US2884568A - Control for electrical closing of circuit breaker - Google Patents

Description

April 28, 1959 c. J. YARRICK CONTROL FOR ELECTRICAL CLOSING OF CIRCUIT BREAKER Filed May 10, 1954 3 Sheets-Sheet 1- April 28, 1959 c. u. YARRICK CONTROL FOR ELECTRICAL CLOSING OF CIRCUIT BREAKER Filed May 10, 1954 I5 Sheets-Sheet 3 NYN I INVHVTOR. 67/1445: Kill/ck United States Patent CONTROL FOR ELECTRICAL CLOSING OF CIRCUIT BREAKER Charles J. Yarrick, West Collingswood, N..l., assignor t0 I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 10, 1954, Serial No. 428,638

3 Claims. (Cl. 31736) My invention relates to an automatic closing means for circuit breakers and is more particularly directed to a novel apparatus which incorporates a time delay in the drop out of the closing control relay armature to prevent pumping operation.

It is frequently desirable to energize a closing relay and closing coil of a circuit breaker from the studs of the circuit breaker itself.

Heretofore, a pick up or closing relay construction has been used whereby the armature of the closing relay is latched to the control means of the closing coil auxiliary contacts when the armature is in the neutral position.

Following the energization of the closing relay coil, the relay armature, when moved to its engaged position, will move the auxiliary contacts of the closing coil into engagement due to the latch engagement. However, movement of the closing plunger, following the energization of the closing coil, will automatically unlatch the auxiliary contacts of the closing coil from the relay armature. Hence, even though the operator may continue to energize the closing relay coil, the unlatching will prevent the continued energization of the closing coil.

This arrangement has proved satisfactory in circuit breaker applications wherein the closing apparatus and circuitry are energized and operated from an auxiliary source of energy. However, a disadvantage is encountered when the closing circuit is energized from the line being protected by the circuit breaker. That is, in the event the circuit breaker should be closed on a short circuit or low impedance fault, the voltage will drop as soon as the arcing contacts come into engagement. The drop in voltage will thus cause the closing relay armature to drop out thereby permitting relatching between the relay armature and the auxiliary contacts on the closing coil.

Accordingly, if the operator continues to maintain the closing button in the closed position, the closing coil will again be energized as the relay armature and auxiliary contacts are picked up. Hence, pumping operation results when the circuit is energized in the last mentioned manner.

It is a primary object of my invention to provide closing means for circuit breakers wherein the drop out of the closing relay armature is time delayed so that relatching is prevented in the event the circuit breaker is closed on a low impedance fault.

I achieve time delay operation of the relay armature or plunger in one of three ways.

In one embodiment of my invention, I provide a guide sleeve for the relay plunger which is made of a conducting material. Thus, when the arcing contacts of the circuit breaker is engaged and the line voltage drops out, the collapse of the field of the relay coil will induce a short circuit current in the short circuited secondary comprised of the conducting sleeve. Thus, this short circuited current in the sleeve guide will result in maintaining the relay plunger in the engaged position for a predetermined length of time.

Tests have indicated that the time delay by this electromagnetic means can be obtained in the order of approximately one half second.

In a second embodiment of my invention, I provide a pneumatic time delay for the relay plunger. In this arrangement, a non-conducting stationary sleeve is placed around the plunger of the relay.

A very small clearance is allowed between the plunger and the sleeve and the end of the sleeve is sealed ofl. Thus, in the event that the biasing spring attempts to force the plunger to drop out of position, a vacuum will be created thereby delaying the movement of the plunger to the open position. By providing this air check for the relay plunger, I have been able to obtain time delay of the magnitude of two and three seconds before the relay plunger drops out.

In a third embodiment of my invention, I combine embodiments 1 and 2 wherein a conducting sleeve provides for electromagnetic time delay and the close tolerance between the conducting sleeve and the relay plunger provides for pneumatic time delay.

With the time delay of my invention, engagement of the arcing contacts resulting in a drop of the line voltage will not result in subsequent pumping. Since the main cooperating contacts of the circuit breaker will open thereby restoring the voltage, the relay coil will again be energized thereby holding the relay plunger in the engaged position and thus preventing it from relatching with the auxiliary contacts of the closing coil. Hence, if the trip mechanism of the circuit breaker does not have a time delay, the time delay of the closing relay plunger need only be longer than the period of time between the engagement of the circuit breaker arcing contacts and their subsequent separation.

In the event the closing means is utilized in connection with a time delay circuit breaker, then it is necessary for the time delay of the relay plunger to be longer than the time delay of the circuit breaker. That is, since the main contacts of the circuit breaker will be in engagement, that is, closed on a fault, the line voltage will drop out and hence, the relay coil will not be energized. However, by providing time delay for the plunger which is longer than the time delay of the circuit breaker, anti pumping operation is achieved. That is, aft r the main contacts of the circuit breaker separate, line voltage will again be restored and hence, the closing relay coil will be energized to hold and maintain the relay plunger in the engaged position to prevent relatching.

Accordin ly, one object of my invention is to provide a time delay closing relay plunger to prevent pumping operation of the circuit breaker.

A further object of my invention is to provide electromagnetic time delay for the plunger of a closing relay to prevent relatching in the event the circuit breaker is closed on a fault.

Another object of my invention is to provide pneumatic time delay to prevent the reset of the closing relay to thereby insure anti pumping operation.

Still another object of my invention is to provide a pneumatic-electromagnetic time delay for the closing relay which will maintain disengagement of the latch between the relay plunger and the auxiliary contacts of the closing coil.

Still another object of my invention is to provide a closing means for a circuit breaker wherein a time delay is provided for the drop out of the closing relay. The time delay period is provided for the closing relay which is greater than the time delay operation of the circuit breaker.

A still further object of my invention is to provide automatic closing means for a circuit interrupting equip ment which results in anti pumping operation for both instantaneous and time delay circuit breakers.

A still further object of my invention is to provide a circuit breaker closing means energized from the line being protected by the circuit breaker which can utilize either pneumatic or electromagnetic or a combination of these two for the time delay drop out of the relay plunger.

These and other objects of my invention will be apparent from the following description when taken in connection with the drawings in which:

Figure l is an exploded perspective view of the operating mechanism of a circuit breaker showing the cooperating contacts in the disengaged position. This figure also illustrates the latch controlled relay and the closing coil controlled thereby.

Figure 2 is a side schematic view illustrating the automatic closing system used in connection with the circuit breaker of Figure 1. This figure illustrates the position of the parts of the control relay and a closing solenoid immediately following an attempt to close the circuit breaker on a fault. This figure illustrates the trip free position of the circuit breaker.

Figure 2a is a cross-sectional view of the first embodiment of my invention illustrating a close fit between a non-conducting sleeve and the armature to achieve time delay by pneumatic means.

Figure 2b illustrates a second embodiment my invention wherein a loose fitting sleeve made of a conducting material is positioned concentric with the armature to achieve time delay of electromagnetic means.

Figure 2c illustrates a third embodiment of my invention wherein a conducting close fit sleeve is provided for the armature to achieve time delay by both pneumatic and electromagnetic means.

Figures 3 through 6 are schematic views of the circuit breaker of Figures 1 and 2 illustrating the position of the various components for various positions of the circuit breaker.

Figure 3 illustrates the closed position.

Figure 4 illustrates the initial trip position.

Figure 5 illustrates the collapsed position.

Figure 6 illustrates the completely open position.

Referring now to Figure 1, under over current conditions, an energized overcurrent coil pulls the armature 143 toward trip member 140. The screw 145 acts to rotate bar 140 upon the energizing of the overcurrent coil by engaging extension plate 146 which is bolted to the shaft 140. The shaft 140 is caused to rotate in a counterclockwise manner looking from the right of the circuit breaker, which is the view of Figure 1? The shaft 140 is also caused to rotate by means of a coil 150 which, upon being energized, attracts armature member 151. The link 152 is attached to an angle which in turn is movably attached to the member 151 by means of a pin. A restoring spring 147 attached to the member 151 resets the armature upon de-energization of the coil 150.

The link 152 is attached to the shaft 140 by means of another angle and cap 160.

Thus, the shaft 140 can be caused to rotate by two methods, one due to the energization of an overcurrent trip coil and armature 143 and the other due to the energizing of the coil 150. The coil 150 may be remotely energized by manual operation of a remote push-button switch. The rotation of shaft 140 causes a link 162 to be moved by means of an angle 163 which is bolted to the shaft 140 by means of two bolts 164. The angle 163 has an indentation 165 near the farthest edge 166 from the shaft 140. The link 162 has two slots 168 and 1127. The slot 167 engages the indentation 165 of angle 1 3.

The translatory movement of link 162 causes the rotation of a milled shaft 170. The milled shaft 170 has another angle 171 rigidly attached to it by means of two bolts 172. This angle has an indentation 173 near the end 174 which is farthest from the shaft 170. The indentation 173 of angle 171 engages the slot 168 of link 162. Thus, the rotation of shaft causes the rotation of milled shaft 170. When milled shaft rotates to release a latch 177, as is hereinafter described, the circuit breaker movable contact 61 is allowed to be disengaged from the stationary contact 60.

The angle 171 described above has an abutment 178. This abutment 178 is engaged by a roller 179 which is rotated manually by means of the closing handle 184 attached to the shaft 180. Shaft 180 has a crank 181 which is rigidly attached to the shaft 180 by means of a screw 182. The roller 179 is attached to one end of the crank 171. When the shaft 180 is rotated by the closing handle 184, the roller 179 engages abutment 178 of angle 171 and rotated milled shaft 170. Thus, milled shaft 170 can be made to rotate by a plurality of methods. It can be made to rotate manually by means of closing handle 184; it can be made to rotate by means of an over current condition in the trip coil; and it can be made to rotate by means of an excitation of coil 150, as described above.

The latch 177 is an integral part of trip arm 185. The latch 177 engages the milled shaft 170 so that a small revolution of shaft 170 releases the latch 177, as hereinafter described. The shaft 170 is milled slightly past center at 186. The trip arm 185 is pivoted at 187 on a long pin 188. The pin 188 is also engaged on the trip arm extension 187 at point 183. The pin 188 breaks a movable arm 190. The movable arm 190 is pivoted on pin 188 at points 191 and 192 and extends beneath a roller 193. The roller 193 is the pivot point of a toggle mechanism consisting of two links 194 and 195 and is carried by a pin 202 which pivots the meeting of links 194 and 195.

The links 194 and 195 each comprise two arms, 194A and 194B, and 195A and 195B, respectively. Arms 194A and 194B are pivoted on floating pin 196, described below, and arms 195A and 195B are pivoted on pin 204, also described below.

The arms 194A and 194B support a rod 197 at 198 and 199, respectively. The rod 197 carries one end of a restoring spring 203 which is tensed by means of a stationary shaft 212, hereinafter described. The restoring spring 203 exerts a tension on the link 194 which tends to open or break the toggle mechanism. Link 194 is pivoted on a floating pin 196 which is supported by link arm 185 and its extension 189 being parallel to the pin 188. The other link 195 of the toggle is pivoted on movable link 200 which is connected by means of an adjustable insulator 201 to the movable contact assembly 61, described below.

When the toggle mechanism consisting of links 194 and 195 is straightened out by means hereinafter described, pressure is put on movable link 200 by means of link 195 and bearing pin 204. The movable link 200 is pinned to insulator 201 by a pin 205 and moves so as to advance the insulator 201 and the movable contacts 61 towards the stationary contact 60.

In the exploded view shown in Figure 1, the contacts are open and the toggle mechanism consisting of links 194 and 195 is collapsed. The circuit breaker may be closed by a variety of methods. The circuit can be closed manually by means of shaft 180 rotated by closing handle 184, described above. If shaft 180 is rotated in the direction indicated by the arrow 184A, the roller 179 will engage the bottom of arm 190 and force the arm 190 against roller 193, thus straightening out the toggle mechanism and closing the circuit breaker contacts.

The movable links 200 are under an opening tension by means of opening spring 210 so that if no additional locking action other than described above for supporting the toggle existed, the circuit breaker would reopen immediately upon releasing the shaft 180. The locking device .is supplied by means of a crank 211 which is located on a shaft 212, mentioned above, whose longitudinal axis is parallel to the axis of the milled shaft 170 open, adjacent the roller 193. When the roller 19.3

Is-forced upward, as due to the pressure of arm 190, the

roller pushes against arm 213 ,of crank 211 rotating the crank 211 slightly on shaft .212. When the roller 193 has cleared the top of arm 213, the arm 213 snaps underiieath the roller 193 due to the compression of a spring 220. The spring 220 which is wound .on the shaft 212 has one end on an indentation 221 of crank 211 and the other end borne against a shaft 222 which pierces the t-riparm 185. The shafts 212 and 222 have been moved out of position in the exploded view for the sake of clarity. Actually, the shaft 222 pierces the trip arm 185 at point 207. The longitudinal axis of shaft 222 is essentially parallel to the longitudinal axis of shaft 212 andmilled shaft 170.

When the roller 193 is moved, straightening the toggle, it causes crank 211 to rotate compressing spring 220. The roller clears the top of arm 213 letting the crank rotate in the opposite direction until the arm 213 is directly be eath and supporting the roller 193. The other arm 214 of crank 211 bears against the shaft 222 preventing further rotation of the crank 211 so that the arm 213 is stopped directly beneath the roller 193. The spring 220 is under compression normally so that the arm 214 is constantly bearing against the shaft 222. When the toggle is straightened, the rotation of the crank 211 moves the arm 214 away from the shaft 222 until the roller 193 clears the top of arm 213. Then the reverse rotation of the crank 211 occurs until the arm 214 again bears against shaft 212.

Thus, when the toggle is straightened, and the circuit breaker closed, the crank 211 locks the toggle and thus locks the circuit breaker in a closed position.

The closing handle 184, by means of the shaft 180, after closing the circuit breaker by means of the rotation of roller 179 against the arm 190, as described above, is returned to its normal position by means of a crank 230. The crank 230 is pivoted on a stationary pin 231.

The crank 181, described above, has an indentation 232 which meets a roller 233 of crank 230. The crank 230 supports a pin 234 which has a restraining spring 235 engaged at one end 236. The restraining spring 235 is attached to an angle 237 and is tensed on the pin 236 causing the crank 230 to rotate. The rotation of crank 230 causes the roller 233 to meet the indentation 232 returning the crank 181 to its normal position.

The various positions of the operating mechanism are shown in Figures 3 through 6.

Figure 3 shows the closed position thereof with link 1 95 pushed forward to raise the crank 200 and close the contact arm or insulator 201 and with the roller 193 on the arm or abutment 213.

The latch arm 185 is shown in appropriate latching engagement with the milled shaft 170.

When the shaft 180 described above is turned to release the mechanism, the condition as shown in Figure 5 W l Qn the occurrence of tripping conditions, the milled shaft 170 is rotated to permit the latch arm 185 to move into the milled section of position 186 of the milled shaft 170, as seen in Figure 4. Then as seen in Figure 5, the roller 193 drops off the abutment 213 to open the circuit breaker.

Thereafter, as seen in Figure 3, the latch arm 185 is restored to its initial position and the milled shaft 170 is restored to latching position so that the circuit breaker may again be moved from the open position of Figure 6 to the closed position of Figure 3.

The circuit breaker may also be closed by means of the closing mechanism shown in Figures 1 and 2. The

6 closingmechanismis comprised of the control relay and .theclosing solenoid.

The control relay is comprised of the coil 300 which is energized from the studs of the circuit breaker through the closing button 500. That is, the control relay is energized from the same source which is being protected by the circuit breaker.

The relay is of the latched type described in copending applications Serial No. 254,349, filed November 1, .1951, now Patent No. 2,792,534, Serial No. 383,714, filed Octoher 2, 1953, and Serial No. 423,782, filed April 16, 1954, now Patent No. 2,832,917.

The control relay illustrated in Figures 1 and 2 differs from the relay set forth in the above noted copending applications in that the armature .of the relay is of -a plunger type which moves in and out of the control coil 300. Also, the relay incorporates my novel time delay means which will maintain the plunger type armature in its energized position for several seconds after the control relay is de-energized. Except for these two distinctions, the control relay with its function and operation are the same as set forth in the above identified applications.

A brief review of this structure follows.

The cooperating contacts 308-502 which control the energizing circuit for the closing coil 241 are carried by the bracket 306. The bracket 306 and the extension 301 of the armature 312 are latched together by the screw 324 and shaft 326 when these two components are in the normal position illustrated in Figure l.

The spring 513 biases the bracket 306 around the pivot 302 to the neutral position and the biasing spring 523 biases the armature 312 and its extension 301 about the same pivot 302 to its neutral position.

When the closing button 500 is moved from its normally open position to the closed position in order to initiate a closing operation, the coil 300 of the control relay is energized from the line 517-578 being protected by the circuit breaker. Thus, the energizing circuit for the control coil is through the lines 519-520, the regulator 525 to the control coil 300.

Since the bracket 306 is latched at 324-326 to the armature 312-301, these two units will be moved to their energized position. The forward movement of the bracket 301 will result in the closing of the contacts 308-502 thereby completing the energizing circuit for the closing coil 241 of the closing solenoid.

Energization of the closing coil 241 will result in the upward movement of the closing plunger 240 and its extension 320-322, as best seen in Figure 2, to thereby close the breaker through the operating mechanism heretofore described.

The extension 322 of the closing plunger will engage the head 323 of the screw 324 thereby unlatching the bracket 306 from the armature 312-301. Hence, the bracket 306 will now be influenced by its biasing spring 513 and be moved to its neutral position, when the movement of the bracket 306 to its neutral position will interrupt the energizing circuit for the closing coil 241 by the opening of the contacts 308-502. Hence, if the control relay and closing solenoid are energized from an auxiliary source, this unlatching operation will prevent pumping of the circuit breaker even though the operator may continue to depress the closing button 500.

However, as will hereinafter be more fully described, additional difficulties are encountered when the closing means is energized from the source being protected by the circuit breaker.

After the circuit breaker has either latched closed, it will remain closed if it is closed on circuit carrying normal load current or will have strip free operation if it is closed on a line having a fault. The position of the components in Figure 2 illustrate the last mentioned trip free operation.

Since the energizing circuit for the closing coil 241 is interrupted by the movement of the bracket 306 to its the line being protected by the circuit breaker.

' neutral position, the closing plunger 240 will fall back to the armature 312301 by means of the screw 324 and the pin 326.

Accordingly, all of the components will now be in their neutral position so that a subsequent intentional closing operation can be performed when the closing button 500 is reclosed.

As heretofore noted, my invention is particularly directed to a closing mechanism which is energized from In this type of arrangement, the circuit breaker may be closed on a low impedance fault. Hence, even though the closing button 500 is maintained by the operator in its closed position, there will be a drop in voltage at the instant of engagement of the circuit breaker cooperating contacts 6061 to thereby remove the energizing voltage for the control coil 300. If this situation exists, the biasing spring 523 will move the armature 312-301 to its neutral operations may be performed if the operator holds the closing button 500 in closed position for one or two seconds. That is, there will be pumping of the circuit breaker even though the operator only intended a single closing operation.

My invention is directed to a novel means whereby a time delay is introduced to control the drop out of the control relay armature to prevent pumping operation even though the operator may maintain the closing button in the closed position for one or two seconds immediately following trip free operation.

That is, in a circuit wherein the closing means are energized from the studs of the circuit breaker, my invention intentionally introduces a time delay of two or three seconds for the drop out of the control relay armature to thereby prevent relatching with the contact carrying bracket until the operator has released the closing button.

The time delay is introduced by one of three methods-(a) pneumatic means, (12) electromagnetic means, combined pneumatic and electromagnetic means.

In the pneumatic time delay, a non-conducting sleeve 524, preferably made of brass, is positioned between the coil 300 and the armature 312. The cylindrical sleeve 524 and the cylindrical armature 312 are provided with a very close fit with a clearance of approximately 0.0025" between the armature and the sleeve.

A check valve 525 is provided at the end of the armature.

After the voltage on the control coil 300 has been removed, the biasing spring 523 will attempt to move the armature 312 to its neutral position. However, due to the very close fit between the armature 312 and its encompassing non-conducting sleeve 524, a vacuum will be created in the space 526 to thereby prevent the immediate removal of the armature from the sleeve. However, after a two or three second delay, there will be a sufiicient drop of pressure in the area 526 to open the air check valve 525.

, As soon as the air check valve 525 is opened, the armature 312 will immediately be moved to its neutral position by its biasing spring to thereby allow relatching of the brackets 306 with the armature 312-301 in the manner heretofore described.

The cross-sectional view of Figure 2a illustrates the relative positions of the coil 300, the non-conducting sleeve 524 and the armature 312. The space 527 between the armature 312 and the non-conducting sleeve 524a is 0.0025".

In the second embodiment of my invention, I provide an arrangement wherein the sleeve around the armature 312 is made of a conducting material such as copper. In this arrangement, the cross-sectional view of which is shown in Figure 2b, the movement of the armature 312 is delayed by electromagnetic action rather than pneumatic action so that a large clearance can be provided between the armature 312 and the conducting sleeve 52417.

The operation of the second embodiment is as follows.

When the voltage for the coil 300 is removed, the magnetic field will collapse thereby inducing a voltage in the conducting sleeve 5241). Since the sleeve 524b represents a shortcircuited secondary winding for the control coil 300, a shortcircuit current will flow therein immediately following the de-energization of the control coil 300. The flow of shortcircuit current in the conducting sleeve 524b will tend to hold and maintain the armature 312 in its energized position against the force of the biasing spring 523.

I have found that I can introduce a time delay of onehalf to one second by this electromagnetic means.

In the third embodiment of my invention, I provide .a combination of pneumatic and electromagnetic time delay for the armature control relay. Thus, the structural arrangement is similar to that heretofore described in connection with the pneumatic time delay. However the sleeve 524 is now made of a conducting material.

The cross-sectional area of this embodiment is shown in Figure 20 wherein the sleeve 5240 is made of a conducting material such as copper. Hence, time delay for the drop out of the control relay armature 313 is achieved as a result of the close fit vacuum and air check valve and also as a result of the shortcircuit current which now flows through the conducting sleeve. Hence, the sleeve 5240 introduces time delay by both pneumatic and electromagnetic means.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound not by the specific disclosure herein but only by the appending claims.

I claim:

1. In a circuit breaker having a pair of cooperating contacts movable between an engaged and disengaged position and connected in series with an electrical system; said circuit breaker having a solenoid operating mechanism comprising a solenoid plunger and an operating winding therefor, said solenoid plunger being operatively connectable to at least one of said pair of cooperable contacts for moving said cooperable contacts to their said engaged position responsive to energization of said operating winding; a control relay for controlling the energization of said operating winding; said control relay comprising a first and a second cooperating relay contact movable between an engaged and disengaged position, a contact arm for carrying said first cooperating relay contact, a relay armature, and a relay winding; said relay armature being positioned with respect to said relay winding to be moved from a first position to a second position responsive to energization of said relay winding; said contact arm being biasedto move said first relay contact to a disengaged position with respect to said second relay contact, said relay armature being biased to its said first position; a latch means; said latch means operatively connecting said armature to saidcontact arm, said contact arm being movable with said reiay armature when said latch means is in a latched condition; said latch means being latchable only when said relay armature is in its said first position and said contact arm is in said position to maintain said first relay contact in said disengaged position; said solenoid plunger being constructed to defeat said latch means when moved by said operating winding to engage said circuit breaker cooperating contacts; a closing contact; said closing contact being connected in series with a voltage derived from said electrical system containing said circuit breaker and said relay winding; said operating winding being connected in series with a voltage derived from said electrical system containing said circuit breakers and said first and second relay contacts; and a time-delay means; said time-delay means being operatively connected to said relay armature and elongating the time required for said relay armature to move from its said second position to its said first position after deenergization of said relay winding to delay the time said relay armature and said contact arm relatch after closing of said circuit breaker by said closing contact and deenergization of said relay winding.

2. The device of claim 1 wherein said time-delay means comprises a short circuited Winding surrounding said armature.

3. The device of claim 1 wherein said armature is formed of a plunger; said time-delay means comprising a sleeve structure surrounding said plunger to pneumatically time delay movement of said plunger.

References Cited in the file of this patent UNITED STATES PATENTS 1,885,157 Traver Nov. 1, 1932 2,064,657 Goff Dec. 15, 1936 2,157,810 Bany May 9, 1939 2,304,865 Thumim Dec. 15, 1942 2,346,147 Boisseau Apr. 11, 1944 2,534,115 Favre Dec. 12, 1950

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