US2820118A - Circuit closer - Google Patents

Description

Jan. 14, 1958 E. ZANTOP 2,820,118

CIRCUIT CLOSER Filed Sept. 50, 1954 I INVENTOR ERA/5 T 214mg ITTORNEYJ,

United States Patent 2,820,118 CIRCUIT CLOSER Ernst Zantop, Wettingen, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland, a joint stock company Application September 30, 1954, Serial No. 459,266

Claims priority, application Switzerland October 2, 1953 6 Claims. (Cl. 200-87) This invention relates to a circuit closer and particularly to a sensitive and quick-acting circuit closer for use in the protection of contact rectifiers against damage by excessive currents or reverse currents.

Protective devices employed in rectifier engineering have included short-circuiters comprising a normally open switch spring-biased towards closing and latched against closing, the latch being released by an electromagnet to permit closing of the switch to short the leads from the transformer feeding the main rectifier contacts, thereby resulting in actuation of the protective circuit breakers.

Objects of the present invention are to provide circuit closers which are sensitive and quick-acting, the circuit closers being biased to closed position by springs and latched open by mechanisms which exert but little force in opposition to that developed by the closing springs, whereby the latching mechanism may be released by relatively light electromagnets. More specifically, an object is to provide a circuit closer including a contact on a spring-tensioned rod, a roller on a rolling abutment at a slight angle to a plane normal to the path of movement of the rod, a latch member normally retaining the roller on the abutment, and an electromagnet for actuating the latch member to permit the roller to slip from the abutment.

These and other objects and the advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which Figs. 1 and 2 are schematic diagrams of circuit closers embodying the invention.

In the drawing, the reference characters a a identify the fixed contacts of a normally open switch having a cooperating movable contact b supported on and separated by insulation d from a slide rod 2. The rod e is guided for vertical movement by a body 1 forming a part of the structural assembly of a contact rectifier, and the fixed contacts are connected electrically with the conductors from the transformer feeding the main contacts of one phase of the rectifier. In the case of a three phase rectifier, a shorting switch is provided for each phase and the sets of fixed contacts are preferably arranged in a triangle.

The slide e is of frame or yoke form at its upper end and includes a cross-frame or bar e' which rests upon the supporting roller g superposed upon abutment roller g supported on the inclined upper surface of an extension 11 at the base of the guide body f. The lower face of the bar e may be formed as a knife edge contacting the roller g or, as shown, it may be rounded ofii. The rollers are held against the vertical face of the guide body f by a latch member 1' which is a one-arm lever forming the armature of an electromagnet k which is normally energized so long as the rectifier is operating correctly, for example is energized by the rectifier output voltage.

The slide e is biased downwardly by a spring m acting upon the lower extension n of the slide e. The spring m is preferably formed of a stack of domed spring plates which may be telescoped or, as shown, may be arranged 2,820,118 Patented Jan. 14, 1958 2 in pairs of oppositely facing domed members, and is supported below and clear of the fixed contact members.

The inclination of the top surface of the extension h to a plane normal to the vertical path of movement of the slide e is about 05 to 12, whereby the horizontal component of the pressure exerted on the roller g by the vertical pull of spring m is relatively small and may be readily overcome by the armature i and electromagnet k. A larger angle of inclination would of course require a heavier electromagnet to retain the switch in open position.

Upon de-energization of the electromagnet, the armature i swings away to permit the rollers to drop from the extension h, and the switch closes when the rod e is pulled down by the spring m to engage the bridge contact b with the fixed contacts a, and 11,. The abutment roller g rolls downwardly and outwardly along the slightly inclined surface of the fixed extension h. The supporting roller g supporting the bar 2' then has in effect an abutment consisting of a downwardly and outwardly abutment roller g and will roll to the right with a rotation opposite to that of the abutment roller g Thus the roller detent means will provide an extremely quick-acting release with small friction components upon de-energization of the electromagnet.

As shown in Fig. 2, the fixed extension h is replaced by an abutment roller r upon which supporting roller 3 is normally retained by a latch i which is urged towards the guide body f by an adjustable spring s. The shaft r of abutment roller r is of course mounted in the guide body outside of the path of movement of the slide e. In this embodiment, the electromagnet k is normally deenergized and must be energized by some appropriate control circuit to overcome the force of spring s when the switch is to be closed. Upon energization, the rolling and downwardly inclined abutment for the supporting roller g, is provided by the abutment roller r arranged for rotation about an axis offset from the longitudinal travel of the slide rod. Thus the supporting roller g has an effective abutment comprising the periphery of an offset rolling surface. Since the abutment roller r is offset, an effective inclination is obtained by the periphery of the roller. Thus this embodiment will similarly provide an extremely quick-acting release upon energization of the magnet.

I claim:

1. A circuit closer comprising a pair of normally-open fixed contacts, a movable contact adapted to bridge said fixed contacts, a slide rod connected to said movable contact and adapted to move axially at right angles to the plane of said fixed contacts, spring means urging said mov able contact in a direction to cause engagement of the same with said fixed contacts, a guide body guiding said slide rod during its axial movement, and means normally latching said slide rod against switch closing movement by said spring means; said latching means including an abutment on said guide body, said abutment having a rotary periphery, a supporting roller superposed upon said abutment, an extension on the end of said slide rod supported by said supporting roller, a latch retaining said roller upon said abutment, and electromagnetic means for releasing said latch, said roller rolling downwardly upon said rolling abutment with a direction of rotation opposite thereto.

2. A circuit closer as defined in claim 1, wherein said abutment comprises an inclined extension on said guide body, and an abutment roller supported by said extension and supporting said supporting roller superposed thereon.

3. A circuit closer as defined in claim 2, wherein said inclined extension has a downward inclination of the order of 12 to a. plane normal to the path of movement of said slide rod.

4. A a circuit closer as defined in claim 3 wherein said extension on saids'lidc'igdlidsfhg inclined surface coop- References Cited in the file of this patent Grating With said supporting 1131161. UNITED STATES PATENTS 5. A circuit closer as defined in claim 3 wherein said extension on said slide rod has a k-nife-ed-ge surface coop- 1982521 Johnson 1934 crating with said supporting goller. 5 2150566 Scott 1939 6. A circuit closer a's defined in claim 1 wherein said 2543398 Bohn 1951 abutment comprises an abu'jt men t 01km journgllcd on FOREIGN PATENTS said guide body offset inwardly toward the guide body from the longitudinal motion of t 'z vel of s i said abutment Follephaving a larger'diarneter than that 10 445 215 Germany June 2 1927 of Sald SUPPmtmg 993:669 France Nov. 5, 1951

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