US2294824A

US2294824A - Circuit interrupter

Info

Publication number: US2294824A
Application number: US357686A
Authority: US
Inventors: Benjamin P Baker; Richard C Cunningham
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1940-09-21
Filing date: 1940-09-21
Publication date: 1942-09-01
Anticipated expiration: 1959-09-01
Also published as: BE483536A

Description

Sept. l, 1942. B. P. BAKER ET A1.

' CIRCUIT INTERRUPTER Filed Sept, 2l, 1940 3 Sheets-Sheet l INVENTORS .L WITh ESSES B. P. BAKER ET Al. 2,294,824

CIRCUI'I INTERRUPTER Filed sept. 21, 1940 Sept. 1, 1942.

3 Sheets-Sheet 2 wlTNEssEs: ,7

Sept. 1, 1942. B, P. BAKE-R ET AL 2,294,824

7 CIRCUIT INTERRUPTER Filed Sept` 2l. 1940 3 Smets-Sheet 5 4Patented Sept.v 1, 1942 UNITED STATES PATENT OFFICE l 2,294,824 l l cmcUrr rNTEnaUP'rEa Benjamin P. Baker, Turtle Creek, and Richard (l.r Cunningham,` Wiikinsburg, Pa., assigner-s to Westinghouse Electric a Manufacturing Company, East Pittsburgh,

Pennsylvania la., a corporation of Application September 21, 1940, Serial No. 357,686

(Cx. 20o-14s) 8 Claims.

In the application of A. H. Bakken, Serial No.

313,745, filed January 13, 1940, and assigned to the assignee of the instant application, is shown and described a gas blast circuitinterrupter in which the gas blast valve is mechanically controlled in accordance with the contact movement. The aforesaid application also broadly contemplates an arrangement i'or mechanically opening the gas blast valve only during the opening operation of the interrupter so as to conserve arc extinguishing gas. This result has been achieved by the use of a single action cam mechanism of the collapsible type driven by the contact operating mechanism for actuating the blast valve. The structural arrangement is such that during the opening movement of the contacts the cam is maintained in an extended or operative position, whereas during the closing movement of the contacts the cam is collapsed to an in- IfV an interrupter of this type is closed against a short circuit, there is a hazard that the contact structure may be reversed before the valve operating mechanism has opportunity to restore itself to operative position due to the application f of a tripping impulse to the interrupter before the contacts are fully closed. ,Under this condition the interrupter would open without the aid of an arc extinguishing blast of gas which may cause considerable damage to the interrupting structure. The main object of the instant invention is to improve the operation of circuit interrupters of the aforesaid type by the provision of operating mechanism for the gas blast valve which insures reliable operation of the valve under all operating conditions.

A further and more specic object resides in the provision of an improved gas blast valve 0perating mechanism for circuit interrupters of the gas blast type which insures positive valve action during the opening operation of the interrupter and conserves arc extinguishing gas during the closing operation.

Other objects and advantages will become apparent in the following description when considered in Aconnection with the accompanying drawings, in which:

Figure 1 is aside elevation view partly in section o1' a circuit interrupter illustrating our invention; Fig. 2 is an enlarged view of the blast valv operating mechanism of the interrupter shown in Fig. 1;

Fig. 3 is an enlarged view of theV mechanism shown in Fig. 2 illustrating the several parts thereof in relatively different positions;

Fig. 4 is asectional view of -a portion of the blast valve operating mechanism taken along the line IV-IV of Fig. 2;

Fig. 5 is a fragmentary and partially schematic illustration of a modified form of blast valve operating mechanism; and

Fig, 6 illustrates another arrangement of gas blast valve operating mechanism also in fragmentary and partially schematic form:

Referring to the drawings, the reference numeral 'l designates a tank for storing gas, such as air, under pressure. Extending from the upper end of the tank 'I is a relatively short ilanged conduit 9 which, in turn, carries a valve casing Il. Secured to the upper end of the valve casing II is a tubular insulator I3 which has secured to its upper end an insulating support I5.

yThe insulating support I5 may be given additional support by an insulating member Il. The support I5 carries a stationary contact assembly I9 which, in this instance, is enclosed within an arc extinguishing structure 2|, only a portion of which is shown. The arc extinguishing structure 2i may be of conventional form and does not constitute a specific embodiment of the instant invention.

Coacting with the stationary contact assembly I9 is a movable contact 23 which is preferably of blade-like construction and generally C- shaped, and mounted for swinging movement about a pivot 25 carried by a conducting bracket 2l. External circuit connections to the interrupter are made through a pair of terminal members` 29 and 3|, the first of which is secured to the stationary contact assembly I9, and the second one of which is connected to the conducting bracket 212, Thus, when the interrupter is in the closed circuit'position as 'shown in Fig. l, an

electrical circuit is established between the tery mina-1s 29 and 3| through the stationary contact I9, the movable contact 23 and the conducting bracket 21. i

The movable contact 23 is actuated to open and closed circuit positions, by an insulating operating rod 33 actuated by a crank arm 35 carried by a shaft 31, in turn joumaled in a suitable bracket 39. The shaft 31 is actuated by a crank arm 4I coupled by suitable linkage 49 to the connecting rod 45 of an air actuated piston operated within the cylinder 41. The connecting rod 45 may be moved up and down to effect closing and opening movement of the movable contact 23 by the admission of compressed gas from the tank 1 to the operating cylinder 41 by suitable valves well known in the art.

The tubular insulator I3, in addition to serving as a support, also provides a passage for conducting an arc extinguishing blast ci gas from the storage tank 1 to the space between the contacts i9 and 23. This gas blast passage proceeds through the short conduit 9 to the valve casing II, through the tubular insulator I3, and opening 49 through the insulating support I5 which is preferably coextensive with the passage within the tubular insulator I3.

In the event themoving contact 23 is moved to the open circuit position while the circuit interrupter is carrying load, an arc will be drawn across the upper end of the passage 49 and will be subjected to a blast of arc extinguishing gas caused to dow through the tubular insulator I3, whereby the arc will be extinguished. Control of the blast of gas to the arc in this instance may be obtained by a valve 5I disposed in the lower end ci the valve casing II, The valve 5I has a stem 53 operatively coupled to one end oi' an actuating member 55. In this instance the actuating member 55 is rigidly secured to a rock shaft 51 journaled in the side of the valve casing II. The shaft 51 extends xteriorly o! the casing i I, and has a pair of actuating arms 59 secured to the opposite ends thereof. The actuating arms 59 carry a roller assembly generally indicated at 5I in Fig. 1, which is adapted to be actuated by a cam 63 in this instance forming an integral part of the crank arm 35.

A more complete illustration of the arrangement of the roller assembly 9| in connection with the actuating arms 59 will be found in Figs. 2 and 4.

The two actuating arms 59 are joined by a pin 95. Jcurnaled about the pin 55 and disposed between the arms 59 is a rocker arm 51. 'I'he rocker arm 51, as shown in Fig. 2, is pivoted at A, 69 to a spring guide rod 1 I, the upper end of which is slidably operative in a bracket 13 which forms an extension of the valve casing II. A compression spring 15 encircling the guide rod 1I biases the rocker arm 91 in a clockwise direction, as viewed in Fig. 2. The rocker arm 61 is channeled on opposed sides as shown at 11. in Fig. 4 i'or slidably receiving the parallel legs of a U-shaped yoke member 19. The lower end of the yoke member 19 has a pin 8| journaled therein which, in turn, rotatably carries the roller 83. The pin 8| also carries a pair o! bell crank shaped arms 95 disposed on the outer sides oi' the yoke 19. The right-hand end of the arms 95 are provided with an elongated slot 81 through which the pin 55 also extends. From the foregoing description, it will be apparent that the yoke 19 carrying the pin 9| and the roller 99 thereon will be movable in the slots 11 an amount determined by the relative motion as aiforded by the elongated slots 91, between the pin 65 and the arms 95. Thus, the position of the roller 93 is movable with respect to the actuating arms 59. In order to fix the position of the roller 93 with respect to the arms 59, an adjustment is provided which includes the bolt 99 secured at its lower end to the rocker arm 51 and extending upwardly through the yoke 19. A nut 9| adjustable on the upper end of the bolt 99 determines the upper limiting position which the yoke 19 may assume with respect to the rocker arm 51. An S-shape locking member 93, as more clearly shown in Fig. 2, maintains the nut 9| against rotation once thev proper adjustment of the roller 93 has been made. From the foregoing description, it will appear that the rocker arm 91, the yoke 19, roller 93, and the arms 95y are so united as to be rotatable as a unit'about the pin 55, The spring 15, therefore, biases the entire roller assembly in a clockwise direction about the pin 55, as viewed in Fig. 2.

The roller assembly is normally maintained in a fixed or set position with respect to the actuating arms 59, the outer ends of which serve as stops for two short sleeves 94 surrounding the ends of the pin 9i which engage the lower sides of the arms 59 at 95, as shown in Fig. 2. Also as long as the roller assembly is held in a set position with respect tothe actuating arms 59, the spring 15 serves the further function of biasing the

arms

55 and 59 i'or rotation in a counterclockwise direction about the axis 51 so as to maintain the valve 5I in thev closed position.

As shown more particularly in Fig. 1, the valve operating mechanism is so arranged that when the valve 5I is closed, the roller 93 is disposed in the path of movement of the cam 53. It will be noted that the cam 53 has a leading edge 91 which rises steeply and a relatively large top surface 99 and a trailing edge IUI also of slope similar to the leading edge 91. When the movable contact 23 is in the closed circuit position, the roller 93 assumes a position adjacent vthe leading edge 91 ci the cam 93, as shown in Fig. 1. Upon movement oi' the contact 23 to the open circuit position, the leading edge 91 of the cam 53 y engages the roller 83, causing the actuating arms 59 and the actuating member 55 to be rotated clockwise against the bias o! spring 15 so as to open the valve 5I permitting a blast of gas to iiow from the tank 1 to the tubular insulator I3 to extinguish the arc.

It will, of course, be apparent that during the timethe roller 93 travels over the top surface 99 of the cam 63, as more clearly shown in Fig. 2, the valve 5I will be held in the open position.

Just prior to the time the contact 23 reachesits i'ull open circuit position, cam 53 will have moved a distance suicient with respect to the roller 83 so that the roller will descend along the sloping trailing surface IDI of the cam, thereby permitting the valve 5I to close.

During the closing operation of the interrupter, crank arm 35. and the cam $3 are rotated in a clockwise direction. At thebeginning of the closing movement thesloping edge'il of the cam 53 engages the roller 83 and rotates the entire roller assembly comprising the rocker arm 61, yoke 19 and arms B5 about the pin 55 in a counterclockwise direction as viewed in Fig. 3. This counterclockwise rotation of the roller assembly continues until the roller again rides on the top surface 99 of the cam 53. 'Ihe pivotal axis of the roller assembly 9| and the pin 99, as well as the various lever arms tending to rotate the assembly and also the angular displacement between the various lever linkages, is such that rotation o! the roller assembly will take place in the counterclockwise direction,

thereby compressing the spring but without impartingmovement to the actuating arms 59 and the valve 5|. Thus during the closing stroke of the interrupter, the valve 5| is permitted to remain closed so as to conserve arc extinguishing gas during an opening-closing operation.

In the event the interrupter is being closed under conditions of overload on the connected circuit, the circuit may be completed as a result of sparkover between the contacts prior to the actual engagement or movement of the contacts to the fully closed circuit position. While closing the interrupter against an overload, the interrupter will immediately receive a tripping impulse so as to cause the contacts to bel reversed before being moved to the fully closed position.

This requires the opening of the gas blastvalve 5| to admit an arc extinguishing blast of gas to interrupt the arc.

However, the roller assembly 5| during the greater portion of the closing movement of they contacts is in the inoperative position and ineffective to cause an opening of the blast valve 5|. Fig. 3 more clearly illustrates the position of the roller assembly 5| during the closingr stroke just prior to engagement of the interupter contacts. It will be noted that the roller 03 is still on the top surface 99 of the cam 53 and maintains the assembly in the inoperative position. The roller assembly 5| would normally reset to the operative position as the roller 93 is permitted to move over the leading edge 91 in the event the actuating arm is moved to the fully closed circuit position. However, if opening movement of the interrupter is initiated under conditions of. overload, where an arc has been established during the closing movement of the interrupter and the operating mechanism has a position as illus-` rotate the entire roller assembly 6| about the pin in a counterclockwise direction, as viewed in Fig. 3, momentarily raising the roller 93 from the upper surface 99 of the cam 53 until the pin |03 passes beyond the arms 95 to the lower sidc thereof.

It will thus be apparent that if the operating arm 35 is reversed from a position shown in Fig. 3, the pin |03 willengage the lower edges of the arms 85 to cause the entire roller assembly 9| to be rotated in a clockwise direction until the sleeves 94 on pin 8l again rest against the surfaces 95 of the actuating arms 59, in which position the roller assembly 5I is operative to effectively actuate the actuating arms 59 and cause the valve 5| to be opened. Therefore, even though the interrupter is caused to be opened before the contacts have reached their fully closed circuit position, the blast valve will be positively actuated to provide the necessary arc extinguishing blast for interrupting the circuit.

In Figs. 5 and 6, dierent arrangements for controlling the actuating member 55 of the blast valve operating mechanism are shown. In these n gures like parts will be given the corresponding numbers of reference as used in the previous iig- -secured at its upper end by a pin ||9.

ures. With particular reference to Fig. 5, the actuating arms 59 formerly illustrated are replaced by an arm |05'having an elongated slot |01 adjacent the left-hand end. The slot |01 is provided with teeth at its left-hand side so as to provide a rack |09, as shown. The rack |09 is adapted to coact with a pinion translatable in the slot |01. The pinion is preferably coaxially secured to a cam roller ||9 adapted to operate over the surface of the cam B3. Thus, if the crank arm 35 is rotated in a counterclockwise direction to effect an opening movement of the interrupter, cam 63 will engage the roller ||3 to rotate the same in a clockwise direction. This clockwise rotation of roller ||3 will also impart a similar rotation to the pinion Since the pinion is in-engagement with the rack |09. therack |09 will be raised by the pinion to cause the pinion to assume a position at the lower end of the slot |01. Raising of the rack |09 obviously raises the actuating arr'n |05, causing it to rotate in a clockwise direction about the axis 51 so as to open the gas blast valve. As the roller ||3 travels beyond the trailing edge |0| of the cam 53, the spring 15 causes the actuating arm |05 to again close the air blast valve. During the closing operation of the interrupter, the crank arm 35 and cam 63 are rotated in a clockwise direction so that the cam |33 in its engagement with the roller II3 causes the roller to be rotated in a counterclockwise direction. Consequently, the pinion will also be rotated in a counterclockwise direction and will be caused to travel upwardly along the rack |39 without imparting motion to the actuating arm |05. The gas blast valve is thereby not actuated during the closing operation.

If for any reason during the closing operation of the interrupter the contacts are caused to be reversed as, for example, when closing the interrupter against a short circuit, the reversal of contact movement will also be accompanied by reversal of the movement of the cam 63 which will again cause rotation of the roller ||3 in a clockwise direction actuating the pinion in the same direction so as to raise the actuating arm |05 and open the gas blast valve. If the angle between longitudinal axis through the slot |01 and the tangent to the upper surface 99 of the cam 63 is maintained small, as

illustrated in Fig. 5, less friction is required between the roller ||3 and the surface 99 of the cam`83 to cause the roller to actuate the arm` |05. I f more rapid valve action is desired, greater gripping action is required between the cam surface 99 and the roller ||3 which may be obtained by roughening these respective surfaces.

Another arrangementfor obtaining the objects of our invention is shown in Fig/6. In this arrangement an actuating arm ||5 replaces the arms 59 of Figs. 1 to 4 or the arm |05 of Fig. 5. The arm ||5 carries a cam follower ||1 hingedly The lower end of the follower ||1 has a rounded bearing surface |2| normally adapted to bear against the surface ofcam E3 when the cam is rotated in a counter-clockwise direction during the opening movement of the interrupter. The follower ||1 is maintained in this position by a stop pin |23 which is caused to bear against the lower edge of the actuating arm ||5. Thus, if the bearing surface |2| is caused toride over the top surface 09 of the cam 63, the actuating arm ||5 will be moved upwardly, rctating the actuating member 5I in a clockwise direction about the axis 51 to open the gas blast valve. Obviously, as the bearing surface 2| moves beyond the top surface ll of the cam $3, the gas blast valve is again permitted to close. During the closing movement of the interrupter, as the crank arm 35 and cam 63 are moved clockwise, the edge IUI of cam 63 engages the cam follower H1, rotating it about its pivotal support ||9 which permits the follower to ride over the top surface 99 of the cam without imparting motion to the actuating arm IIB, thereby allowing the gas blast valve to remain closed during the closing operation of the interrupter.

When the crank arm l! is in the fully closed position, the cam follower will again assume a reset position adjacent the leading edge $1 of the cam 63. In order to render the cam follower operative at or near the end of the closing stroke in the event of reversal of contact movement initiated by a tripping impulse as a result of closing the interrupter against a short circuit, the lower end of the cam follower is provided with a pawl |25, and the top cam surface 99 has a plurality of notches |21 therein to provide a ratchet to engage the pawl |25. Thus, if the crank arm 35 and cam 63 are rotated in a counterclockwise direction from the position shown in Fig. 6, the pawl |25. as illustrated in the dotted line position of the follower |I'|, will engage one of several of the notches |21 positively rotating Athe cam follower in a clockwise direction about its pivotal axis ||9 to the set or operative position, thereby again causing the bearing surface |2| to ride over the top surface 99 of the. cam 63 to actuate the gas blast valve to the open circuit position.

Thus, the arrangement shown in Fig. 6, as the structures previously described, provides for a positive actuation of the gas blast valve during the opening movement of the contact structure irrespective of the circuit conditions and at the same time provides for the conservation of arc extinguishing gas during the closing operation of the interrupter.

Although we have shown and described specific structures, it is to be understood that the same is for the purpose of illustration and that changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter of the gas-blast type. separable contacts for establishing an arc, operating means for actuating said contacts to open and closed positions, a source of gas under pressure, a valve for releasing a blast of gas from said source to extinguish said arc, an operating member for actuating said valve to open and closed positions, said contact operating means including a cam movable in accordance with the opening and closing movements of said contacts, and a cam follower operative on the surface of said cam during the opening movement `of said contacts to actuate said operating member to cause said valve to open, said cam having an inclined surface portion to cause said follower to open the valve during the initial portion of the opening movement of the contacts from the fully closed position of said contacts, said cam follower being arranged to be inoperative to cause a valve operation during the closing movement of said contacts, and means in advance of said inclined surface during closing movement of the contacts operable to cause said follower to open said valve when opening movement of said contacts occurs prior to the time the contacts reach the fully closed position.

2. In a circuit interrupter of the gas-blast type, separable contacts for establishing an arc, operating means for actuating said contacts to open and closed positions, a valve arranged to be supplied with gas under pressure, an actuating member for operating said valve to establish an arc extinguishing blast of gas, said contact operating means including a cam movable in accordance with the opening and closing movements of said contacts, a cam follower coacting with said cam and arranged to have a set position with respect to said valve actuating member for causing said member to be operated during the opening movement of said contacts, said cam having an inclined surface portion for causing said follower to open the valve during the initial portion of the opening movement of said contacts from the fully closed position of said contacts, said cam follower being movable from said set position to an inoperative position during movement of said contacts to the closed position without imparting motion to the valve actuating member, and means other than said inclined surface portion and rendered operative during the closing movement of said contacts a predetermined time prior to complete closing of said contacts to cause said cam follower to be moved to set position in the event of reversal of contact movement from closing to opening movement prior tothe time the contacts reach fully closed position.

3. In a circuit interrupter of the gas-blast type,

separable contacts for establishing an arc, operating means for actuating said contacts to open and closed positions, a valve arranged to be supplied with gas under pressure, an actuating member for operating said valve to establish an arc extinguishing blast of gas, said contact operating means including a cam movable in accordance with the opening and closing movements of said contacts, a coacting cam roller hingedly secured to said valve actuating member, means biasing said cam roller to a set position with respect to said valve actuating member to cause said cam to operate said valve actuating member during the opening movement of said contacts, said cam having an inclined surface portion for causing said cam roller to open said valve during the initial portion of the opening movement of said contacts from the fully closed position of said contacts, said cam roller being movable by said cam relative to said valve actuating member without imparting motion to said member during the closing movement of said contacts, and means other than said inclined surface portion operative in accordance with movement of said contacts for restoring said cam roller to its set position in the event of contact reversal from closing to opening prior to the time the contacts reach the fully closed position.

4. In a circuit interrupter of the gas-blast type, separable contacts for establishing an arc, operating means for actuating said contacts to open and closed positions, a valve arranged to be supplied with gas under pressure, an actuating member for operating said valve to establish an arc extinguishing blast of gas, said contact operating means including a cam movable in accordance with the opening and closing movements of said contacts, an arm hinged to said valve actuating member, a roller carried by said arm adapted to coact with said cam, means biasing said arm to a set position with respect to said valve actuating member to cause said cam to operate said valve actuating member during the opening movement of said contacts, said caml having an inclined surface portion for causing said arm to open said valve during the initial portion of the opening movement of said contacts from the fully closed position of said contacts, said arm being moved relative to said valve actuating member by said cam without imparting motion to said valve actuating member during the closing movement of said contacts, and means on said cam for engaging said arm to restore it to its set position in the event of reversal of contact movement from closing to opening prior to the time the contacts reach fully closed position and prior tothe time said roller engages said inclined surface.

5. In a circuit interrupter of the gas-blast type, separable contacts for establishing an arc. operating means for actuating said contacts to open said valve to the closed position, an actuatingV- Y A member for operating said valve to establish an arc extinguishing blast of gas, said'contact operating means including a cam movable in accordance with the opening and closing movements of said contacts, a coacting cam follower hingedly secured to said valve actuating member and biased by said valve biasing means to a set position with respect to said valve actuating member to cause said cam to operate said valve actuating member during the opening movement of said contacts, said cam having an inclined surface portion for causing said cam follower to open said valve during theinitial portion of the opening movement of the contacts from the fully closed position of said contacts, said cam follower being movable by said cam relative to said valve actuating member without imparting motion to said member during the closing movement of said contacts,'and means independent of said inclined surface portion operative to-move said follower to set position to opengsaid valve in the event of contact reversal from closing to' opening prior to the time the contacts reach fully closed position.

6. In a circuit interrupter of the gas-blast type, separable contacts for establishing an arc, operating means for actuating said' contacts to open and closed positions, a valve arranged to be supportion forcausing said follower to Aopen said valve during the initial portion'of the opening movement of said contacts from the fully closed position of said contacts and having another surface portion for causing said follower to maintain said valve in substantially full open position for a predetermined distance of the opening movement of said contacts, said cam follower being moved by said cam'with respect to said valve actuating member to an inoperative position ,during the closing movement of said contacts. and means including a pawl and ratchet arrangement between said cam and said cam follower operative to move said cam follower to said set position upon reversal of contact movement from closing to opening movement prior to the time said contacts reach the fully closed position.

7. In a circuit interrupter of the gas-blast type, separable contacts'for establishing an arc, operating means for actuating said contacts to open and closed positions, a valve arranged to be supl plied with gas under pressure, an actuating memsaid rackand pinion being so arranged that rotation of said cam roller imparts motion'to said valve actuating member only during'the opening movementof said contacts;

8. In a gas-blast circuit interrupter, separable contacts for establishing an arc, a source of gas under pressure, a valve for releasing gas undery pressure from said source to extinguish said arc, operating means for said valve operative during opening movement of said contacts from the closed position to open said valve and to maintain the valve in its fully open position during a substantial portion of the opening movement oi plied with gas under pressure, an actuating member for operating said valve to' establish an arc ating means to operative condition to cause opening of the valve upon contact reversal from closing to opening occurring during the time when thecontactr are within a predeterminedl distance of the fully closed position.

BENJAMIN P. BAKER. moHARD c.' CUNNINGHAM.