Westinghouse Electric Corporation

Electric Power Research Institute Incorporated

Paul G Slade

John A Wafer

Clive W Kimblin

Francis A Holmes

Joachim V Heberlein

Joseph G Gorman

Maurice G Fey

Carl Baldwin Freidhoff

Roy E Voshall

Ram Kossowsky

William J Lange

Norman S Hoyer

Howard R Ryden

An electrical vacuum interrupter comprising a pair of separable contacts enclosed within a vacuum enclosure whose walls have joints formed of a polymeric material which can maintain sufficient vacuum, mechanical, thermal, and electrical properties to permit proper operation. Major part of the vacuum enclosure, in addition to the joint, may be formed of a polymeric material. A method of assembly is provided that avoids need for high temperatures and includes use of electrical discharge between the contacts for cleaning the interior of the vacuum enclosure.

Vacuum interrupter with simplified enclosure and method of assembly

A vacuum interrupter characterized by an all-ceramic envelope forming an evacuated chamber in which a pair of separable contacts are disposed. The envelope is comprised of two substantially half portions having abutting end surfaces that are secured together in a vacuum-tight manner.

Vacuum interrupter with ceramic enclosure

An axial magnetic field vacuum-type circuit interrupter. Provided in an evacuated housing is a pair of opposed contacts at least one of which is movable with respect to the other and is movable between a closed position in engagement with the other contact to an open position spaced apart from the other contact to form an arcing gap therebetween during circuit interruption. Each contact includes a disc-shaped backing plate having at least two radially spiraling slots therethrough and a contact and arcing ring secured to and positioned about the face of the backing plate. The backing plates are substantially parallel to one another with the direction of the spiraling slots therethrough being reversed with respect to those of the opposing contact. Because of the reversed direction of spiraling in the opposed faces of the backing plates, an axial magnetic field is created by the flow of current through the contact structure which causes the arc to remain diffuse during the circuit interruption. In a further embodiment, the contact and arcing ring is provided with a plurality of axially skewed closed end radially slots extending therethrough. The slanted slots provide a transverse component to the magnetic field which drives any columnar arc formed around the rim of the contact and arcing rings.

Axial magnetic field vacuum-type circuit interrupter

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

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

An electrical contact suitable for use in high-current switching or circuit breaking, comprising a mixture of silver or copper with an alloy of tungsten carbide and titanium carbide. The contact material preferably uses from about 10% to about 90% silver by weight, the remainder being (WTi)C alloy, and preferably the alloy component comprises from about 35% to about 50% of WC, the remainder of the alloy being TiC. The contact is preferably made by a powder metallurgical process, and provides not only good impact resistance, weld resistance and erosion resistance but, even more importantly, provides low contact resistance, i.e. low electrical resistance when current flows through the closed contacts even after repeated cycling, as shown by the low temperature rise of the contact in use.

Electrical contact material of TiC, WC and silver

A circuit interrupter having a fixed elongated contact arm, with a fixed contact disposed at the end thereof, and an elongated movable contact arm, with a movable contact disposed at the end thereof, and a magnetic driving device for rapidly separating the contacts. The magnetic driving device is formed of a ferromagnetic material and has a slot formed therein which is magnetically open on one end. The fixed contact arm is partially disposed in the slot near the closed end and the movable contact arm is partially disposed within the slot towards the open end. The magnetic drive or slot motor rapidly separates the contacts upon a predetermined overload. Divergent arc rails lying in the same general plane extend from the fixed contact and the movable contact. A magnetic arc gun or yoke having an opening therethrough disposed around the movable contact, the stationary contact and a portion of the arc rails when used concentrates the arc and provides for rapid arc movement by concentrating the magnetic forces generated by current flow which acts upon the arc.

Current limiting circuit interrupter

A motor controller having a single set of contacts and two contact operating systems is provided for operation and protection of a motor and the associated circuitry over a complete range of possible currents. For a normal motor starter operation and for fault current up to a predetermined value, an electromagnetic actuator is used to open the contacts a relatively small distance such as 1/4 inch. For higher fault currents a magnetic drive or linear slot motor opens the contacts to a greater spacing such as 1 inch. The slot motor opens the contacts very rapidly giving rise to good current limiting. The disclosed integral motor starter utilizes a bridging contact arm on which are mounted a pair of movable contacts which are aligned to engage a pair of stationary contacts when the disclosed motor starter is closed, completing an electric circuit to the controlled motor.

Integral motor controller

A combination motor-starter circuit breaker comprising a single set of separable contacts and providing the function of motor starting, circuit interruption, and current limiting. The combination employs three separate means for separating the contacts to provide these functions; a solenoid, an overcurrent trip mechanism, and a magnetic drive device for high overcurrent conditions. Arc rails and spaced conductive plates are provided to aid in extinguishing any arcs established. Movable contacts are mounted on a bridging contact arm which can be provided with two open positions, a first position for use during motor control wherein the contacts are separated by a relatively small distance and a second position for use during circuit interruption and current limiting.

Combination motor-starter and circuit breaker

A motor controller providing a disconnect and a single set of movable contacts, to provide operation and protection of a motor and associated circuitry over a complete range of possible currents. Plug-in modules for a circuit disconnect, a solid state overload relay, and an instantaneous trip unit are provided. The disclosed integral modular motor controller consists of five major components: (1) an isolator switch, (2) arc chambers, (3) a linear slot motor drive, (4) a drive operator, and (5) a solid state control. For a normal motor starting operation and for fault currents up to a predetermined value, such as 1200 amperes, an electromagnetic actuator is used to open the contacts a relatively small distance such as 0.25 inch. For higher fault currents a drive or linear slot motor opens the contacts to a greater separation such as 1 inch. The disclosed modular integral motor controller utilizes a disconnecting switch connected in series with a movable bridging contact arm on which arm mounted a pair of spaced apart movable contacts aligned to engage a pair of stationary contacts when the motor controller is in the closed position to complete an electric circuit to the controlled motor. The bridging contact arm is provided with two open positions; one for use in motor control and relatively low fault currents, wherein relatively small contact separation is involved, and a second open position used during high fault currents and current limiting situations, wherein the movable contacts are separated from the stationary contacts by a relatively large separation.

Modular integral motor controller

A latch for a circuit interrupter is provided wherein a movable member having a contact attached thereto is latched in a selected position by a spring member which is deflected by the movable member until a predetermined distance is exceeded at which time the spring member moves into a latching position with respect to a latching surface provided on the movable member. In its simplest form the latch uses a single piece of spring wire. As a movable member moves past, the spring wire moves aside and once the movable member has completely passed the wire, the wire springs back into place preventing the contacts from reclosing. A reset is provided which permits the contact arms to be closed by moving the spring member to one side. The disclosed latch is very fast acting, can be independently actuated for each phase, and can be positioned so as to not interfere with low current operation of the switching device on which it is employed.

Latch for a circuit interrupter

An improved low-voltage circuit-breaker, adaptable for both alternating-current and direct-current is provided having small contact separation, when opened, and a pair of adjoining arcing-rails arranged in generally-parallel relationship, and having only a small gap therebetween of the order of 1/4 inch or less. Preferably, at the ends of the parallel-arranged arcing-rails are a pair of diverging arc-horns, constituting integral extensions of the parallel-arranged arcing-rails, and resulting in considerable elongation of the established arc upon its movement onto the diverging portions of the arcing-rails. Preferably, although not necessary, a suitable spaced-plate arc-extinguishing structure is arranged in the vicinity of the diverging portions of the arcing-rails to further facilitate arc extinction, by either elongating the arc around the splitter portions of the insulating plates, if the latter are of insulating material, or causing the formation of a plurality of serially-related arc-portions between spaced conducting metallic plates, if the arc extinguisher is of the spaced-metallic-plate variety.

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Pittsburgh, PA, United States of America

Paul G Slade