US2296300A - High speed reclosing mechanism - Google Patents

Description

Sept. 22, 1942. c. THUMIM HIGH SPEED RECLOS'ING MECHANISM 0 (Fon MMM/4L :M1-no4) (me nur-MTM cur/mg) Filed July 18, 1939 Inventor' Thum'm,

His Attorney.

Patented Sept. 22, 1942 UNITED STATE S PATENT OFFICE Carl Thumim, Yeadon,

9 Claims.

My invention relates to'high speed reclosing mechanisms, more particularly as applied to electric circuit breakers which are connected to high voltage networks or power transmission lines, and has for its principal object the prol vision of an improved high speed reclosing mechanism that is efficient, positive and Very rapid in operation, and that is effective to apply the reclosing force instantly at a predetermined intermediate point in the opening stroke.

In electric ldistribution systems where continuity of service is a very important factor, means have been provided for quickly reclosing an electric circuit breaker one or more times after automatic opening in response to a fault, on the assumption lthat a very large percentage of faults, such as surges due to lightning, for example, are of a temporary nature. From the standpoint cf service continuity, the ideal condition is that the breaker be reclosed instantly after the breaker has cleared the fault. Accordingly, where standard opening and closing mechanisms are employed, reclosure does not actually start until the full opening stroke has been completed, i. e., an appreciable time after the fault current has been interrupted,

The function of a circuit breaker is not only to open a circuit and clear faults, but also to maintain the circuit clear in the open circuit position under adverse voltage conditions. That is, the length of stroke of the circuit breaker must be sufficient to prevent restriking of the arc in case the line voltage is several times that of normal. As contrasted with this isolating function of the breaker, it should be borne in mind that a well designed breaker can actually clear a fault within a few inches of opening stroke.

There is disclosed and claimed in my application, Serial No. 85,789, filed June 1'7, 1936, for High speed reclosing mechanisms (D-58,99l), a reclosing mechanism wherein a pair of separately energized motor mechanisms are interrelated with respect to each other and to a trip-free type circuit breaker for the purpose of obtaining rapid reclosure of the breaker.

In accordance with the present invention, a motor operated cam is operatively related to the circuit breaker for effecting closing and reclosing thereof and is controlled so as to be preset at an intermediate position for high speed reclosing of said breaker.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of Pa., assigner to General Electric Company, a corporation of New York Application July 18, 1939, Serial N0. 285,090

novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification. Referring to the drawing, thel single figure thereof is a partly diagrammatic layout of a high speed reclosing mechanism embodying the present invention.

rlhe automatic reclosing mechanism illustrated by the drawing consists essentially of a suitable source of motive power, such as a motor M, a trip-free thrust transmitting linkage indicated at T and an operating cam I. The thrust transmitting linkage which is fundamentally of the character disclosed and claimed in my Patent No. 1,827,626, granted October 13, 1931, for Switch operating mechanism is operatively connected to the circuit breaker operating rod 2 by means of a rocking lever 3 pivotally mounted at 4. The operating power is transmitted from the motor M through a gear train 5 to the cam shaft indicated at 6.

The cam I is rotated clockwise by the motor M upon energization thereof so as to rotate in counter-clockwise direction the floating lever 1 providedwith a cam follower or roller 8. The lever 1 is pivotally connected at 9 to a supporting link I0 that is adapted to be latched and held stationary by means of a latching device L1 comprising a normally underset toggle II and an electromagnetically operated latch I2. The toggle II includes a link I3 that is connected at'one end to the pivot 9 and is provided with a latching roller I4 for engagement with the latch It will therefore be noted that the latching device Li controls the pivot point 9 and that the breaker operating rod 2, which is connected to the floating lever 'I through the lever 3 and link I6, is free to move to the upper or open circuit position when the latch I2 is tripped by solenoid I5.

The floating lever 1 is also maintained in the thrust-transmitting position holding the breaker closed independently of the cam I by means of a pivoted prop member I1 that is biased to engage the under side of the roller 8 for the purpose of holding the floating lever 1 in the position shown against the normal opening bias of the breaker itself. The prop I1 is in turn controlled by means of a latching device L2 which comprises a hammer element I8 co-pivotally mounted at I9 with the prop. The hammer is latched at the roller 20 by a pivoted latch 2I that is electro-magnetically controlled at 22 by a tripping solenoid. The prop I1 is provided with an extension il that carries an offset roller or lug I'i disposed in alignment with the lower striking edge I8 of the hammer I3.

As illustrated the hammer I3 after being tripped moves a certain distance before engaging the prop extension il' so that the prop will be quickly released under the impact. For the purpose of obtaining the impact effect of the hammer I3 when it is released by the latch 2|, a spring 23 is connected to the hammer so as to be stressed in the normally latched position. Accordingly under iniiuence of the spring 23, the hammer IS when released is effective to drive at high speed the prop Il from beneath the roller 8 to cause opening of the breaker.

When the breaker is in either the fully open or fault-clearing position, (i. e. when rocking lever 3 has moved approximately 30 counterclockwise from the position shown) the latches L1 and L2 are in the reset positions and the roller E is lowered so as to be in engagement with the surface of the cam l. Accordingly when the motor M is energized to rotate the cam I, the roller V8 is elevated thereby causing clockwise rotation of the lever 3 and closing of the breaker. When the breaker reaches the closed position the prop Il snaps under action of spring II'I into holding position beneath the roller 8 to hold the linkage in that position until a tripping operation is initiated. As illustrated, the breaker is in the closed circuit position and the cam is preset at an intermediate position for high speed reclosing upon tripping.

The cy-cle of operation of the mechanism will now be described. Starting with the breaker fully ropen, the closing operation under the manual control of the operator is initiated by closing the closing switch C, whereupon the motor M is energized through the motor starting relay MR. The energizing solenoid 24 of the relay is energized from the control source indicated at 25 through the contacts s2 of the limit switch S and the closing switch C. Also coil 26 of the seal-in device 27 connected in parallel with coil 2li is energized. T-he coil 26 when energized is not eifective to attract the armature 23 of the vseal-in magnet y2*.9, but is effective to hold the armature in closed magnetic circuit position after it Vhas been actuated by other means to such position in a manner that will presently be described.

When the motor relay picks up, the motor circuit is completed through the relay contacts mri and the contacts s1 of the limit switch S. During the closing operation the motor circuit is maintained for insuring energization of the motor throughout the operation by the relay contacts mm, the coil 24 thereby being energized notwithstanding opening of the closing switch C.

At the end of the closing operation the motor is de-energized by the cut-off or limit switch S that is actuated vby means including a pin 30 mounted on the cam I and an arm 3| freely mounted on the cam shaft When the cam I reaches a predetermined angular position corresponding to closure of the breaker the pin 3i) strikes the arm 3I which in turn causes opening of the limit switch S through a pivoted member E2 anda connecting link 33. The link 33 through a crank 34 operates both the limit switch S and-the armature fS so that when the breaker is closed the armature :23 is closed through the medium of spring 3S and bothsets of contacts at s1 and s2 of the switch S open.

For the purpose of absorbing the excess energy at the end of the closing stroke the arm SI is arranged to co-act with a dashpot 35 through an intermediate pivoted member 35. A buffer spring 37 also co-acts with the arm SI at the opposite side thereof.

At the end of the closing stroke the cam I is automatically returned by a coil spring to an intermediate preset position as illustrated. This preset position is intermediate the high and .low points of the cam for the purpose of initiating and completing the automatic reclosing operation in much shorter time than would be necessary if the reclosing operation were to start from the low point of the cam corresponding to the beginning of the breaker stroke from fully open position. That is, a fractional part of the cam travel is utilized instead of a complete revolution thereof.

The cam I is held in the aforesaid preset position against the bias of spring 3B by a linkage including a pivoted member 39 that is connected to the main linkage T through a lost motion connection comprising a link it having a pin and slot connection at 4I with the member 39. When the breaker is closed the member 39 is in the position shown so as to check further counterclockwise rotation of the cam i. Accordingly in. this position the mechanism is in readiness for an automatic reclosing operation upon tripping of the breaker due to a fault condition.

The operation for the reclosing cycle is initi- -ated by energization of the fault or over-load relay FR. When the contacts fri of the fault relay are closed a lcircuit, is established to energize the coil 22 of the latch L2 through auxiliary switch a, and contacts tri of the transfer relay TR. The prop I7 is then tripped in the man ner above described to permit opening movement of the breaker to the extent deiined by the dise tance between the -cam surface and the cam follower 8.

As the lever 3 rotates counter-clockwise following tripping the auxiliary switches o and ai remain closed during the first part of the opening movement by reason of a lost motion connection with the lever 3 at 42. The auxiliary switch at 43 for initiating reclosing is closed after predetermined rotation of the lever 3 through a lost motion connection therewith at 44. Thereby the coil 24 of the motor relay MR is energized to close the motor circuit in the vmanner previously described. This circuit includes a manual opening switch O of the snapoVer type, which -is in the position to close contact oi when the automatic reclosing cycle is employed, and is operated to close contact o2 only for opening under manual control. The motor relay energizing circuit therefore includes contacts o1 of switch O, auxiliary switches 43 and a1, contacts M2 of the transfer relay TR, coil 24 and the contacts s2 of the switch S.

When this circuit is completed it will also be noted that the coil 4t of the transfer relay TR is also energized to open the circuit atirl and r2 and to-close the-*contacts at tra. The motor relay is at this time, however, sealed in at the contacts mrz so that the cam I is rotated through the fractional stroke above described immediately to reclose the breaker. scribed therefore results in reclosing of the breaker after it has tripped open and moved but a fraction of its full stroke toward open circuit position. During this reclosing operation, the transfer relay TR remains in its upper position to close the contacts at tra notwithstanding The operation above de.

deenergization of coil 45. For this purpose a retarding device, such as a dashpot tri, is operatively connected to the relay as indicated. This feature is disclosed and claimed in an application, Serial No. 192,782, led February 26, 1938, by Carl Thumim of High speed reclosing mechanism.

In case the fault should still persist after reclosing, the tripping circuit is now transferred by the relay TR at the contacts tra to the tripfree latching device L1. That is, since the fault relay FR is still held closed at tra by the dashpot in, the tripping coil I of the latch L1 is now energized through the fault relay contacts fri, auxiliary switch a, and the transfer relay contacts tra. Therefore in case of a serious fault the breaker is again tripped to open circuit position by means of the latch L1.

During this tripping operation following collapse of toggle Il, the linkage T collapses so that the pivot 9 moves counter-clockwise with corresponding movement of the pivoted member 39 which now permits cam l to reset to its lowpoint position under influence of coil spring 38. As the breaker reaches the normal open circuit position the auxiliary switches a and a1 are opened and the motor relay MR deenergized. As a precautionary measure in case the operative holds the closing switch C closed throughout the above described operations, the coil 28 of seal-in device 21 remains energized to hold armature 28 closed and limit switch S open. This prevents pumping or repeated operation. The breaker cannot be further operated until the switch C is opened to deenergize the magnet 29 thereby causing closing of switch S.

lThe apparatus is now in position for a fullstroke closing operation under control of the manual closing switch C from the low point of the cam in the manner previously described.

It will be noted that the pin and slot connection at 4l between the linkage T and the member 39 permits the pin Sli-on the cam to return beyond the pivoted member 39 when the cam is rotated through the full stroke to close the breaker from the low point of the cam. When, however, the cam is returned to the preset position under the counter-clockwise bias of spring 3S upon deenergization of the motor, the member 39 is directly in the path of the pin (latch L1 being reset) to prevent further movement thereof. The resetting of the latch L1 is accomplished when the roller 8 drops to the low point of the cam, at which point the linkage is stretched and the latch is automatically reset.

For the purpose of insuring high speed resetting o1 the laten L2, a pivcted member 50 having a cam surface at 5I adapted to coact with a roller 52 carried by the lever 3 is provided with a jaw-like extension 53 disposed beneath the roller 29 of the hammer I8. Therefore when the breaker starts to open the member 59 is camrned about its pivot 50' in counter-clockwise direction so as to return the hammer I3 to its original latched position and also to recharge the spring 23. Accordingly the latch 2l is enabled to reset at high speed after deenergizing of its tripping coil 22. This high speed resetting of the latch is an essential factor in automatic high speed reclosing. In View of the fact that the latch L2 is actually reset during the breaker opening movement, the time ordinarily required for the resetting of latches need not be considered in calculating the reclosing speed.

For thev purpose of facilitating understanding ofthe above described mechanism and reclosing system, the complete cycle of operation starting from the closed breaker position illustrated will be briefly summarized.

Tripping automatic-For automatic control, the manual switch O is closed at o1. Therefore, when the fault relay FR picks up in response to a fault or overload on the main power circuit, the solenoid 22 of latch L2 is energized through the contacts fri, a and the transfer relay contacts tr1. Upon tripping of latch L2, the breaker moves through part of the normal stroke toward open position and the cam follower roller 8 comes to rest on the surface of cam l at the previously described preset position.

Reclosiiig, automatic-During the above described tripping operation, the auxiliary contacts at 43 are closed but the auxiliary contacts at a and a1 do not open by reason of the lost motion connection at 42. Therefore, upon closing of switch 43, the coil 24 of the motor relay MR is energized, the circuit being completed through o1, auxiliary switches 43 and a1, transfer relay contacts im and limit switch contacts s2. The motor is now energized through contacts mn and s1, the motor relay 24 being electromagnetically sealed in for the closing operation at the contacts mrz. The cam thereupon is rotated clockwise from its preset position to reclose the breaker through the fractional stroke above referred to. As the cam completes the reclosing operation, it causes opening of the limit switch S through the pin 30 in the manner previously described to cle-energize the motor.

During the reclosing stroke and before opening of the auxiliary switch 43, the coil 45-01 the transfer relay is energized through auxiliary contacts frz, a1, 43 and switch o1. The transfer relay accordingly picks up thereby transferring the tripping control to the solenoid I5 of the latch L1 in case the fault still exists on the line and trip-free operation is required. In such a case, solenoid I5 is energized through auxiliary contacts fri, a and tra. The retarding device for the dashpot at im holds the transfer relay in the aforesaid transfer position for a short time to msure the necessary tripping protection at latch L1 during reclosing,

Trip-free operation-The latch L1 is actuated as above described, causing tripping of the linkage T and movement of the cam stop 39 to an unobstructing position. Since the motor is deenergized by limit switch S after predetermined rotation of the cam independently of trip-free operation of the mechanism, it simply returns to its initial position under bias of spring 38 so that the cam follower 8 now rests at the low point of the cam. During this resetting of the cam, the l resetting shock is absorbed by the spring buffer 31 and, substantially coincident therewith the limit switch S closes under bias of spring 32. This spring puts a clockwise torque on member 32 and provides contact pressure at S. With the breaker now in the fully open position, the auxiliary contacts a and a1 are open.

Closing, manual control-with the breaker fully open as above described, closing under control of the operative is accomplished by closing the switch C whereby coil 24 of the motor relay is energized through this switch and auxiliary contacts s2. The cam then completes the full closing stroke in the manner above described and in this particular case, if trip-free operation is required, it is obtained simply through the latch L1 in response to operation of the fault relay. That` is, since auxiliary switch a closes near the end of the breaker closing stroke, the latch solenoid I5 is energized through fri, a and tra. After the deenergization of the motor at switch S, the cam returns to the preset position shown for high speed reclosing.

Opening, manual control- For manual control of tripping, the switch O is closed at o2 thereby energizing the tripping solenoid 2'2Y of the latch L2 through the auxiliary contacts a and. tri. By reason of the fact that the control circuit is now open at o1, automatic reclosing cannet take place and the breaker remains open.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention,

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

1. An automatic reclosing circuit breaker system comprising circuit breaker operating means, a motor operated cam adapted to close the circuit breaker through said means, means for presetting said cam at an intermediate point in the full operating stroke thereof, and means for energizing said motor in response to tripping of said circuit breaker whereby said circuit breaker is immediately reclosed by said cam after but a fractional part of the full opening stroke of said circuit breaker,

2. An automatic reclosing circuit breaker system comprising a circuit breaker having a collapsible thrust transmitting operating linkage, a motor operated cam operatively related to said linkage for closing said circuit breakery means for presetting said cam at an intermediate point in the full operating stroke thereof whereby upon tripping of said circuit breaker said linkage is restrained by said cam at an intermediate point in the full opening stroke of said circuit breaker, and means for energizing said motor in response to tripping oi said circuit breaker whereby said circuit breaker is immediately reclosed by said cam from said intermediate point.

3. An automatic reclosing circuit breaker system comprising circuit breaker operating means including a trip-free linkage, a motor operated cam adapted to close the circuit breaker through said linkage, means for presetting said cam at an intermediate point in the full operating stroke thereof with respect to said trip-free linkage, opening of said circuit breaker in response to tripping of said linkage being limited by said cam at said preset position to a fraction of the full opening stroke, and means for energizing said motor in accordance with tripping of said circuit breaker whereby said circuit breaker is immediately reclosed by said cam through said linkage from said intermediate point in the opening stroke.

4. An automatic reclosing circuit breaker system comprising circuit breaker operating means, a motor operated cam adapted to close the circuit breaker through said means, means for biasing said cam toward the initial point of its full operating stroke upon closure of said circuit breaker, restraining means for holding said cam in an intermediate position in its operating stroke after said closing stroke, means operatively interconnecting said circuit breaker cperating means and said restraining means for rendering said restraining means inoperative only upon full opening of said circuit breaker,

and means for energizing said motor in accordance With automatic tripping of said circuit breaker whereby said circuit breaker is immediately reclosed by said cam after but a fractional part of the full opening stroke of said circuit breaker.

5. An automatic high speed reclosing circuit breaker system comprising circuit breaker operating means including a trip-free linkage, a motor operated cam for closing said circuit breaker through said linkage, spring means for biasing said cam toward a reset position in opposition to said motor, means related to said linkage for blocking said cam at an intermediate preset position after initial closure of said breaker, trip-free releasing means related to said linkage, a second releasing means related to said linkage, and means for energizing said motor in accordance with tripping of said linkage by said second releasing means whereby said circuit breaker is immediately reclosed from said intermediate preset cam position, actuation of said trip-free releasing means upon reclosure causing movement of said blocking means to a non-obstructing position for permitting said cam to move to its initial reset position.

6. An automatic high speed reclosing circuit breaker system comprising circuit breaker operating means including a trip-free linkage, a motor operated cam for closing said circuit breaker through said linkage, spring means for biasing said cam toward a reset position in opposition to said motor, means related to said linkage for blocking said cam at an intermediate preset position after initial closure of said breaker, trip-free releasing means related to said linkage, a second releasing means related to said linkage, and means for energizing said motor in accordance with tripping of said linkage by said second releasing means whereby said circuit breaker is checked at an intermediate point in its opening stroke and is immediately reclosed from said intermediate preset cam position, means responsive to said reclosing operation for transferring the tripping control to said tripfree releasing means, actuation of said trip-free releasing means upon reclosure causing movement of said blocking means to a non-obstructing position for permitting said cam to move to its initial reset position.

7. An automatic high speed circuit breaker reclosing system comprising circuit breaker operating means including a trip-free linkage for closing said circuit breaker, a motor operated cam related to said linkage for effecting a fullstroke closing operation from substantially the low point of said cam, spring means for biasing said cam toward sai-d initial low-point position upon completion of said closing stroke, means for blocking return of said cam to said initial position at a point intermediate the high and low points of said cam, a fault relay, a tripping device responsive thereto for tripping said lnkage and opening of said breaker, means for energizing said motor in accordance with said tripping operation whereby said circuit breaker is immediately reclosed from said intermediate cam position after but a fraction of the full opening stroke, a second tripping device for causing trip-free opening of said linkage, and means for transferring the fault relay tripping control from said first-named tripping device to said second tripping device during the circuit breaker closing and reclosing operations.

8. Electric circuit breaker operating means comprising a lever for transmitting closing force to said circuit breaker, a restraining member for holding said lever in closed position, a hammer spring-biased to move said member to a non-restraining position for causing opening of said circuit breaker, a tripping device for releasing said hammer, and a cam having a fixed pivot, one cam face being operatively related to said circuit breaker and another cam face being operatively related to said hammer for moving said hammer to its initial reset position in ac cordance with the circuit opening operation whereby said member is free to reset.

9. An automatic reclosing circuit breaker system comprising circuit breaker operating means, a motor-operated cam adapted to close the circuit breaker through said means, said cam having an operating face defining a high point corresponding to the end of the breaker closing stroke and a low point corresponding to the end of the breaker opening stroke, means for presetting said cam after the breaker closing stroke so that said cam operating face is positioned for operating said breaker at an intermediate point with respect to said high and low points whereby a reclosing stroke can start from said intermediate point, and means 'for starting said motor cam at a predetermined point in the opening operation of said breaker whereby said breaker is immediately reclosed by said cam after but a fractional part of the full opening stroke of said breaker.

CARL THUMIM.

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