Abstract: The invention relates to a method (100) for detecting faults in a LVDC electric line (500) characterized in that it comprises the following steps: acquiring (101) a first detection signal (VLOW) indicative of low-frequency components of an unbalancing current (IG) between a plurality of conductors of said electric line, said first detection signal being obtained by means of a low-pass filtering of a corresponding measuring signal (VM1) indicative of said unbalancing current; acquiring (102) a second detection signal (VHIGH) indicative of high-frequency components of an unbalancing current (IG) between a plurality of conductors of said electric line, said second detection signal being obtained by means of a high-pass filtering of a corresponding measuring signal (VM2) indicative of said unbalancing current; obtaining (103) a third detection signal (RT) by calculating the ratio between said first and second detection signals (VLOW, VHIGH); checking (104) whether a DC current (IF) is present by comparing said

Abstract: A medical device has a first controller that has a control section responsible for sequence control of a device and is for controlling the medical device, a second controller that operates if a failure occurs in the first controller, and an alarm that makes a notification output based on exclusive OR between notification outputs of the first controller and the second controller. The second controller, after acquiring the notification output of the first controller, outputs its own notification output as it is if the notification output of the first controller is in an OFF state, or inverts its own notification output so as to output an inversion result if the notification output of the first controller is in an ON state.

Abstract: An apparatus and method for interconnecting mains cables used for underground secondary low-voltage AC network systems utilizing an improved crab joint connector arranged to maximize the number of interconnections in a compact design wherein the plurality of legs are arranged in a rectangle configuration and a single bus leg is positioned at an end of an insulated housing.

Abstract: A sheet switch (142) has a bottom layer (144) and a top layer (160). First and second conductors (148, 162) located on the bottom layer (144) form two separate conductive paths, with a voltage potential applied to the conductors (148, 162). The top layer (160) includes a ground conductor (172). Spacers (178) are positioned between the top and bottom layers (160, 144). When forces are externally applied, the spacers (178) collapse and the ground conductor (172) contacts the first and second conductors (148, 162), and establishes a conductive path therebetween.

Abstract: The wireless tag includes an antenna conductor; a first power-supply conductor which is electromagnetic-inductively coupled with the antenna conductor; and a second power-supply conductor which is loop-shaped and which is electrically coupled with the first power-supply conductor.

Abstract: An electrical ground terminal block assembly and arrangement to make ground fault situation accessible comprise a ground terminal housing to hold the wire linking elements and a characterized ground fault indicating device. The ground terminal block based on the invention is comprised with signalling means to indicate ground fault. Fault current is detected by the ground fault indicating device through upper linking element detection device of said ground terminal block.

Abstract: An electrical tripping mechanism for protecting an electrical device from mechanical and over temperature problems. The tripping mechanism includes a copper conductor encased within an insulative layer, where the insulative layer is provided with a helically wound metallic strip amenable to easy tearing when subjected to mechanical damage. When the continuity of the strip is broken, a sensor detects the damage and shuts-down the electrical device.

Abstract: The invention comprises a set of methods to detect the resistance of a connection to safety ground and to detect the presence of voltage hazardous to people in systems where an unknown amount of current intermittently flows in the safety ground circuit. Samples of voltage between two points in the safety ground circuit are taken repeatedly. When the voltage caused by the unknown currents in the safety ground circuit is below a preset threshold, a known current is applied and another voltage sample is taken to detect the electrical resistance of the safety ground circuit. If an excessive resistance or voltage is detected, one or more outputs are activated or deactivated to indicate the problem and remove power from the system. The invention requires no current sensor for its operation.

Abstract: A portable bearing test device includes a power supply that is operable to supply direct current (DC) electrical power via a plurality of power supply outputs and a circuit common. Independent bearing test circuits are coupled to receive output electrical power from one of the power supply outputs, and are further adapted to independently couple to a separate rotating machine test bearing. Separate indicator lights are electrically coupled in series in each of the independent bearing test circuits.

Abstract: A home control protection system includes at least one surge protection strip having a plurality of power outlet receptacles, and a wall mountable central control unit that is in electrical communication with the at least one surge protection strip. The surge protection strip includes a replaceable surge protector module. The surge protection strip includes a circuit for detecting and counting the number of power surges which are shunted by the surge protector module, and compares the number of power surges with a predetermined threshold power surge number that corresponds to a predicted maximum number of power surges before failure of the surge protector module will occur.

Abstract: An electrical ground terminal block assembly and arrangement to make ground fault situation accessible comprise a ground terminal housing to hold the wire linking elements and a characterized ground fault indicating device. The ground terminal block based on the invention is comprised with signalling means to indicate ground fault. Fault current is detected by the ground fault indicating device through upper linking element detection device of said ground terminal block.

Abstract: Systems and methods for detecting ground fault at the common DC bus in a high impedance ground system. A fault detection component can detect characteristics of an electrical signal including phase number (n) and fundamental frequency (H). A fast Fourier transform is performed at (n×H) and (2n×H), and the two values are compared. A healthy system (no ground fault) can display a large difference between (n×H) and (2n×H), while in an unhealthy system the difference can be minimal. A system and method of detecting variable phase number and fundamental frequency can be used in the calculation to perform the ground fault detection when these characteristics are variable.

Abstract: A current monitoring device (CMD) with a set of electromagnetic field sensors located within one or more grounded housings positioned within the combined electromagnetic fields generated by one or more electric power lines. The CMD includes electronics, typically located within the grounded housings, defining impedance networks that combine the measurements received from the field sensors to create output signal indicative of electric current values for the phase conductors. The housings can be conveniently attached and to transmission line towers, distribution line poles, and high voltage power line supports in transmission and distribution substations. The CMD controls response equipment, such as a circuit interrupter that responds to current disturbances detected by the CMD. The CMD may also include communication for sending the current values to a remote controller, such as a central control station, that implements a wide range of response equipment.

Abstract: A device for detecting a fault current in an electronic apparatus has a first and at least one second electric conductor, the first electric conductor carrying a first electric potential and the at least one second electric conductor carrying a second electric potential. The device is characterized by the fact that an electric sensing conductor having a fixed electric rest potential whose value lies between the first and the at least second electric potential is situated between the electric conductors.

Abstract: A signal analyzer for calculating the power consumption and power factor of a three-phase power system driving a motor includes logic that determines whether the analyzer's own input terminals are wired in a proper or inverted manner. To do this, the signal analyzer observes a pattern of zero crossing slope values of the three line-to-line voltages of the three-phase power system and observes a pattern of zero crossing slope values of the current in the three power lines. The analyzer also compares the slope of a voltage signal as the signal passes through zero volts and the sign of a corresponding current signal that exists as the voltage signal crosses zero volts. Based on the observed voltage and current patterns and the voltage-to-current relationships, the analyzer can positively identify which of a plurality of inputs or signal wires are inverted.

Abstract: A supervisory method and apparatus provide for detection of “partial fault” conditions such as a relatively high series impedance in the wiring, or a relatively low parallel impedance across the wiring. A non-linear element, such as a semiconductor diode, can be used as an end of line element. The element functions as a current controlled dynamic impedance such that currents through the element can be used to detect low parallel leakage currents. Higher currents through the element can be used to detect partial open circuits.

Abstract: Method and system for managing cabling rooms that include a plurality of communication panels, which are arranged closely to one another. Each cabling room has a plurality of patch panels, structurally connected to form vertical structures. An operator is automatically guided to a communication panel or a plurality of communication panels, in which changes are to be made to modify the connectivity status or to deal with connectivity problems that may arise for any reason. The system automatically indicates to an operator optimal ports that are available and optimal patch cords for connecting them, based on distances between ports and on the electrical characteristics of the electrical signals that it is intended to pass between the ports.

Abstract: Self-registration systems and methods for dynamically updating information related to a network, are provided. A self-registration system for dynamically updating information related to a network, comprises: a connector comprising an integrated circuit that stores a first block of information; an adapter coupled to the connector; a reader that receives the first block of information from the integrated circuit via the adapter; and a communication line coupled to the adapter via the connector, where the first block of information comprises a first block of information about network elements associated with the integrated circuit, and where the first block of information about network elements associated with the integrated circuit comprises information other than information identifying the connector, the adapter, the communication line and the integrated circuit.

Abstract: A short circuit detector for a fieldbus network which includes power/data wires that are typically positive and negative, respectively, and a shield conductor connected to a ground includes first and second high-impedance semiconductor circuits coupled between each of the leads and the shield conductors. Both circuits may either have a dedicated alarm indicator which indicates the presence of a short circuit between that conductor and the shield and/or may be coupled together to an alarm circuit which activates an alarm whenever a short circuit exists between either of the power/data leads and the shield conductor. The alarm circuit may have a ground which is isolated from the shield ground and may thus employ an isolation device such as an opto-isolator.

Abstract: The present invention relates to a method for location of a fault which has occurred on one of a plurality of lines in a power distribution network where the location is performed with the measured values of the common supply voltage of the plurality of lines and the currents of the plurality of lines after the occurrence of a fault; calculating the equivalent positive-sequence impedance Z1kf and zero-sequence impedance ZZ0kf of the network in a pre-fault steady state for all M nodes based on knowledge of the configuration and topology of the network, and obtaining, via a superordinate protection system, which of plurality of lines has become faulty and which type of fault has occurred.

Abstract: Active and spare circuit cards are each paired with switch cards. Each switch on the switch cards is daisy chained with prior and succeeding switches. A master controller senses a faulty circuit indication signal from each of the active circuit cards. When the faulty circuit indication signal indicates a fault on a particular active circuit card, the controller instructs the switch card that is paired with that circuit card to switch it out and switch in a spare circuit card.

Abstract: This invention relates generally to monitoring systems and more particularly concerns devices and systems used to monitor bed patients in hospital or other care-giving environments. In accordance with a first aspect of the instant invention, there is provided a binary switch-type device (e.g., a “mat”) for use in patient monitoring situations which contains, in addition to a conventional patient detection circuit, identification circuitry that can be sensed by an attached electronic monitor. The identification circuitry can be sensed by the electronic monitor and is designed to be configured to serve many different purposes, including, by way of example only, identification of the type of mat attached thereto, detection of connectivity problems, tracking mat usage time, and identifying mats that are nearing the end of their useful lives.

Abstract: A ground fault location system is used in a multi-phase ungrounded or high-impedance grounded power network. A signal generator is coupled to the network at a first location and generates for each network phase an individual non-DC voltage signal between such phase and ground. A ground fault detector is coupled to the network at a second location and has a summing device and an annunciator. The summing device is coupled to all of the phases of the network at such second location, sums any current passing therethrough, and produces a sum signal. The annunciator receives the sum signal and provides an indication when such signal is non-zero. Each phase of the network at the second location has a distribution current passing therethrough, the sum thereof normally being substantially zero and resulting in a substantially zero sum signal and the lack of an indication from the annunciator based on such distribution currents.

Abstract: A self-contained unit intended primarily for tracing the circuit connection between an electrical outlet or lighting receptacle and its corresponding circuit-breaker. The preferred embodiment includes a housing, a male two prong electrical plug, and a sound-producing means. A second embodiment includes a male three prong electrical plug. A third embodiment incorporates a momentary switch which permits testing of a ground fault interrupt across either a hot wire and a neutral, or across a hot wire and the ground. Adapters are used to temporarily adapt bare wires or a lighting receptacle to a female plug so that the device may be used.

Abstract: A circuit includes a plurality of inexpensive resistors connected at one end to the open collector outputs of an output array of NPN output transistors which are connected to a wiring harness or the like for selectively powering a preselected load. The opposite ends of the resistors are connected to the base of an NPN sense transistor. The output NPN transistors, when in the on condition, are biased well into saturation for normal loads and therefore provide a very low Vce (sat) when properly connected through the harness to the intended load. In the off condition, the output NPN transistors look essentially like an open circuit. Vce (sat) is lower than the base turn-on voltage of the NPN sense transistor which has a grounded emitter. The collector of the NPN sense transistor is connected to a source of voltage through a pull-up resistor and to an input of the microprocessor which controls the signals to the output array transistors.

Abstract: A circuit arrangement for monitoring leakage currents of a circuit which includes a plurality of valve coils connected in parallel to a supply line and adapted to be connected to ground by way of individual switches, and wherein the supply line is connected by way of a main switch to the positive pole of the supply voltage source and, further, to a testing current source used as a test signal source, is designed such that prior to each closing of the main switch, with the individual switches still open, the testing current source is connected to the supply voltage source and thereby activated. The result is an increase of the voltage potential on the supply line. A comparator establishes the difference between the potentials on the supply line and the supply voltage. If the difference exceeds a threshold value, this indicates leakage current.

Abstract: A method and apparatus for detecting silent faults in feeding diodes of redundant DC power supplies. The voltages on both sides of the feeding diodes are measured. Arrangements are then made to ensure that if corresponding feeding diodes are both operative, that current flows through a particular one of these diodes. The measurements of voltage under the various conditions will reveal any open or shorted feeding diodes. The voltage across a diode can be altered by heating the diode through the process of heating a power resistor that is in thermal contact with that diode. Alternatively, a controllable rectifier of a power source can be controlled to reduce the voltage of that power source, and thereby drive current through the diode connected to the other power source. Advantageously, this arrangement allows silent faults in these diodes to be detected without substantial risk of causing the failure in the powered system.

Abstract: An electronic apparatus is provided that can eliminate unlawful cartridges while preventing a malfunction by checking whether there is a short-circuit of pin terminals at the time of turning on the power source and conducting further improved security checks. The electronic apparatus has an electronic apparatus body 2 and a cartridge 5 to be detachably mounted to the electronic apparatus body 2. The cartridge 5 is equipped with a connector having a plurality of terminals and is connected to the electronic apparatus body 2 via the connector. The electronic apparatus body 2 outputs a first and a second short-circuit detecting signal for conducting a short-circuit detection of a circuit portion connected via the plurality of terminals.

Abstract: A sound warning circuit for PCI hot plug basically comprises: a timer that takes as inputs a fixed frequency clock and the system port B's bit 0, and which controls the system; a logic AND gate that takes as inputs the timer output and the system port B's bit 1; a speaker driver that takes as an input the AND gate's output; and a speaker that operates based on the speaker driver. In a further embodiment, the timer takes as inputs a fixed frequency clock and either the system port B's bit 0 or a PCI card VDD input, while the AND gate takes as inputs the timer output and any one or more of the system port B's bit 1, a chassis ground cable 0 input, and a chassis ground cable 1 input. In a further embodiment, the AND gate takes as inputs the timer output and either the system port B's bit 1 input or the output of a D Flip-Flop, the latter having the chassis ground cable signal as an input and receiving a reset signal from an AND gate, the latter having as inputs a reset switch input and a system reset # input.

Abstract: A method and system for detecting faults with a self-exciting sensor includes a monitor circuit coupled to the self-exciting sensor for monitoring a signal associated with the sensor and generating a failure signal. A voltage limiting circuit is coupled to a receiver circuit associated with the self-exciting sensor for generating a first output signal within a valid range of operation in the absence of the failure signal. The voltage limiting circuit also generates a second output signal outside the valid range of operation in response to the failure signal so as to eliminate the necessity of an additional input to control logic associated with the self-exciting sensor.

Abstract: An earth-leakage monitoring method for a power distribution system, and in particular a DC 4-rail traction system, incorporating a pair of current-conductors (current rails) and an earth reference (a pair of running rails or an earthing system), comprises measuring the conductor-to-earth voltage for each conductor; forming a ratio of these voltages; connecting a known resistance between one conductor and earth; re-measuring the two conductor-to-earth voltages; forming a new voltage ratio, and calculating the value of leakage resistance existing between each conductor and earth using the known resistance value and the two voltage ratios.

Abstract: A ground fault circuit interrupt system with uncommitted contacts is provided which includes line-side system, phase, neutral and ground terminals electrically connectable to phase, neutral and ground terminals of an AC power source and load-side system, phase, neutral and ground terminals electrically connectable, respectively, to phase, neutral and ground terminals of an electrical load. The system includes a ground fault circuit interrupter including line- and load-side phase and neutral terminals for electrical connection to the line-side system, phase and neutral terminals for controlling a state of conduction of AC current between the source and electrical load in accordance with a detection of an interrupt condition.

Abstract: A plurality of cores of a multi-core cable are collectively conducted at first ends side thereof and are isolated from one another at second ends side thereof. The cores are engaged at the first ends side with grooves formed on a movable member one by one so as to be picked up and are sequentially transported toward an electrode. The picked-up core is cut during :its transportation so as to be electrically separated from a collective conducting part at the first end side. A high voltage is charged to the picked-up core through the electrode and based on an electric conduction characteristic of its charging current a judgment is made about whether there is a defective contact (dielectric breakdown) between the picked-up core and other cores. Further, the electric charge of the picked-up core is discharged, the picked-up core is recharged, and based on electric conduction characteristics of these discharging current and charging current a confirmation that the above judgment was not a misjudgment is made.

Abstract: The apparatus for automatically coupling an internal ground of an electric appliance to an external ground, comprises first and second AC power lines for supplying an AC input to a load; a neutral ground generating circuit for combining the first and the second AC power lines to produce a neutral ground point; a first detection circuit for detecting a current flow from the first AC power line to the internal ground to generate a first current detection signal; a second detection circuit for detecting a current flow from the second AC power line to the internal ground to generate a second current detection signal; and a ground coupling circuit for connecting, in response to the second current detection signal, the first AC power line as the external ground to the internal ground; for connecting in response to the first current detection signal, the second AC power line as the external ground to the internal ground; and for connecting the neutral ground point as the external ground to the internal ground when t

Abstract: A diagnostic device for testing a false warp stop in an industrial loom caused by a failing or offending drop wire. The device provides a connector that is operably engaged with the warp bars of an industrial loom. When a drop wire becomes worn or pliable and bridges the warp bar to stop the loom, the connector assists to create a circuit that includes the affected warp bar, a power source, a rectifier and an indicator device. The indicator device is activated by completion of the circuit and remains actuated even after the loom is restarted. The apparatus is thus effective to help locate a failing drop wire as opposed to a drop wire that has fallen due to a slack or broken warp thread.

Abstract: A fault sensor device which can detect and distinguish abnormal current and voltage events on an alternating current overhead and underground power transmission or distribution line. The abnormal current events are momentary outage, sustained outage, normal overload, and inrush on transmission or distribution lines. The sensor can further distinguish whether the momentary or sustained fault is a line to ground fault, line to line fault or a three phase fault. It can also identify the faulted phase(s). In the overload scenario, the sensor can identify if the overload has occurred on all three phases or only on one or two phases of the power line in an unbalanced situation. The voltage events are open line(s) on one, or two of the phases with a possibility of a fallen live wire and voltage sag. The sensor can identify which of the three phases or if all three phases of the power line are open or on the ground.

Abstract: A household electrical service (10) is protected against overheating by running a sensor line or wire (36 or 38), coextensively together with hot, neutral and ground lines or wires (12, 13, 14 or 31, 32, 33), from a power company hookup (50) to a main breaker switch (18), and from respective branch circuit breakers (19) throughout the branch circuits (21, 22). The sensor line or wire (36 or 38) may be a length of heat fusible or otherwise temperature variant material which has a load end connected to ground and a source end connected to a control circuit (51) which trips the breaker (18 or 19) when an overtemperature condition melts the wire. Protection is extended through to individual devices (43) by continuing the sensor wire through the device cord (42). For this purpose, a plug ground prong (46) and receptacle ground prong connection (45) provide isolated ground and sensor wire connections.

Abstract: An electrical sensing circuit has a sensor device and an indicator such as a warning light. The system of the present invention continuously monitors the operational status of the sensing circuit. Normally open sensors are provided with a resistance across the open circuit contacts to provide a small leakage current. For each sensor, high and low comparators are provided. The high comparator is ground seeking and is used to detect closure of open circuit sensors, grounded connections and systems tests. The low comparator detects open circuits or high resistances such as might be caused by broken or loose wires, improperly connected sensors or electrically degrated sensors. The comparators drive logic components, which in turn drive indicators of circuit operational readiness.

Abstract: Imbalances between currents to and from a remote point are detected by passing the outgoing currents and the return current through different, oppositely-oriented coils on a saturable core, and an excitation current is applied to another coil in the same core sufficient to drive the core into saturation in at least one direction. When the outgoing and return currents are the same, the excitation produces successive voltage pulses of the same durations, as measured by an up-down counter; if an imbalance is present, the remainder in the up-down counter shows this. To detect excessively high imbalances, which might place the core always in saturation, another counter preferably senses the sum of the widths of successive pulses, and indicates an imbalance if this sum falls below a preselected threshold.

Abstract: An alarm device adapted particularly for the indication of electrical leakage and mal-insulation of electrical appliances disposed in association with a marine tank for use in fish raising. An electrical leakage sensor unit is provided in the tank, to which are electrically plugged the illumination light, air pump, temperature controller, water filter member, germicidal light, so that an alarm signal led via an IC comparator and further to a sonic frequency vibrator for transformation and further to an signal amplifier and subsequently to a parallelly-connected buzzer and red-light indicator to simultaneously alarm the operator of the hazard of electrical leakage and mal-insulation.

Abstract: To detect a short circuit condition between guide paths embedded in the floor for automatic guided vehicles, a detection relay has a pair of current transformers having primary windings connected into a guide path circuit at points on the source and the return side of the circuit, the transformer secondary windings being connected in opposition to yield a null signal when there is no short and a finite signal when primary current inequalities are present. Amplifier circuitry discriminates between null and finite signals and controls a relay which activates an annunciator.

Abstract: A method and apparatus for determining the conductive integrity of a plurality of lines which transmit electromagnetic radiation.

Abstract: Apparatus for the detection of ground leakage in a normally ungrounded DC system includes a DC power supply and conductors from the supply for supplying power to a load connected to the DC system. There is an indicator connected between the DC system and a ground point such that a ground leakage in the system closes a circuit to activate the indicator. With such activation, a pulser periodically interrupts the circuit to effectively generate an interrupted ground fault signal. Such signal is detected by a sensor located relative to the DC system such that an interrupted ground signal detected by the sensor locates the ground fault. Noise introduced into the pulse signal by the periodic interruption of the circuit during the ground fault occurrence is suppressed by the sensor means.

Abstract: A control module is connected to a table strip having a number of jacks. A sensor probe which consists of a sensor detector and a sensor cable has at the end of the cable a plug which is connected to the table strip jack. Each sensor cable is provided with a continuity circuit and a floating circuit such that cutting of the cable or shorting of the cable will energize an indicator circuit and an alarm annunciator in the control module.

Abstract: A ground fault detector and locator for use in servicing ungrounded d-c or a-c power distribution systems. A pulsating ground current is introduced between the unfaulted side of the distribution system and earth ground. A current probe and associated sensing circuits are then employed to identify the faulted branch circuit without interrupting service to unfaulted branch circuits.

Abstract: A device for remote metering, comprising a meter (4) for measuring a consumption, a transmission circuit for transmitting information relating to quantities consumed, and consisting essentially of a modulating circuit (5,6) and of a bifilar line (3), and a counter circuit for counting sets of information. The modulating circuit comprises a capacitive network (6) and at least one switch (5) which is actuated by the meter and which is capable of modifying the capacity of the capacitive network. The device further comprises a circuit (7,14) suitable for evaluating the value of the capacity of the transmission circuit, and thus for distinguishing two states of the modulating circuit and one state of a fault in the line. Such a device is, in particular, usable for the remote metering of a consumption of gas or of electricity.

Abstract: Apparatus for testing wiring harnesses either during or after the harness fabrication process comprises test points, each of which is connected to a corresponding terminal of the harness. Associated with the test points are a current source, a current sourcing means, a current sink, and a current sinking means. Each current sourcing means and current sinking means comprises a controlled conduction path which is selectively operable to a conductive state or a non-conductive state. The tester operates to test individual circuits of the harness for continuity and shorts. In doing this the controlling conduction paths are selectively operated in accordance with information correlating the wiring harness circuits with the test points. A current sensing means senses the present or absence of current during open and short circuit tests and provides appropriate indicator signals to indicate opens or shorts if such faults are present.

Abstract: A data distribution apparatus for controlling the distribution of data signals from field mounted devices to a central processor includes a backplate having wiring connected thereto between the backplate and the field mounted devices and between the backplate and the data processor. A cover for the backplate includes a printed circuit board mounted thereon with an electrical connector extending therefrom. The cover connector is arranged to mate with an electrical connector board mounted on the backplate to selectively connect the printed circuit board on the cover to electrical circuits connected to the connector board on the backplate. Thus, the removal of the cover which is keyed to the backplate to ensure a correct orientation thereof on the backplate is effective to interrupt the electrical connections provided by the printed circuit board among the wiring connected to the electrical connector board and vice versa.

Abstract: A device for monitoring ungrounded power distribution systems that indicates the total hazard current from the isolated power conductors to ground. A measurement signal having at least two frequency components different from the power system line frequency is applied across the combined fault impedances that occur between the power conductors and ground. Voltage responses to the measurement signal components are separated from the power system line voltage and from each other by frequency selective means. These distinct voltage responses are proportional to the fault admittance magnitude at the different measurement frequencies. The voltage responses are applied to the computational circuit whose output is proportional to the maximum fault admittance magnitude at the line frequency. A gain signal related to the imbalance of the fault impedances of the different power conductor is used to scale the previously described voltage responses.

Abstract: A bi-directional system for ensuring that a ground connection is made in a three-wire conductor system including a line "hot" conductor, a line neutral conductor, and a ground conductor includes a circuit for generating direct current potential related to the potential difference between the line "hot" conductor and ground and a second circuit for generating a direct current potential related to the potential difference between the line "hot" conductor and ground. A circuit including a male plug for insertion into a female receptacle includes a first prong for coupling alternatively to the line "hot" conductor or the line neutral conductor, a second prong for coupling alternatively to the line "hot" conductor or the line neutral conductor, and a third prong for coupling to the line ground conductor.