US2078784A - Electric circuit breaker - Google Patents

Description

April 27, 1937. R. WILLHEIM 2,078,734

ELECTRIC CIRCUIT BREAKER 1 Filed Nov. 19, 1956 1 I i /7 i g Invemtor:

Raoul Willhe 'm, b v M MMZ His tcorney.

Patented Apr. 27, 193 7 PATENT OFFICE ELECTRIC CIRCUIT BREAKER Raoul Willheim, Berlin-Oberschoneweide, Germany, assignor to General Electric Company, a corporation of New York Application November 19, 1936, Serial No. 111,733

' In Germany April 30, 1936 5 Claims.

My invention relates to electric circuit breakers and more particularly to means for protecting a circuit breaker in the event that failure of the circuit opening means results in an incomplete circuit opening operation.

In certain types of electric circuit breakers for interrupting large amounts of power, failure of the circuit opening means, particularlyin case of pneumatic operating means, may occur during the circuit opening operation with the result that the movable contact structure remains in an intermediate position, or is moved too slowly away from the fixed contact structure. Consequently the arc drawn between the contacts tends to persist and causes more or less damage to the circuit breaker.

In accordance with the present invention, the circuit breaker operating mechanism is arranged so that a force is continually applied to the movable contact structure, tending to move such structure to the closed circuit position. Thus, in the event that there is failure of the circuit opening means before the movable contact structure has reached the fully open circuit position, the breaker is again immediately reclosed so that damage which might be caused by the persisting arc is prevented. The present invention is particularly suitable for circuit breakers actuated by pneumatic operating means, such as gas blast circuit breakers, for example, wherein the. source of gas pressure for operating the switch is also the source of the arc interrupting gas blast. In such a case, it will be apparent that failure of the source of pressure would ordinarily result in failure of the breaker.

A principal object of my invention is the provision of an improved circuit breaker of the aforesaid type which functions to reclose the breaker immediately upon failure of the circuit opening means.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, the single figure thereof is an elevational view. partly in section, and partly diagrammatic, of an electric circuit breaker embodying the present invention.

The circuit breaker shown by way of example is of the liquid-break or oil type and comprises a tank I containing a suitable insulating and arc extinguishing liquid 2 such as oil, within which are immersed the coacting fixed and movable is inadequate to complete the opening operacontact structures 3 and 4 respectively. The contact structure is of the double break bridging type, the bridging member at 4 being operated in a manner well known in the art by a lift rod 5, between the open and closed circuit positions. 5 In the lowered position, the bridging or movable contact structure 4 is in the open circuit position, the circuit being closed by elevating the lift rod 5 so that the contacts 4' carried by the bridging member engage coacting fixed contact struc- 10 tures at 3. The lift rod 5 is guided through the cover structure I of the circuit breaker, said cover also supporting the lead-in conductor bushings 6 at the lower ends of which the fixed contacts 3 are mounted. 15

The actuating means for effecting the circuit operation is generally indicated at I, and in the present instance, a pneumatically operated device is shown. The operating device comprises a piston 8, operably connected to the lift/rod 5 through a lever 9, which is pivoted at i0, and suitably connected at H and 12 to the pistonand lift rod respectively. The piston 8 operates within a cylinder 13 which is adapted to be in communication with a source of gas pressure, the application of pressure being controlled by a twoway valve I4. In the position shown, the valve is closed and the cylinder I3 is thereby provided with an exhaust port to atmosphere so that reverse movement of the piston 8 during the re-" closing operation is not retarded.

In normal operation of the circuit breaker, the valve I l is opened in any suitable manner, such as by a solenoid l5 energized from the conventional current transformer I6 to admit gas under pressure through the pipe I! to the piston 8. Upward movement of the piston causes opening of the circuit breaker, the breaker being held in such position by a suitable latching means indicated at 18, coacting with the lift rod 5.

In the event that the source of pressure falls before the breaker is open, there is provided a spring i9 seated at one end on a fixed abutment 20 and bearing on a collar 2| secured to the lift rod 5 so as to exert a continual bias on the lift rod in the circuit closing direction. The spring I9, however, is designed so that it is readily overcome by the normal operating force for opening the breaker. When, however, this force falls or tion in such a manner as to quickly extinguish the arc, the spring I9 is effective immediately to reclose the breaker and to preve'nt possible damage due to continuing of the are.

In the normal operation of'the breaker, the 55 closing operation is performed by the spring I! in response to release of the latch i! which ordinarily engages the lift rod 5 when the same reaches its open circuit position.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising relatively movable contact structure, actuating means for efifecting circuit opening movement of said contact structure, means holding said contact structure in open circuit position when the opening operation is fully completed, and means biasing said contact structure towards closed circuit position, said means being efifective to reclose said contact structure in the event of failure of said actuating means resulting in incomplete or inadequate opening movement.

2. An electric circuit breaker comprising relatively movable contact structure, actuating means for biasing said contact sructure in the direction of circuit opening movement, means holding said contact structure in open circuit position when the opening operation is fully completed and means biasing said contact structure at all times towards closed circuit position, said first-named biasing means normally overcoming said second biasing means, and said second biasing means being eflective immediately to reclose said contact structure in the event of failure of said first named biasing means.

3. An electric circuit breaker comprising relatively movable contact structure, actuating means for effecting circuit opening movement of said contact structure, a latch for holding said contact structure in the open circuit position only when the opening operation is fully completed, and a spring normally biasing said contact structure towards closed circuit position, said actuating means normally overcoming said spring in the opening operation, and said spring being effective immediately to reclose said contact structure upon a iailure of said actuating means during an opening operation.

4. An electric circuit breaker comprising relatively movable contact structure, pneumatically operated means for efiecting a circuit opening movement of said contact structure, latching means for holding said contact structure in open circuit position only when the opening operation is fully completed, and means normally biasing said contact structure towards closed circuit position, said biasing means being effective to close said circuit breaker upon failure of said pneumatic means during a circuit opening operation.

5. An electric circuit breaker comprising fixed and movable contact structure, a piston operatively connected to said movable contact structure, valve means for controlling application of gas under pressure to said piston for causing opening movement of said contact structure, latching'means for holding said contact structure in the open circuit position only when the opening operation is fully completed, and a spring normally biasing said movable contact structure towards closed circuit position, said spring being eifective to reclose said contact structure in the event of failure of gas pressure at said piston during the opening operation, said valve means providing an exhaust port for the release of back pressure at said piston during said reclosing operation.

RAOUL WILLHEIM.

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