US2251171A - Circuit breaker - Google Patents

Description

y 1941- 'r. G. A. SILLERS ET AL 2,251,171

- CIRCUIT BREAKER Filed Sept. 21, 1938 4 Sheets-Sheet l July r. s. A. SILLERS ET AL 2,251,171

CIRCUIT BREAKER Filed Sept. 21,, 1938 4 Sheets-Sheet 2 July 29, 1941.

T. G. A. SILLERS ET AL 2,251,171

"TTECUIT BREAKER I I Filed Sept. 21, 1958 4 Sheets-Sheg 3 July 29, 1941. T, s s ET AL 2,251,171

CIRCUIT BREAKER Filed Sept. 21, 1938 4 Sheets-Sheet 4- Patented July 29, 194-1 CIRCUIT BREAKER Thomas G. A. Siilers, Wauwatosa, and Adolph Erncstus, Milwaukee, Wis., assignors to Allis- Chalmcrs Manufacturing Company, Milwaukee, Wis, a corporation of Delaware Application September 21, 1938, Serial No. 230,922

15 Claims.

This invention relates in general to circuit makers and breakers and the mechanism therefor and particularly to a circuit breaker having a contact biased to circuit opening position and an improved operating mechanism for closing said contact and an improved means for tripping the contact free of the closing mechanism.

In circuit breakers utilizing a direct motor drive for closing a contact against a heavy spring bias, utilized for opening the contacts, various disadvantages have been found. Reversing switches have been necessary to reverse the direction of the motor rotation in order to return the operating mechanism to the original position ready for the next succeeding operation. Such operation required an almost instantaneous stopping of the motors exactly at closing position of the contact, thereby causing a shock to the operating mechanism due tov the stopping impact. The reversing operation was an additional operation after opening of the breaker and necessitated. a switching operation in the motor control circuit. Slip clutches have been utilized to take up the stopping impact but these caused uncertain operation and considerable maintenance.

In providing a trip free mechanism in an operating means of the above type, the tripping coil has been mounted on the moving element of the operating mechanism. Such construction necessitates electrical connection to the tripping coil through flexible leads which are subject to crystallization and breakage due to the flexing.

It is therefore an object of the present invention to provide an improved circuit breaker and operating means therefor which avoids the above disadvantages.

It is another object of the present invention to provide a circuit breaker contact closing mechanism having a plurality of motors for operating the mechanism.

It is another object of the present invention to provide a circuit breaker operating mechanism which resets itself for an additional operation immediately upon closing of the contact.

It is another object of the present invention to provide in a circuit breaker a motor operated contact closing mechanism in which the motors run in one direction only and slowly come to rest without load after the contact is closed.

It is a further object of the present invention to provide in a circuit breaker operating mechanism having fixed and movable parts, a means for tripping the contacts free of the closing mechanism, in which the tripping coil is mounted on a fixed rather than a movable member.

It is also an object of this invention to provide a circuit breaker operating mechanism. that is.

simple and rugged in construction andoperation, low in first cost and maintenance costs.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection. with. the ac companying drawings, in which:

Fig. l is a diagrammatic view of" a circuit breaker and operating mechanism therefor embodying the present invention. and: with the elements in the closed position;

Fig. 2 is a partial side view partly in section taken on the line IIII of Fig. 1';

Fig. 3' is a diagrammatic view of the circuit breaker shown in Fig. 1 but with the elements in. the tripped position;

Fig. 4 is a diagrammatic showing of the construction of. Fig. 1 but with. the elements in. the

open position;

Fig. 5 is an end view of the gear assembly of the embodimentshown in Figs. 1-, 3 and-4;

Fig. 6 is a front. view of the gear assembly shown in Fig. 5;

Fig. '1 is a detailed view of the outer gear member of the assembly shown, in Figs. 5 and 6;

Fig. 8 is a detailed view of the inner driven, member of the assembly shown. in Figs..5 and: 6..

As shown generally in, Figs. '1, 3 and 4, a movable contact lllisbiased to its open position relative to fixed contacts II by a spring l2. In closing the contact ID, the operative force is supplied.

by four motors l3. through a linkage of cranks and toggles. These motors supply the closing force to the linkage through a gear assembly which is shown in detail in Figs. 5, 6, '7 and. 8. An outer gear 14 is driven by the motors l3 which are spaced symmetrically thereabout. The

driving force of the gear I4 is transmitted to thelinkage by means of a projection I6 on the gear M, which projection cooperates with a projection H on an inner member I5 of the gear assembly. The members Hand 15 rotate relative .to each other on roller bearings l8 held in position by retaining ring I4 bolted to gear M. The

motors I3 run in one direction only, therefore driving the gear It in a counterclockwise direction, as viewed in the drawings. The inner driven member I5 is free to rotate relative to the gear M in a counterclockwise direction.

By utilizing a plurality of motors for supplying the closing torque, various advantages are obtained. The motors. may be spaced on the main driving gear so that the closing torque is provided symmetrically around thedriving shaft, thus reducing tooth pressure on the gear and bearing wear on the main shaft. The driving force component against the main shaft is balanced between the motors. In large installations necessitating a heavy closing mechanism of the type shown herein, the use of a plurality of motors permits using small standard motors to obtain the necessary power. By using small motors, the starting inertia of the motor element is easily kept low, while to accomplish this same result with one motor would require a machine having a very lengthy small diameter rotor which would be dimcult to mount.

The use of a plurality of motors is additionally advantageous in providing a standard circuit breaker operating mechanism which may be utilized on circuits having diiierent voltages. For example, if the motors are standard 110 volt motors, this drive arrangement can be utilized on 110, 220 or 440 volts merely by change of connection in series, parallel, or series-parallel groupings. In any of the above arrangements having two groups or more of motors in parallel, the failure of one motor would not prevent the mechanism from being operative for the mechanism is designed to be sufiiciently powerful to close with only one-half normal power provided. In such a case, the closing time, of course, would be increased.

The mechanism as shown in Fig. i is in the contact open position with the elements in normal position for performing the closing operation. If the motors are energized, the gear 14 is driven in a counterclockwise direction. The motors accelerate without load until the projection l6 encounters the projection ii on the inner member i5. Rotation of the member i5 and the shaft it raises he link 23 in harmonic motion by means of pin 2%. Raising of the link 23 pulls upwardly on pin 25 in the crank 23 which is keyed to the lower driving shaft 27.

In the diagrammatic showing of the drawings, the motors l3, the gear assembly, link 23 and shaft 2? are shown displaced from their true positions which are directly behind the toggle linkage and tripping mechanism. For the sake of clarity, these elements have been moved to the left and the shaft 2? shown in perspective. The shaft ill extends in a plane perpendicular to the paper and rotates in a counterclockwise direction to transmit the closing torque, as shown by the arrow, in Fig. i.

The rotation of lower shaft 27 rotates crank 28 which is keyed thereto, until pin 35 is against resetting stop 54. As this position of pin 35 is to the left of the center line between pin 3d and shaft 2'1, links 23 and 38 form an over-center toggle. Rotation of crank 28 transmits an upward movement to saddle 29 by means of link 35 which is pinned to the crank 28 and to the saddle by pins 35 and 34 respectively. The saddle is guide by rollers 30 between fixed points 33. In the absence of a tripping operation, links 39, t0 and 43 move with the saddle 29 as one link rotating the crank 3 about the fixed bearing poLnt in a clockwise direction. Such movement of crank moves the contact it against the bias of the opening spring E2 to the closed position shown in Fig. 1.

It will be noted from the closed position shown in Fig. 1, that the pin 26 is just at upper dead center and therefore the link 23 in its uppermost position. The motors continue to rotate, under no load, and as soon as pin 2% is past upper center, the action of gravity on link 23 and member l5 moves them to the position shown in pin 25 sliding in the slot 24.

This improved operating and resetting mecha nism provides many advantages. The motors l3 need run in one direction only, thereby eliminating need of reversing switches for resetting the operating mechanism. The mechanism is reset for the next closing operation immediately, rather than taking additional resetting time after the circuit breaker has been opened. The motors (3 may be easily and simply controlled by limit switches for the necessity of instantaneously stopping the motors i3 under the heavy closing load is avoided. The closing impact is not, therefore, suddenly transmitted through the linkage to the operating gear.

The motors I 3 are allowed to slowly come to rest with the elements in the position shown in Fig. 3 and a space is left between the cooperating projections l3 and H. At the start of the closing operation, the entire power input to the motors can be utilized in acceleration of the motors prior to cooperation of projections i6 and i'! to take up the closing load. As the member [5 is free to move in a counterclockwise direction relative to the gear i i. any force transmitted through the linkage due to tripping out of the breaker cannot be transmitted back to the gear teeth where such impact could do considerable damage. By avoiding instantaneous stopping and reversal of parts, the resultant shock to the operating parts is avoided. lhe closing force is supplied to the pin 25 substantially in harmonic motion, thereby providing a high torque and low speed during acceleration and deceleration of the closing mechanism and providing a high speed during the major portion of the closing stroke. Thus a high torque is supplied at the beginning of the stroke which is desirable to overcome the inertia of the mechanism and to provide the high torque desirable just as the contacts are being closed. Further during the major portion of the stroke a high speed is utilized to lower the total time of the closing stroke. In other words, the greater speed is obtained when the load is less, and the greater power when the load is greater.

The tripping mechanism is so arranged that the contact i0 may be tripped free of the operating mechanism at any time during the closing stroke. The link 39 has a hardened plate which bears against rollers 85 as shown in Figs. 1 and 2. The rollers $5 are mounted on pin 38 which is slidable in the slot 3! of the saddle 29. The angle of the plate :38 is so set relative to the roller 65 that the link 39 tends at all times to move toward the left as viewed in the drawings. Tripping movement of this link 39 is restrained by a toggle composed of link 58 which is pinned to the link 39 by pin 8i] and link H which is pinned to the saddle by pin 34 and pinned to link 58 by pin 62. This toggle of links 53 and ll is held in over-center position against an abutment of the saddle forming the stop i 2.

When a tripping impulse is supplied to the coil 55, the core 5% thereof is moved upwardly and the trippin arm 5'! raises the tripping hammer 59 to break the toggle between links 'H and 58. This action allows the contact iii and the operating mechanism to move to the position shown in Fig. 3. The link 48 has a slot 13 in which the pin 38 may move and link 43 moves downwardly, the pin 33 sliding in the slot 3'! in the saddle. The shock of the movement of the link 39 to the left against the saddle is broken by the action of Fig. i, the

an extension 6! of the link 39- against a spring bumper 68. The action of extension 61 on the bumper 68, which is mounted in the link 36, is such that the pin is forced to the right of the center line between pin 34 and shaft 21 and therefore the toggle between crank 28 and link 36 is broken allowing the saddle 29 to drop. As the saddle 29 is quite heavy, a dashpot 69, acted upon by an extension 13 of the saddle, absorbs the impact due to the downward movement.

It is noted that the tripping latch is mounted on a movable portion of the mechanism which allows the coil 55 to be mounted on a stationary part of the mechanism. Stationary mounting of the coil permits solid electrical connection thereto, thus avoiding the disadvantages of flexible cable leads for carrying current to moving elements. By providing the long tripping arm 57, the right hand end of which is substantially fixed and the left hand end of which moves in an are about the right hand end, the motion of the moving end is approximately equalized around the horizontal position of the arm. As the center, about which the tripping hammer 59 rotates, moves (when the saddle moves) substantially on the circle of movement of the left hand end of the arm 51, the right hand end of arm 51 and hence the tripping coil 55, can be fixed.

Although but a single embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired Patent:

1. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, and means comprising a plurality of magnetically independent electric motors for moving said biased contact to circuit closing position.

2. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, a shaft operably connected to said biased contact to move the same to circuit closing position, and means for operating said shaft comprising a plurality of magnetically independent electromotive devices operatively connected to said shaft at points spaced symmetrically thereabout.

3. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, and means having a low starting inertia for moving said biased contact to circuit closing position, said means comprising a plurality of magnetically independent electric motors.

4. The combination of a pair of contacts cooperable to make and break an electric circuit and means for biasing one of said contacts to circuit opening position with means for operating said biased contact to circuit closing position, said operating means comprising a rotatable member, a plurality of motors operatively connected to said member, at points uniformly spaced thereabout, a member driven by said rotatable member in one direction and free during said driving to move relative to said rotatable member in said one direction, and a toggle mechanism operatively connecting said driven member and said biased contact through a lost motion connection.

to secure by Letters 5'. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, operating means provided with fixed and movable members cooperable to move said biased contact to circuit closing position, said movable members comprising a toggle linkage and further comprising a saddle member guided in motion by said iixed member, and means for tripping said biased contact free of said operating means during contact closing movement, said tripping means comprising cooperable latching members supported on said saddle member.

6. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, operating means provided with fixed and movable members cooperable to move said biased contact to circuit closing position, said movable members comprising a toggle linkage and further comprising a saddle member guided in motion by said fixed member, and means for tripping said biased contact free of said operating means during contact closing movement, said ripping means including a solenoid mounted on said fixed member.

'7. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, operating means provided with fixed and movable members cooperable to move said biased contact to circuit closing position, said movable members comprising a toggle linkage and further comprising a saddle member guided in motion by said fixed member, and means for tripping said biased contact to circuit opening position independently of movement of said saddle member.

8. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, means for operating said biased contact to circuit closing position, said operating means comprising a driving member, a driven member and an operating connection therebetween whereby said driven member is rotated and guided by said driving member in one direction and is free to rotate relative to said driving member but guided thereby in said one direction, means for tripping said biased contact to circuit opening position, and means for insuring movement of said driving member through a predetermined cycle independently of tripping movement of said biased contact.

9. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, a linkage system connected to said biased contact and operable to move the same to circuit closing position, means for tripping said biased contact free of said linkage system, means for actuating said linkage system comprising a motor operated member rotatable in one direction only, and means comprising a pin and slot connection between said motor operated member and said linkage system for operating said motor operated member through a predetermined contact closing cycle independently of actuation of said tripping means.

10. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, a shaft operably connected to said biased contact to move the same to circuit closing position, a motor operated member rotatable in one direction only independently of movement of said biased contact, and means for operatively connecting said member and said shaft, said means comprising a link provided with a pin and slot connection.

11. The combination of a pair of contacts cooperable to make and break an electric circuit and means for biasing one of said contacts to circuit opening position, with means for operating said biased contact to circuit closing position, said operating means comprising a rotatable driving member, a member driven by said rotatable driving member in one direction and free during said driving to rotate relative to said rotatable driving member in said one direction, a toggle mechanism operatively connected to said biased contact, and means comprising a lost motion operative connection between said driven member and said toggle mechanism whereby after said toggle is set said driven member continues rotation to initial contact closing position independently of said driving member.

12. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, means for operating said biased contact to circuit closing position, said operating means comprising a pair of members concentrically rotatable relative to each other, a pin and slot connection between said biased contact and one of said members, and a motor for rotating the other of said members.

13. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, means for operating said biased contact to circuit closing position, said operating means comprising a pair of members concentrically rotatable relative to each other, a pin and slot connection between said biased contact and one of said members, and a plurality of motors connected to the other of said members at circumferentially uniformly spaced points for rotation thereof.

14. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, means for operating said biased contact to circuit closing position, said operating means comprising a pair of members concentrically rotatable relative to each other, a toggle linkage connected to said biased contact, a pin and slot connection between said toggle linkage and one of said members, and a plurality of motors connected to the other of said members at circumferentially uniformly spaced points for rotation thereof.

15. In combination, a pair of contacts cooperable to make and break an electric circuit, means for biasing one of said contacts to circuit opening position, means for tripping said biased contact to circuit opening position either from circuit closing position or during closing movement thereof, and means for operating said biased con tact to circuit closing position, said means comprising a driving member rotatable in one direction only through a predetermined contact closing cycle independently of operation of said tripping means and further comprising a driven member rotatable by said driving member concentrically therewith and guided thereby and provided with a lost motion connection with said biased contact.

THOMAS G. A. SILLERS. ADOLPH ERNESTUS.

Images