US2394036A - Circuit breaker - Google Patents

Description

CIRCUIT BREAKER Filed Aug. 26, 1943 33 L "35 l I 23 l I 13 H- I 25- TQl' 97 63 I07 61 37 7; a; 31 69 9a 35 2 2 4 i J 99 I l I w WITNESSES: v Y INVENTORS Samuel 194300 672 and James MUummzn a.

. BY W Patented Feb. 5, 1946 CIRCUIT BREAKER Samuel H. Boden and James M. Cumming, Turtle Creek, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 26, 1943, Serial No. 500,063

17 Claims.

This invention relates to circuit breakers and more particularly to circuit breakers of the type which are operated by compressed gas motors.

The load curve of usual types of circuit breakers is such that maximum operating power is needed during the final portion of the closing movement when the contacts are being moved into high-pressure engagement. A solenoid is ideally suited for closing a circuit breaker since its power curve is very similar to "the mechanical load curve of the circuit breaker developing maximum power near the end of its stroke. Compressed gas or air motors while being more desirable than a solenoid in other respects for closing a circuit breaker develop maximum power almost immediately at the beginning of the closing stroke. Because of this, excessive kinetic energy will be developed during the closing stroke and excessive slamming of the circuit breaker will result on normal closing operations unless some arrangement is made to take care of the difference in the power and load curves. On the other hand the application of full power is needed to quickly reverse and reclose the circuit breaker on quick reclosing operations.

An object of the present invention is the provision of a circuit breaker with an improved operating mechanism of the compressed gas operated type having means for preventing excessive acceleration during normal closin operations but which provides for the application of full power to the circuit breaker during the final portion of the closing stroke.

Another object of the invention is the provision of a ircuit breaker with an improved operating mechanism of the compressed gas operated type having means for preventing excessive acceleration of the moving parts during normal closing operation but which provides for the application of full power to the circuit breaker during the final portion of the closing operation and also during quick reclosing operations.

Another object of the invention is to provide a circuit breaker with a device for equalizing the closing load on the operating mechanism.

Another object of the invention is to provide a circuit breaker wherein the closing load on the operating mechanism is increased for a predetermined portion of the closing stroke.

Another object of the invention is to provide a circuit breaker having means for applying an additional load on the operating mechanism and means for neutralizing the additional load at a predetermined time during a closing operation.

Another object of the invention is to provide a circuit breaker with means interposed between the breaker and the operating mechanism for applying a force opposing closing movement of the breaker for a predetermined time during a closing operation.

Another object of the invention is to provide a circuit breaker having a load controlling device for providing a substantially even load on the operating mechanism throughout a closing operation thereof.

Another object of the invention is the provision of a circuit breaker having a compressed gas operating mechanism for closing the breaker with a device arranged to impose an additional load on the mechanism from the start of the closing stroke and release the additional load shortly prior to the time of contact engagement thus transferring the additional power used to move the superimposed load to the breaker at this time.

Another object of the invention is the provision of a circuit breaker with an improved operating mechanism of the compressed gas operated type which is simple, reliable in operation, inexpensive to manufacture and which provides improved operating performance and efliciency.

The novel features that are considered characteristic of the invention are set forth in the appended claims. The invention itself, however, 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 connection with the accompanying drawing, in which:

Figure 1 is an elevational view, partly in section and partly schematic, of a circuit breaker embodying the principles of the invention,

Fig. 2 is an elevational view of the load equalizing device shown in the closed position of the breaker.

Referring to the drawing, the circuit breaker indicated generally at H, may be of any conventional construction either of the oil break, air break or gas blast type and is operated to the closed position by means of a compressed gas operated mechanism indicated generally at l3 on the drawing.

The operating mechanism includes a main casting l5 which is formed to provide a cylinder l1 closed at the upper end by an integral part of the casting. The lower end of the cylinder I1 is' closed by means of a member I9 secured thereto and having a relatively large port 2| therein which is open to the atmosphere. An operating lever 23 is pivotally mounted at one end on the casing I and consists of a pair of spaced parallel levers (only one being shown) connected at one end by means of a pivot pin 25 to the upper end of a pair of parallel links 21. The lower ends of the links 2'! are pivoted by means of a pivot pin 29 on ears SI (only one being shown) projecting from the main casting IS. Th free ends of the operating levers 23 between them carry a short shaft 33 on which is mounted a latch roller 35 disposed between the levers 23.

The circuit breaker I I is biased to open circuit position by means of an acceleratin spring 3'! and is connected to the operating mechanism 13 by means of a linkage comprising an operating rod 39 pivotally connected at its upper end by means of a pivot pin 4| to a bell crank 43. The bell crank 43 is rotatably mounted on a shaft 45 and is pivotally connected by means of a pivot pin 41 to a connecting rod 49 having its other end connected by means of a pivot pin 5I to a bell crank 53. The bell crank 53 is rotatably mounted on a shaft 55 supportedon a fixed part and is connected by means'of a pivot pin 51 to the breaker rod 59.

The breaker operating rod 39 is pivotally connected by a'pivot pin 98 to the mid portion of the operating lever 23. In order to hold the breaker closed, following a closing operation thereof, the operating lever 23 is held in closed position by means of a latch mechanism indicated generally at SI. The latch mechanism comprises a main latch 63 pivotally supported on themain casting I5 by means of a pivot pin 65 and biased to latching position by a spring '61. The latch 63 is adapted to engage the latch roller 35 carried by the operating lever 23 to restrain the operating mechanism and the breaker in closed position. The latch face of the main latch 63 is so constructed that it will not, by itself, hold the operating lever 23 in closed position against the biasing influence of the accelerating spring 31. An auxiliary latch 69 is provided for engaging and holding the main latch 63 in latchin position. The auxiliary latch 69 is pivotally mounted on the main casting I5 by means of a pivot pin II and is biased to latching position by means of a spring I3.

Means is provided to prevent engagement of the auxiliary latch 69 with themain latch 63 when the mechanism is in the open position and until the breaker is closed. This means consists of a lever pivoted on the pin II and biased in a counterclockwise direction by means of aspring ll. The lever 15 has a projection I9 extending beneath a tail 8I of the auxiliary latch 69and since the spring TI is stronger than the spring I3, the lever I5 will hold the auxiliary latch 69 in unlatching position when the breaker is in the open position. Upon closing operation ofthe mechanism, the operatin lever 23 engages-the free end of the lever I5 and rotates it in a clockwise direction to permit the'latch 69 to engage the main latch.

The latch mechanism GI is adapted to be operated to release the operating lever- 23 and permit opening of the breaker, by means-of anelectromagnetic trip device indicated generally at 63. This trip device comprises a core member-85 of magnetic material, an energizing coil 81, a movable armature 89 and a trip plunger 9|. Thetrip plunger 9I is secured tothe-armature 89 and extends upwardly through a guide opening inthe center portion of the core 65 and throughan opening in a projection of the'ca-sing- I5.

and to the operating rod 39.

When the trip device 83 is energized, the armature 89 is moved upwardly causing the trip plunger 9I to engage the tail 8| of the auxiliary latch 69 and move the latch to unlatching position. The latch roller then forces the main latch 63 to unlatching position which permits opening movement of the breaker mechanism.

The breaker'is adapted to be closed by compressed gasadmitted to the cylinder II above an operating piston 93. The piston 93 is secured to a piston rod 95 slidable through an air-tight opening in the top wall of the cylinder. A connector 91 is threadedly connected to the piston rod 95 The connector 9'! is also pivotally connected to the operating lever 23by means of the pivot pin 98 thus directly connecting the piston 93 to the breaker operating rod 39.

Compressed gas is admitted from an auxiliary reservoir 99 to the upper end of the cylinder I! through an inlet passage IOI controlled by a main inlet valve I63 secured to the side of the casting I5. The opening operation of the main inlet valve I03 is, in turn, controlled by an electromagnetically operated-pilot valve I05.

The pilot valve I95 is operated by an electromagnet I01 which, when energized, causes opening of the pilot valve I05 to admit compressed air'frem the tank 99-to operate the main inlet valve I93. Actuation of the inlet valve admits compressed gas to the-upperend of the operating cylinder ll which drives the piston 93 quickly downwardly to close the breaker.

When the mechanism is operated to closed position, thelatch roller 35 engages the inclined surface of the main latch 63 and rotates the latch in a counterclockwise direction until the roller passes the noseofthe latch. The spring 61 thereupon restores the main latch to latching position.

The mechanism cylinderis also provided with a dump valve (not shown) for quickly'reducing or exhausting backpressure in the cylinder to permit high-speed opening ofthe circuit breaker. The dump valve 'isoperated to open position by the pressure air in-the cylinder when a pilot valve I98 is opened by the operation-of the trip device 83. The fluid motor mechanism including the inlet-and-dump valve mechanisms i similar to that disclosed in the copending application of J. M. Cumming and R. C. Cunningham, Serial No. 410,686, filed September 13, 1941, and assigned to the assignee of the'present-invention. For details of construction-of the fluidmotor mechanism'and its inlet and dump valve mechanisms reference may be had to the aforementioned copending application.

During a closing-operationthe greatest power of t-he operating mechanism is-required to complete the closingstroke'after the contacts touch to thereby provide the necessary contact pressure. It will be obvious that-during-the closing movement prior to the engagementof-thecontacts,-the breaker mechanism moves relatively free'andthe fullpowerof the closing mechanism has a tendency t0 cause slamming of the mechanism-and circuit-breaker. In order to prevent undesirable-slamming and to provide a more even load curve for themechanism, an additionalor equalizing load is imposed upon the mechanism from the-start of the closing stroke up until shortlybefore the engagement of the contacts, and the equalizing load is automatically removed at about the time the contacts touch or shortly before this time.

The load equalizing device comprises a loading coil spring I09 having the end coils of one end tightly coiled about a grooved spring anchor III which is pivo-tally supported on the pivot pin 4| connecting the operating rod 39 to the bell crank 43. The other end of the spring I09 is similarly attached to a spring anchor II3 pivotally connected by means of a pivot pin II5 to the free end of a lever I H which is pivotally supported on a shaft H9. The shaft 45 supporting the bell crank 43 and the shaft II9 are mounted in the side walls I2I (only one being shown) of a housing which encloses the load equalizing device. The housing, including the sides I2I, is secured in a suitable manner to the breaker frame or housing (not shown).

The spring anchors I I I and I I3 are respectively provided with reduced portions I23 and I25 which extend toward and normally abut against each other, thus forming a solid but separable connection between the bell crank 43 and the lever Ill. The lever II'I carries a pin I21 upon which is mounted an antifriction roller I29 adapted to cooperate with a cam I3I loosely mounted on the shaft 45 for rotary movement relative to the shaft and to the bell crank 43. Integral with the bell crank 43 is an arcuate projection I33 extending toward the cam I3I and adapted to cooperate with an arcuate projection I on the cam to form a lost motion connection between the cam I3I and the bell crank 43. The cam I3I is biased in clockwise direction about the shaft 45 by means of a spring I31 having one end hooked over a pin I39 on the cam and the other end anchored to an adjustable member I4I secured to the bottom of the housing I2 I.

Assuming the breaker to be in the open position, as shown in Fig. 1, when compressed gas is admitted to the top of the cylinder II above the piston 93, the piston is driven downwardly to close the breaker. This movement of the piston,

through the piston rod 95 and the breaker operating rod 39 rotates the bell crank 43 in counterclockwise or closing direction. Since at this time the lower ends of the projections I33 and I35 are in engagement, the cam I3I will be rotated with the bell crank 43 and in the same direction. counterclockwise rotation of the cam I3I permits the lever I I 1 to follow in a counterclockwise direction, but the configuration of the cam surface engaging the roller I29 is such that the lever I I1 moves at a slower rate of speed than the bell crank 43; consequently the spring anchors I II and H3 separate stretching the load spring I09 and the force of the spring I09 will be imposed upon the operating mechanism opposing closing movement thereof.

At a predetermined time during the closing movement, substantially when or shortly before the moving contacts engage the stationary contacts, the cam I3I, in its counterclockwise movement, releases the roller I29 whereupon the spring I09 rotates the lever II'I sharply counterclockwise until the projecting ends I23 and I25 of the members III and H3 engage. Thereafter the lever II 'I is free to move counterclockwise and the force of the spring I09 no longer opposes closing movement of the mechanism. This permits the full power of the closing mechanism I3 to be applied to the breaker during the latter part of the closing stroke.

When the cam I3I frees the roller I29 and the spring I09 rotates the lever II'I counterclockwise, the roller I29 moves the cam I3I in a counterclockwise direction relative to the bell crank 43,

thus partially closing the gap, indicated at I43, between the projections I33 and I35 and separating the projections at the point indicated at I 45.

'As' the closing movement continues, the projections I33 and I35 again engage at the point I45 and the parts assume the positions shown in Fig. 2 in the fully closed position of the mechanism.

When the breaker is in the fully closed and latched position and the trip device 83 is energized to trip the breaker in the previously described manner, the accelerating spring 3'! actuates the movable contact and the operating mechanism to the open position (Fig. 1). During an opening operation, it is not desired that the force of the spring oppose the opening movement. During an opening operation the bell crank 43 is rotated in a clockwise direction from the Fig. 2 position to the open position (Fig. 1). The members I23 and I25 remain in contact during the entire opening movement and the solid connection formed thereby causes the lever ill to rotate clockwise with the bell crank 43. During the closing movement, the spring I31 causes the cam I3I to rotate clockwise under the control of the roller I29 but since the spring I31 is much weaker than the spring I09, it cannot cause separation of the members I 23 and I25. The projection I33 on the bell crank 43 will separate at the point I45 from the projection I35 on the cam I3I during the opening movement but the gap I43 will not completely close, and at no time during the opening movement is the cam I3I actuated by the bell crank. The bias of the spring I3! is applied during opening operations in a direction to aid the accelerating spring 31 in opening the breaker.

The circuit breaker is adapted for quick automatic reclosing operations which are preferably initiated immediately after the contacts are opened a predetermined distance and the arc is extinguished, and before the circuit breaker reaches full open position. The quick automatic reclosing operations of the breaker are initiated by admitting compressed gas to the operating cylinder at the proper time during the opening stroke. This is effected by the breaker control circuits which are fully described and shown in the previously mentioned copending application.

During such high-speed reclosing operations it is essential that the operating mechanism be relieved of the additional load imposed thereon by the spring I09 as full power is needed to quickly reverse the movement of the breaker and effect quick reclosing thereof. Referring to Fig, 2 which shows the load equalizing device in the fully closed position of the breaker, it will be remembered that the clockwise rotation of the bell crank 43 in opening direction through the now solid link I23I25 rotates the lever II! also in a clockwise direction. During this action the cam I3I is prevented from immediately resuming its Fig. 1 position by engagement thereof with the roller I29, the bell crank moving clockwise relative to the cam I3I due to the lost motion connection I33-I35. The contactsseparate and the arc is extinguished just before the roller I29 releases the cam I3I and at this time compressed gas is admitted to the cylinder quickly driving the piston toward the bottom of the cylinder to thereby efiect quick reclosing of the contacts. The counterclockwise movement of the bell crank 43 draws the roller I29 back under the cam I3I without causing separation of the members I23 and I25 and therefore does not apply the spring load 109 to the mechanism during the quick reclosing operation.

From the foregoing description, it will be seen that there is provided a load equalizing device of simple construction, reliable in operation which applies an auxiliary load to the closing mechanism of a circuit breaker during a portion of the closing movement and which at a predetermined time during the closing movement automatically removes the auxiliary load to permit the full power of the closing mechanism to be applied to close the breaker contacts.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from some of the essential features of the invention.

We claim as our invention:

1'. A circuit breaker comprising relatively movable contacts, operating mechanism for moving said contacts to closed position, spring means having one end attached to said operating mechanism for at times applying a force opposing closing movement of said breaker during a major part of the closing stroke, and means related to the other end of said spring operable by said operating mechanism near the end of a closing movement to render said spring means inefiective to oppose opening movement.

2. A circuit breaker comprising relatively movable contacts, operating mechanism operable to close said contacts, a spring having one end attaohed to said mechanism and normally disposed to oppose closing movement of said breaker at least during a portion of the closing movement, and means attached to the other end of said spring operable by said operating mechanism near the end of the closing movement to render said spring inefiective, said spring being ineffective to oppose opening movement of said breaker.

3. In a circuit breaker, power operating mechanism for closing said breaker, a spring having one end attached to said operating mechanism for opposing closing movement of said breaker, said spring being normally ineffective, means automatically operable during an opening operation to-cause said spring to oppose closing movement of the breaker, said mean bein operable at a predetermined time during the closing movement to neutralize the force of said spring.

4. A circuit breaker comprising relativelymovable contacts, power operated .means for closing said contacts, a spring having one end attached to said power operated means, a member attached to the other end of said spring, means automatically operable during a closing operation to first restrain said member to thereby cause the spring to oppose the closing movement and then near the end of the closing movement to release said member and render said spring ineffective to oppose the final portion of said closing movement, and said spring being at all times ineffective to oppose opening movement.

5. A circuit breaker comprising relatively movable contacts, a fluid motor operable to close said contacts, a rotatable member operable by said motor to close the contacts, a spring having one end attached to said rotatable member, and a cam member automatically operable during an opening movement to cause said spring to apply a force-opposing closing movement of the motor during a substantial portion of the closing movement of said motor.

6. A circuit breaker comprising relatively movable contacts, a fluid motor operable to close said contacts, a source of fluid under pressure, means for admitting fluid under pressure to said motor to cause the motor to operate the breaker to closed position, means connected to said motor for applying an additional load to said motor during the closing operation, and means operable by said motor to reduce said additional load near the end of the closing operation.

7. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts comprising a cylinder, a piston movable in said cylinder, a source of compressed gas, means for admitting compressed gas to said cylinder to cause the piston to operate the breaker to closed position, spring mean having one end attached to said operating mechanism for applying an additional load to said piston during the major portion of the closing stroke, and means comprising an element attached to the other end of said spring and operable to reduce the additional load at a predetermined time near the end of the closing stroke.

8. A circuit breaker comprising relatively movable contaots, operating mechanisms for said contacts comprising a cylinder, a piston movable in .said cylinder, at source of compressed gas, means for admitting compressed gas to said cylinder for operating said piston to close said contacts, a spring having one end attached to a part movable with said piston for at times applying a force opposing closing movement of said piston, and means comprising a member connected to the other end of said spring and operable by said part near the end of a closing operation to reduce the force of said spring.

9. In a circuit breaker, a fluid motor operable to close the breaker, resilient means connected to a part movable with the breaker for at times applying a force opposing closing operation of the breaker, a cam rendered effective by movement of the breaker to open position to cause said resilient means to oppose a closing operation during a substantial portion of the closing operation, and means for operating said cam to reduce the force of said resilient means.

10. In a circuit breaker, power operated operating mechanism for closing said breaker, a load equalizing device comprising means for applying a force to said operating mechanism during a major part of the closing movement for retarding the closing movement of the breaker, and means automatically operable during the latter part of the closing operation and before the breaker reaches fully closed position to reduce the retarding force.

ii. A circuit breaker raving relatively movable contacts, a motor operatively related to the movable contact for closing the circuit breaker, a spring having one end attached to a part movable with saidrnotonmeans automatically effective to cause-said spring toimposean additional load on themotor durin a substantial part of the circuit breaker closing stroke of said motorand to release said additional load from the motor beiore the circuit breaker reaches the fully closed position on normalclosing operations of the circuit breaker.

12. A circuit breaker having relatively movable contacts, a fluidmotor operatively related to the movable contact for closing the circuit breaker, means automatically effective to apply an additional load on the fluid motor during a-substantial part of the circuit breaker closing stroke of motorand to release said. additional load from the motor before the circuit breaker reaches-the fully closed position on normal closing operations of the circuit breaker, and an element controlled by said motor to render said means ineffective to apply said additional load on said motor during quick reclosing operations of the circuit breaker initiated before the circuit breaker reaches full open position.

13. A circuit breaker having relatively movable contacts, a fluid motor operatively related to the movable contact for closing the circuit breaker, means automatically effective to apply an additional load on the fluid motor during a part of the circuit breaker closing stroke of said motor and to release said additional load from the motor during the latter part of the closing stroke and before the circuit breaker reaches the fully closed position on normal closing operations of the circuit breaker, and means for preventing application of said additional load on said motor during quick reclosing operations of the circuit breaker.

14. A circuit breaker having relatively movable contacts, a fluid motor operatively related to the movable contact for closing the circuit breaker, spring means automatically effective to apply an additional load on said fluid motor during a sub-.

15. A circuit breaker having relatively movable A contacts, a fluid motor operatively related to the movable contact for closing said breaker, means comprising a spring automatically efiective to apply an additional load on said fluid motor during a part of the closing stroke of said motor, a

cam operable during the latter part of the closing stroke of the motor to release said additional load, and means controlling said cam to prevent application of said additional load on said motor during quick reclosing operations of the circuit breaker.

16. A circuit breaker having relatively movable contacts, a fluid motor operatively related to the movable contact for closing the circuit breaker, means comprising a spring connected to a part movable with said motor for imposing an additional load on said fluid motor during a substantial part of the closing stroke of said motor, a cam for controlling said spring and operable during a normal closing operation of the breaker to release said additional load, and means for controlling said cam to prevent application of said additional load on said motor during quick reclosing operations of the breaker.

17. In a circuit breaker, operating mechanism for closing said breaker comprising a cylinder, a piston movable in said cylinder, a source of gas under pressure, means operable to admit gas under pressure to said cylinder to cause a closing operation of said piston, a load equalizing device comprising means for applying an additional load to said operating mechanism during a substantial portion of the closing operation, means operable near the end of the closing operation and before the breaker reaches fully closed position to automatically release the additional load, and means for controlling said load equalizing device to prevent application of the additional load to said operating mechanism during quick reclosing operations 'of the breaker initiated before the breaker reaches full open position.

SAMUEL H. BODEN. JAMES M. CUMMING.

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