Apparatus and method for detecting and locating faults in shielded conductors

Abstract

An apparatus (30) and method (400) for detecting and locating an electrical fault in an insulated supply conductor (32) armored in a conductive mask (70) is disclosed. The device (30) is positioned along the insulated supply conductor (32) between the power source (36) and the electrical load (46). The conductive mask (70) is coupled to the electrical ground (55) via a first resistive element (41). A voltage (Vm) across the conductive mask (70) is sensed and compared to a threshold value (Vr) to determine if a fault condition exists. The device (30) is configured to inject an incident signal (63) into the conductive mask (70) and to detect a reflected signal (63a) from the conductive mask (70). The location of the fault condition is determined based on an elapsed time between the injection of the incident signal (63) and the detection of the reflected signal (63a).

Description

Technical Field

[0001] The present disclosure relates generally to fault detection and location, and more particularly to electrical fault detection and location in power cables. Background Art

[0002] Commercial aircraft and other applications (including industrial, commercial, and residential applications) typically include an electrical power distribution system. The purpose of the electrical power distribution system is to distribute electrical power to the loads, protect the lines and loads from hazards, and route the most appropriate power source to each load.

[0003] Such electrical power distribution systems typically include insulated conductive cables to transmit signals (such as power or data signals) from a source to a destination (such as a device or application). These cables are subject to damage or degradation during the life cycle of the power distribution system. For example, wire wear due to wire handling during maintenance operations, or wire corrosion due to exposure to moisture can cause damage or degradation, which can cause failures or faults in the cable. Typically, the device or application is taken offline to locate the fault within the length span of the cable and provide for repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] In the figure:

[0005] Figure 1 is a schematic diagram of an aircraft with a power distribution system having wiring distributed throughout the aircraft.

[0006] Figure 2 is a schematic diagram of a fault detection and localization device according to aspects as described herein.

[0007] Figure 3 is a schematic diagram of another fault detection and localization device according to aspects as described herein.

[0008] Figure 4 A flow chart depicting a method for detecting and locating faults according to aspects as described herein. DETAILED DESCRIPTION

[0009] Aspects of the present disclosure relate to fault detection and location devices. For purposes of illustration, the present disclosure will be described with respect to a power distribution system for an aircraft. The disclosure may have applicability in a variety of power distribution systems and may be used to provide benefits in other industrial, commercial, military, and residential applications. Other non-limiting examples of other vehicles or engines to which the disclosure may relate may include ships, helicopters, cars, or other water, air, space, or land vehicles. Disclosed industrial, commercial, or residential applications may include, but are not limited to, marine power devices, wind turbines, hybrid motors, or small power devices. However, it will be understood that the present disclosure is not so limited and may have general applicability in non-aircraft applications, such as other fault detection requirements in non-aircraft power distribution applications.

[0010] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless explicitly identified otherwise, all aspects described herein should be considered exemplary.

[0011] As used herein, the terms "first", "second" and "third" can be used interchangeably to distinguish one component from another, and are not intended to represent the position or importance of an independent component. The singular forms "one", "an" and "the" include plural references unless the context clearly indicates otherwise. In addition, as used herein, the terms "group" or a "group" of elements can be any number of elements (including only one). All directions refer to (for example, radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, rear, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, rear portion, etc.) only for identification purposes, to help readers understand the present disclosure, and do not generate restrictions, particularly do not generate restrictions on the position, orientation or use of the present disclosure.

[0012] Connection references (eg, attached, coupled, connected, and joined) are to be construed broadly and may include intermediate components between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other.

[0013] As used herein, an element of "electrical connection", "electrical coupling" or "signal communication" includes an electrical transmission or signal sent, received or transmitted to or from such connection or coupling elements. In addition, such electrical connection or coupling may include a wired or wireless connection, or a combination thereof. In a non-limiting example, the connection or disconnection may be selectively configured to provide, enable, disable, etc., electrical connections between corresponding elements. The non-limiting example electrical connection or disconnection may be enabled or operated via switching, bus connection logic or any other connector, which is configured to enable or disable the excitation of the electrical load connected downstream. Additionally, although terms such as "voltage", "current" and "power" may be used herein, it will be apparent to those skilled in the art that these terms may be interrelated when describing aspects of circuits or circuit operations.

[0014] As used herein, a controllable switching element or "switch" is an electrical device that is controllable to switch between a first operating mode in which the switch is "closed" to transfer current from the switch input to the switch output, and a second operating mode in which the switch is "open" to prevent current from being transferred between the switch input and the switch output. In a non-limiting example, a connection or disconnection (such as a connection enabled or disabled by a controllable switching element) can be selectively configured to provide, enable, disable, etc., an electrical connection between corresponding elements.

[0015] As used herein, a "controller" (e.g., a "control module," "regulator module," and "integrator module") includes a component configured or adapted to provide instructions, control, operation, or any form of communication to an operable component to affect its operation. Such controllers or modules may include any known processor, microcontroller, or logic device, including, but not limited to, a field programmable gate array (FPGA), a complex programmable logic device (CPLD), an application specific integrated circuit (ASIC), a full authority digital engine controller (FADEC), a proportional controller (P), a proportional integral controller (PI), a proportional differential controller (PD), a proportional integral differential controller (PID), a hardware accelerated logic controller (e.g., for encoding, decoding, code conversion, etc.), etc., or a combination thereof. Although described herein as including separate elements, in non-limiting aspects, such controllers and modules may be incorporated on one or more devices, which include a common device, such as a single processor or microcontroller. Non-limiting examples of such controllers or modules may be configured or adapted to run, operate or otherwise execute program code to achieve operational or functional results, including performing various methods, functionalities, processing tasks, calculations, comparisons, sensing or measurement of values, etc., to achieve or complete technical operations or operations described herein. The operational or functional results may be based on one or more inputs, stored data values, sensed or measured values, true or false indications, etc. Although "program code" is described, non-limiting examples of operable or executable instruction sets may include routines, programs, objects, components, data structures, algorithms, etc. that have the technical effect of performing specific tasks or implementing specific abstract data types. In another non-limiting example, the controller module, regulator module or integrator module may also include a processor-accessible data storage component, which includes a memory, whether a conversion memory, a volatile memory or a non-transient memory, or a non-volatile memory. Additional non-limiting examples of memory may include random access memory (RAM), read-only memory (ROM), flash memory, or one or more different types of portable electronic memory, such as disks, DVDs, CD-ROMs, flash drives, universal serial bus (USB) drives, etc., or any suitable combination of these types of memory. In one example, program code may be stored in the memory in a machine-readable format accessible to the processor.

[0016] Additionally, the memory may store various data, data types, sensed or measured data values, inputs, generated or processed data, etc., which the processor can access when providing instructions, controlling or operating to achieve functions or operational results, as described herein. In another non-limiting example, the control module may include comparing a first value with a second value, and operating or controlling the operation of an additional component based on the satisfaction of the comparison. For example, when the sensed, measured or provided value is compared with another value (including a stored or predetermined value), the satisfaction of the comparison may result in an action, function or operation controllable by the controller module. As used herein, the term "satisfaction" or "satisfaction" of the comparison means that the first value satisfies the second value, such as being equal to or less than the second value, or within the value range of the second value. It will be understood that such determinations can be easily changed to be satisfied by positive / negative comparisons or true / false comparisons. Example comparisons may include comparing the sensed or measured value with a predetermined threshold value or a threshold value range.

[0017] As used herein, the term “electrically insulating” or “insulator” refers to a material that exhibits low electrical conductivity (eg, less than about 10 −8 Siemens / meter (S / m)).

[0018] As used herein, the term "ground" or "electrical ground," or "system ground" refers to a reference point in an electrical circuit from which voltage may be measured or referenced. As used herein, a "ground" will provide a common return path for electrical current. For example, in the context of a power system in an aircraft, in some cases, the "electrical ground" may be the internal metal landing gear, or the external frame of the body of the aircraft itself. It will be appreciated that an element coupled to an electrical ground via a resistive element or impedance is considered to be electrically isolated relative to the electrical ground.

[0019] In addition, as used herein, sensors may be described as "sensing," "monitoring," or "measuring" a corresponding value. As used herein, sensing, monitoring, or measuring includes determining a value indicative of or associated with a corresponding value, rather than directly sensing or measuring the corresponding value itself. The sensed, monitored, or measured value may be further provided to an additional component. For example, a signal indicative of a particular sensed, monitored, or measured value may be provided to a controller module or processor, and the controller module or processor may perform processing based on the signal to determine a representative value or an electrical characteristic representative of the value.

[0020] The disclosed aspects may be implemented in any circuit environment having switches and adapted or configured to determine impedance or electrical fault characteristics in a conductor or electrical load during normal transmission operation (e.g., when the circuit is energizing the electrical load or when data transmission occurs). In other words, the disclosure may be implemented while the circuit is in operational use for its intended purpose, and the circuit is not "removed" for use in performing determined normal or routine operations. For example, a power distribution system in a "test mode" or "maintenance operation" is not "in operational use," whereas a power distribution system of an aircraft is "in operational use" during flight and energizing a set of electrical loads via the power distribution system.

[0021] In many cases, conventional aircraft and industrial applications may be electrically noisy environments. Electrical noise can typically radiate or conduct as electromagnetic interference (EMI), and can disrupt the correct operation of connections and nearby equipment. Typically, conductive power cables can be the main transmission source of EMI, both as a source and as a receiver. As a source, the cable can conduct EMI to nearby equipment, or act as an antenna for radiated noise. As a receiver, the cable can receive or pick up EMI radiated from other sources. Although the electrical insulation on the conductor (such as a cable) can mechanically protect the conductor from wear and environmentally protect the conductor from moisture, the electrical insulation is permeable to electromagnetic energy and does not provide protection or shielding from EMI. Therefore, conventional power distribution circuits often use so-called "shielded cables" or "armored cables". Shielded cables typically have a central signal or power carrying main conductor, which is arranged in an electrically insulating outer layer and is further surrounded by an EMI shielding layer to reduce the impact of EMI. Typically, the shielding layer surrounds the insulating main conductor and can reduce EMI by reflecting energy, conducting energy to a ground portion, or both.

[0022] Conventional shielded cables typically employ foil shields, braided (or meshed) conductive shields, or combinations thereof. The foil shield is typically a thin layer of a conductor (e.g., aluminum) attached to an insulating carrier (e.g., polyester) and circumferentially wraps around the main conductor or wire. The braided conductive shield is typically a woven mesh formed as a tubular sheath of bare copper wire or tinned copper wire that provides a low impedance path (e.g., short circuit) to ground. In some cases, unshielded insulated cables may be routed through a braided conductive sheath or shield that may act as an EMI shield. A low impedance drain wire is typically connected to the sheath to electrically couple or short the sheath directly to ground.

[0023] Shielded cables can reduce line damage in the event of an electrical fault, and can further achieve deterministic fault detection. For example, a time domain reflectometer (TDR) device is commonly used to locate faults or interruptions (e.g., open circuits) in armored cables. TDR devices are typically arranged to sense or measure reflections or echoes of low voltage pulses or incident signals provided to the internal main conductor in the shielded cable. In order to measure those reflections, the TDR device will transmit the incident signal to the conductor and listen to its reflections. If the conductor has a relatively consistent impedance along its length, there will be no reflection. On the contrary, if there is an impedance change, such as a discontinuity in the conductor, some of the incident signal will be reflected back to the TDR device from the discontinuity. The impedance of the discontinuity can be determined from the amplitude of the reflected signal. The distance to the reflected impedance can also be determined from the time it takes for the reflected signal to return.

[0024] For example, a conventional TDR device may have two leads; one lead is connected to the main conductor, and the other lead is connected to a conductive sheath electrically connected to a ground portion. The main conductor and the surrounding conductive sheath can be regarded as two conductors in parallel. Typically, the TDR device will send a low voltage pulse into the main conductor, and will sense the reflected signal returned to the TDR device. The reflection of the low voltage pulse is caused by a change in impedance, such as an interruption or discontinuity between two parallel conductors (e.g., the main conductor and the grounded conductive sheath). For example, a low voltage pulse travels from the TDR device through the main conductor and will be positively reflected at any interruption point (open circuit) in the main conductor or at the end of the cable, and will be negatively reflected at a short circuit point in the main conductor.

[0025] Conventional TDR devices can additionally be used to identify the location of a fault or interruption in a primary conductor. For example, a TDR device typically measures the elapsed time between releasing a low voltage pulse at a known propagation velocity and returning (i.e., reflecting) the low voltage pulse back to the TDR device. By knowing the propagation velocity and measuring the elapsed time, the distance to the reflection (e.g., the interruption or fault location) can be easily calculated.

[0026] However, in some cases, it can be challenging to locate faults in shielded cables using conventional techniques. For example, in order to locate a fault using an electronic device such as a conventional TDR device, it is typically necessary to disconnect the cable associated with the fault. Additionally, due to the uncontrolled impedance and non-constant propagation speed in conventional unshielded feeder cables, conventional devices and techniques often do not provide sufficiently accurate indications of the fault location. In addition, the process of disconnecting and interfering with the cable harness can also lead to the introduction of more faults. Therefore, it would be desirable to have improved devices and methods to detect and locate faults in power transmission cables when in operational use. For example, a device for detecting and locating faults along wiring within a power distribution system without disconnecting the wiring from a power source or load can be advantageous for maintenance and safety. Aspects of the present disclosure discussed herein provide improved detection and location systems for faults in electrical power transmission lines or cables such as in aircraft. Non-limiting examples of electrical environments that may include aspects of the disclosure may include an aircraft power system architecture that enables the generation of electrical power from at least one rotating shaft of a turbine engine (preferably a gas turbine engine) and the delivery of the electrical power to a set of electrical loads via at least one solid-state switch (such as a solid-state power controller (SSPC) switching device).

[0027] As used herein, TDR refers to a method or apparatus for measuring the reflection of a waveform or signal along a shielded conductor. TDR may include transmitting a pulse signal (e.g., an "incident signal") to a conductor, and then detecting, receiving, measuring, etc., a reflection of the incident signal (e.g., a "reflected incident signal"). Based on various parameters, the location of a fault in a conductor may be determined. Such parameters may include, but are not limited to, the propagation velocity (VoP) of the incident signal, the impedance of the conductor, the time to receive a reflection of the incident signal, the length of the conductor or the end points of the conductor (e.g., electrical load), the end points, the fault location, or a combination thereof.

[0028] Reference will now be made in detail to the present aspects of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and the specification are used to refer to like or similar parts of the disclosure.

[0029] Figure 1An aircraft 2 is shown, which may also include a fuselage 4, a cockpit 6 positioned in the fuselage 4, and wing assemblies 8 extending outwardly from the fuselage 4. The aircraft 2 may also include a plurality of engines, including a turbine engine 10, which may be a turbojet engine, a turbofan engine, or a turboprop engine, as non-limiting examples. Although a commercial aircraft 2 is shown, it is contemplated that the disclosed aspects described herein may be used in any type of aircraft 2. Furthermore, while two turbine engines 10 are shown on each of the wing assemblies 8, it will be understood that any number of turbine engines 10 may be included, including a single turbine engine 10 on the wing assembly 8, or even a single turbine engine mounted in the fuselage 4.

[0030] The power distribution system 12 is shown in phantom. The power distribution unit 14 may be coupled to at least one generator 16 via a main power supply 18 to receive electrical power. It is contemplated that the power distribution unit 14 may be coupled to multiple generators 16, as shown. The power distribution unit 14 may then distribute power throughout the aircraft via electrical wires 20 depending on the load requirements of different operating systems. An aircraft structure 22 (e.g., landing gear or fuselage) may be used as a return line (e.g., system ground) for certain operating systems. It should be understood that other unit arrangements for different aircraft engine arrangements will also benefit from the disclosed aspects disclosed herein, and the exemplary electrical wires 20 are for illustrative purposes only and are not meant to be limiting.

[0031] Figure 2 is an exemplary fault detection and location device 30 that may be used in the power distribution system 12. The power distribution system 12 may include a power supply 36 configured to provide a supply voltage Vs to an electrical load 46, such as a resistive load, via the insulated supply conductor 32. The electrical load 46 may be any type of electrical load, such as in an aircraft, including but not limited to auxiliary hydraulic pumps, fuel boost pumps, lighting, avionics, ice and rain protection, commercial loads, and cargo loading.

[0032] The power supply 36 may include any number of power sources or aircraft architecture topologies and may be associated with multiple voltages. As non-limiting examples, a 28Vdc or 270Vdc system may be distributed by the insulated supply conductors 32 and returned through the electrical ground 55. In other non-limiting aspects, the power supply 36 may be a 115Vac system and may be distributed as three-phase or single-phase and returned through the electrical ground 55.

[0033] In non-limiting aspects, the power source 36 may be selectively coupled to the insulated supply conductor 32 via the switch 44 to provide a supply voltage Vs to the electrical load 46. The fault detection and locating device 30 may be coupled to the insulated supply conductor 32 between the power source 36 and the electrical load 46. It will be appreciated that in operation, the supply voltage Vs provided to the insulated supply conductor 32 at the supply end 38 may result in a load voltage VL at the load end 48.

[0034] The fault detection and locating device 30 may be disposed at any suitable location along the supply conductor 32. The fault detection and locating device 30 may be electrically coupled to the electrical load 46 via the insulated supply conductor 32. A first conductive shield 70 or shield circumferentially surrounds the insulated supply conductor 32 and is spaced from the insulated supply conductor 32 by an insulator (not shown) disposed between the insulated supply conductor 32 and the first conductive shield 70.

[0035] The fault detection and location apparatus 30 may include a control module 50, a protection device 34, a first reflectometer module 61, a first voltage sensor 51, a first reflective line 64, a first resistive element 41, and a second resistive element 42. The first reflectometer module 61 may include a first signal generator 66 and a first pulse detector 65. The first reflectometer module 61 may be electrically coupled to the first conductive shield 70. The first signal generator 66 is configured to generate a first incident signal 63 (indicated by a dashed arrow), such as a voltage pulse. The pulse detector is configured to detect a first reflected signal 63a. The first reflected signal 63a (indicated by a dashed arrow) may be a portion of the first incident signal 63 that is reflected back toward the first reflectometer module 61 (e.g., due to a fault condition). The first pulse detector 65 is communicatively coupled to the control module 50 via a communication line 67.

[0036] The fault detection and locating device 30 may be electrically coupled to the power supply 36 to receive a supply voltage Vs relative to the electrical ground 55 or a return path therefrom. The protection device 34, the first reflectometer module 61, and the first voltage sensor 51 may be communicatively coupled to the control module 50. The fault detection and locating device 30 may optionally be communicatively coupled to a user interface 57 such as a display or monitor. The user interface 57 may be in a remote location physically separated from other parts of the fault detection and locating device 30.

[0037] The insulated supply conductor 32 may be a conventional insulated conductive cable or wire. For example, in one non-limiting aspect, the insulated supply conductor may include an M27500 component wire SAE WC27500 cable. In other non-limiting aspects, the insulated supply conductor 32 may be insulated using any desired electrical insulation or dielectric material without departing from the scope of the present disclosure. In non-limiting aspects, the insulated supply conductor 32 may include a cable of any desired size (e.g., American Wire Gauge (AWG)), and may range, for example, from 1 AWG to 26 AWG. The insulated supply conductor 32 may extend between a first end and a second end, wherein the first end is a load end 48 at an electrical load 46 and the second end is a supply end 38 at a power source 36. The load end 48 may be at an end of the insulated conductor 32 opposite to the supply end 38.

[0038] The insulated supply conductor 32 may be coupled to the protection device 34 at the supply end 38. The protection device 34 may be electrically coupled between the power source 36 and the insulated supply conductor 32. The protection device 34 may be communicatively coupled with the control module 50. The protection device 34 may include a switch 44, such as a circuit breaker, a contactor, a solid state power controller (SSPC), etc. In some non-limiting aspects, the protection device 34 may include a transistor (not shown).

[0039] The first conductive shield 70 may circumferentially surround the insulated supply conductor 32 and may extend from the supply end 38 to the load end 48. In non-limiting aspects, the insulated supply conductor 32 and the first conductive shield 70 may be embodied in a conventional shielded insulated cable. However, as described herein, unlike conventional reflectometer arrangements, the first conductive shield 70 may be electrically isolated from the electrical ground 55 (e.g., the aircraft structure 22 or the landing gear) via a predetermined relatively high impedance path.

[0040] The control module 50 may include a processor 71, a memory 72, and a communication module 73. The control module 50 may be a system of controllers or a single controller. In some non-limiting aspects, the control module 50 may include a SSPC. The processor 71 may be configured to perform a variety of computer-implemented functions and / or instructions (e.g., perform methods, steps, calculations, etc. as disclosed herein and store related data). When executed by the processor 71, the instructions may cause the processor 71 to perform operations as described herein. The control module 50 may be communicatively coupled to one or more of the protection device 34, the first reflectometer module 61, the first signal generator 66, and the first pulse detector 65, and is configured to control their respective operations.

[0041] The first signal generator 66 and the first pulse detector 65 may be electrically coupled to the first conductive shield 70 at the supply end 38 via the first reflective line 64. Optionally, an isolation capacitor C1 may be electrically coupled in series along the first reflective line 64. In non-limiting aspects, a first source impedance 75 having a known value or a predetermined value may be electrically coupled in series between the first signal generator 66 and the first conductive shield 70. The value of the first source impedance 75 may be selected based on the impedance of the first conductive shield 70. While aspects of the first signal generator 66 may include a standard step or pulse signal generator, it will be appreciated that non-limiting aspects may alternatively include other drivers or signal generators as desired without departing from the scope of the present disclosure. For example, in other aspects, the first reflectometer module 61 may include or be adapted to include a more complex driver arrangement, such as a frequency domain reflectometer (FDR), a spread spectrum time domain reflectometer (SSTDR), a noise domain reflectometer (NDR), etc., without departing from the scope of the present disclosure.

[0042] The first resistive element 41 is electrically coupled in series between the first conductive shield 70 at the supply end 38 and the electrical ground 55, which may be the aircraft structure 22 (e.g., landing gear) as a non-limiting example. The first resistive element 41 may define a relatively high impedance path from the first conductive shield 70 to the electrical ground 55. In a non-limiting aspect, the first resistive element 41 may be a first voltage divider including a first resistor R1 of known resistance electrically coupled in series with a third resistor R3 of known resistance at a node 41a. The first conductive shield 70 may be said to be coupled to the electrical ground 55 via the high impedance path via the first resistive element 41.

[0043] The second resistive element 42, such as a first resistor R2 of known resistance, is electrically coupled to the insulated supply conductor 32 at the load end 48 and is electrically coupled to the first conductive shield 70 at the load end 48. The first voltage sensor 51 is arranged to detect, measure, or otherwise sense a measured voltage Vm indicative of a voltage across the first conductive shield 70. For example, in a non-limiting aspect, the first voltage sensor 51 may be electrically coupled in parallel with the first resistor R1 such that a voltage across the first resistor R1 may be sensed as the measured voltage Vm during operation.

[0044] In operation, the fault detection and locating device 30 can determine whether a fault condition exists with respect to the insulated supply conductor 32, the first conductive shield 70, or both. When the fault detection and locating device 30 determines that the fault condition exists between the insulated supply conductor 32 and the first conductive shield 70, the fault detection and determining device 30 is also configured to determine the location of the fault condition. For example, in a non-limiting aspect, the fault detection and locating device 30 can be configured to determine whether the fault condition exists on the insulated supply conductor 32 or the first conductive shield 70 or both based on a comparison of the measured voltage Vm with a reference voltage Vr or a threshold value (not shown). The reference voltage Vr or the threshold value can be predetermined and stored in the memory 72. In one non-limiting example, during normal operation, the power supply 36 is operative to provide a supply voltage Vs of a known value relative to the electrical ground 55 to the electrical load 46 via the insulated supply conductor 32. The current supplied to the electrical load 46 (indicated by the dashed arrow 37) can be a known amount based on the known supply voltage Vs, the known electrical load 46, and the known values ​​of the first and second resistance elements 41 and 42. The respective resistance values ​​of the first and second resistance elements 41 and 42 can be predetermined or selected based on a calculated or determined reference voltage Vr (not shown). The reference voltage Vr can be calculated, derived, or otherwise determined based on the known supply voltage Vs at the supply end 38 and the load voltage VL at the load end 48. For example, the reference voltage Vr can be a fraction of the amount of the supply voltage Vs at the supply end 38 or the load voltage VL at the load end 48. For example, in non-limiting aspects, the reference voltage Vr can be 1 / 3 of the supply voltage Vs. In other non-limiting aspects, the reference voltage Vs can be 1 / 3 of the load voltage VL at the load end 48. In some aspects, the reference voltage Vr can be defined by a range. It will be appreciated that because the reference voltage Vr is based on the supply voltage Vs and the load voltage VL, the value of the reference voltage Vr will depend on the particular circuit to which the first voltage sensor 51 is connected, and may therefore be any desired voltage or range of voltages in various aspects.

[0045] In operation, the first voltage sensor 51 measures or senses the measured voltage Vm, for example, by sensing the measured voltage Vm across the first resistor R1. The measured voltage Vm across the first resistor R1 may indicate the voltage across the first conductive shield 70. The first voltage sensor 51 may sense the value of the voltage Vm and provide a first signal 52 indicating the sensed value of the voltage Vm to the control module 50.

[0046] In some non-limiting aspects, under normal operating conditions, the measured voltage Vm may meet or be equal to the reference voltage Vr. However, in the case where the insulated supply conductor 32 or the first conductive shield 70 is damaged or broken, the measured voltage Vm may no longer be equal to the reference voltage Vr. For example, in the case where the insulated supply conductor 32 is damaged or broken, a high impedance or serial arc fault may occur. In this case, the measured voltage Vm will be less than the reference voltage Vr. In the case where the first conductive shield 70 is damaged or broken, a short circuit to ground will occur. In this case, the measured voltage Vm will be less than the reference voltage Vr. In the case where the insulated supply conductor 32 includes a short circuit to ground, the measured voltage Vm will have a value less than the reference voltage Vr. In the case where the insulated supply conductor 32 is damaged and the damaged portion is within the first conductive shield 70, a parallel arc may occur. In this case, the measured voltage Vm will be greater than the reference voltage Vr.

[0047] In such cases of a fault or failure event of the insulated supply conductor 32, the first voltage sensor 51 will sense a measured voltage Vm that deviates from a reference voltage Vr. In this sense, the reference voltage Vr can be considered a threshold voltage. In aspect, the control module 50 can be configured to determine the occurrence of a fault event or condition based on the value of Vm indicated by the first signal 52, for example, by comparing the value of Vm indicated by the first signal 52 with a threshold value (such as the reference voltage Vr) that can be stored in the memory 72. For example, the control module 50 can compare the value of the measured voltage Vm with the reference voltage Vr or a threshold value, and determine that a fault condition exists when the value of the measured voltage Vm deviates from the value of the reference voltage Vr, or otherwise satisfies the threshold value. The threshold value can be selected as a predetermined level to minimize erroneous or inadvertent indications of a fault condition by the control module 50. For example, the control module 50 can be configured to determine that a fault condition exists only when the measured voltage Vm deviates from the reference voltage Vr by more than a predetermined threshold amount.

[0048] In the event that the control module 50 determines that a fault condition exists, the control module 50 may further provide instructions to the user interface 57 to display or otherwise indicate that the fault condition exists. For example, the indication that the fault condition exists may be one of a light, an audible signal, or a processor output. In non-limiting aspects, the indication that the fault condition exists may include the value of the measured voltage Vm.

[0049] Additionally, or alternatively, in non-limiting aspects, in the event that the control module 50 determines that a fault condition exists, the control module 50 may be further configured to send a second signal 53 to the protection device 34 to trip the protection device or transition from a closed or conducting state to an open or non-conducting state. For example, in response to the second signal 53 received from the control module 50, the switch 44 may be capable of switching between an open state or a closed state (not shown). It will be appreciated that when the switch 44 is in the closed state, the supply voltage Vs is transmitted to the insulated supply conductor 32, and when the switch is in the open state, the supply voltage Vs is cut off or blocked from the insulated supply conductor 32 and the electrical load 46. The situations described herein are for illustrative purposes only and are not meant to be limiting. The situation may be any situation in which a fault in the insulated supply conductor 32 is detected.

[0050] In the event that the control module 50 determines that a fault condition exists, the control module 50 may be further configured to determine the location of the fault condition. For example, in a non-limiting aspect, in the event that the control module 50 determines that a fault condition exists, the control module 50 may be further configured to trigger injection of the first incident signal 63 to the first conductive shield 70 through the first signal generator 66. The first signal generator 66 may provide the first incident signal 63 to the first conductive shield 70 via the first reflective line 64. In a non-limiting aspect, the first incident signal 63 may be provided by the first source impedance 75 or the isolation capacitor C1 or both. The characteristics of the first incident signal 63 may be predetermined or selected based on any number of parameters that are specific to a particular power distribution system 12, supply conductor 32, first conductive shield 70, or a combination thereof. It is contemplated that the first incident signal 63 may include any desired predetermined duration (e.g., 2.3 milliseconds), rise time (e.g., 20 picoseconds), shape (e.g., square, rectangular, Gaussian, etc.), and amplitude (e.g., 5 volts) without departing from the scope of the present disclosure.

[0051] The first incident signal 63 will propagate over the first conductive shield 70 at a known or predetermined propagation speed toward the electrical load 46. As will be appreciated, when a fault condition exists on the insulated supply conductor 32, the conductive shield, or both, a portion of the first incident signal 63 will be reflected from the fault back to the first reflectometer module 61 as a first reflected signal 63a. In non-limiting aspects, the isolation capacitor C1 may block DC signals but allow the first reflected signal 63a to pass through to the first pulse detector 65. The first reflected signal 63a may be detected by the first pulse detector 65. The first reflectometer module 61 may provide an indication of the first reflected signal 63a to the control module 50. In non-limiting aspects, the indication of the first reflected signal 63a may include an indication of a waveform or other characteristic of the first reflected signal 63, or an indication of the elapsed time between injection of the first incident signal 63 and detection of the first reflected signal 63a, or both.

[0052] Based on the indication of the first reflected signal 63a, the control module 50 may be configured to determine the first elapsed time between the injection of the first incident signal 63 and the detection of the first reflected signal 63a. The control module 50 may further determine the location of the fault condition based on the first elapsed time. In non-limiting aspects, the control module 50 may additionally or alternatively provide instructions to the user interface 57 to display information indicating the first reflected signal 63a (e.g., the waveform of the first reflected signal 63a), the elapsed time, or both. For example, the information may include a determined location of the fault condition relative to the insulated supply conductor 32. In some aspects, the user may determine the location of the fault condition by viewing the information displayed by the user interface 57. In non-limiting aspects, the control module 50 may additionally or alternatively provide instructions to the user interface 57 to display information indicating the indication of the second reflected signal 183a. In some aspects, the user may determine the location of the fault condition by viewing the information displayed by the user interface 57.

[0053] Although for ease of understanding Figure 2 However, other aspects are not so limited with respect to the detection and location of faults on a single insulated supply conductor 32 surrounded by a first conductive shield 70. For example, other aspects contemplate fault detection and location on a shielded cable that is disposed with a group of shielded cables within a conductive overbraid or shield.

[0054] Figure 3 Another arrangement of a fault detection and locating device 130 according to another aspect is shown. The fault detection and locating device 130 may be provided at any suitable location along an electrical line (not shown), for example along an insulated supply conductor 32, such as an insulated shielded cable. Figure 3 Similar to Figure 2 In an aspect of the present invention, the insulated supply conductor 32 is circumferentially surrounded by a corresponding first conductive shield 70 extending from the supply end 38 to the load end 48. Figure 2 A significant difference in the aspects of the invention is that the insulated supply conductors 32 are bundled together with a set of shielded insulated supply conductors 33 that are each circumferentially surrounded by a corresponding first conductive shield 70 within a conductive overbraid or second conductive shield 80. The second conductive shield 80 is electrically coupled to an electrical ground 55, such as an aircraft structure 22. The second conductive shield 80 may define a known or predetermined impedance. The grounded second conductive shield 80 enables yet another TDR capability with respect to the fault detection and locating device 130 to locate a short circuit fault condition between the corresponding first conductive shield 70 surrounding the corresponding insulated supply conductor 32 and the electrical ground 55.

[0055] Figure 3 Aspects and Figure 2 Another significant difference from the aspects depicted in FIG. 1 is that, as shown, the fault detection and locating device 130 may optionally include an auxiliary switching device 45. The auxiliary switching device 45 may be electrically coupled to the power source 36 to receive the supply voltage Vs from the power source 36. The auxiliary switching device 45 may also be coupled to the insulated supply conductor 32 via a second reflective line 184. In a non-limiting aspect, a second source impedance 175 having a known value or a predetermined value may be electrically coupled in series between the auxiliary switching device 45 and the insulated supply conductor 32. For example, the value of the second source impedance 175 may be selected based on the impedance of the insulated supply conductor 32.

[0056] Additionally, aspects of the fault detection and location apparatus 130 may include a second reflectometer module 162, which may include a second pulse detector 185. The second pulse detector 185 is communicatively coupled to the control module 50 via the communication line 68. The second reflectometer module 162 is communicatively coupled to the second reflectance line 184. The control module 50 is communicatively coupled to the auxiliary switching device 45 and the second reflectometer module 162.

[0057] In a non-limiting aspect, in the event that the control module 50 determines that a fault condition exists, the control module 50 may be further configured to provide a third signal 54 to the auxiliary switching device 45 to trigger operation of the auxiliary switching device 45 to inject a second incident signal 183 (indicated by a dashed arrow), such as a voltage pulse, into the insulated supply conductor 32. The auxiliary switching device 45 may provide the second incident signal 183 to the insulated supply conductor 32 via a second reflective line 184. In a non-limiting aspect, the second incident signal 183 may be provided by a second source impedance 175. In a non-limiting aspect, the auxiliary switching device 45 may include any desired switching device (e.g., a MOSFET) that is selectively operable to provide a second incident signal 183 having a predetermined waveform. For example, in the illustrated non-limiting aspect, the auxiliary switching device 45 may provide a fast-rising voltage pulse (e.g., rising from zero volts to a supply voltage Vs) for a desired wavelength (e.g., 2.5 milliseconds). The characteristics of the second incident signal 183 may be selected based on any number of parameters that are specific to a particular power distribution system 12 and supply conductor 32. It is contemplated that the second incident signal 183 may include any desired predetermined duration (e.g., 2.5 milliseconds), rise time (e.g., 20 picoseconds), shape (e.g., square, rectangular, Gaussian, etc.), and amplitude (e.g., 5 volts) without departing from the scope of the present disclosure.

[0058] The second incident signal 183 will propagate on the insulated supply conductor 32 at a known or predetermined propagation speed toward the electrical load 46. Because the second resistive element 42 is coupled to the insulated supply conductor 32 at the load end 48 and to the first conductive shield 70 at the load end 48, the second incident signal 183 will propagate through the second resistive element 42 and into the first conductive shield 70. As will be appreciated, in the event that a short circuit fault condition exists between the respective first conductive shield 70 surrounding the respective insulated supply conductor 32 and the electrical ground 55, a portion of the second incident signal 183 will be reflected from the fault back to the second reflectometer module 162 as a second reflected signal 183a. The second reflected signal 183a may be detected by the second pulse detector 185. The second reflectometer module 162 may provide an indication of the second reflected signal 183a to the control module 50. In non-limiting aspects, the indication of the second reflected signal 183a may include an indication of a waveform of the second reflected signal 183a, or an indication of a second elapsed time between injection of the second incident signal 183 and detection of the second reflected signal 183a, or both.

[0059] Based on the indication of the second reflected signal 183a, the control module 50 may determine the second elapsed time between the injection of the second incident signal 183 and the detection of the second reflected signal 183a. Additionally, the control module 50 may determine the location of the short circuit fault condition based on the second elapsed time. In non-limiting aspects, the control module 50 may additionally or alternatively provide instructions to the user interface 57 to display information indicating the second reflected signal 183a (e.g., the waveform of the second reflected signal 183a), the second elapsed time, or both. In non-limiting aspects, the display may include the location of the fault condition relative to the insulated supply conductor 32. In some aspects, the user can determine the location of the fault condition by viewing the information displayed by the user interface 57.

[0060] Figure 4 A non-limiting example of a method 400 for locating a fault in an insulated supply conductor 32 in a power distribution system 12 is shown. Although for ease of understanding, reference will be made to Figure 1 The power distribution system and Figure 2The method 400 is described with reference to the fault detection and locating device 30 of FIG. 1 , but aspects of the method 400 are not so limited and may be implemented in other power distribution systems without departing from the scope of the present disclosure. The power distribution system 12 may include a power supply 36 configured to provide a supply voltage Vs to an electrical load 46 via an insulated supply conductor 32. The fault detection and locating device 30 may be disposed at any suitable location along the supply conductor 32. The fault detection and locating device 30 may be electrically coupled to the electrical load 46 via the insulated supply conductor 32. A first conductive shield 70 may circumferentially surround the insulated supply conductor 32, wherein an insulator is disposed between the insulated supply conductor 32 and the first conductive shield 70.

[0061] The fault detection and location device 30 may include a control module 50, a protection device 34, a first reflectometer module 61, a first voltage sensor 51, a first reflection line 64, a first resistive element 41, and a second resistive element 42. The first reflectometer module 61 may include a first signal generator 66 and a first pulse detector 65. The first reflectometer module 61 may be electrically coupled to the first conductive shield 70. The first signal generator is configured to generate a first incident signal 63. The first pulse detector 65 is configured to detect a first reflected signal 63a. The fault detection and location device 30 may be electrically coupled to a power supply 36 to receive a supply voltage Vs relative to an electrical ground 55 or a return path therefrom. The protection device 34, the first reflectometer module 61, and the first voltage sensor 51 may be communicatively coupled to the control module 50. The fault detection and location device 30 may optionally be communicatively coupled to a user interface 57 such as a display or monitor.

[0062] The insulated supply conductor 32 may extend between a first end, which is a load end 48 at an electrical load 46, and a second end, which is a supply end 38 at a power source 36. The insulated supply conductor 32 may be coupled to a protection device 34 at the supply end 38. The protection device 34 may be electrically coupled between the power source 36 and the insulated supply conductor 32. The protection device 34 may be communicatively coupled to a control module 50. The protection device 34 may include a switch 44, such as a circuit breaker, a contactor, a solid state power controller (SSPC), etc. The method 400 may be performed when the insulated supply conductor 32 is coupled to the power source 36 or the electrical load 46, or both.

[0063] The method 400 may include coupling the first resistive element 41 between the first conductive shield 70 and the electrical ground 55 at 410. The first resistive element 41 is electrically coupled in series between the first conductive shield 70 and the electrical ground 55 at the supply end 38. The first resistive element 41 may define a relatively high impedance path from the first conductive shield 70 to the electrical ground 55. In non-limiting aspects, the first resistive element 41 may be a first voltage divider including a first resistor R1 of known resistance electrically coupled in series with a third resistor R3 of known resistance at a node 41a. The first voltage sensor 51 may be configured to detect, measure, or otherwise sense a measurement voltage Vm indicative of a voltage across the first conductive shield 70. For example, the first voltage sensor 51 may be electrically coupled in parallel with the first resistor R1 such that a voltage across the first resistor R1 is the measurement voltage Vm.

[0064] Method 400 may include coupling second resistive element 42 between insulated supply conductor 32 and first conductive shield 70 at 415. Second resistive element 42 may be a second resistor R2 of known resistance coupled to insulated supply conductor 32 at load end 48 and to first conductive shield 70 at load end 48.

[0065] The method 400 may optionally include determining at 420 that a fault condition exists in the insulated supply conductor 32. For example, in a non-limiting aspect, the control module 50 determines that a fault condition exists in the insulated supply conductor 32. In a non-limiting aspect, determining that a fault condition exists may be based on a comparison of the measured voltage Vm with a reference voltage Vr or a threshold. The reference voltage Vr or the threshold may be predetermined and stored in the memory 72. For example, the reference voltage Vr may be calculated, derived, or otherwise determined based on a known supply voltage Vs at the supply end 38 and a load voltage VL at the load end 48, respectively. The measured voltage Vm may be determined based on a voltage across the first resistor R1. In a non-limiting aspect, the control module 50 may determine that a fault condition exists when the value of the measured voltage Vm deviates from the value of the reference voltage Vr, or otherwise satisfies a threshold. The method 400 may include, for example, injecting a first incident signal 63 into the first conductive shield 70 at 430 when the control module 50 determines that a fault condition exists. For example, the control module 50 may be configured to trigger injection of the first incident signal 63 to the first conductive shield 70 through the first signal generator 66. The first signal generator 66 may generate the first incident signal 63, such as a voltage pulse, and provide the first incident signal 63 to the first conductive shield 70 via the first reflective line 64. The first incident signal 63 may be injected or provided through the first source impedance 75 or the isolation capacitor C1, or both. The characteristics of the first incident signal 63 may be predetermined or selected based on any number of parameters that are specific to the particular power distribution system 12, the supply conductor 32, the first conductive shield 70, or a combination thereof. It is contemplated that the first incident signal 63 may include any desired predetermined duration (e.g., 2.3 milliseconds), rise time (e.g., 20 picoseconds), shape (e.g., square, rectangular, Gaussian, etc.), and amplitude (e.g., 5 volts) without departing from the scope of the present disclosure.

[0066] It is contemplated that, in non-limiting aspects, determining that a fault condition exists in the insulated supply conductor 32 at 420 may be omitted without departing from the scope of the present disclosure. That is, in some cases, even in the absence of a detected fault, a user may desire to inject the first incident signal 63 into the first conductive shield at 430. For example, a user may desire to inject the first incident signal 63 into the first conductive shield 70 via a "pre-closure" or "pre-energization" check of the insulated supply conductor 32. In such cases, the fault condition may be identified and located prior to closing the switch 44.

[0067] The method 400 may include detecting a first reflected signal 63a at 435. The first reflected signal 63a may be a portion or reflection of the first incident signal 63 that reflects or propagates back toward the first reflectometer module 61 due to the fault condition. The first reflected signal 63a may be detected by the first pulse detector 65. The first reflectometer module 61 may provide an indication of the first reflected signal 63a to the control module 50. In non-limiting aspects, the indication of the first reflected signal 63a may include an indication of a waveform or other characteristic of the first reflected signal 63a, or an indication of an elapsed time between injection of the first incident signal 63 and detection of the first reflected signal 63a, or both.

[0068] The method 400 may further include determining a first elapsed time between injection of the first incident signal 63 and detection of the first reflected signal 63a at 440. For example, the control module 50 may determine the first elapsed time between injection of the first incident signal 63 and detection of the first reflected signal 63a based on an indication of the first reflected signal 63a.

[0069] The method may include determining the location of the fault condition based on the first elapsed time at 450. Non-limiting aspects of the method 400 may further include displaying an indication of the fault condition on the user interface 57 at 460. For example, the control module 50 may provide instructions to the user interface 57 to display information indicating the first reflected signal 63a. In non-limiting aspects, the information may include the location of the fault condition relative to the insulated supply conductor 32. In some aspects, the user may determine the location of the fault condition by viewing the information displayed by the user interface 57.

[0070] Non-limiting aspects of the method 400 may further include triggering, at 470 , a protection device 34 electrically coupled between the power source 36 and the insulated supply conductor 32 to transition from a closed state to an open state.

[0071] The order depicted is for illustrative purposes only and is not meant to limit method 400 in any way, as it should be understood that portions of the method may be performed in a different logical order, may include additional or intervening portions, or the described portion of the method may be divided into multiple portions, or the described portion of the method may be omitted without compromising the described method. For example, method 400 may include various other intervening steps. The examples provided herein are meant to be non-limiting.

[0072] The disclosure discussed herein provides a solution for detecting and locating arcs or power losses within electrical power wiring and connectors of a power distribution system. A fault detection device can detect and locate failures in wiring before there is significant energy loss and thus damage. Unlike conventional techniques, aspects as described herein can be implemented without disconnecting the power wiring from the load, the power source, or both.

[0073] Aspects of the present disclosure reduce the workload of maintenance personnel in determining the location of a fault condition on an insulated supply conductor. Aspects of the disclosure discussed herein minimize the likelihood of an arc fault occurring within a power distribution system. Likewise, minimizing the likelihood of an arc fault also minimizes maintenance requirements. A fault detection device as described herein can be used to perform necessary maintenance.

[0074] To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. The fact that a feature may not be shown in all embodiments is not meant to be interpreted as not being possible, but is done so for the sake of brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, regardless of whether the new embodiments are clearly described. All combinations or permutations of the features described herein are covered by the present disclosure.

[0075] To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. The fact that a feature is not shown in all embodiments is not meant to be interpreted as not being included, but is done so for the sake of brevity of description. Therefore, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, regardless of whether the new embodiments are clearly described. All combinations or permutations of the features described herein are covered by the present disclosure.

[0076] This written description uses examples to disclose the invention (including the best mode) and also to enable those skilled in the art to practice the invention (including making and using any devices or systems and performing any incorporated methods). The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. These other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that are not significantly different from the literal language of the claims.

[0077] The various features, aspects and advantages of the present disclosure may also be embodied in any permutation of the disclosed aspects, including but not limited to the following technical solutions as defined in the enumerated aspects:

[0078] A device (30) for locating a fault condition in an insulated supply conductor (32) and a first conductive shield (70) surrounding the insulated supply conductor (32), the insulated supply conductor (32) being coupled to an electrical load (46) at a first end (48) and to a power source (36) at a second end (38), the power source (36) being configured to provide a supply voltage (Vs) to the electrical load (46) via the insulated supply conductor (32), the device (30) comprising: a first resistive element (41) coupled between the first conductive shield (70) and an electrical ground (55); a second resistive element (42) connected between the insulated supply conductor (32) and the first conductive shield (70) at the second end (38); a first reflectometer module (61) electrically coupled to the first conductive shield (70) via a first reflective line (64), the first reflectometer module (61) comprising a signal generator; A signal generator (66) and a first pulse detector (65), the signal generator (66) being configured to selectively inject a first incident signal (63) into the first conductive shield (70), the first pulse detector (65) being configured to detect a first reflected signal (63a) from the first incident signal (63) on the first reflective line (64); a voltage sensor (51) being configured to detect a measured voltage (Vm) on the first conductive shield (70); and a control module (50) being communicatively coupled to the reflectometer module (61) and the voltage sensor (51), the control module (50) being configured to: trigger injection of the first incident signal (63) from the signal generator (66) to the first conductive shield (70); receive an indication of the first reflected signal (63a) from the first pulse detector (65); and determine a location of the fault condition based on the first reflected signal (63a).

[0079] An apparatus (30) according to any preceding clause, wherein the control module (50) is further configured to: determine a first elapsed time between the injection of the first incident signal (63) and the detection of the first reflected signal (63a), and to determine the location of the fault condition based on the first elapsed time.

[0080] An apparatus (30) according to any preceding clause, wherein the control module (50) is further configured to receive a first indication of the measured voltage (Vm) from the voltage sensor (51) and to determine that the fault condition exists based on a difference between the measured voltage (Vm) and a predetermined reference voltage (Vr).

[0081] The device (30) according to any preceding clause, wherein the control module (50) is configured to trigger injection of the first incident signal (63) from the signal generator (66) to the first conductive mask (70) when the fault condition is determined.

[0082] According to the device (30) described in any of the preceding clauses, the device (30) also includes a protection device (34), which is communicatively coupled to the control module (50) and electrically connected between the power supply (36) and the insulated supply conductor (32), wherein the control module (50) is further configured to trigger the protection device (34) to transition from a closed state to an open state when the fault condition is determined.

[0083] The apparatus of any preceding clause, wherein the control module (50) is further configured to determine that the location of the fault condition is between the insulated supply conductor (32) and the first conductive shield (70).

[0084] The apparatus (30) of any preceding clause, wherein the fault condition is an arc fault.

[0085] The device (30) according to any preceding clause, further comprising a user interface (57) communicatively coupled to the control module (50), wherein the control module (50) is further configured to cause the user interface (57) to display an indication of the fault condition.

[0086] Apparatus (30) as claimed in any preceding clause, wherein the indication of the fault condition comprises a location of the fault condition.

[0087] Device (30) according to any preceding clause, wherein the resistance value of the first resistive element (41) is based on a reference voltage (Vr).

[0088] The device (30) according to any of the preceding clauses, further comprising a second conductive shield (80) spaced apart from and surrounding the first conductive shield (70), the second conductive shield (80) being electrically coupled to the electrical ground (55); an auxiliary switching device (45) electrically coupled to the power supply (36) to receive the supply voltage (Vs) from the power supply (36), the auxiliary switching device (45) being coupled to the insulated supply conductor (32) via a second reflective line (184) and configured to selectively inject a second incident signal (183) into the insulated supply conductor (32) via the second reflective line (184); a second reflectometer module (162) electrically coupled to the second reflective line (184) , the second reflectometer module (162) includes a second pulse detector (185), the second pulse detector (185) is configured to detect a second reflected signal (183a) from the second incident signal (183) on the second reflective line (184); the control module (50) is further communicatively coupled to the second reflectometer module (162) and the auxiliary switching device (45), wherein the control module (50) is further configured to: trigger injection of the second incident signal (183) from the auxiliary switching device (45) to the insulated supply conductor (32); receive an indication of the second reflected signal (183a) from the second pulse detector (185); and determine the location of the fault condition based on the second reflected signal (183a).

[0089] An apparatus (30) according to any preceding clause, wherein the control module (50) is further configured to: determine a second elapsed time between the injection of the second incident signal (183) and the detection of the second reflected signal (183a), and determine the location of the fault condition based on the second elapsed time.

[0090] The device (30) according to any preceding clause, wherein the second resistive element (42) is a resistor.

[0091] A method (400) for locating a fault condition in an insulated supply conductor (32) circumferentially surrounded by a first conductive shield (70), the insulated supply conductor (32) being coupled to an electrical load (46) at a first end (48) and to a power source (36) at an opposite second end (38), the power source (36) being configured to provide a supply voltage (Vs) to the electrical load (46) via the insulated supply conductor (32), the method (400) comprising: coupling a first resistive element (41) between the first conductive shield (70) and an electrical ground; a first resistive element (42) connected between the insulated supply conductor (32) and the first conductive shield (70) at the second end (38); injecting a first incident signal (63) into the supply end of the first conductive shield (70); detecting a first reflected signal (63a) from the first incident signal (63); determining a first elapsed time between the injection of the first incident signal (63) and the detection of the first reflected signal (63a); and determining the location of the fault condition based on the elapsed time.

[0092] The method (400) of any preceding clause, further comprising sensing a measurement voltage (Vm) across the first conductive shield (70).

[0093] The method (400) of any preceding clause, further comprising determining, based on the measured voltage (Vm), that a fault condition exists in the insulated supply conductor (32).

[0094] A method (400) according to any preceding clause, wherein determining that a fault condition exists is based on a difference between the measured voltage (Vm) and a predetermined reference voltage (Vr).

[0095] A method (400) according to any preceding clause, further comprising displaying an indication of the fault condition on a user interface (57).

[0096] A method (400) as described in any preceding clause, wherein the indication of the fault condition comprises a location of the fault condition.

[0097] The method (400) of any preceding clause, further comprising triggering a protection device (34) electrically coupled between the power source (36) and the insulated supply conductor (32) to transition from a closed state to an open state.

Claims

1. An apparatus for locating a fault condition in a supply conductor and a first conductive shield surrounding the supply conductor, the supply conductor being coupled at a first end to an electrical load and at a second end to a power source, the power source being configured to provide a supply voltage to the electrical load via the supply conductor, the apparatus comprising: a first resistive element coupled between the first conductive shield and an electrical ground; a second resistive element connected between the supply conductor and the first conductive shield at the second end; a first reflectometer module electrically coupled to the first conductive shield via a first reflective line, the first reflectometer module comprising a signal generator and a first pulse detector, the signal generator being configured to selectively inject a first incident signal into the first conductive shield, the first pulse detector being configured to detect a first reflected signal from the first incident signal on the first reflective line; a voltage sensor configured to detect a measured voltage across the first conductive shield; and a control module communicatively coupled to the first reflectometer module and the voltage sensor, the control module configured to: triggering injection of the first incident signal from the signal generator into the first conductive shield; receiving an indication of the first reflected signal from the first pulse detector; and The location of the fault condition is determined based on the first reflected signal.

2. The device according to claim 1, wherein: The control module is further configured to: determining a first elapsed time between said injection of said first incident signal and detection of said first reflected signal, and A location of the fault condition is determined based on the first elapsed time.

3. The device according to claim 1, wherein: The control module is further configured to receive a first indication of the measured voltage from the voltage sensor and determine that the fault condition exists based on a difference between the measured voltage and a predetermined reference voltage.

4. The device according to claim 3, wherein: The control module is configured to trigger the injection of the first incident signal from the signal generator into the first conductive shield when the fault condition is determined.

5. The apparatus of claim 3, further comprising a protection device communicatively coupled to the control module and electrically connected between the power source and the supply conductor, wherein the control module is further configured to trigger the protection device to transition from a closed state to an open state when the fault condition is determined.

6. The device according to claim 1, wherein: The control module is further configured to determine that the location of the fault condition is between the supply conductor and the first conductive shield.

7. The device according to claim 6, wherein: The fault condition is an arc fault.

8. The apparatus of claim 1, further comprising a user interface communicatively coupled to the control module, wherein the control module is further configured to cause the user interface to display an indication of the fault condition.

9. The device according to claim 8, wherein: The indication of the fault condition includes a location of the fault condition.

10. The device according to claim 1, wherein: The resistance value of the first resistance element is based on a reference voltage.

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