body capacitance (C B ) are proportional to the frequency, and thus the frequency (f O ) of the AC voltage (V O ) in the conductor under test 722 can need to be measured to determine the ratio of the reference frequency (f R ) to the signal frequency (f O ), which is used in equation (1) listed above or the reference frequency is known because the reference frequency is generated by the system itself.

[0106] The input current (I O R ) has been conditioned by the input amplifier 736 and digitized by the ADC 902, the frequency components of the digital sensor current voltage signal can be determined by representing the signal in the frequency domain using the FFT 906. When both the frequencies (f O R ) are measured, a frequency window can be determined to calculate the fundamental magnitude of the currents (I O R ) and (I R ) from the FFT 906.

[0107] The magnitude of the current (I R ) and / or the current (I O ) can vary as a function of the distance between the reference signal sensor or electrode (e.g., electrode 726) and the conductor 722 of the insulated wire 706. Thus, the system can compare the measured current (I R ) and / or the current (I O ) to the expected individual currents to determine the distance between the reference signal sensor or electrode and the conductor 722. Since the insulated wire 706 can be positioned adjacent to the reference signal sensor or electrode (e.g., via an adjustable clamping assembly) during the measurement, the distance between the reference signal sensor and the conductor 722 of the insulated wire 706 is approximately equal to the thickness of the insulation layer 724. As described above, the position feedback sensor operatively coupled to the adjustable clamping assembly provides the overall diameter of the insulated wire 706. Thus, using the determined overall diameter of the insulated wire and the determined thickness of the insulation layer 724, the system can accurately determine the diameter or wire gauge of the conductor 722 inside the insulated wire 706. This information, along with the magnetic field measured by the magnetic field sensor (e.g., sensor 116, 312, 412, or 512) can be used by the system to accurately determine the magnitude of the current flowing through the conductor 722 inside the insulated wire 706.

[0108] As shown in block 908, the ratio of the fundamental harmonics of the currents (I R O ) designated I R ,1 and I O ,1, respectively, can be corrected by the determined frequencies (f O R ) and this factor can be used to calculate the measured raw fundamental or RMS voltage by adding the harmonic (V O ) in the wire 722, which is done by calculating the square root of the sum of the squares of the harmonics, and in implementations can be presented to the user on the display 912, where the non-contact measurement system also determines the AC voltage in the insulated wire 706.

[0109] The coupling capacitor (C​​​O The capacitance value can typically range from about 0.02 pF to 1 pF, depending, for example, on the distance between the insulating conductor 706 and the conductive sensor 726, as well as the specific shape and size of the sensor 726. Bulk capacitance (C) B It may have a capacitance value of approximately 20pF to 200pF.

[0110] From equation (1) above, it can be seen that the AC reference voltage (V) generated by the common-mode reference voltage source 730 R It is not required to be at an AC voltage (V) with conductor 722. O To achieve the same range for signal current (I) O ) and reference current (I R Similar current magnitude. By selecting a relatively high reference frequency (f R AC reference voltage (V) R The value may be relatively low (e.g., less than 5V). For example, the reference frequency (f) R The frequency (f) can be selected as 3kHz, which is higher than the signal frequency (f) of 60Hz. O Typical 120V VRMS AC voltage (V) O 50 times higher. In such cases, the AC reference voltage (V) can be... R The voltage is selected to be only 2.4V (i.e., 120V ÷ 50) to generate the signal current (I). O The same reference current (I) R Typically, the reference frequency (f) is used. R ) is set to the signal frequency (f O N times the allowable AC reference voltage (V) R ) has AC voltage (V) in line 722 O The value is (1 / N) times the value of the current (I) to produce a current (I) that is in the same range as the others. R ) and (I O ), to achieve I R and I O Similar uncertainties.

[0111] Any suitable signal generator can be used to generate a signal with a reference frequency (f). R AC reference voltage (V) R ).exist Figure 9 In the example shown, a Σ-Δ digital-to-analog converter (Σ-Δ DAC) 910 is used. The Σ-Δ DAC 910 uses a bitstream to generate a signal with a defined reference frequency (f). R ) and AC reference voltage (V R). In at least some implementations, the sigma-delta DAC 910 can generate a waveform (e.g., a sinusoidal waveform) that is in phase with the window of the FFT 906 to reduce jitter.

[0112] In at least some implementations, the ADC 902 can have a resolution of 14 bits. In operation, for a nominal 50 Hz input signal, the ADC 902 can sample the output of the input amplifier 736 at a sampling frequency of 10.24 kHz to provide 2 n samples (1024) in 100 ms (10 Hz window of the FFT 906) to be ready for processing by the FFT 906. For a 60 Hz input signal, the sampling frequency can be, for example, 12.288 kHz to obtain the same number of samples per cycle. The sampling frequency of the ADC 902 can be synchronized to the full number of cycles of the reference frequency (f R ). For example, the input signal frequency can be in the range of 40 Hz to 70 Hz. From the measured frequency of the AC voltage (V O ), the window of the AC voltage (V O ) can be determined using the FFT 906, and further calculations using a Hanning window function to suppress phase shift jitter caused by incomplete signal cycles captured in the aggregate interval.

[0113] In one example, the common mode reference voltage source 730 generates an AC reference voltage (V R ) with a reference frequency (f R ) of 2419 Hz. For a 60 Hz signal, this frequency is between the 40th and 41st harmonics, and for a 50 Hz signal, this frequency is between the 48th and 49th harmonics. By providing an AC reference voltage (V O ) with a reference frequency (f R ) that is not a harmonic of the expected AC voltage (V R ), the AC voltage (V O ) is less likely to affect the measurement of the reference current (I R ).

[0114] In at least some implementations, the reference frequency (f R ) of the common mode reference voltage source 730 is selected to be the frequency that is least likely to be affected by harmonics of the AC voltage (V O ) in the conductor under test 722. For example, when the reference current (I R) over the limit (which can indicate that the conductive sensor 726 is approaching the conductor 722 under test), the common mode reference voltage source 730 can be turned off. Measurements (e.g., 100 ms measurements) can be taken with the common mode reference voltage source 730 turned off to detect signal harmonics at a number (e.g., three, five) of candidate reference frequencies. Then, the magnitude of the signal harmonics in the AC voltage (V O ) at the number of candidate reference frequencies can be determined to identify which candidate reference frequency can be least affected by the signal harmonics of the AC voltage (V O ). The reference frequency (f R ) can then be set to the identified candidate reference frequency. This switching of the reference frequency can avoid or reduce the impact of possible reference frequency components in the signal spectrum, which can add to the measured reference signal and reduce accuracy, and can produce unstable results. Other frequencies with the same characteristics other than 2419 Hz include, for example, 2344 Hz and 2679 Hz.

[0115] Figure 11 is a block diagram of a signal processing portion 1100 of a non-contact measurement system that implements an electronic filter. The signal processing portion 1100 can receive a sensor current voltage signal (I O + I R ) from a current measurement subsystem (e.g., the input amplifier 736) that is proportional to the conductive sensor 726 current.

[0116] As described above, the signal current (I O ) has a different frequency than the reference current (I R ). To isolate the signal current (I O ) from the reference current (I R ), the signal processing portion 1100 can include a first filter 1102 to pass the signal current (I O ) and reject the reference current (I R ). The filtered signal can then be rectified by a first rectifier 1104 and digitized by a first ADC 1106. The digitized signal can be fed to a suitable processor 1108 for computation, as described above. Similarly, to isolate the reference current (I R ) from the signal current (I O ), the signal processing portion 1100 can include a second filter 1110 to pass the reference current (I R ) and reject the signal current (I O). The filtered signal can then be rectified by a second rectifier 1112 and digitized by a second ADC 1114. The digitized signal can be fed to a suitable processor 1108 for computation. The first and second filters 1102 and 1110 can be any suitable analog filter, and each can include multiple discrete components (e.g., capacitors, inductors).

[0117] Figure 12 is a schematic circuit diagram of a portion of a non-contact measurement system, such as any of the non-contact measurement systems discussed above, showing a loop formed by a common mode reference voltage source 730, a body capacitance (C B ), a coupling capacitor (C O ), a line 722, an external ground 728, and an internal ground 738.

[0118] Figure 13A is a schematic diagram of a non-contact measurement system 702 showing various leakage and stray capacitances. Generally, even with sophisticated shielding techniques, the effects of different stray capacitors seen through the system (e.g., sensor 726) cannot be completely eliminated through special sensor design and shielding methods. As discussed above, particular implementations of the present disclosure utilize a common mode reference voltage source 730 to generate a reference voltage having a reference frequency (f O ) that is different from the measured signal frequency (f R ) to compensate for the stray capacitances seen through the system.

[0119] In particular, in addition to the coupling capacitor (C O ), Figure 13A shows a body capacitance (C B ), a capacitance (C X ), a capacitance (C 传感器-参考 ), and a capacitance (C G ). The body capacitance (C B ) is in series with the coupling capacitor (C O ), and in typical applications, the body capacitance (C B ) is much larger than the coupling capacitor (C O ). Thus, the body capacitance (C B ) only affects the magnitude of the current (I O + I R ), but not the ratio of the currents (I O / I R ).

[0120] As shown in Figure 13A and Figure 14 , the capacitance (C X ) is the sensor capacitance between the conductive sensor 726 and the external ground 728. The coupling capacitor (C OThis is not the only capacitor between line 722 and sensor 726. There is also a capacitor (C) between sensor 726 and external ground terminal 728. X This is especially true for fine lines that do not essentially cover the area of ​​sensor 726. Capacitance (C) X For signal current (I) O It has a capacitive voltage divider effect and can cause AC voltage (V) to drop. O The lower voltage measurement of capacitance (C) is used. X Reduce current (I) O + I R The magnitude of ). However, the reference current (I) R Divide by the same ratio, and thus also compensate for stray capacitors (C). X Therefore, the ratio (I) O / I R Unaffected. Furthermore, to prevent any internal current from flowing outside the non-contact measurement system, as discussed above at least in some specific embodiments, the entire measurement system, except for the sensing area, can be shielded from the external environment by the reference shield 734 and connected to the output of the common-mode reference voltage source 730 to generate a reference current (I0). R ).

[0121] like Figure 13A As shown, capacitor (C) 传感器-参考 The capacitance (C) is the remaining capacitance between the reference shield 734 and the conductive sensor 726. 传感器-参考 This causes the sensor current (I) to increase. O + I R The offset of ) even without measuring the AC voltage (V) in line 706 O The sensor current also exists.

[0122] like Figure 13A and Figure 15A As shown, capacitor (C) G The capacitance (C) is the capacitance between the internal ground terminal 738 and the external ground terminal 728 or the reference potential. G ) is the reference current (I) R The parallel branch of the capacitor (C) reduces the reference current. G This causes the AC voltage (V) in line 706 to increase. O The calculation result increases. See also Figure 15B It shows the capacitance (C) G The effect of capacitance (C). Specifically, the effect of capacitance (C) G ) to I R and I O There are different effects, and therefore the effect ratio I O / I R .

[0123] (2)

[0124] (3)

[0125] (4)

[0126] (5).

[0127] As can be seen from the above equations (2)-(5), the ratio of I O / I R depends on C B / C G . When the reference screen surrounds the entire housing and sensor of the non-contact measurement system 702, the capacitance C G is much smaller.

[0128] Figure 13B An implementation is shown that provides compensation for the effect of the reference voltage (V R ) on the sensor 726 by using an inverted reference signal (-V R ) and coupling that inverted reference signal to the sensor 726. Figure 13C An exemplary sensor arrangement is shown that includes inverted reference signal compensation.

[0129] In Figure 13B , an adjustable inverting amplifier 741 is used to provide an inverted reference signal (-V R ) to the sensor 726 to compensate for the effect of the reference voltage (+V R ) on the sensor. This can be accomplished by a capacitive coupling (C C ) that is positioned in close proximity to the sensor 726. The capacitive coupling (C C ) can be in the form of a wire, screen, shield, etc. that is positioned in close proximity to the sensor. Compensation can be particularly advantageous when the insulated conductor 706 has a relatively small diameter, as in such cases the reference voltage (V R ) from the reference shield 734 can have the greatest effect on the sensor 726.

[0130] Figure 13C An exemplary sensor arrangement 739 in an implementation for providing the above-described reference signal compensation is shown. The sensor arrangement 739 includes a sensor 739a, an insulating layer 739b (e.g., Kapton ® tape), an internal ground guard 739c, an inverted reference signal layer 739d (-V R ), an insulating layer 739e, and a reference signal layer 739f (+V R ).

[0131] Figure 16 is a perspective view of an exemplary sensor and protection assembly 1600 for a non-contact measurement system, such as any of the non-contact measurement systems described above. In this example, the sensor and protection assembly 1600 includes a conductive sensor 1602, an internal ground protection 1604, and an isolation layer 1606 disposed between the sensor and the internal ground protection. Generally, the sensor assembly 1600 should provide good coupling capacitance (C O ) between the sensor 1602 and the line to be measured, and should suppress capacitance to other adjacent conductive lines and to an external ground terminal. The sensor assembly 1600 should also minimize capacitance (C 传感器-参考 ) between the sensor 1602 and a reference shield (e.g., the reference shield 734).

[0132] As a simple example, the sensor 1602, the protection 1604, and the isolation layer 1606 can each comprise a piece of foil. The protection 1604 can be coupled to a carrier (see Figure 17 ), the isolation layer 1606 (e.g., Kapton ® tape) can be coupled to the protection, and the sensor 1602 can be coupled to the isolation layer.

[0133] Figure 17 A cross-sectional view showing an example of a sensor implementation for a probe or front end 1700 of a non-contact measurement system that includes a shell layer 1702 (e.g., plastic) covering the sensor assembly 1600 to avoid direct current contact between the sensor assembly and any objects. The front end 1700 can be similar or identical to the front end 712 of the non-contact measurement system 702 shown in Figure 7A and Figure 7B . In this illustration, the sensor assembly 1600, including the sensor 1602, the protection 1604, and the isolation layer 1606, is shaped in a "U" or "V" shape to allow the sensor assembly 1600 to wrap around insulated lines of different diameters to increase the coupling capacitance (C O ) and better shield adjacent conductive objects through the protection.

[0134] In Figure 17In the illustrated example, the sensor assembly 1600 is shaped to accommodate insulated wires of various diameters, such as the relatively large diameter insulated wire 1704 or the relatively small diameter insulated wire 1706. In each case, the sensor assembly 1600 substantially surrounds the wire when the wire is positioned in the recess 1708 of the front end 1700. The walls of the front end 1700 that define the recess 1708 and that are between the sensor assembly 1600 and the wire under test can be relatively thin (e.g., 1 mm) to provide galvanic isolation while still allowing proper capacitive coupling. Because the recess 1708 has a "V" shape, the relatively thick wire 1704 has a greater distance than the relatively thin wire 1706 to reduce the width range of the coupling capacitance and also to reduce the environmental capacitance to a reduced dependence on wire diameter.

[0135] Figure 18 A front view of an arcuate front end 1800 of a non-contact measurement system is shown. The front end 1800 includes a recess 1802 defined by first and second extensions 1804 and 1806. The recess 1802 includes a relatively large upper arcuate portion 1808 that receives an insulated wire 1810 having a relatively large diameter. The recess 1802 also includes a relatively small lower arcuate portion 1812 below the portion 1808 that receives an insulated wire 1814 having a relatively small diameter. The sensor assembly 1816 shown can be similar to the sensor assembly 1600 shown and covered by the portions 1808 and 1812, and can have a shape that substantially conforms to the arcuate portions 1808 and 1812 so that the sensor assembly 1816 substantially surrounds a wire having a relatively large diameter (e.g., the wire 1810) and a wire having a relatively small diameter (e.g., the wire 1814). Figure 16 The sensor assembly 1816 shown and covered by the portions 1808 and 1812 can have a shape that substantially conforms to the arcuate portions 1808 and 1812 so that the sensor assembly 1816 substantially surrounds a wire having a relatively large diameter (e.g., the wire 1810) and a wire having a relatively small diameter (e.g., the wire 1814).

[0136] Figure 19 A perspective view of a cylindrical front end 1900 of a non-contact measurement system is shown. In this example, the front end 1900 includes a cylindrical inner ground shield 1902 having a sidewall 1904 and a front surface 1906 that can be positioned in proximity to a wire under test. The front surface 1906 of the inner ground shield 1902 includes a central opening 1908. A conductive sensor 1910 that forms a coupling capacitor (C O ) with the wire under test is recessed behind the opening 1908 of the inner ground shield 1902 to avoid capacitive coupling with adjacent objects. For example, the sensor 1910 can be recessed a distance (e.g., 3 mm) from the front surface 1906 of the inner ground shield 1902.

[0137] The sidewall 1904 of the inner ground guard 1902 can be surrounded by a cylindrical reference shield 1912 that is isolated from the inner ground guard by an isolation layer 1914. A common mode reference voltage source (e.g., voltage source 730) can be connected between the inner ground guard 1902 and the reference shield 1912 to provide the above-described functionality.

[0138] Figure 20A and Figure 20B A top view of a front end 2000 of a non-contact measurement system is shown, and Figure 21 A perspective view of a portion of the front end is shown. In this example, the front end 2000 includes an inner ground guard 2002 that includes a front surface 2004 against which a wire under test 2006 (not shown) Figure 21 ) can be positioned. The front surface 2004 includes an edge 2007, in this case rectangular, that defines an opening 2008 in the front surface. This small and long rectangular opening accommodates the wire shape, which also has a long and thin shape from the side. This again reduces the influence of adjacent wires and also greatly reduces the environmental capacitance associated with the sensor. This results in high accuracy independent of the wire size. A conductive sensor 2010 that forms a coupling capacitor (C O ) with the wire under test is recessed a distance (e.g., 3 mm) behind the opening 2008 of the front surface 2004 of the inner ground guard 2002.

[0139] The inner ground guard 2002 also includes sidewalls 2012 and 2014 that extend forward (toward the wire under test) from the side edges of the front surface 2004. This sidewall reduces sensor stray capacitance and direct reference signal coupling. The inner ground guard 2002 can also include a conductive guard ring clamp 2016 that includes a first clamp arm 2016A and a second clamp arm 2016B. The clamp arms 2016A and 2016B can be selectively moved to an open position as shown in Figure 20B to allow the wire under test to be positioned adjacent to the front surface 2004 of the inner ground guard 2002. Once the wire is in the correct position, the clamp arms 2016A and 2016B can be selectively moved to a closed position as shown in Figure 20A to provide a shield around the sensor 2010 to shield from capacitive coupling with the outside environment (e.g., adjacent conductors, adjacent objects). When in the closed position, the guard ring clamp 2016 can be substantially cylindrical in shape, for example, with a height that extends above and below the sensor 2010. The clamp arms 2016A and 2016B can be selectively moved using any suitable manual or automated actuation subsystem 2018. For example, the clamp arms 2016A and 2016B can be biased toward the closed position by springs or other biasing mechanisms that act as the actuation system 2018. Figure 20Abias that can be overcome by an operator to move the clamp arms to an open position Figure 20B such that the wire under test can be positioned proximate to a front surface 2004 of the internal ground shield 2002.

[0140] The foregoing detailed description has set forth various embodiments of the devices and / or processes via the use of block diagrams, schematics, and examples. Insofar as such block diagrams, schematics, and examples contain one or more functions and / or operations, it will be understood by those skilled in the art that each function and / or operation within such block diagrams, flowcharts, or examples can be implemented, individually and / or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, the subject matter described herein can be implemented via Application Specific Integrated Circuits (ASICs). However, those skilled in the art will recognize that the embodiments disclosed herein, in whole or in part, can be equivalently implemented by other means, e.g., one or more computer programs running on one or more computer systems, one or more programs running on one or more controllers (e.g., microcontrollers) and / or one or more programs running on one or more processors (e.g., microprocessors), as well as firmware or any combination thereof, as will be apparent to those skilled in the art. The embodiments disclosed herein can also be implemented by mechanical means, e.g., in the case of a system that does not employ software or firmware.

[0141] Those skilled in the art will recognize that many of the methods or algorithms presented herein can employ additional acts, can not employ certain acts, and / or can employ the acts in a different order than specified herein. For example, in at least some embodiments, the non-contact current measurement system can not utilize a processor to execute instructions. For example, the non-contact current measurement system can be hardwired to provide some or all of the functionality discussed herein. Additionally, in at least some embodiments, the non-contact current measurement system can not utilize a processor to cause or initiate the different functionality discussed herein.

[0142] Furthermore, those skilled in the art will appreciate that the mechanisms taught herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment applies equally to any variety of signal bearing media. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a CD-ROM, a digital tape, and a computer memory.

[0143] Various implementations can be combined to provide further implementations. To the extent not contradictory, U.S. Provisional Patent Application 62 / 421,124, filed November 11, 2016; U.S. Patent Application 15 / 345,256, filed November 7, 2016; U.S. Patent Application 15 / 413,025, filed January 23, 2017; and U.S. Patent Application 15 / 412,891, filed January 23, 2017, are incorporated by reference in their entirety.

[0144] These and other changes can be made to the implementations in light of the above Detailed Description. The terms used in the following claims should not be construed to limit the claims present application to the specific implementations disclosed in the specification and the claims are to include all modifications and equivalents thereof. Accordingly, the claims are not limited by the foregoing description, but are to be interpreted by the terms of the claims.

Claims

1. A current measurement system, comprising: An adjustable clamping assembly configured to move to clamp an insulating wire at a position within the adjustable clamping assembly; A magnetic field sensor is positioned close to the adjustable clamping assembly, wherein the adjustable clamping assembly is configured to place the insulating wire adjacent to the magnetic field sensor, wherein in operation the magnetic field sensor is configured to generate a magnetic field sensor signal indicating at least one characteristic of the current flowing through the insulating wire clamped within the adjustable clamping assembly. A position feedback sensor is configured during operation to autonomously sense the position of the insulating wire, determine the diameter of the insulating wire clamped within the adjustable clamping assembly, and generate a position feedback sensor signal indicating the diameter of the insulating wire clamped within the adjustable clamping assembly. and A control circuit, communicatively coupled to the position feedback sensor and the magnetic field sensor, wherein in operation, the control circuit is configured to: Receive the position feedback sensor signal from the position feedback sensor and the magnetic field sensor signal from the magnetic field sensor; The clamping position of the insulating wire held within the adjustable clamping assembly is determined based on the position feedback sensor signal, wherein the clamping position indicates the diameter of the insulating wire; and By taking into account the effect of the diameter of the insulating wire on the relationship between the detected magnetic field and the current flowing through the insulating wire, at least one characteristic of the current flowing through the insulating wire is determined, at least in part based on the received position feedback sensor signal and the magnetic field sensor signal. The at least one characteristic includes at least one of the magnitude or frequency of the current flowing through the insulating wire.

2. The current measurement system of claim 1, wherein the adjustable clamping assembly includes a first clamping surface and a second clamping surface, wherein the second clamping surface faces the first clamping surface, and at least one of the first clamping surface and the second clamping surface is movable toward and away from the other of the first clamping surface and the second clamping surface to clamp the insulating wire between the first clamping surface and the second clamping surface.

3. The current measurement system of claim 2, wherein the first clamping surface includes the front end surface of the front end of the housing of the current measurement system, and the second clamping surface is disposed on a clamping member movable relative to the front end surface.

4. The current measurement system of claim 3, wherein the magnetic field sensor is positioned close to the front surface of the front end of the housing.

5. The current measurement system of claim 1, wherein the adjustable clamping assembly includes a slider clamping assembly, and the position feedback sensor is configured to generate a linear position feedback signal indicating the linear position of the slider clamping assembly.

6. The current measurement system of claim 1, wherein the adjustable clamping assembly includes a first clamping portion having a first clamping surface and a second clamping portion having a second clamping surface facing the first clamping surface, and a biasing member biases the first clamping portion toward the second clamping portion.

7. The current measurement system according to claim 6, wherein at least one of the first clamping surface and the second clamping surface functions as a shield for the magnetic field sensor.

8. The current measurement system of claim 1, wherein at least one characteristic of the current flowing through the insulating wire includes the magnitude of the current flowing through the insulating wire.

9. The current measurement system according to claim 1, wherein the position feedback sensor includes a resistance sensor, a magnetoresistive sensor, a Hall effect sensor, a capacitive sensor, an inductive sensor, or an optical sensor.

10. The current measurement system according to claim 1, further comprising: A reference signal type sensor, which senses a reference signal in the insulated wire during operation without coming into contact with the current in the insulated wire. The control circuit receives the reference signal and determines, at least one characteristic of the current flowing through the insulating wire, based at least in part on the reference signal.

11. A method for measuring the current in an insulated wire without contact with the conductor current in the insulated wire, the method comprising: The insulating wire is held between the first clamping surface and the second clamping surface via an adjustable clamping assembly including a first clamping surface and a second clamping surface, such that the insulating wire is held near the magnetic field sensor; The position of the insulating wire clamped between the first clamping surface and the second clamping surface is determined autonomously via a position feedback sensor, wherein the position indicates the diameter of the insulating wire clamped between the first and second clamping surfaces; A magnetic field generated by the current flowing through the insulating wire is sensed via a magnetic field sensor, the magnetic field indicating at least one characteristic of the current flowing through the insulating wire; as well as By taking into account the effect of the diameter of the insulating wire on the relationship between the detected magnetic field and the current flowing through the insulating wire, at least one characteristic of the current flowing through the insulating wire is determined via a processor, based at least in part on the determined position of the insulating wire clamped between the first clamping surface and the second clamping surface and the sensed magnetic field generated by the current flowing through the insulating wire. The at least one characteristic includes at least one of the magnitude or frequency of the current flowing through the insulating wire.

12. The method of claim 11, wherein determining the at least one characteristic of the current flowing through the insulating wire includes determining the magnitude of the current flowing through the insulating wire.

13. The method of claim 11, further comprising: A reference signal in the insulating wire is sensed by a reference signal type sensor positioned in the housing, without contacting the current in the insulating wire; as well as The at least one characteristic of the current flowing through the insulating wire is determined via a control circuit, based at least in part on the reference signal.

14. The method of claim 13, wherein at least one physical dimension of the inner conductor of the insulated wire is further determined via the control circuit, at least in part based on the reference signal.

15. The method of claim 13, wherein at least one physical dimension of the inner conductor of the insulated wire is further determined via the control circuit, based at least in part on the reference signal and the position feedback sensor signal.

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