US2362313A

US2362313A - Auxiliary switch

Info

Publication number: US2362313A
Application number: US480941A
Authority: US
Inventors: Harold N Schneider
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1943-03-29
Filing date: 1943-03-29
Publication date: 1944-11-07
Anticipated expiration: 1961-11-07

Description

Nov. 7, 1944. H. N. SCHNEIDER AUXILIARY SWITCH Filed March 29, 1943 2 Sheets-Sheet i a M W :e n w r L WSZUV e V A .n@ a [07 T b 1944. H. N. SCHNEEDER 2,352,313

AUXILIARY SWITCH v Filed March 29, 1945 ZSheets-Sheet 2 Inventor": Hare! N.5chneiden His Attorney.

Patented Nov. 7, 1944 UNITED STATES PATENT OFFICE AUXILIARY SWITCH Harold N. Schneider, Philadelphia, Pa., assignor to General Electric Company, a corporation of New York Application March 29, 1943, Serial No. 480,941

5 Claims.

- and opened at the same point during the circuit breaker closing and opening strokes. For high speed reclosing type circuit breakers it would be desirable to have an auxiliary switch which completes the trip circuit insofar asthe auxiliary switch is concerned at a given point during the closing stroke of the circuit breaker and which opens the trip circuit at an entirely difierent point during the opening stroke of the circuit breaker. If the circuit breaker is closed on a fault an arc is likely to strike when the contacts are still separated by a sizable proportion of the entire stroke. Consequently it is desirable to have the trip circuit completed early during the closing stroke so that opening of the circuit breaker in the event of closing on a fault may occur very early during the closing stroke and long before the contacts are completely closed. Similarly, it is desirable to have the contacts of the auxiliary switch opened early during the opening stroke so that the contacts of protective relays and the like if sealed in by the tripping current may reset to be ready to again properly control the trip circuit upon immediatereclosing of the circuit breaker. Also, if the particular circuit breaker with which the auxiliary switch is associated happens to be the wellknown'air blast type circuit breaker, such an early opening and early closing auxiliary switch will be an aid in preventing the Waste of air. Heretofore, in order to open the trip circuit during the opening stroke of the circuit breaker at a point entirely independent of the closing of the trip circuit during the circuit breaker closing stroke, a combination of switches and sometimes relays, have been used which were not only cumbersome, but to a large extent were not very reliable.

Accordingly, it is an object of my invention to provide a new and improved auxiliary switch for an electric circuit breaker which is opened or closed in response to the opening and closing of the circuit breaker.

It is another object of my invention to provide a new and improved auxiliary switch for during the closing stroke of the circuit breaker at which the auxiliary switch closes the trip circuit of the circuit breaker.

Further objects and advantages of my invention will become apparent as the following description proceeds 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.

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1 is a partly diagrammatic layout of an electric circuit breaker and a con- .trol system therefor embodying my invention,

Fig. 2 illustrates a portion of the apparatus and system of Fig. 1 showing a. different operating position thereof, and Figs. 3 and 4 are diagrammatic layouts similar to Figs. 1 and 2 respectively illustrating a modification of my invention.

Since my invention is applicable to any electric circuit breaker, single phase or polyphase, I have chosen to illustrate it as applied to an electric circuit .breaker in schematically illustrated as a single pole breaker for controlling the flow of power between two circuits II and I! which have been illustrated as single phase circuits. It should be understood that circuits II and I2 and circuit breaker I0, might equally well be polyphase. Circuit breaker ID has been illustrated as a latched closed circuit breaker including a latch 13 for holding circuit breaker in closed. Latch l3 maybe operated by means of a trip coil ll. In series with trip coil II are the contacts l5 of my new and improved auxiliary switch, generally indicated at I 8 and to be described in greater detail hereinafter.

Circuit breaker I0 is, illustrated as being provided with a closing winding 11 connected across a source of control potential I8 through a manually operable closing switch l9. In order to simplify the disclosure I have not illustrated the circuit for controlling the automatic reclosing of circuit breaker Ill upon opening thereof. However, such automatic reclosing controls are well-known in the art and any such suitable control may be provided.

an electric circuit breaker which opens'the trip circuit at a point during the opening stroke of the circuit breaker independently of the point The trip circuit including trip coil I4, andthe contacts 15 of auxiliary or a switch It are connected across a source of control potential either through a manually operable opening switch 20, or through the contacts 2| of fault responsive relay 22 which has a winding 23 thereof energized in response to the current flowing in circuits H and. It by virtue of a current transformer 24.

Since the contacts 2| are usually rather delicate although they can close the trip circuit, are incapable of opening the trip circuit without damage thereto, some form of sealing action is usually employed. As illustrated in Fig. 1 this sealing action comprises a separate winding 25 on fault responsive relay 22 which winding is associated with a separate magnetic structure. This winding 25 is energized through the contacts 2| of fault responsive relay 22 so that whenever fault responsive relay 22 is energized by virtue of an abnormally high current flowing in the windings of current transformer 24, the contacts 2| are closed by a contact controlling member 28 and winding 25 is energized to maintain these contacts in the closed position until the contacts |5 of the auxiliary switch |6 are opened. Fault responsive relay 22 is often provided with some time delay means to prevent high speed closing thereof whereby transients will not cause false tripping of circuit breaker l0. As a practical matter the contacts 2| also require some time to open and although that time is maintained as small as possible, it nevertheless may be suflicient to cause difficulty in connection with high speed reclosing type circuit breakers unless resetting of fault responsive relay 22 is permitted early during the opening stroke of circuit breaker |0.

Auxiliary switch l6, embodying my invention, is very simple and compact and yet provides an arrangement whereby the trip circuit is dee ergized during the opening stroke of the circuit breaker at a point independent of the point during the closing stroke of the circuit breaker when the trip circuit is completed insofar as the contacts l5 are concerned.

As illustrated in the drawings, auxiliary switch I6 comprises a member 21, pivotally mounted at 28. Pivotal movement of member 21 in response to opening and closing movements of circuit breaker ID is obtained by means of a gear 29 which engages a rack 30 on the operating rod of circuit breaker i0. Opening or closing of circuit breaker it) will cause gear 29 to rotate in a clockwise or counterclockwise direction respectively. One end of lever 21 is connected by means of a link 3| and a crank 32 with the shaft 33 to which gear 29 is attached so that opening and closing of circuit breaker l will cause member 21 to rotate about pivot 28. The other end 21' of pivotally mounted lever 21 is adapted to engage a pivotally mounted contact controlling member 34 which is normally biased to the open position indicated in Fig. 2 by means of a spring 35. A suitable stop 36 limits the opening movement of switch or contact controlling member 34. As long as the end 21' of lever 21 engages the switch or contact controlling member 34 as indicated in Fig. 1, the contacts of auxiliary switch l6 are held closed. Upon opening of circuit breaker i0 lever 21 begins to rotate about pivot 28 in a counterclockwise direction, thereby permitting early opening of contacts |5 of auxiliary switch l6 as is indicated in Fig. 2.

Although the arrangement described thus far provides early opening of contacts |5 of the auxiliary switch i6 during the opening stroke of circuit breaker i0, this arrangement alone would rovide late closing of the contacts |5 during the closing stroke of circuit breaker H) which,

as has been pointed out above, would be undesirable. In order to control the closing of contacts l5 at a point of the breaker stroke which is independent of the opening point of thesecorl- Full 'closing stroke and causes contacts tacts, I provide apivotally mounted dog or member 31, which is pivotally mounted to the end 21' of lever 21 as indicated at 39. A suitable spring 39 which is a lighter spring than spring 35 mentioned above, biases dog 31 in a counterclockwise direction against an adjustable screw 4| in stop member 40. During the opening stroke of circuit breaker [0 dog 31 rotates in a clockwise direction since spring 39 is insufficient to maintain switch controlling member 34 closed against the action of spring 35. During the closing stroke of circuit breaker l0, however, as may be clearly seen from Fig. 2 dog 31 engages switch controlling member 34 early during the |5 to be closed since the adjustable stop comprising screw 4| prevents relative rotation between dog 31 and member 21. With this arrangement the surface 34' of switch controlling member 34 engaged by the end 21' of lever 21, controls the point where contacts I5 are opened with rcference to the circuit breaker opening stroke. while the length of surface 31 of dog 31, controls the point at which the contacts |5 are closed with reference to the circuit breaker closing stroke. By changing the relation of these surfaces and in extreme cases the gear connecting auxiliary switch IS with the operating mechanism of circuit breaker l0, it is possible to obtain any practical variation between the point of make and the point of break of contacts l5 that may be required.

In view of the detailed description included above, the operation of the auxiliary switch of my invention will be obvious to those skilled in the art. In Fig. 1 the circuit breaker is closed and the auxiliary switch contacts |5 are also closed. Upon opening the breaker, gear 29 rotates in the direction of the arrow indicated in Fig. 1 to cause member 21 to rotate in a counterclockwise direction. Since dog 31 which is pivoted on lever 21 can rotate in clockwise direction in Figs. 1 and 2 it will have no influence in holding switch controlling member 34 in a position to maintain contacts l5 closed, but instead will collapse allowing contacts |5 to open as soon as the surface 34' is free of the end of lever 21.

Referring to Fig. 2 showing the circuit breaker. and consequently the auxiliary switch H5 in the open position, closing of circuit'bre aker l0 will cause gear 29 to rotate in the direction of the arrow indicated in Fig. 2. Lever 21 first moves in a counterclockwise direction and when this 5 motion has progressed to a predetermined point it rotates in a clockwise direction. As this clockwise motion continues, dog 31 engages the surface 34' of contact controlling member 34 so as to close contacts [5. Further clockwise rotation of lever 21 carries dog 31 clear of the surface 34' but the end 21' of lever 21 then maintains the contacts IS in the closed position.

Although I have disclosed my invention in Figs. 1 and 2 as employing a gear 29, a rack 30 and a crank 32, it should be understood that my invention might be applied to a circuit breaker without these members. Accordingly in Figs. 3 and 4 I have disclosed my invention in a similar manner as in Figs. 1 and 2 respectively with the corresponding parts thereof designated by the same reference numerals. However, gear 29, rack 30, crank 32 and shaft 33 have been omitted and instead the end of link 3| remote from member 21 is pinned directly to the operating rod of circuit breaker III as indicated at 42. The auxiliary switch I6 is identical with that shown in Figs. 1 and 2 except that the entire switch and mechanism is rotated 180 degrees about a horizontal axis.

The operation of the arrangement indicated in Figs. 3 and 4 will be obvious in view of the detailed description included above.

Although I have disclosed dog 31 as pivotally mounted on member 21 it will be obvious that it might be pivotally mounted on member 34 instead. Also, although I have disclosed auxiliary switch It as one which opens the circuit when the circuit breaker is opened, it might equally well be one which closes the circuit when the circuit breaker is opened.

It should be understood that my invention is not limited to the specific details of construction and arrangement herein illustrated and that changes and modifications may occur to one skilled in the art without departing from my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. An auxiliary switch for performing a controlling function for a circuit breaker which switch opens and closes in response to the operation of said circuit breaker, comprising a pivotally mounted member movable in response to opening and closing movements of said circuit breaker, contact controlling means, and means including a pivoted element arranged on said pivotally mounted member so as to cause said contact controlling means to operate early during both the closing and opening strokes of said circuit breaker. I

2. An auxiliary switch for controlling the trip circuit of a circuit breaker which switch is open when the circuit breaker is open and closed when the circuit breaker is closed, comprising a pivotally mounted member movable in response to opening and closing movements of said circuit breaker, contact controlling means, and means including a pivotally mounted dog on said pivot trolling function for a circuit breaker which,

switch opens and closes in response to the operation of said circuit breaker, comprising a pivotally mounted member movable in response to opening and closing movements of said circuit breaker,

contact controlling means, and a pivotally mounted dog on said pivotally mounted memher for causing said contact controlling means to operate at a point during the opening stroke oi! said circuit breaker, independently of the point during the closing stroke of saidcircuit breaker at which said contact controlling means is operated.

4. An auxiliary switch for controlling the trip circuit of a circuit breaker which switch is open when the circuit breaker is open and closed when the circuit breaker is closed comprising a pivotally mounted member movable in response to opening and closing movements of said circuit breaker, contact controlling means, and a pivotally mounted dog on said pivotally mounted member for causing said contact controlling means to open at a point during the opening stroke of said circuit breaker, independently of the point during the closing stroke of said circuit breaker at which said contact controlling means is closed.

5. An auxiliary switch for controlling the trip circuit 0! a circuit breaker which switch is open when the circuit breaker is open and closed when the circuit breaker is closed comprising a pivotally mounted member movable in response to opening and closing movements of said circuit breaker, contact controlling means, and means on said pivotally mounted member for causing said contact controlling means to open at a point during the opening stroke of said circuit breaker, independently of the point during the closing stroke 01' said circuit breaker at which said contact controlling means is closed.

HAROLD N. SCHNEIDER.