US3559137A - Electric circuit breaker - Google Patents

Abstract

AN ELECTRIC CIRCUIT BREAKER CONSISTS OF A PLURALITY OF ALIGNED UNITS. EACH UNIT HAS TWO PAIRS OF CONTACT BRIDGES ADAPTED TO ENGAGE STATIONARY CONTACT PIECES. SPRINGS PRESS THE CONTACT BRIDGES AGAINST THE CONTACT PIECES. THE CONTACT BRIDGES OF EACH PAIR MAY BE OPENED BY CAMS OPERATED BY AXLES. A FUSE MAY BE LOCATED BETWEEN THE PAIRS OF CONTACT BRIDGES AND MAY BE CONNECTED THEREWITH BY CONTACT

MEMBERS. AN ARC QUENCHING CHAMBER IS LOCATED CLOSE TO THE OUTER PAIR OF CONTACT BRIDGES. THE AXLES ARE INTERCONNECTED BY A MECHANISM WHICH PROVIDES THAT THE OUTLET PAIR OF CONTACT BRIDGES WILL BE ALWAYS OPEN AHEAD OF THE INLET PAIR OF CONTACT BRIDGES.

Description

JM. 26, 1971 T BERGMAN ETAL ELECTRIC CIRCUIT BREAKER Filed March 19, 1969 Q fm2 l Fifa INVENTORS T Bergman .1 CLI/Han au ATTORNEYS United States Patent 3,559,137 ELECTRIC CIRCUIT BREAKER Tage Bergman and Asbjorn Gjellan, Sundsvall, Sweden, assignors to Kafak Aktiebolag, Sundsvall, Sweden, a corporation of Sweden Filed Mar. 19, 1969, Ser. No. 808,469

Claims priority, application Sweden, Mar. 20, 1968,

3,643/ 68 Int. Cl. H01h 85 /48 U.S. Cl. 337-8 3 Claims ABSTRACT F THE DISCLOSURE An electric circuit breaker consists of a plurality of aligned units. Each unit has two pairs of contact bridges adapted to engage stationary contact pieces. Springs press the contact bridges against the contact pieces. The contact bridges of each pair may be opened by cams operated by axles. A fuse may be located between the pairs of contact bridges and may be connected therewith by contact members. An arc quenching chamber is located close to the outlet pair of contact bridges. The axles are interconnected by a mechanism which provides that the outlet pair of contact bridges will be always open ahead of the inlet pair of contact bridges.

This invention relates to a circuit breaker and refers more particularly to an electric circuit breaker having aligned and spaced stationary contacts as well as movable contact bridges adapted to bridge over the space between two stationary contacts.

Circuit breakers of this type are intended for use in electric switchgear cabinets for distribution of electric energy to individual consumers. Such switchgear cabinets are often very large, having a length of up to some tens of meters and a minimum width, for example 0.6 meter, which cannot be reduced ywithout the risk of impairin g easy serving and safety for the personnel. It is therefore desirable to arrange separately switching appliances for each consumer and make them as compact and nevertheless as safe as possible. The width of the cabinet can be utilized to the best extent by arranging units of the apparatus upon a disc and making the apparatus low, so that the largest possible number of apparatus units can be placed Within each of the cabinet units.

An object of the present invention is to improve circuit breakers of the described type by providing a more etfective construction and arrangement.

Other objects will become apparent in the course of the following specification.

It should be noted that usually each apparatus unit has a standard fuse of knife type for each phase conductor. Reduction in space can be achieved according to the present invention by making the connecting members of these fuses as parts of the circuit breaker. It is necessary to avoid, however, that the contact members of the fuses be affected by electric arcs produced when the circuit breaker is disconnected, since the contact members of the fuses Were not intended originally to be influenced by heat or to be corroded by the operation of the circuit breaker. However, the contact members of the fuses can effectively form, without any danger, the fulcrum of swingable switch members constituting a part of the circuit breaker. This saves the necessity of having an additional constructional element for the fulcrum of the circuit breaker.

IFurthermore, the swingable switching members of the switch can be constructed as spring-loaded contact bridge pieces adapted to retain the connecting contactmembers of the fuses in a clamping relationship. Then the circuit breaker will have the additional function of serving as a receiving and holding member for the fuse. Such conice structions will eifectively reduce the space necessary for the switching apparatus without affecting the safety requirements.

Finally the required space can be further reduced by placing the casing of the apparatus unit as closely as possible to the circuit breaker and the fuse. It is necessary,7however, to make the Walls of the casing of an insulating material which will not inuence magnetically the current conductors and which will be able to withstand very high shock-like temperatures that may be produced by a short circuit within the casing surrounding the switching apparatus. By eliminating the magnetic influence on the current conductors it is possible to use the inherent dynamic forces of the current along with an arc quench chamber to let the arc which occurs at current interruption to extinguish itself.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing, showing by way of example only, a preferred embodiment of the inventive idea.

In the drawing:

FIG. l is a section through a current breaker of the present invention illustrating its use in a switching apparatus unit of an electric switchgear cabinet;

FIG. 2 is a section along the line II-II of FIG. l;

FIG. 3 is a partial diagrammatic view illustrating the arrangement of the switching units in a switchgear cabinet.

As shown in FIG. 1, the switching apparatus of the present invention includes a base disc 10 made of tireproof insulating material which should not contain any magnetic substance and should not influence the breaking capacity of the switching apparatus. The disc 10 is slidable in a slot 12 provided in a casing 14 made of the same material as the disc. Thus the disc 10 can be moved out of the casing 14 whenever it is desired to inspect the parts carried by the disc.

The base disc 10 carries two bolts 16 and 18. Each bolt carries an upper helical spring 20` and a lower helical spring 22. The spring 20 of the bolt 16 presses from above against a contact bridge 24 while the spring 22 of the bolt 16 presses from below against a contact bridge 26. Similarly, a contact bridge pair 24', 26' is pressed from opposite sides by the helical springs carried by the bolt 18. The contact bridge pair 24, 26 abuts at one end a stationary contact piece 28 extending through a wall of the casing 14. The other end of the contact bridge pair 24, 26 abuts an exchangeable standard fuse 30 provided with connection knife contacts 32 and 34. The contact bridge pair 24', 26 cooperates with a stationary contact piece 28 extending through an opposite wall of the casing 14. The contact piece 28 is considerably longer than the contact piece 28 since it receives an arc quenching chamber of known type provided with plates 36.

In FIG. 1 the contact bridge pair 24, 26 is shown in the closed position while the contact bridge pair 24', 26 is shown in the open position. The bridge pairs are actuated by axles 38 provided with cam members 40 consisting of an insulating material. Handles 42 located outside of the casting and fixed to the axles 38 are used to actuate the cams 40. FIG. 1 shows the lefthand cam 40 in the closed horizontal position so that the contact bridges 24, 26 will provide current closing. The righthand cam is shown in a vertical position wherein the contact bridges 24', 26 are moved away from the stationary contact member 28. lf the lefthand cam 40 is moved to its vertical position, the contact bridges 24, 26 will be moved away from the connecting knife contact 32 of the fuse 30. During these movements, the contact bridge pairs 24, 26 and 24', 26 are swung around the abutment edges of the stationary contact members and fuse contacts, respectively, against the action of the springs 20, 22.

In operation, the switching apparatus is opened by always opening first the righthand circuit breaker 24', 28', 26. The reason for this is that the electrical current lows in the direction of the arrow 44 from the contact piece 28 to the contact piece 28', Thus when the contact bridge pair 24', 26' is opened, an arc 46 will be produced which will tend to widen its length away from the energy source. The arc is driven into the plate system 36 of the arc quenching chamber which will cause a. momentary cooling of the high gas temperature of the arc and consequently a blowout. To make certain that the circuit breaker located at the quenching chamber will be always the irst to open, the two actuating axles 38 are interlocked by a mechanism comprising a pin 48 which is movable longitudinally and one end of which is engaged by a cam 50 fixed upon the righthand axle 38. The other end of the pin 48 is adapted to t into a hole 52 provided in the lefthand axle 38. A tension spring 54 presses the pin 48 against the cam 50. The construction is such that the pin 48 by being located in the hole 52 will lock the lefthand axle 38 and prevent its operation except when the cam 40 of the righthand axle 38 is in its vertical position, namely, when the contact bridge pair 24', 26' is open. Thus the lefthand contact bridge pair 24, 26 can be opened only after the opening of the righthand contact bridge pair 24', 26.

As shown in FIG. 2, a plurality of circuit breakers are arranged in the same plane one behind the other. Usually there are three circuit breakers in a three phase system (transversal array). Should a fault occur in the circuit breakers, the operator rst opens the righthand ones, then the left ones and then pulls the disc out of the casing, so that only the stationary contact pieces 28, 28 with the quenching chambers 36 are left within the casing. This makes it easy to test the individual parts of the circuit breakers both upon the base disc and inside the casing and to replace the damaged parts, for example, the fuses 30.

If fuses are not desired, they can be eliminated and then the contact pieces 28 will extend directly to the contact bridges 24', 26'.

Furthermore, the fuses 30 can be replaced by plain continuous metal pieces 30.

FIG. 3 shows a cabinet 60 provided with a plurality of switching devices of the type shown in FIGS. 1 and 2, which are placed one above the other and are connected at their input side to common bus bars 62 in a bus bar channel 64 and at their output side to cables 66 which transmit electrical energy to individual consumers. The cabinet 60 should consist of the same material as the base discs .10 and the casings 14. However, if steel plates are required for security reasons, they should be located as a sufficiently large distance from the current paths of the switching apparatus.

If desired, the axles 38 can be actuated by suitable driving means, such as an electro-magnet or a driving motor which will turn the axles 38 between closed-circuit and open-circuit positions, so that the switching apparatus will be remotely controlled.

We claim:

1. An electric circuit breaker, comprising in combination, two pins, at least two pairs of contact bridges, each pair of contact bridges being carried by a separate pin and consisting of an upper contact bridge and a lower contact bridge, the two pairs of contact bridges extending opposite each other, separate springs pressing the two contact bridges of each pair against each other, cam members, axles swinging said cam members, each cam member being located between upper and lower contact bridges 0f a separate pair of contact bridges and being adapted to swing opposed ends of the upper and lower contact bridges of the same pair toward and away from each other, a fuse located between two pairs of contact bridges, two contacts extending from opposite sides of said fuse, the ends of upper and lower contact bridges of one pair engaging from opposite sides one of said contacts, the ends of upper and lower contact bridges of the other pair engaging from opposite sides the other one of said contacts, two other contacts, opposite ends of upper and lower contact bridges of said one pair engaging from opposite sides one of said other contacts when actuated by a cam member and upper and lower contact bridges of said other pair engaging from opposite sides the other contact of said two other contacts, when actuated by the other cam member, and means actuating the axles of the cam members.

2. A circuit breaker in accordance with claim 1, comprising a casing surrounding said contact bridges and consisting of reproof nonmagnetic insulating material, said other contact piece extending through and being secured to said casing.

3. A circuit breaker in accordance with claim 2, comprisinga disc slidably and removably mounted in said casing and carrying said springs and said contact bridges.

References Cited UNITED STATES PATENTS 3,009,035 11/1961 Reichert et al. 337--7 2,643,312 6/1953 Rodden 200--l68(B) 2,544,761 3/1951 Kilminster 20D- 168(D) 2,458,511 l/1949 Harlow 337-9 2,307,258 1/1943 De Smidt et al. 200-168(B) 2,254,914 9/1941 Rugg 200-166(E) FOREIGN PATENTS 963,895 7/1964 Great Britain 200-166(E) OTHER REFERENCES W. German Printed Application DAS 1,034,744, July 1958, G. Vedder, 200-6(B1).

BERNARD A.` GILHEANY, Primary Examiner D, M. MQRGAN, Assistant Examiner

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