US2308214A - Fluid pressure operated mechanism for circuit breakers - Google Patents

Description

-Jan. 12, 1943.

H. S'ILEGELITZ ETAL FLUID PRESSURE OPERATED MECHANISM FOR CIRCUIT BREAKERS Original Filed Feb. 26, 19:58

Inventor's: Hans .Stegelitz,

Wilhelm Schr ein W 'MMZ Their Attorney.

Patented Jan. 12, 1943 UNITED STATES PATENT OFFICE FLUID PRESSURE; OPERATED MECHANISM FOR CIRCUIT BREAKERS Hans Stegelitz, Berlin-Johannisthal, and Wilhelm Schreiner, Berlin-Nieder-Schonhausen,

Ger-

many; vested in the Alien Property Custodian 4 Claims.

Our invention relates to fluid pressure operated mechanisms, such as, for example, pneumatically actuated mechanisms for an electric circuit breaker operable between open and closed circuit positions.

It has been recognized that the operating mechanism for closing a large capacity electric circuit breaker, for example, should include a socalled seal for automatically insuring continuation of the operating impulse throughout substantially the entire closing stroke of the breaker, and for discontinuing the impulse substantially at that point. Burning of the breaker contacts due to incomplete closure is therefore precluded and the usual trip-free feature assures short circuit protection. Methods heretofore used have generally included electric relays and auxiliary circuits which have not always worked satisfactorily and which often complicate the operating mechanism.

The principal object of our invention is the provision of an improved fluid-operated mechanism wherein an actuating impulse once initiated is automatically carried through to completion of the circuit closing operation and then discontinued.

This application is a division of our application Serial No. 192,804, filed February 26, 1938, for Fluid pressure operated mechanism, now Patent No. 2,281,337.

Our invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize our 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 a partly diagrammatic layout of circuit breaker operating means embodying the present invention including a pneumatic seal for carrying through the breaker actuating impulse.

The pneumatic circuit breaker operating system illustrated by way of example comprises a suitable source of fluid pressure, such as a conduit I connected to a gas reservoir (not shown), means adapted to be actuated by fluid pressure, such as a fluid motor of the piston type generally indicated at 2, and a main valve 3 for controlling the fluid connection 4 between the pressure source and the actuating piston.

As specifically illustrated, the fluid motor 2 comprises a piston 5 reciprocally operable within a cylinder 6 which is connected at its lower part to the fluid connection 4. The piston 5, through its piston rod 5', is operatively connected in any suitable manner to the movable contact I of an electric circuit breaker, such as by a pivoted link 8 and an insulating connecting rod 9. The circuit breaker, which is diagrammatically illustrated, comprises terminal conductors Ill and II which are connected respectively to the fixed contact structure I2 and the movable rod contact I.

The circuit breaker, which may of course be of the trip-free type but which is shown as non-tripfree in the interest of simplicity, is shown latched in the closed circuit position by a pivoted latch member I3 arranged to be controlled by the usual tripping solenoid i i. The breaker is normally biased toward open position by the spring l5 so that when the tripping solenoid I4 is actuated in response to an overhead or tripping impulse, the latch I3 is rotated clockwise against the bias of its resetting spring l3 causing downward or circuit opening movement of the rod contact 1. In the open circuit position, the roller 8 of the breaker lever -8 engages the upper end of the piston rod 5' so that a working stroke of the piston in response to opening of valve 3 is effective to cause counter-clockwise rotation of the lever 8 and closing movement of the contact 1. As the contact "1 reaches closed circuit position, the latch 13, under bias of its spring 13, snaps beneath the roller 8" carried by the lever 8 to latch and hold the breaker in closed position.

For the purpose of sealing the pneumatic operating impulse acting on the piston 5 when the valve 3 is first opened, we provide a pneumatic time delay device for automatically effecting closure of the valve 3 only after it has been held open by fluid pressure for a predetermined period, 1. e., for the time required to complete the working stroke of the piston 5. This assures complete closing of the circuit .breaker and precludes the possibility of damage to the breaker by arcing that might result if the operating impulse were prematurely checked.

Specifically, the valve 3 controlling communication between the pressure source I and the fluid connection 4 is adapted to be actuated by a lever It pivoted at I5 having suitable actuating means, such as a push-button shown at IT. The lever I6 can be adjustably related to the valve stem I8 of the valve 3 as indicated at [8. For the purpose of sealing open the valve 3 after initial operation of the push-button, a diiierential piston 19 having two portions 20 and 2| is connected as at 22 to the lever [6. The differential piston operates Within a stepped-cylinder housing 23, one end of which forms a cylinder for the piston portion 20 connected at 24 through the connection 4' to the main fluid connection 4. The other part of the housing forms a cylinder for the large piston 2| that is in communication at 25 with the connection 4' through a time delay device 26. The device 26 may comprise simply a fluid reservoir, the entrance of which at 21 can be suitably restricted with reference to an adjustable escape at 28, so that fluid pressure may build up in the cylinder of the piston 2i only after a predetermined time.

The operation of the pneumatic operating system will now be clear from the above description. When the push-button I1 is operated to cause initial opening of the valve 3, the diiferential piston 2Q2l is also moved toward the left. As the gas under pressure enters the fluid motor 2 by way of the connection 4, it also by way of connection 4' acts upon the piston 20 of the dif ierential piston to hold it and the lever l6 so as to seal the valve 3 in open position. When, however, the fluid pressure transmitted through the time delay device 26 builds up sufilciently at the working face of the differential piston portion 21, the lever i and hence the valve 3 under influence of fluid pressure, is returned to the initial position shown. The main valve 3 is now closed and held closed by the source pressure and the fluid motor in the meantime has received fluid pressure for e, suflicient period to assure complete closing of the breaker.

It should be understood that our 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 our invention.

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

1. Circuit breaker fluid operated actuating mechanism comprising a source of pressure, means adapted to be actuated by fluid pressure for closing said circuit breaker, a valve for controlling a fluid connection between said source and means, means for initiating the opening of said valve, an auxiliary pressure responsive device in communication with said connection for holding said valve in open position, a second fluid responsive device having a larger effective pressure area for closing said valve when fluid pressure in said connection is transmitted thereto, and a fluid reservoir between said connection and said second device for introducing a time delay in the operation of said device for assuring complete closure of said circuit breaker.

2. Circuit breaker operating mechanism of the pneumatic type comprising a source of gas pressure, a piston arranged to be actuated by said pressure for closing the circuit breaker, a valve for controlling a gas connection between said source and piston, means for initiating the opening of said Valve, 2. difierential piston, the small diameter portion of which is in communication with said gas connection, means operatively connecting said valve and differential piston, and a gas reservoir disposed between said gas connection and the large diameter portion of said differential piston, said reservoir having mean for introducing a, time delay in the building up of fluid pressure at said large diameter portion for delayin the closing of said valve and assuring complete closing of said circuit breaker.

3. Circuit breaker operating mechanism of the pneumatic type comprising a source of gas pressure, a piston arranged to be actuated by said pressure for closing the circuit breaker, a valve for controlling a gas connection between said source and piston, a member arranged to engage and open said valve, and time delay means for holding said member in the valve-open position for a predetermined time for assuring complete closing of said circuit breaker comprising a differential piston connected to said member, means for admitting gas under pressure from said connection directly to the small diameter portion of said differential piston, a gas reservoir for receiving gas under pressure from said connection and means for connecting said reservoir to the large diameter portion of said piston, said reservoir having restricted pressure-transmitting openings so that there is a predetermined time delay in the build-up of pressure at said large diameter portion tending to return the differential piston and said member to the valve-closed position.

4. A circuit breaker fluid operated actuating mechanism comprising a source of fluid pressure, a fluid motor adapted to be actuated by fluid pressure for closing said circuit breaker, a valve for controlling the fluid connection between said source and motor, a push button control for causing opening of said valve, said control being normally biased toward the valve-closed position, an auxiliary pressure responsive device including a differential piston adapted to be actuated to one position by fluid pressure from said source for maintaining open said push button control substantially throughout the circuit closing period of operation of said motor, and a fluid connection includin a pneumatic time-delay device for connecting said source to said differential piston for actuating it to another position for causing closing of said valve.

HANS STEGELITZ. WILHELM SCHREINER.

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