US1873787A

US1873787A - Electric switch operating mechanism

Info

Publication number: US1873787A
Application number: US409983A
Authority: US
Inventors: William K Rankin
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1929-11-26
Filing date: 1929-11-26
Publication date: 1932-08-23
Anticipated expiration: 1949-08-23
Also published as: GB363795A; FR707639A

Description

W. K. RANKIN ELECTRIC SWITCH OPERATING MECHANISI Aug. 23,' 1932.

' Filed Nov. 26, 1929 Inventor-n William K. Rankin,

Patented Aug. 23, 1932 UNITED .STATES PATENT OFFICE WILLIAMk xs or EANDSDOWNE PEN,NsYLvaNJLA,l lAss'IGNoR 'ro GENERAL ELECTRIC 'Columna CORPORATION or NEw Yom:

f ELECTRIC SWITCH OPERATING MECHANISM Application area Number 26,1929. -semi No.'.4o9,aea.

My invention relates to hydraulic operating mechanism, and more particularly to operating mechanism for circuit breakers having large interrupting capacities wherein the 5 operating means for closing the breaker musty overcome repellent forces during closing movement thereof. In circuit breakers of comparatively large size and interrupting capacity it is desirable 10 that the movable contact structure ofthe closing thek switch is ineffective to overcome' the aforesaid repellent forces,fthe switch may I6 not only remain open, but' arcing between the contacts may, as in the case of oil switches forY example, cause destruction of the switch. y

It is a principal objectof my invention to provide an improved electric switch operatau ing mechanism r'which shall .be reliable and and simple4 and rugged l rcenter prevent any fluid beingv carried bef positive in roperation in construction.

f It is a further object of my invention to provide hydraulic operating means for a c ircuit breaker of large interrupting capac1ty arranged so that a switch actuating member may be moved towards its closed circuit poj sition at a substantially constant or uniform speed by yfluid pressure notwithstanding the existence or variations in magnitude of forces opposing said movement.v

It is a further object of my invention to provide hydraulic operating 'means'v for effectin g closure of switch mechanism wherein the kinetic energy' of rotation of a flywheel is effective to cause a substantially constant or uniformdischarge of fluid formoving at a substantially constant or uniform'rate an operatingv member coacting with said mech-k 50 amsm.

' -My invention will be morefully set forthl in thek following description referring to the accompanying drawing, and the features of novelty which characterize my invention will n,

be pointed' out with particularity in the claims annexed toand forming a part of this specification.

v Referring to the drawing, thesingle fig-r' ure thereof illustrates an elevational view, partly in section, of a hydraulic operating mechanism for a circuit breaker system;

yA tank orfiuid reservoir 1 is provided containing a suitable hydraulic medium 2 such tas oil, for example. Disposed within the reservoir is a structure 3 for defining fluid pas-k sages and for serving as mounting and guid` ing means'for elements acting upon or acted upon by the fluid traversing s aid passages. The structure 3 forms a main passage 4, at one" endof which is disposed a: source of luid pressure or pump of suitable character, as a gear pump comprising a driving gear 5 andy a driven gear' (not shown) meshed therewith.

for urotation withina pump casing, in cornmunication with the fluid in the main part of the reservoir'.y The gear pumpmay be of the usualwell known type wherein the gear teeth pickupl the liquid and' carry it raround in the spaces between the teeth, the pum cas' ing rforming therewithaluid-tight joint. The teeth lof the two gears meshing'at the shall be capable-of discharging luidat ak rate corresponding to its operating speed.

That is, if the speed of the pump ismain tained constantthe yrate of iluid discharge from the pump islikewise constant. At the opposite end of passage 4 there is disposed ar valve 6 adapted toseat at 7 for preventingv flow of the fluid 'from the lpassage into the' main part ofthe reservoirthroughthe ports 8. An" operating member, comprising a piston 9 and a pistonv rod 9', is mounted for reciprocal movement within a cylindrical casing 10, which isin open communication at its' lower endwiththe passage 4. The cylindri- CTI cal casing 10 is provided with the exhaust ports or openings 11 in communication with the reservoir for bypassing the fluid acting upon the piston 9 when the lower end thereof has uncovered the exhaust ports.

lVhen the valve 6 is closed actuation of the Junio 5 serves to force fluid from the main l part of the reservoir into the passage 4, now

closed at its opposite end, thereby exerting fluid pressure on the piston 9 tending to force it upwardly until the exhaust ports 11 have been uncovered. v

The operating member may serve to actuate suitable mechanisnnas for example circuit breaker mechanism used for switches of the oil break type, through a switch actuating member 12. In circuit breakers of the above described character it is desirable that the closing operation be effected with sufficient force to insure closing at a substantially constant or uniform speed. Due, however, to the fact that there are often repellent forces set up by the magnetic forces of the current against which the switch is to be closed, and moreover since these currents in the case of short circuit or overload may vary in magnitude within a wide range, it will be apparent that considerable difficulty maybe experienced in effecting closing of the circuit breaker at a substantially constant or uniform speed in the event that provision is not made for overcoming these resisting forces.

The hydraulic operating member 9 and the switch actuating member 12 may be interconnected in any suitable manner to provide the usual trip free action in case of predetermined overload or short circuit, and in the present instance the interconnecting means comprises a bell crank 13 pivotally mounted as at 13 to a frame structure 14 secured to or mounted upon the reservoir 1. One arm of the bell crank 13 is connected as at 15 to the switch actuating member 12 and the other arm is connected as at 16 to one end of a toggle 17. The center or thrust-receiving portion of the toggle 18 is adapted to be engaged by the upper end of the piston rod 9', the other end of thetoggle being connected as at 19 to a link 20 pivoted at its opposite end to a stationaryT lug or support 21. For the purpose of maintaining the pivot 19 of the toggle stationary so that upward movement of the piston rod 9 may extend the toggle to rotate the bell crank 13 in a counter clockwise direction thereby effecting closing movement of the switch actuating member'12, there is provided a latcliing member 22 pivoted at one end to the frame 14 and having a hook portion 23 at its opposite or free end for engaging the pivot 19 forming a part of the link 20 for restraining it from clockwise movement. It will be apparent, therefore, that disengagement of the latch from the pivot 19 of the toggle permits the link 2O to move in a clockwise direction thereby allowing immediate collapse of the toggle and return of the bell crank and the switch actuating member to their original positions as illustrated. In other words, the latch 22 permits what is known as trip-free action, and to accomplish this end the usual tripping magnet 24 is adapted, when energized a predetermined extent, to engage one arm of a bell crank 25 pivoted as at 26 to the frame 14, and rotate it in a clockwise direction. This movement lifts the link 27, which is connected to the other arm of the bell crank 25 and to the latch 22, to cause counter clockwise movement of the latch 22suticiently to disengage it from the toggle.

As previously stated, it is desirable that the hydraulic operating member be actedv upon by suflicient force to cause closing of the switch actuating member at a substantially constant speed. To this end the rotatable element of the pump 5 is operated by a sha-ft 28 driven by suitable motive means, as a motor 29, the driving shaft 28 having fixed thereon a comparatively large and massive rotatable member, as a flywheel 30. Or, the rotor of the motor itself, if of the rotating field type, may comprise the rotatable mass. The motor 29 may be energized from any suitable source of supply 31, and may be controlled by a manually operated switch 32 and a limit switch 33 connected to any suitable part of the switch actuating mechanism, as the bell crank 13 and insulated therefrom as at 33. When the bell crank 13 is in the open circuit position switch 33 is closed, and when the bell crank has moved to substantially the closed circuit position, the limit switch 33 is opened, thereupon deenergizing the motor 29 and pump 5.

In order that the initial starting movement of the operating member 9 shall be att-ended by sufficient fluid pressure, the valve 6 is not closed until the motor 29 has come up to predetermined or normal speed thereby enabling the gear pump to deliver fluid at itsA full rated capacity. For this purpose 'the valve 6 is adapted to be closed by an electromagnet 35 coacting with a magnetiizable core 36 secured to the valve stem 37. The valve 6 is normally biased towards its open position, as illustrated, by suitable means as a spring 3S seated at its upper end against the cover of the reservoir, and bearing at its lower end against a collar 39 securedr'to the valve stem. Energization of the electromagnet 35 serves to close the valve`6, and deenergization of the electromagnet permits the spring 38 to return the valve to its open position when the piston 9 has reached the end of the stroke and the fluid pressure is reduced by the opening of the ports 11. Energization and deenergization of the electromagnet may be automatically controlled by a centrifugal switch device 40 secured in any suitable man-A ner to the rotating structure of the motor 'maman thereby placing the electromagnet 35 partly under the control of the operator, as where the operation of the mainy breaker yshould be in accordance with the indication of a synchroscope. 'In the present instance the centrifugal switch comprises a pair of flyball contacts 41k mounted upon a portion of the rotor shaft and normally biased towards each other by a spring or other suitable means.k Rotation of the rotor shaft servesto force the' free ends of the flyball contacts outwardly towards a collector ring 42`connected to a stationary terminal 43.r The other terminal 44 may be connected to the flyball contacts throughk a slip ring 45. Accordingly, rotation of the motor at a predetermined or normal speed is effective to close the circuit through the centrifugal switch, thereupon partially completing the circuit so that the closing switch 40 in series may be operated at the proper time to complete the circuit, energizing the electromagnet 35 from the source 31 and closing the valve 6.

The operation of the mechanism and associated system may be briefly described as follows:

Assuming the parts of the mechanism to be in the positions illustrated,`and that it is desired to close the circuit breaker, switch 32 is first closed, causing energization vof the motor 29 and pump. Due to the fact that the actual circuit closing operation is effected within a comparatively short time,ythe operator may readily hold the switch 32 closed until the operation is complete.r Or, by closing the switch 32 a relay may be energized for maintaining the motor circuit closed. Initial actuation of the gear pump serves simply to force fluid through the passager 4 back into the main port of the reservoir through the open valve 6 and ports 8. That is, the application'of fluid pressure to the piston is delayed while the pump is discharg ing fluid at a rate less than normal. kAs the motor attains its normal speed and the pump is discharging fluid atfull capacity into the passage 4. the valve 6 may be closed through the centrifugal switch 40 so that the effect of the fluid pressure within the passage 4, which rapidly increases due tothe fact that the valve 6 is now closed and the pump discharging a substantially nonfcompressible fluid into the passage 4, causes the piston 9 to move upwardly at a yrate corresponding to the rate of fluid discharged by the pump. When the closing operation ispcontrolled bv the centrifugal kswitch 40 without the additional control switch 40 in series therewith, the system is applicable to feeder circuits.

In the event that the switch actuating mechanism is acting against large repellent forces, any tendency on the part of the piston 9 to slow up is counteracted by the effect of the .lange amoimt of stored energy inthe flywheel f 30 to maintain operation` of the'pump 'at uirmstant speed and thereby maintain .a --constantrateof dischargetherefrom. `.As the piston .9i is'lifted touncover thehexhaust ports .1lat which point kthe* switch actuating mech- .anism has been moved to the circuit` closing ipositi`on,1the fluidisz byLpassed into the .reservoir and causes no further movement of the rpiston.' yAs previously described, the motor 129 is deenergized by the limit switch 33 when the toggle 17 has been straightened to Vclose `the switch, and in y the event thatv abnormal circuitconditions are-:present in 'the circuit` yto be "controlled-fthe' tripping magnetr24l -serves to disconnect the hydraulic operating member from the `switch actuating member and to permit immediate opening oftheccircuitfbreaker. i f' f lIt shallbe understoodthat myiinv'entionis 4not limited;v to `the specific arrangement and .detailspof construction inthe embodiment .il- Alustratediand that various changes and modiyficatio'nswill occur to those skilled inthe art ywithout departing from Vthespirit yof my -in- .ventiom L 'f `'VVhatI claim as new;and desire to secure by Letters Patent of the United Stateszis: 51. Acircuit controllingsystem comprising la switchactuatingmember, a fluid operated member operatively 'connected with f said switchactuating member,'a'pump for effect-V ingmovement of saidfluid operated memberto.circuit-closingposition at a rate correspondingtofthe rate of'fluid discharged from the g'pump, afflywheel "for maintaining 'the speed offsaid pump substantially constant notwithstanding appreciable Vforces tending ti'resistclosure` of said'switch actuating mem-' `ber randrnotive meansv deenergizedupon closy,

i'ng movement'o'fl said switchk actuating member'for-actuatirrg said flywheel. f. n l 2. yAfcircuit controlling system comprising a 1 switch f actuating member, a. fluid operated member, means operativelyconnecting said members av pump foreffecting discharge of fluid so asfto cause vmovement of the fluid operatedfmember and kcircuit closing movement ofthe i switch actuating member, a flywheel operatively connected'tosaid pump for maintaining discharge ofi'fluid therefromat a substaintally uniform :,rate, thereby effecting closing `movement of the switch actuating memberfatja substantially constant or uniform' yrate lnotwithstanding forces i opposing such movement, and means delaying the application i of r fluid ,pressure to said yfluid operated member `until* said;pump attains norm'a'l speed of operation. 1

3. Arcircuit controlling system. comprising afewitch actuatingfmemberya piston opera-` tively connectedtherewith, a collapsible connection between said piston and switch actuating menibsfna pump .for discharging fluid at a rate corresponding tothe speed of the pump for effecting circuit closing movement of the piston, means causing opening movement of said switch actuating member through said collapsible connection dur- 5 ing switch closing movement of said piston, motive means for driving said pump, and a flywheel operatively connected to said motive means and pump for maintaining the rate of fluid discharge from the pump substantially constant notwithstanding forces opposing movement of the switch actuating member.

4. A circuit controlling system comprising in combination a switch actuatingmember, a fluid operated member, toggle structure operatively connecting said members for transmitting closing movement to the switch actuating member, a pump for discharging fluid to cause movement of the fluid operated member, a flywheel operatively connected to said pump for maintaining the rate of fluid discharge therefrom substantially constant, the rate of movement of the fluid operated member corresponding to said rate of fluid discharge, and means operable to effect collapse of said toggle structure during closing movement of the switch actuating member thereby permitting immediate reverse movement of the switch actuating member to open position.

5. A circuit controlling system comprising in combination a switch actuating member, a piston operatively connected with said member, a piston operatively connected with said member, a fluid pump for discharging fluid to cause movement of the piston, the rate of movement of the piston in a switch closing direction corresponding to the rate of fluid discharge from the pump, a flywheel operatively connected to said pump maintaining the rate of fluid discharge therefrom substantially constant and closing the switch against repellent forces, a fluid reservoir in which said pump is immersed, a valve disposed within said reservoir in communication with the discharge of the pump, and electromagnetic means controlling said valve for delaying application of fluid pressure to the piston until the pump is discharging fluid at a predetermined rate, said electromagnetic means energized in response to predetermined speed of said pump.

6. A circuit controlling system comprising in combination a switch actuating member, a piston opera-tively connected with said member, a fluid pump for discharging fluid to cause positive and substantially uniform movement of the piston, and speed responsive means for delayingv application of fiuid pressure to the piston until the pump is discharging fluid at a predetermined rate.

In witness whereof I have hereunto set my hand this 21st day of November, 1929.

WILLIAM K. RANKIN.