Showing papers on "Fault current limiter published in 1973"

Means for detecting fault current in a conductor and indicating same at a remote point

Abstract: The rectified output of one or more current transformers associated respectively with one or more conductors of a high voltage alternating current system is applied to a fault responsive winding on a magnetic circuit of a fault responsive device for magnetizing it with unidirectional magnetic flux in one direction. A normally open reed switch in the magnetic field of the magnetic circuit is closed on flow of fault current in one or more of the conductors and is connected to control signalling or control means located at a point remote from the fault responsive device. For demagnetizing the magnetic circuit, a reset winding is positioned on the magnetic circuit and is connected for energization to a direct current source under the control of a manually operable switch at the remote point.

Ground fault interrupter with pulsed neutral-to-ground fault detector

Abstract: Apparatus for monitoring an alternating-current circuit having a differential current transformer to sense line-to-ground faults includes a pulsed ringing circuit for evidencing freedom of the alternating-current circuit from neutral-to-ground faults that could reduce the sensitivity of the line-to-ground fault detector.

Ground fault interrupter circuit with excited secondary winding on differential transformer

Abstract: A ground fault interrupter circuit employing a transformer whose primary windings are respectively in series with the two conductors of a power distribution system. A multi-turn secondary winding of the transformer is continuously excited by current from the conductors to produce in the transformer core a continuous flux whose magnitude is substantially equal in magnitude and in opposite direction to the flux produced in the core by a differential current which flows in the primary windings when a fault current of minimum unacceptable magnitude is present. In the absence of a fault, the steady current through the secondary winding actuates sensing circuitry which permits a circuit breaker to maintain the source connected to the conductors. Upon presence of a fault on a conductor, flux in the core goes to zero, or reverses phase, and the sensing circuitry responds thereto to cause the circuit breaker to disconnect the source.

Ground current powered ground fault protector

Abstract: An equipment protection system uses a differential transformer to detect ground faults and energizes a shunt trip coil of a circuit breaker solely with energy induced in secondary windings of the differential transformer by the fault current. Uniform time delay is provided regardless of the magnitude of the fault current and means are provided to prevent partial timing out of the time delay circuit at fault currents below the minimum tripping point. The system provides instantaneous tripping of the circuit breaker upon occurrence of large ground fault currents. A switching triac avalanches into conduction upon occurrence of a relatively large ground fault current to protect circuit components from damage while still permitting energization of the shunt trip coil.