US2290977A - Circuit breaker - Google Patents

Description

July 28, 1942. H. J. UNGAL 2,290,977

CIRCUIT BREAKER Filed Aug. 28, 1940 3 Sheets-Sheet l n: use

WITNESSES: INVENTOR July 28, 1942. J. LlNGAL 2,290,977

CIRCUIT BREAKER Filed Aug. 28, 1940 3 Sheets-Sheet 2 WITNESSES: INVENTOR BY sz/ 7 ATTORNEY July 28, 1942. H. J. LINGAL 2,290,977

CIRCUIT BREAKER Filed Aug. 28, 1940 s Sheets- Sheet ,s

WITNESSES! INVENTOR t 4/7 jlzkz 42/ f BY j Patented July 28, 1942 CIRCUIT BREAKER Harry J. Lingal, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Com.- pany, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 28, 1940, Serial No. 354,535

13 Claims.

The invention relates to circuit breakers and more particularly to the operating means and latching means therefor.

Circuit breakers of the type embodying a releasable operating member adapted to be restrained by a latch to maintain the breaker closed, or in operative condition for closing, usually employ a latch checking switch operated by the latch to insure that the circuit breaker operating mechanism is in operative latched condition ready for closing before the closing means can be energized. The latch checking switch is also sometimes used to control the operation of a counting element of the reclosing relay. Considerable difliculty has been experienced in applying latch checking switches to circuit breaker operating mechanisms due to rebounding of the latches when they are returned from the released to the latching position. This rebounding causes the latch checking switch to falsely open thereby falsely operating the counting device of the reclosing relay: As a result the reclosing relay may cause a lesser number of automatic reclosing operations than the number for which it is set.

In the case of a single shot recloser, i. e. one which is set to produce only a single automatic reclosing operation following tripping of the breaker, the extra openings of the latch checking switch caused by the rebound of the latch, delays automatic reclosing of the breaker longer than is desired.

An object of the invention is the provision of a circuit breaker having a releasable operating mechanism normally held in operative position by a latch, with a means for preventing rebound of the latch when it moves to latching position.

Another object of the invention is the provision of a circuit breaker mechanism having a releasable latch biased to latching position and a latch checking control switch operated by the latch, with means for preventing rebound of the latch to prevent false operation of the latch checking switch.

In accordance with the invention a metal weight, of a mass approximately equal to the mass of the latch and the parts which move with the latch, is loosely or slidably attached to either the latch or one of the parts which move with the latch. The weight is arranged so that when the latch starts to rebound toward the released position the weight is still moving toward the latched position and due to its momentum and mass overcomes and prevents the rebound motion of the latch.

The invention, both as to structure and operation, together with additional objects and advantages thereof will be best understood from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawings, in which:

Figure 1 is a side elevational View of a circuit breaker mechanism constructed in accordance with the invention, the position of the parts being shown an instant after the circuit breaker mechanism has been tripped, and the breaker being shown schematically.

Fig. 2 is a plan view of the circuit breaker operating mechanism, the parts being shown in the closed latched position,

Fig. 3- is an end elevational View of the circuit breaker operating mechanism the parts being shown in the closed latched position.

Fig. 4 is an enlarged fragmentary view, partly in section, showing the latching mechanism moving to the latching position an instant after the releasable member has been automatically retrieved to its normal position, and

Fig. 5 is a fragmentary view similar to Fig. 4 showing the latching mechanism in the latched position and the releasable lever in the retrieved position.

Referring to the drawings, the circuit breaker comprises in general circuit interrupting means 5 which may be of conventional construction, and an operating mechanism therefor indicated generally at l. The circuit interrupting means 5 is indicated schematically as comprising stationary contacts 9 and a cooperating movable bridging contact I I connected by a suitable linkage system shown schematically at I3 to the operating rod l5 of the circuit breaker operating mechanism 1. I The circuit breaker operating mechanism 1, with the exception of its latching means, is generally similar to the mechanism disclosed in Patent 2,144,502 to J. B. MacNeill et al., issued J anuary 17, 1939, and also to the mechanism shown in the copending application of Lloyd W. Dyer, et al., Serial No. 294,048, filed September 9, 1939; both of which are assigned to the assignee of the present invention. The operating mechanism 1 comprises, in general, a fabricated metal frame H, on which is mounted a closing solenoid It, a tripfree lever mechanism indicated generally at 2| which normally serves to connect the movable circuit breaker contact II to the closing solenoid IS, a latching mechanism 23 for normally holding the trip free lever mechanism in operative or thrust-transmitting condition, and an electromagnetic trip device 25 operable to move the latching mechanism to released position to cause opening of the breaker.

The closing solenoid l9 comprises a stationary core 21, a movable core 29, and an operating winding 3| which when energized pulls the movable core downwardly to effect a closing operation of the breaker.

The trip-free lever mechanism comprises a closing lever 33 consisting of a pair of spaced parallel rigidly connected levers 35 pivoted at one end to the frame H by means of pivots 31, and a breaker lever 39, consisting of a pair of parallel rigidly connected levers 4| which are pivoted at one end by a pivot pin 43 to the closing lever 33 adjacent the free end thereof and disposed in the space between the levers 35 which comprise the closing lever.

The closing lever 33 is connected intermediate its ends by links 45 to the movable core 29 of the closing solenoid l9, and the breaker lever 39 is pivotally connected intermediate its ends by a pivot pin 41 to the breaker operating rod l5. The breaker lever 39 carries at its free end a trip-free roller 49 which extends transversely between the free ends of the levers 4| comprising the breaker lever, and this roller is adapted to be normally engaged and held by the latching mechanism 23 to hold the circuit breaker closed and also to hold the circuit breaker mechanism in operative condition for closing when the mechanism is automatically reset following a tripping operation.

The movable contact ll of the circuit breaker is biased to open circuit position by means of a relatively strong spring (not shown) so that when the breaker lever 39 is released by the latching mechanism, the circuit breaker will be quickly moved to open circuit position. The closing lever 33 is biased in a counterclockwise direction about its pivot axis 31 by a pair of retrieving springs 5| positioned between the levers 35 and the frame |1. These springs serve to move the closing lever to open position when the closing lever is released during a tripping operation to cause clockwise movement of the breaker lever 39 about the pivot 41 as a fulcrum to return the trip free roller 49 to the normal or latched position where it is reengaged by the latching mechanism 23. When the trip free roller 49 and the breaker lever 39 are thus reset to latched position and engaged by the latching mechanism 23, the breaker lever 39 is reconnected to the closing lever 33 for movement thereby so that the breaker will be reclosed when the closing solenoid is energized.

A latch 53 is pivotally mounted on the frame |1.by a pivot pin 55 and is biased by a spring 51 to latching position for engaging a roller 59 carried by the closing lever 33 to hold the closing lever in closed position. The latch 53 is adapted to be moved to released position by a cross bar Bl on the breaker lever 39 during the opening movement of the breaker lever 39, thereby allowing the retrieving springs 5| to automatically reset the mechanism following each tripping operation.

When the circuit breaker is held latched in the closed circuit position, the trip free roller 49 is held down by the latching mechanism 23 in a position of alignment with the pivot axis 31 of the closing lever 33, and the closing lever 33 is also held latched down in the closed position by the holding latch 53. In this closed position, the levers 33 and 39 are in alignment with each other. When the trip device 25, which is preferably a shunt trip, is energized either by the operation of suitable fault responsive relays, or by the closing of a manually controlled shunt trip circuit, the latching mechanism is thereby caused to move to the released position effecting release of the trip free roller 49 and the breaker lever 39. The movable contact ll of the circuit breaker being no longer held in closed position is quickly moved to open circuit position by its biasing spring and in doing so moves the breaker lever 39 in a clockwise direction about its pivot 43 to the open position shown in Fig. 1. During the movement of the breaker lever 39 to open position, the cross bar 6| thereof engages and moves the holding latch 53 to the released position effecting release of the free end of the closing lever 33. The retrieving springs 5| then move the closing lever counterclockwise about its fixed pivot axis 31 to open position indicated by the dotted lines in Fig. 1. This opening movement of the closing lever 33 moves the breaker lever 39 in a counterclockwise direction about the pivot pin 41 as a fulcrum to return the trip free roller 49 to the latched position where it is reengaged by the latching mechanism 23. Both levers 33 and 39 now occupy the position indicated by the dotted lines in Fig. l and the mechanism is reset and ready to be reclosed. When the solenoid I9 is energized to reclose the breaker, the two levers 33 and 39 are rotated together in a clockwise direction about the pivot axis 31, to closed position, and the roller 59 of the closing lever is reengaged and latched by the holding latch 53 to hold the closing lever in closed position.

The latching mechanism 23 comprises a latch 63 pivotally mounted on the frame l1 by a pivot pin 65 and having a latch projection 61 for engaging the trip free roller 49 of the breaker lever 39 to hold the roller 49 and the lever 39 in latched position. The latch 63 also comprises a pin 69 adjacent the free end which pivotally supports one member 1| of a toggle; the other member 13 of the toggle being pivotally mounted on the frame H by means of a rotatable shaft 15 to which the member 13 is rigidly clamped at its lower end by screws 11. The shaft 15 is rotatably mounted in bearings 19 provided there for on the frame I1, and one end of the shaft extends laterally beyond the side of the frame 11 as shown in Figs. 2 and 3. The adjacent ends of the toggle members 1| and 13 are pivotally connected together by a knee pivot pin 8|.

A tension spring 83 is connected at one end to the toggle member 13 adjacent the knee of the toggle and this spring serves to bias the latch 63 to latching position and the toggle to the extended or in toggle position to thereby maintain the latch in latching position. The inward movement of the latch 63 and latch toggle 1 |-13 is limited by cooperating stop surfaces 85 and 81 formed on the adjacent ends of the toggle members 1| and 13.

In the latching position of the latch 63, the toggle 1|13 is approximately in dead center position, i. e., the knee pivot pin 8| is located approximately on a line joining the axis of the pivot shaft 15 and the axis of the pivot pin 69. In the embodiment shown, the center of the knee pivot pin 8| is located a small distance to the right of this center line so that the toggle 1|13 is very slightly overset. It is to be understood, however, that the toggle may be disposed exactly on dead center or slightly under set if desired and reliance placed on the spring 83 to maintain the latch in latching position.

The toggle member 13 is provided with a projection 89 adjacent its fixed pivot end which is disposed over the trip plunger of the trip device 25 so as to be engaged and moved by the trip plunger to effect tripping of the breaker when the trip device is actuated. The projection 89 carries an adjustable spring bumper 9| which is adapted to engage the frame I! when the latch is moved to latching position to absorb some of the kinetic energy of the moving latch parts. The spring bumper also assists in initiating move ment of the latch parts to released position upon operation of the trip device 25.

The trip device 25 comprises a solenoid having a stationary core 93, a movable core 95, and an energizing winding 9'1. A trip plunger rod 99 is carried by the movable core 95 and extends up through aligned openings in the stationary core 93 and the frame I "I. When the winding 9'! is energized, the trip plunger 99 is moved upwardly by the core 95 and engages and moves the toggle member I3 in a counterclockwise direction causing collapse of the toggle and movement of the latch 63 toward released position thereby eifecting release of the trip free roller 49 and breaker lever 39.

A toggle locking lever 86 is provided for the purpose of preventing the latch 63 from returning to latching position following release until after the trip free roller 49 has been automatically retrieved or reset to its normal position. This prevents the latch checking switch, hereinafter described, which is controlled by the latch from being operated more than one time for each opening operation of the breaker. The toggle locking lever 86 is pivotally mounted on the pivot pin 65 at the side of the latch 63 and is biased in a clockwise direction, as viewed in Fig. 1, by the spring 83 which is anchored at one end to a tailpiece of the toggle locking lever 86. A projection 88 of the toggle locking lever is disposed to be engaged by the end of the breaker lever 39 which carries the trip free roller 49, so as to hold the toggle locking lever down in an inoperative position whenever the trip free roller 49 is in its normal or latched position. The toggle locking lever 86 is provided with another projection 90 which is adapted to be moved into blocking relation in the path of the knee pivot pin BI of the toggle II-l3 whenever the trip free roller 49 is away from its normal position thereby preventing movement of the toggle I I'I3 and latch 63 to latching position until the trip free roller 49 is retrieved to normal position. The toggle locking lever 88 is shown in looking position in Fig. 1. When the trip free roller 49 is automatically retrieved to its normal position as shown in Fig. 4, the end of the breaker lever 39 engages the projection 88 of the toggle locking lever 86 and depresses the toggle locking lever thereby causing the projection 90 thereof to be moved out of the path of the knee pivot pin 8I of the toggle to permit the toggle and latch 63 to be moved to latching position by the spring 83. Fig. shows the position of the parts after the latch 63 has been moved to latching position in engagement with the trip free roller 49. In

this position, the circuit breaker mechanism is fully reset and ready to be reclosed.

A latch checking switch I03 is mounted on the frame IT at the side of the latching mechanism 23 and this switch is adapted to be operated in response to the movement of the latch 63 to check the position of the latch. The switch I03 is biased to open circuit position by a spring (not shown) and is adapted to be closed by depressing a pushbutton I05 which projects through the top of the switch casing. The switch I03 is held closed only as long as the pushbutton I05 is held in depressed position. The latch checking switch I03 is adapted to be operated in accordance with the movement of the latch 63 by means of an arm I01 which is secured to the shaft I5 of the toggle member I3. When the latch 63 and toggle II'I3 move to latching position, the arm I01 depresses the pushbutton I05 closing the latch checking switch I03, and the switch remains closed as long as the latch 63 remains in latching position.

The latch checking switch is usually connected in series with the operating coil of the reclosing relay and with an auxiliary switch of the breaker which is arranged to close when the breaker reaches open position as disclosed in the copending application of Lloyd W. Dyer, et 2.1., Serial No. 294,048, previously referred to. In such instance, the closing solenoid cannot be energized to reclose the breaker until the operating mechanism has been automatically reset and the latch 63 is in latching engagement with the trip free roller 49. It has been found, however, that due to the high speed operation of the parts, the latch 63 rebounds several times when it moves to latching position in engagement with the trip free roller 49. These rebounds of the latch 63 cause undesired opening operations of the latch checking switch I03 and as a result the operating coil of the reclosing relay does not effect sufficient energization of the closing solenoid I9 toinitiate automatic reclosing of the breaker until after the latch 63 stops rebounding and remains in latched position. This delay is longer than is desired particularly where high speed automatic reclosing is required. In other types of automatic reclosing circuit breaker systems, the latch checking switch in addition to controlling the reclosing relay also operates the counting element of the reclosing relay, and in such instance if the latch rebounds, the latch checking switch opens thereby causing the counting element of the reclosing relay to falsely operate. Consequently, a reclosing relay set to cause a definite predetermined number of automatic reclosing operations of the breaker, would actually cause a lesser number of reclosures because of faulty counting of the reclosing relay which was due to the rebound of the circuit breaker operating mechanism latch.

In Figure 5 of the drawings I have illustrated a bound of the latch 63 and the consequent false operation of the latch checking switch I03 is prevented by a weight which is loosely mounted to move with the latch and has a mass approximately equal to the effective free weight and mass of the latch and the parts which move with the latch. In the embodiment of the invention illustrated, a metal weight I99 is loosely disposed in a recess or pocket III provided therefor in the toggle member I3. The metal weight I99 is freely movable a limited amount in the pocket I II relative to the toggle member '59 in the direction of movement of the member I3, and the weight is retained in the pocket by a cover plate II3 which is secured to the toggle member 1'3 over the open side of the recess or pocket III by a plurality of screws I I5.

The weight I09, as determined by experiment, should preferably have a weight and mass approximately equal to the effective free weight and mass of the movable latch parts comprising the latch 63 and its toggle ll-J3. The Weight should preferably be carried by the moving latch part having the longest travel and moving at the highest speed. Moreover, it is desirable that the weight should be mounted so as to move as nearly as possible in a horizontal path to reduce the effects of gravity and so as not to materially affect the normal operating speed of the latch parts.

When the latch 63 is moved toward latching position by the spring 83, after retrieving of the trip free roller 49, the weight I09 at this instant is in its outermost position against the cover plate H3 as, shown in Fig. 4, but is still moving in a direction toward the latch 63. By the time the latch 63 and toggle member 13 start to rebound from latching position, the Weight I69 which is still moving inwardly toward the latch strikes the toggle member 13 and overcomes the rebound movement due to the momentum and mass of the weight. The rebound of the latch 63 and toggle member 13 is thus prevented or reduced to such a very slight amount that the latch checking switch I03 will not be opened thereby.

While the invention has been disclosed in ac cordance with the patent statutes, it is to be understood that various changes may be made in construction disclosed without departing from some of the essential features of the invention.

I claim as my invention:

1. In a circuit breaker having an operating member releasable to cause opening of the breaker, a movable latch for engaging and holding said operating member in operative position, said latch being biased to latching position, trip means operable to move said latch to released position to effect release of said operating member, an auxiliary switch controlled by said latch, and means operable to prevent rebound of said latch toward released position to thereby prevent false operation of said auxiliary switch, said last mentioned means normally permitting movement of said latch toward released position.

2. In a circuit breaker having a member releasable to cause opening of the breaker, a movable holding means for restraining said member in operative position, spring means biasing said holding means to holding position, trip means operable to move said holding means to released position to release said member, an auxiliary switch operated by said holding means, means automatically effective to prevent return of said holding means to holding position until said releasable member is returned to its operative position, and means operable to prevent rebound of said holding means toward released position when said holding means is moved to holding position, said rebound preventing means permitting movement of said holding means to released position at all other times.

3. In a circuit breaker having a member releasable to cause opening of the breaker, a movable holding means for restraining said member in operative position, spring means biasing said holding means to holding position, trip means operable to move said holding means to released position, an auxiliary switch controlled by said holding means and means operable by the movement of said holding means to holding position for opposing rebound of said holding means toward released position to thereby prevent false operation of said auxiliary switch.

4. In a circuit breaker having a member releasable to cause opening of the breaker, a movable latch for engaging and restraining said member in operative position, spring means biasing said latch to latching position, trip means operable to move said latch to released position, an auxiliary means controlled by said latch, means automatically effective to prevent return of said latch to latching position until said releasable member is returned to operative position, and means movable with said latch operable to oppose rebound of said latch toward released position to thereby prevent false operation of said auxiliary means.

5. In a circuit breaker having a member releasable to cause opening of the breaker, a movable latch for engaging and restraining said member in operative position, spring means biasing said latch to latching position, trip means operable to move said latch to released position, an auxiliary switch controlled by said latch, and means comprising a weight of predetermined mass movable by said latch and operable to oppose rebound of said latch to thereby prevent false operation of said auxiliary switch.

6. In a circuit breaker having a member releasable to cause opening of the breaker, a movable latch for engaging and restraining said member in operative position, a toggle connected to said latch, spring means connected to said toggle for biasing said latch to latching position, trip means operable to effect movement of said latch to released position to release said member, and means comprising a weight of predetermined mass movable with said latch and operable to prevent rebound of said latch toward released position when said latch is moved to latching position.

'7. In a circuit breaker having a member releasable to cause opening of the breaker, a movable latch for engaging and restraining said member in operative position, a toggle connected to said latch, spring means connected to said toggle for biasing said latch to latching position, trip means operable to effect movement of said latch to released position to release said member, and means comprising a weight of predetermined mass carried by said latch toggle operable to prevent rebound of said latch toward released position when said latch is moved to latching position.

8. In a circuit breaker having a member releasable to cause opening of the breaker, a movable latch for engaging and restraining said member in operative position, a toggle connected to said latch, spring means connected to said toggle for biasing said latch to latching position, trip means operable to effect movement of said latch to released position to release said member, and means comprising a weight of predetermined mass movable with said latch and operable to prevent rebound of said latch toward released position when said latch is moved to latching position, said weight being mounted on said toggle for limited movement relative thereto in the direction of movement of said toggle and having a mass approximately equal to the eifective mass of said latch and toggle.

9. In a circuit breaker having an operating mechanism including a member releasable to cause opening of the breaker, a movable holding means for restraining said member in operative position, spring means for biasing said holding means to holding position, trip means operable to cause movement of said holding means to released position to release said member, an

auxiliary control switch operated by the movement of said holding means, and means comprising a weight of predetermined mass movable with said holding means operable to prevent rebound of said holding means to thereby prevent false operation of said auxiliary control switch.

10. In a circuit breaker having an operating mechanism including a member releasable to cause opening of the breaker, a movable latch for restraining said member in latched position, spring means for biasing said latch to latching position, trip means operable to cause movement of said latch to released position to release said member, an auxiliary control switch operated by the movement of said latch, and means comprising a weight of predetermined mass movable with said latch operable to prevent rebound of said latch to thereby prevent false operation of said auxiliary control switch, said weight being movable a limited amount relative to said latch approximately in the direction of movement thereof.

11. In a circuit breaker having an operating mechanism including a member releasable to cause opening of the breaker, means comprising a toggle for restraining said member in an operative position, a spring for biasing said toggle to restraining position, trip means operable to cause collapse of said toggle to release said memher, an auxiliary control switch operated by the movement of said toggle, and means operative to prevent rebound of said toggle to thereby prevent false operation of said auxiliary control switch.

12. In a circuit breaker having an operating mechanism including a member releasable to cause opening of the breaker, a pivoted latch for restraining said member in latched position, a toggle connected at one end to said latch, spring means connected to said toggle for biasing said latch to latching position, trip means operable to cause movement of said latch to released position to release said member, said member being resettable to latched position following its release, an auxiliary control switch operated by the movement of said latch, and means comprising a weight of predetermined mass movable with said latch operable to prevent rebound of said latch to thereby prevent false operation of said auxiliary control switch.

13. In a circuit breaker having an operating mechanism including a member releasable to cause opening of the breaker, a pivoted latch for restraining said member in latched position, a toggle connected at one end to said latch, spring means connected to said toggle for biasing said latch to latching position, trip means operable to cause movement of said latch to released position to release said member, said member being resettable to latched position following its release, an auxiliary control switch operated by the movement of said latch, and means comprising a weight of predetermined mass carried by said toggle and movable a limited amount relative thereto in the direction of movement of said toggle for preventing rebound of said latch to thereby prevent false operation of said auxiliary control switch.

HARRY J. LINGAL,

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