Westinghouse Electric Corporation

Electric Power Research Institute Incorporated

Other

Eaton Corporation

Clive W Kimblin

Paul G Slade

Francis A Holmes

Joachim V Heberlein

Joseph G Gorman

Roy E Voshall

Robert Tracy Elms

Charles A Peterson

Joseph R Rostron

David Robert Smith

Albert H Maxwell, Jr

Randall N Avery

William H South

Fred Bould

Michael W Thomas

John F Perkins

William J Lange

Thomas D Poyser

Joachim V Heberlei

David W McElroy

John D Borst

John W Bankoske

A vacuum switch having a fixed stationary and moveable contact that functions very much like a conventional vacuum circuit interrupter. In addition, an annular stationary contact is positioned on the opposite side of the moveable contact from the first mentioned stationary contact with the drive rod of the moveable contact slidable within the annular opening of the additional stationary contact. The moveable contact travels between three positions. The first position is in electrical communication with the first mentioned stationary contact, the second position is an intermediate position that opens the circuit, and the third position places the moveable contact in electrical communication with the annular stationary contact. Preferably, one of the stationary contacts is grounded and the moveable contact is connected to the load, so that the switch either connects the power line to the load, opens the circuit in the intermediate position, or grounds the load to facilitate maintenance.

Multiple contact switch

A miniature circuit breaker incorporating ground fault protection and arc fault protection includes a test mechanism including a ground fault test circuit for testing a ground fault detector trip mechanism, and an arc fault test circuit for testing an arc fault detector trip mechanism. A state machine circuit automatically controls the test mechanism to sequentially test both of the ground fault and arc fault detector trip mechanisms. A test push button is interconnected with the state machine circuit and, when pressed, initiates sequential testing of both of the ground fault and arc fault trip mechanisms.

Circuit interrupter with test actuator for ground fault and arc fault

A microprocessor-based transformer monitoring system to provide continuous on-line monitoring and analysis of transformer operation. The transformer monitoring system periodically monitors various parameters related to transformer load and condition. Maximum, minimum, and instantaneous values of the parameters are stored and analzyed. To perform the analysis, a hierarchy of thresholds is associated with each parameter. When a parameter exceeds any one of the thresholds, a response is produced by the transformer monitoring system. The type of response depends on the level of the exceeded threshold in the hierarchy. The range of response produced by the transformer monitoring system includes: continuing normal periodic data collection and analysis, increasing the rate of data collection and analysis, recommending an on-site physical check of the monitored transformer, reducing transformer load, and taking the transformer off line.

Method and apparatus for monitoring transformers

There is provided a novel vacuum detection means utilizing a high frequency, high voltage device to excite an electrical discharge in a vacuum whose characteristics are dependent on the level of the vacuum contained therein. This discharge current allows the degree of vacuum to be continuously monitored.

Vacuum detector

An electrical switch for efficient, high continuous current carrying operation, with at least one movable contact for effecting current interruption. The ambient pressure within the volume defined by the electrical switch body is maintained at or is reducible during contact opening to between 10.sup.-1 to 10.sup.2 Torr to minimize contact erosion. A preferred electrical switch is a hermetically sealed, low voltage d.c., device for shunting an electrolyte cell. The sealed switch module has a reduced pressure atmosphere of inert fill gas at a pressure of from 10.sup.-1 to 10.sup.2 Torr.

Reduced pressure electrical switch

The invention provides a technique for interrupting current employing a plurality of series connected vacuum arcs in parallel with a resonating circuit. At least one of the series vacuum arcs is subjected to an oscillating transverse magnetic field which produces modulations in the arc voltage. The arc voltage modulations initiate oscillations in the parallel resonating circuit, producing current modulations in the series connected vacuum arcs. The current modulations rapidly extinguish the arcs, interrupting the current. Use of a plurality of series connected vacuum arcs improves the recovery voltage hold-off potential of the circuit.

Series connected oscillating transverse field interrupter and method

An improved envelope for a vacuum device circuit interrupter of the type having a pair of relatively movable electrodes within a vacuum envelope and including magnetic field arc suppression. The envelope includes end portions which support the electrodes and an intermediate insulating portion which surrounds and is spaced from the electrodes. Means for producing a magnetic field is outside the envelope. The insulating portion is of a shape which provides a greater distance between the electrodes and the surrounding insulating portion in the direction in which an interelectrode arc is deflected by the magnetic field. In the preferred embodiment the insulating portion is substantially cylindrical in shape with a pair of protruding side tubes. The interrupter envelope is oriented so the arc is deflected down the inside of the side tubes.

Vacuum envelope for current limiter

An improved envelope for a vacuum-type current interrupter of the type having a pair of relatively movable electrodes. The envelope includes end portions which support the electrodes and an intermediate insulating portion which surrounds and is spaced from the electrodes. Baffles are provided along the interior surface of the insulating portion to break up continuous metallic vapor deposits on the interior of the envelope.

Current limiter vacuum envelope

A vacuum arc current interruption device is installed in a current limiting circuit which includes a parallel resonant circuit. Means are provided for producing transverse lines of magnetic force in the arc gap between the electrodes in the vacuum enclosure. The energizing circuit for the magnetic field coils includes a capacitor bank employing unpolarized capacitors and a switch. After the capacitor bank is charged up, the switch is closed, discharging the capacitors through the field coils and producing lines of magnetic force in the arc gap. The field coils and capacitor bank together form a resonant field circuit having a characteristic resonant frequency which causes periodic reversals in the polarity of the lines of magnetic force. The oscillating magnetic field produces responsive oscillations in the arc voltage of an arc present in the arc gap of the vacuum device, which in turn causes oscillations of the arc current. When oscillations of sufficient magnitude are generated to produce a current zero, the arc is driven to extinction and the circuit current is commuted into a parallel current limiting impedance.

Vacuum arc current limiter with oscillating transverse magnetic field

A vacuum arc current switching device employs a shielding arrangement including a plurality of coaxially disposed cylindrical non-conducting members for minimizing exposure of the interior wall surfaces of the enclosure to vapor deposition of cathode material so as to prevent the formation of secondary arc terminals on the interior surfaces of the enclosure. The shielding being non-conducting prevents secondary arc formation which would otherwise permit arcing from the cathode to the shield and then back to the anode. The shielding further comprises annular transverse members disposed at the ends of the enclosure so as to protect the end wall surfaces as well.

Vacuum arc switching device with internal shielding

A vacuum current limiting circuit interrupter having rapidly separable contacts and magnetic field coils disposed to produce a magnetic field transverse to the arc formed during circuit interruption. The transverse magnetic field creates arc instability and causes rapid arc extinction. The relatively movable contacts are disposed in an evacuated insulating envelope and are movable between a closed position completing an electrical circuit through the vacuum interrupter and an open position wherein the contacts are spaced relatively far apart with respect to the necessary voltage withstand level of the circuit interrupter. Magnetic field coils are supported to produce a magnetic field transverse to the arc plasma when the contacts approach maximum separation creating arc instability. An alternate current limiting path is provided in parallel with the vacuum interrupter through which reduced current flows until complete circuit interruption.

Vacuum fault current limiter

A vacuum interrupter is described having improved electrodes. The electrodes are of the cup-shaped type with an insert electrode disposed within the cup-shaped contact closely spaced from the base portion of the cup. The insert electrode has spiral or radial and circumferential extending slots therein. The spirals or slots of the insert electrodes may extend in the same or opposed directions.

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Pittsburgh, PA, United States of America

Clive W Kimblin