US2247862A - Operating mechanism - Google Patents

Description

July 1, 1941. c. THUMIM OPERATING MECHANISM Filed April 3, 1940 2 Sheets-Sheet 1 Fig. l.

Inventor: Car"! Thumlm,

1 Z Hus Attorney July 1, 1941. c. THUMIMI 2,247,862

OPERATING MECHANISM I Filed April 5, 1940 fSheets-Sheet 2 Inventor:

C r! Thumirn y n27 M His 'trtomey.

Patented July 1, 1941 OPERATING MECHANISM Carl Thumim, Yeadon, Pa., assignor to General Electric Company, a corporation of New York Application April 3, 1940, Serial No. 327,624

6 Claims.

My invention relates to operating mechanisms for electric circuit breakers of the reclosing type and more particularly to operating mechanisms which are so constructed and arranged that very high-speed reclosing of the circuit breaker is possible.

It has been found that perhaps 75 or 80 per cent of the abnormal current conditions or faults which initiate operation of protective apparatus, such as circuit breakers, are temporary and, furthermore, of very short duration. For example, abnormal current surges in transmission lines due to lightning often die out within a few microseconds. It would be desirable in order to maintain good continuity of service for the protective apparatus to distinguish between such temporary or transient faults and prevent the circuit breakers from tripping under such conditions. The above problem may be substantially solved by high-speed reclosing circuit breakers which reclose within a very short interval of time so that the synchronism of the system is not disturbed.

One of the factors which limits the minimum time necessary for the reclosing of circuit breakers is the time required for resetting the tripping linkage which holds the circuit breaker in the closed position. In the prior art arrangements, the entire linkage is reset at once so that, in order to decrease the resetting time, arrangements have been proposed wherein large accelerating forces have been provided in the shape of springs or the like. In such arrangements, the resetting time is decreased at the expense of sensitivity of the protective system since the heavier springs require stronger tripping forces. In accordance with my invention, rapid reclosing of the circuit breaker is made possible by preresetting as many of the heavy parts of the tripping linkage immediately after the tripping action is initiated and during the opening stroke of the circuit breaker so as to leave only a latch of negligible mass finally to be reset when the circuit breaker is reclosed, whereby excessively large springs can be avoided and yet resetting time reduced.

It is an object of my invention, therefore, to provide a new and improved operating mechanism for a very high speed reclosing circuit breaker which is simple and economical in construction to the extent that a minimum of mov ing parts are involved and which is eflicient and reliable in operation.

It is another object of my invention to provide a new and improved operating mechanism for electric circuit breakers in which the resetting linkage which is slow to reset is reset during the breaker opening stroke so as to be in readiness for immediate reclosing 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 an elevational view partly in section of a circuit breaker operating mechanism embodying my invention, Fig. 2 is an enlarged perspective View of a portion of the apparatus illustrated in Fig. 1, Fig. 3 represents an operating mechanism embodying a modification of my invention, while Figs. 4 and 5 are modifications of the arrangement illustrated in Fig. 3.

Referring more particularly to Fig. 1, the operating mechanism shown therein comprises an actuating means or solenoid ID for actuating a reciprocally guided rod II which, for example, may be connected to operate a suitable circuit breaker, not shown. A collapsible force-transmitting structure l2 interconnects actuating means It and actuated means or red H. The collapsible force-transmitting structure [2 per se forms no part of the present invention and is illustrated as of the character disclosed and claimed in my United States Letters Patent No. 2,112,054 granted March 22, 1938, and assigned to the same assignee as the present invention.

Although a description of the collapsible forcetransmitting structure [2 is available in the above-mentioned patent, a brief description thereof will be included hereinafter. Solenoid I0 is provided with an armature it which is connected to rod H by a chain linkage l4 normally guided on a grooved roller 55 carried by a bell crank 16 pivotally mounted at IT. When the bell crank I6 is held in the position shown by means of a latching mechanism generally indicated at [8 and described in greater detail hereinafter, energization of solenoid it causes downward movement of armature l3 and closing movement of the circuit breaker, not shown, associated with rod ll against the bias of energystorage means I9, the release of which causes high-speed opening of the associated circuit breaker. In order that energy-storage: means 19 may remain charged after solenoid H! is deenergized, I provide a suitable prop 221 spring biased at 2| which cooperates with pin 22 so that armature i3 is held in its lower position. By this arrangement, the circuit breaier may be held in the closed position by the cooperative action of the prop 2B and latching means it, the latter cooperating with roller as oeiated with crank i5. It will be understood that solenoid H3 is provided with a sm'table control circuit to energize it for automatic reclosing tripping of the circuit breaker.

With the apparatus in the position indicated in Fig. l, the release oi latching means restraining roller 23 and hence oell cran would allow the energy stored in the spring to due to the force on grooved roller 55 acting through the moment indicated at a, cause a clockwise rotation of th bell crank it to the position shown in dott d lines in l. A comparatively sensitive tripping device for latching means Hi can be used if desired since the required tripping force is directly related to the length of the moment arm indicated at a through which the resultant reacting force at the chain linkage tends to produce clockwise rotation of bell crank iii. Where the lever arm a is quite small, the latch-releasing force required is obviously small.

in order that resetting of the collapsible forcetransmitting structure 92 may occur as soon as the tripping action of the circuit breaker is initiated, bell crank it"; is provided with a portion [6 which serves as a cam member for engaging the extension 24 suitably welded to prop 2:3. Hence, after a predetermined rotation of hell crank i8, the member is engaged and prop Z is moved to free pin 22, whereby the energy in spring 25 is released to cause an upward movement of armature l3 of solenoid Iii. This affords additional slack in chain linkage it so that bell crank Hi can immediately reset to the position shown in solid lines in Fig. 1 and, due to the energy stored in spring 26 when bell crank 16 is rotated in the clockwise direction. The above-described arrangement is substantially identical with the apparatus described and claimed in my abovementioned United States Letters Patent.

In order to save time in the resetting of latching means it, with which my invention is particularly concerned, I provide an arrangement wher in the parts which are slow to reset do so immediately after the tripping action and during the opening stroke of the circuit breaker so that only a relatively light part must be finely reset when the breaker is reclosed. Latching means I8 shown in an enlarged perspective view in Fig. 2 includes a collapsible member including pawl 2"! of negligible mass and to a limited extent relatively movable with respect to the remaining portions of latching means i8 which comprise shaft 28 provided with an offset arm or extension 29 rigidly fastened thereto as by suitable fastening means 38. Oifset arm 29 is adapted to engage or coact with the plun er 3! of the conventional tripping solenoid 32. A suitable stop 3-3 is provided for limiting the downward movement of offset arm 29 and a relatively light spring-biasing means 85 may be provided if desired for resetting shaft 23 and oifset arm 29 when tripping solenoid 32 is no longe energized.

Since shaft 28 and extension 23 are relatively heavy, they have considerable inertia and re quire a relatively long time within which to reset after a trip-ping movement thereof especially in view of the fact that spring means 34 should be relatively weak so that a very small tripping force from plunger 3! may cause tripping of the circuit breaker. In order to form the collapsible member of latching means I 8, pawl 21 is mounted for limited rotation on shaft 28 by being provided with an enlarged segmental keyway 35 cooperating with a key 355 suitably fitted into shaft 28. The segmental keyway 35 is of such a size as to allow sufficient relative rotation between pawl 21 and shaft 28 when the resetting of bell crank l5 occurs so that the relatively heavy portions 28 and 29 of the collapsible member of latching means is need not be disturbed after having been reset. A relatively heavy spring 37 is provided to cause pawl 2'! to return to restrain roller 23 immediately after bell crank l6 has been reset.

Manual tripping of the latching means I8 is suitably provided by means of a lever 33 indepondently pivotally mounted on shaft 28 and co acting with a pin 33 carried by the extension 29. A manually operable link 4i! is connected to the lever 38 for rotating the latching means 18 clockwise in the manner above described.

The operation of the apparatus illustrated in Fig. l and more particularly the operation of the latching means l3 best shown in Fig. 2 will be apparent to those skilled in the art and, therefore, will only be briefly described. It is obvious that actuation of the trip-ping solenoid 32 due to some abnormal current condition will cause elevation of tripping plunger 3! and clockwise rotation of extension 29 and rigidly attached shaft 23 which latter may be suitably mounted in the housing which surrounds the operating mechanism. Such clockwise rotation of shaft 28 will cause similar clockwise rotation of pawl 2'! forming the remaining portion of the collapsible member of latching means l8 since key 36 is engaged with one edge of segmental keyway 35. Such rotation of pawl 21 releases roller 23 whereby bell crank i6 is no longer restrained and the energy stored in spring means 19 is released to cause opening movement of the circuit breaker, not shown. As soon as tripping solenoid 32 is deenergized, the collapsible member comprising pawl 27, shaft 28, and extension 28 begins to reset under the relatively small force of spring 34. This resetting may be accomplished immediately after the tripping impulse and dining the opening stroke of the circuit breaker. In order to reclose the circuit breaker, it is merely necessary for pawl 21 of negligible mass to move against the force of its spring 31 relative to shaft 28 so that roller 23 of bell crank l5 may again be restrained by latching means i8. Therefore, high-speed reclosing of the circuit breaker is possible since the relatively heavy and slow parts of latching means l8 are reset early and the final member to be reset is sufliciently small and biased by relatively heavy springs to reset almost instantly after reclosing of the circuit breaker. Furthermore, in the arrangement just described, the relatively heavy spring 31 has no effect in so far as decreasing the sensitivity of the tripping apparatus is concerned.

In certain a'rangements, the tripping force available is so small as to be unsatisfactory for tripping an arrangement even like that described above which requires a relatively small tripping force. In such arrangements, it is necessary to include energy-storage means which may be released. by a very sensitive tripping force and which, in turn, supply a larger tripping force such as is necessary for tripping a circuit breaker. Because of the additional tripping element required, my invention is particularly applicable to such arrangements wherein the sensitive tripping means which requires a great deal of time to reset may be reset immediately so that the apparatus is ready for high-speed automatic reolosing. In the arrangements to be described hereinafter, therefore, the sensitive latch is permitted to start resetting immediately after being tripped even though the associated circuit breaker has completed only a small part of its opening stroke.

In Fig. 3, I have illustrated my invention as embodied in an operating mechanism of the impact trip type with electric spring reset means. The operating mechanism comprises an actuating means or solenoid ll and an actuated means comprising rod 442 which may be operatively connected to a suitable circuit breaker or to any other apparatus to which this operating mechanismmay be applied. A collapsible force-transmitting structure 53 interconnects actuating means ll and actuated means or rod 42. The collapsible force-transmitting structure per se forms no part of the present invention and is illustrated as of the character disclosed and claimed in my United States Letters Patent No. 1,988,287, granted January 15, 1935, and assigned to the same assignee as the present invention.

Although a description of the collapsible force-transmitting structure is available in the above-mentioned patent, a brief description hereof will be included hereinafter. Collapsible force-transmitting struture 13 is trip free in operation, that is, the rod 32 may be released at any time during or after the closing stroke of solenoid E and comprises a member or link at, one end of which is pivoted at iii while its other end provided with a roller d6 coacts with pivoted latch member ll. Link Aid restrained by latch member ll forms a mounting for a floating link 48 pivotally carried at 49 by link it and operatively connected. as at 50 to the rod 32. The floating member is arranged to be rotated about the restraining pivot by means of plunger 5! of solenoid 4i which engages with a roller 52 suitably mounted at the other end of floating member All, thereby causing positive movement of rod 42 in the downward direction to close the associated circuit breaker. In Fig. 3, rod 42 is shown in its lowermost position which represents the closed position of the associated circuit breaker. In order that rod 42 may be restrained in this lowermost position after solenoid 41 is deenergized, a suitable prop 53 is provided pivotally mounted at 54 and normally biased as by a spring 55 in a clockwise direction so that the supporting edge of prep 53 rides under and supports the roller pin 5?. Further movement of prop in the clockwise direction is limited by a stop portion 58 which engages a suitable fixed frame or housing member.

In view of the fact that in large circuit breakers the reacting force between roller "it and latching member e? is relatively large, a feeble tripping force would be insufficient to release roller all from the restraining action of latch ll. For the purpose of efliciently operating the abovedescribed mechanism when but feeble tripping impulses are available, there is provided an auxiliary tripping unit for providing the force nece sary to release roller $6 from the restraining action of latch 47. This auxiliary tripping unit comprises a bell crank 5t pivotally mounted at (ill and having one end thereof connected to a rod 5| through a suitable auxiliary source of tripping energy which, in this case, is illustrated as a spring means E52 arranged to be charged by means of solenoid 63 having its armature G4 Fig. 3

connected with rod 6|. Solenoid 63* is arranged to be energized from a suitable source of energy 65 through overcenter type switch 66 whenever the energy stored in spring 62 is released to trip latch 41. This is accomplished by connecting over center type switch 66 to armature 64 of solenoid 63 so that, whenever the energy stored in spring 62 is released, overcenter type switch 66 is closed to energize solenoid 63 and recharge spring 62 for the next succeeding tripping action. When spring 62 is released, the rapid upward movement of rod 6| causes counterclockwise rotation of bell crank 59 which is provided with a suitable pin 61 to engage as by impact latch 47' which is held in the position shown in Fig. 1 by means of stop 68. Latch 4? is provided with suitable spring means 69 which may be relatively heavy to cause rapid resetting thereof, in view of the relatively large amount of impact trip energy available from spring means 62.

Bell crank 59 and spring 62 are restrained in the position shown in Fig. 3 by means of a collapsible latching member '10 including a pawl H which engages with a roller 72 at one end of bell crank 59. Collapsible member 1B is pivotally mounted at l3 and biased against stop member 54 by spring means 75. Pawl H, which is of negligible mass relative to the remaining portion of collapsible latching means 50, is pivotally mounted to the latter at 18 and biased to the position shown in Fig. 3 where stop member ll of pawl Ti engages with the edge of the relatively heavy portion of collapsible latching means H! by virtue of the bias of spring means 18. Spring means 69 and 18 may be relatively heavy to decrease the resetting time of pawl II and latch ll. Collapsible latching means it) by being pivotally mounted at 13 provides a considerable force reduction at the end thereof supporting roller ill as compared to the force acting at the other end thereof against pawl ll.

Collapsible latching means 19 is restrained in the position shown in Fig. 3 by means of sensitive latch 30 biased to the position shown against stop ill by a very light spring 82 so that it may be tripped by a feeble thrust from sensitive solenoid 33, which is arranged to engage an extension 84 of sensitive latch 80.

The operation of the apparatus illustrated in and more particularly the operation of the latching means will be only briefly described hereinafter. Sensitive latch is rotated in a counterclockwise direction in response to a feeble tripping force from solenoid 33 because of the relatively small mass of sensitive latch 89 and also because spring 82 is very weak. Such counterclockwise movement releases collapsible latching means 10 which also rotates in a counterclockwise direction so that roller i2 is no longer restrained and crank 59 is free to rotate under the force of spring 82 which is now released causing pin ill to strike latch 41 rotating it in a counterclockwise direction so that the collapsible force-transmitting structure 43 will allow the circuit breaker associated therewith to open. Immediately after the initiation of the tripping operation and during the opening stroke of the circuit breaker, collapsible latching means it is reset under the influence of its spring 25 and thereafter sensitive latch 86 may reset under the influence of its spring 82. Since these two members are reset relatively early and have considerable time in which to reset, springs 15 and 82 may be relatively light. Overcenter type contact St is closed when armature 64 is moved upwardly to rotate bell crank 59 whereupon solenoid 63 is energized to recharge spring 62 and reset bell crank 59. In view of the fact that latching means it is collapsible the resetting of bell crank 59 may take place without disturbing the reset positions of sensitive latch 89 and the relatively heavy portion of collapsible latching means 10 since pawl H is free to move relative to the remainder of collapsible member '10 to a sufiicient extent to allow roller 72 to reassume the position shown in Fig. 3. When the circuit breaker is reclosed, all of the latching means are then reset except latch 41 which is of relatively small mass and furthermore may be provided with a heavy spring so that the resetting time thereof is negligible and very high-speed reclosing of t e circuit breaker is possible.

In Fig. 4, I have illustrated a modification of the arrangement shown in Fig. 3 wherein the electric spring reset means is replaced by a mechanical spring reset means. The corresponding parts of Figs. 3 and 4 are designated by the same reference numerals. In this arrangement, spring means 62 for supplying the impact tripping force is arranged to be charged during the opening stroke of the circuit breaker, and, hence, during the upward stroke of rod 42. A pin 85 associated with rod i2 is adapted to strike one end of lever 86 pivotally mounted at 81, the other end of which is connected to rod ii for compressing spring 62. The operation of this arrangement in other respects is identical with that disclosed in Fig. 3 and no further explanation will be included herewith.

In Fig. 5, I have illustrated the sensitive latching means shown in Figs. 3 and 4 as applied to a back pressure type arrangement similar to that shown in Fig. l, where no spring tripping force is applied, the force reduction being sufficicnt in this case so that the sensitive trip may be used. The elements of Fig. 5 which are similar to those of Figs. 3 and 4 are characterized by the same reference numerals. In this case, roller 88 which may be similar to roller 23 of Fig. 1 acting against the inclined surface 89 of bell crank 90 pivotally mounted at 9| gives it a counterclockwise bias Which is restrained by the collapsible latching member 18 described above having the pawl 'H thereof engaging with roller 62 at the other end of bell crank Si). Resetting of bell crank 90 is obtained by means of spring 93. The operation of this arrangement will also be obvious to those skilled in the art and it is apparent that, after tripping, the entire system can reset immediately except bell crank so and pawl H, the latter being the only part which must be snapped behind roller "i2 at the end of the resettin motion of the collapsible forcetransmitting structure, not shown.

In the arrangements disclosed particularly in Figs. 3, 4 and 5, the tripping force available from solenoid 83 is so feeble that it is impossible to use sufficiently heavy springs to reset members 70 and 80 in time for rapid reclosing of the circuit breaker. However, by presetting all the parts which cannot be accelerated by heavy springs as described above, a great deal of time is saved and high-speed reclosing of the circuit breaker is obtained, so as not to disturb the synchronism of an electric distribution system when the tripping of an automatic reclosing circuit breaker is initiated by a fault of very short duration.

While I have shown and described a particular embodiment of my invention as applied to an operating mechanism for an electric circuit breaker, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from my invention in its broader aspects 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. In an operating mechanism for a circuit breaker of the trip-free type, actuating means and means to be actuated, a collapsible forcetransmitting structure interconnecting the aforesaid means, means for latching said force-transmitting structure in the uncollapsed position when the circuit breaker is closed, means responsive to an abnormal electrical condition for tripping said latching means, said latching means comprising a collapsible member including a relatively heavy portion which resets immediately upon tripping of said circuit breaker so that said circuit breaker is in condition for immediate high-speed reclosing and a relatively light portion which resets at high speed upon closing of said circuit breaker.

2. In an operating mechanism for a circuit breaker of the trip-free type, actuating means and means to be actuated, a collapsible forcetransmitting structure interconnecting the aforesaid means, latching means for holding said force-transmitting structure in the uncollapsed position when the circuit breaker is closed, means responsive to an abnormal electrical condition for tripping said latching means, said latching means comprising a collapsible member Which resets immediately upon tripping of said circuit breaker and which includes a relatively heavy portion and a spring biased pawl of negligible mass, said pawl being movable relative to said relatively heavy portion so that said circuit breaker may be relatched in the closed position without moving the relatively heavy portion of said latching means whereby high-speed reclosing of said circuit breaker is possible.

3. The combination with an operating mcchanism including latching means for holding said mechanism in the closed position, of tripping means for actuating said latching means to cause opening of said mechanism comprising a trip coil sensitive to comparatively small tripping impulses, said latching means comprising a collapsible member which resets immediately upon operation of said tripping means including a relatively heavy portion and a relatively light portion, said relatively light portion being arranged for limited movement with respect to said relatively heavy portion so that said operating mechanism may be reset without disturbing said relatively heavy portion of said latching means.

4. The combination with an operating mechanism including latching means for holding said mechanism in the closed position, of tripping means for actuating said latching means to cause opening of said mechanism comprising a trip coil sensitive to comparatively small tripping impulses, said latching means comprising a collapsible member which resets immediately upon tripping or" said circuit breaker and which includes a relatively heavy portion and a springbiased pawl of negligible mass movable to a limited extent with respect to said relatively heavy portion so that said operating mechanism may be reset without disturbing said relatively heavy portion of said latching means.

5. The combination with an operating mechanism including latching means for holding said mechanism in closed position, of tripping means for actuating said latching means to cause opening of said mechanism comprising a trip coil sensitive to comparatively small tripping impulses, a latch related to said trip coil comprising a collapsible member which resets immediately upon deenergization of said trip coil, said latch being so constructed and arranged as to release energy stored in an energy-storage means whereby a releasing blow is delivered to said latching means under the influence of said stored energy in response to actuation of said trip coil, and means for storing energy in said energy-storage means immediately after the tripping of said operating mechanism.

6. In an operating mechanism for a circuit breaker of the trip-free type, actuating means and means to be actuated, a collapsible forcetransmitting structure interconnecting the aforesaid means, latching means for holding said force-transmitting structure in the uncollapsed position when the circuit breaker is closed, tripping means for actuating said latching means to cause opening of said circuit breaker comprising a trip coil sensitive to comparatively small tripping impulses, a latch related to said trip coil comprising a collapsible member which resets immediately upon deenergization of said trip coil and includes a relatively heavy portion and a portion of negligible mass so constructed and arranged that only said portion of negligible mass is moved when relatching said circuit breaker in the closed position, said latch being constructed to release a spring whereby a blow is delivered to said latching means under influence of the spring energy in response to actuation of said trip coil, and means for causing restressing of said spring during the opening movement of said circuit breaker so that said mechanism is in condition for immediate reclosing of said circuit breaker.

CARL THUMIM.

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