Abstract: A fault indicator for indicating the occurrence of a fault current in an electrical conductor includes a core assembly which attaches a circuit module to a monitored conductor and provides a concentrated magnetic flux indicative of the current level in the conductor. A magnetic reed switch in the circuit module responds to the magnetic flux in the core assembly to condition an indicator in a remote indicator module to a fault-indicating state in the event of a fault. To facilitate installation and removal of the circuit module from the conductor, the core assembly is formed by a plurality of laminations secured together and arranged in a generally rectangular configuration with their ends juxtaposed along one side thereof and joined with magnetically conductive interlocking coupling members.

Abstract: A fault indicator for indicating the occurrence of a fault current in a power distribution system includes a test-point-mounted circuit module and a remotely-mounted indicator module. The indicator module incorporates a bidirectional magnetic winding and a magnetic indicating element having a magnetic state conditioned by energization of the winding. Upon the occurrence of a fault in the power system trip circuitry within the circuit module energizes the winding with current in one direction to condition the indicator element to a fault-indicating magnetic state. Upon restoration of current in the system, reset circuitry within the circuit module energizes the winding with current in the opposite direction to condition the indicator to a reset-indicating magnetic state. The use of currents of opposite direction in a single magnetic winding provides greater flux density at the indicating element, and enables the indicator module to be connected to the circuit module by means of a two conductor cable.

Abstract: A fault indicator for indicating the occurrence of a fault current in an alternating current conductor includes a pair of parallel-spaced reed switches in magnetic communication with the conductor. The reed siwtches are electrically connected in parallel by a magnetically conductive bridging element at one end of the pair and by a non-magnetically conductive bridging element at the other end of the pair. A permanent magnet bridging the non-magnetic bridge establishes a magnetic bias circuit which extends serially through the switches to increase the sensitivity of each switch to a fault current during a respective half-cycle of the alternating current cycle.

Abstract: A ground fault indicator for a multi-phase power distribution system includes a split-core magnetic pole assembly having a gap within which is developed a magnetic flux representative of the vector sum of the currents in the individual phase conductors of the system. A magnetic reed switch positioned within the gap responds to the summation current in the gap to trip an indicating circuit in a remotely mounted indicating module in the event of a ground fault.

Abstract: A fault indicator for indicating the occurrence of a fault current in an electrical conductor includes an externally viewable target which is positioned to a fault-indicating position by a trip circuit within the indicator upon occurrence of a fault current. The trip circuit is responsive to a magnetic field within a predetermined sensing plane generally parallel to the conductor. To increase the sensitivity of the indicator to the magnetic field of the conductor, the fault indicator includes flux concentrating pole pieces which form a low reluctance magnetic circuit between the circumference of the conductor and the sensing plane.

Abstract: Indicating devices for mounting on a test point in an alternating current distribution system provide a visual indication of either voltage level or fault occurrence in the system. The indicating devices are contained in a housing which includes an electrically-conductive rubber outer shell adapted to snap-fit over the test point, and a non-conductive inner housing within which the indicating devices are contained. The indicating devices include a bridge-type rectifier which is coupled to a conductor of the system through the test point terminal, and to ground through the electrically-conductive outer shell. In a voltage indicator application, the rectifier circuit charges a capacitor across which a neon lamp visible through a window in the end of the housing is connected, the rate at which the neon lamp flashes providing an indication of the voltage level on the conductor.

Abstract: A combined fault and voltage indicator includes a rotatably-mounted target viewable from the exterior of the indicator for indicating the occurrence of a fault and a lamp viewable from the exterior of the indicator for indicating system operating voltage. The target is positioned in a reset-indicating state by a reset circuit which periodically energizes a first winding to position a permanent magnet mounted for rotation with the target. Upon occurrence of a fault circuitry within the indicator energizes a second winding to reposition the target to a fault-indicating position. The lamp is caused to flash at a rate which indicates the operating voltage of the system.

Abstract: A fault indicator for alternating current distribution systems includes a pair of spaced pole pieces for receiving therebetween at one end the conductor and at the other end a pivoted permanent magnet carrying a target that is biased to a fault indicating position by a stationary permanent magnet. The pole pieces are demagnetized on flow of fault current in the conductor. They are remagnetized by a winding which is energized by discharge of a capacitor that is charged through a rectifier from an oscillator circuit. The winding is carried by a receptacle into which the other ends of the pole pieces are inserted and a circuit is completed thereby to charge the capacitor. The receptacle is carried at one end of a tubular housing the other end of which has an eye to receive a claw of a live line tool for applying the fault indicator to and removing it from the conductor.

Abstract: A test point cap provides a visual indication of the voltage level of an alternating current in the conductor of a connector on which the cap is installed. The test point cap includes a bridge-type rectifier circuit which is capacitively coupled to the conductor through a test point terminal on the connector. The rectifier circuit charges a capacitor across which a neon lamp visible through a window in the end of the cap is connected, the rate at which the neon lamp flashes providing an indication of the voltage level on the conductor.

Abstract: A fault indicator for alternating current distribution systems includes a pair of spaced pole pieces for receiving therebetween at one end the conductor and at the other end a pivoted permanent magnet carrying a target that is biased to a fault indicating position by a stationary permanent magnet. The pole pieces are demagnetized on flow of fault current in the conductor. They are remagnetized by a winding which is energized by discharge of a capacitor that is charged through a rectifier from an oscillator circuit. The winding is carried by a receptacle into which the other ends of the pole pieces are inserted and a circuit is completed thereby to charge the capacitor. The receptacle is carried at one end of a tubular housing the other end of which has an eye to receive a claw of a live line tool for applying the fault indicator to and removing it from the conductor.

Abstract: The occurrence of fault current flow in an alternating current carrying conductor is indicated if the power flow in the conductor is in one or a preferred direction and is not indicated if the power flow in the conductor is in the opposite direction.

Abstract: This invention relates, generally, to fault indicators and it has particular relation to tools for testing fault indicators of the kind and character disclosed in my U.S. Pat. No. 3,906,477, issued Sept. 16, 1975.

Abstract: The reset circuit of a fault indicator is disabled to prevent automatic restoration of the movable target from fault indicating position where it can be observed and manually rest. A manually operable switch is connected across the reset ciruit and its contacts are closed by permanent magnet means or by manually operable switch means.

Abstract: An indicator for flow of fault current in a conductor is enclosed in a housing carrying a metallic clamp for detachable mounting on the conductor. The indicator is operated by closure of a switch in response to flow of fault current in the conductor and is reset by the voltage developed between the clamp and ground. The indicator is checked by application of a permanent magnet to close the switch and an external voltage to reset the indicator. The indicator also can be reset by flow of normal current in the conductor employing a winding on a magnetic core surrounding the conductor and encapsulated with the switch.

Abstract: Detection of fault current flow in any conductor of a polyphase alternating current system is provided by a fault responsive device that is reset only when normal current flows in each conductor. A reed relay is latched in operated condition on the occurrence of a fault and is unlatched by application of a direct current source.