US2824929A - Mechanical trip means for circuit breaker current limiting device combination - Google Patents

Description

Feb. 25, 1958 w. H. EDMUNDS 2,824,929

MECHANICAL TRIP MEANS FOR CIRCUIT BREAKER CURRENT LIMITING DEVICE COMBINATION Flled Nov 12 1954 2 Sheets-Sheet l 3125c T/ON FOR Qa/NG Ada Feb. 25, 1958 w. H. EDMUNDS 2,824,929

MECHANICAL TRIP MEANS FOR CIRCUIT BREAKER CURRENT LIMITING DEVICE COMBINATION Filed Nov. 12, 1954 2 Sheets-Sheet 2 IN V EN TOR. lama/19o; 19/94 040 [DMZ/N05 United States Patent MECHANICAL TRIP MEANS FOR CIRCUIT BREAKER CURRENT LIMITING DEVICE COMBINATION William Harold Edmunds, Havertown, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application November 12, 1954, Serial No. 468,343

3 Claims. (Cl. 200-116) My invention relates to circuit protective equipment which electrically and mechanically coordinates a current limiting device with a circuit breaker and more particularly is directed to a novel arrangement wherein the force of a current limiting device trip pin is multiplied by means of a linkage mechanism in order to trip a large air circuit breaker.

In my copending applications Serial No. 316,221, filed October 22, 1952, and Serial No. 461,378, filed October 11, 1954, I have shown a multiple circuit breaker with a current limiting device electrically and mechanically associated with each pole.

The current limiting device may have an integral construction of the type shown in Patent No. 2,592,399, issued April 8, 1952, so that it is responsive to the rate of current rise and will interrupt severe short-circuit currents within less than a quarter of a cycle. That is, the letthrough current for the current limiting device may be a small percentage of the available short-circuit current which the circuit is capable of delivering. This device is coordinated with the standard time delay and instantaneous trip units of the circuit breaker so that for all current magnitudes below a first predetermined value, either the instantaneous or the time delay trip unit of the circuit breaker will initiate simultaneous opening of all of the cooperating contacts of the circuit breaker.

In the event a fault current is above a first predetermined magnitude, then the current limiting device will rupturebefore the trip units of the circuit breaker operate. In order to prevent single phasing, the current limiting device is provided with a striker pin which, when the fusible element ruptures, will be driven forward to impart a hammer-blow force on the tripper bar of the circuit breaker so that all the cooperating contacts thereof will be simultaneously opened.

With this arrangement of electrical and mechanical coordination, between the circuit breaker and the current limiting device, the interrupting capacity requirements of the circuit breaker is substantially reduced and does not have to be equal to the magnitude of the available short-circuit current which the circuit is capable of delivering. Thus, as fully disclosed in copending application Serial No. 461,378, filed October 11, 1954, the use of this coordinated device is particularly applicable to low voltage, high current circuit application.

As noted in the above identified copending applications, the striker pin of the current limiting device operates directly on the tripper bar of the circuit breaker. However, in an air circuit breaker having a steel back of the type shown in copending applications Serial No. 254,349, filed November 1, 1951, Serial No. 423,782, filed April 16, 1954, and Serial No. 445,094, filed July 22, 1954, a force is required to rotate the tripper bar in order to release the common latch to permit the operating mechanism to move the cooperating contacts to their disengaged position. Thus, in air circuit breakers with steel backs, it is not presently feasible to have the striker pin to operate directly on the common tripper Ice 2,824,929

bar since there is an insufficient force available to ro-' tate the trip bar to achieve release of the latching surfaces.

My instant invention is directed to a novel arrangement wherein the force on the striker pin, which is released when the current limiting device ruptures, is multiplied through a linkage mechanism to thereby insure operation of the common tripper bar whenever one of the current limiting devices ruptures.

Accordingly, a primary object of my invention is to provide a circuit breaker-current limiter combination in which electrical and mechanical coordination is achieved between the protective devices with a force multiplying means so that a current limiting device striker pin will be capable of rotating the common tripper bar when the devices rupture.

Another object of my invention is to provide a link mechanism between a current limiting device and a common tripper bar of a circuit breaker so that a relatively small force released by the rupture of the current limiting device will be multiplied so that all the cooperating contacts of the circuit breaker will be simultaneously opened whenever the current limiting device interrupts a current flowing in the pole associated therewith.

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

Figure 1 is a perspective view of an air circuit breaker.

The circuit breaker can be tripped by either the time delay armature 142, the instantaneous armature 143 or the current limiting device 16.

Figure 2 is a partial side view illustrating a current limiting device electrically associated with each pole and mechanically associated with the circuit breaker.

For the sake of simplicity, the illustration of Figure 1 shows a single pole of a muiti-pole circuit breaker. However, it will be apparent that although there is a common latch 185-186 and a common cradle and latch for all poles of the circuit breaker, there is a time delay trip unit, an instantaneous trip unit and a current limiting device associated with each pole of the circuit breaker, each of which in turn operates on the common tripper bar 170.

The operation of the circuit breaker is as follows.

On the occurrence of an overcurrent or fault current sufiicient to energize the magnets of either the time delay armature 142 or the instantaneous armature 143, so that these units will function prior to the operation of the current limiting device 10, the operated armature will rotate in a clockwise direction thereby engaging the extension 146 on the shaft 140.

The rotation of shaft causes a link 162 to be moved through angle 163. The transitory movement of link 162 causes the rotation of the common tripper bar which is the common tripper bar of the circuit breaker. The counterclockwise rotation of the common tripper bar 170 releases the latch 1851S6 thereby resulting in the automatic movement of the cooperating contacts 6061 from their engaged to their disengaged position, as seen in Figure 1.

It will be noted that the common tripper bar 178 has an abutment 178 which may be engaged by the roller 179 which, in turn, is rotated by means of the manual handle 184. The manual handle 1554 is attached to the shaft 180 which, in turn, is rotated by means of the manual handle 184. The manual handle 184 is attached to the shaft 180 which, in tum, has a crank 181 rigidly attached thereto with the roller 179 on one end thereof. Thus, when the shaft 180 is rotated by the closing handle 184, the roller 179 engages the abutment 173 to rotate the common tripper bar 170 in a clockwise direction so that the cooperating contacts 6il61 can be moved from their engaged to their disengaged position.

Patented Feb. 25, 1958- As will hereinafter be more fully explained, the common tripper bar 170 can also be rotated by means of the .current limiting devices a, 10b or 100 which operate through a linkage mechanism to impart aforce thereto. Thus, the circuit breaker can be opened by either the time delay armature 142, the instantaneous armature 143, the current limiting device 10, or manually by means of the handle 184.

The latch surface 177 is an integral part of the trip arm 185 and engages the milled section 186 of the common tripper bar 171) so that a small angular rotation of the common tripper bar 1711 will release the latch 177- 186.

The trip arm 135 is pivoted at 187 on a long pin 188. The pin 188 is also engaged on the trip arm extension 189 at point 133. The movable arm 190 is pivoted on pin 138 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 which are each comprised of two arms. Arms 194 are pivoted on floating pin 196 and arms 195 are pivoted on pin 204.

The arms 194 support a rod 197 at 198 and 199, respectively. The rod 197 carries one end of a restoring spring 233 which is tensed by means of a stationary shaft.

The restoring spring 2113 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 138. The other link 195 of the toggle is pivoted on movable link 2011 which is connected by means of an adjustable insulator 201 to the movable contact assembly 61 and pivoted on contact bar 406.

When the toggle mechanism consisting of links 194 and 195 is straightened out by means hereinafter described, pressure is put on movable link 2110 by means of link 195 and bearing pin 2114. The movable link 200 is pinned to insulator 2d by pin 2 35 and moves so as to advance the insulator 2111 and the movable contacts61 towards the stationary contact 619.

In the exploded view shown in Figure l, 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 134, described above. If shaft 18% is rotated in the direction indicated by arrow 184a, the roller 179 will engage the bottom of arm 1% and force the arm 190 against roller 193 thus straightening out the toggle mechanism and closing the circuit breaker contacts 6tl-61.

The movable links 2% are under an opening tension by means of opening spring 211! 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 prop latch 211 which is located on a shaft 212 whose longitudinal axis is parallel to the .axis of the milled shaft 170, and the rod 140. The prop latch 211 has two arms 213 and 214.

The latch surface 213 is located, when the circuit breaker is open, adjacent the roller 193. When the roller 193 is forced upward, as due to the pressure of arm 190, the roller pushes against prop latch 211 rotating the prop latch 211 on shaft 212. When the roller 193 has cleared the top of prop latch 213, the prop latch 213 snaps underneath the roller 193 due to the compression of biasing spring 220. The spring 220 which is wound on the shaft 212 has one end on an indentation 221 of crank 211, the other end borne against a shaft 222 which pierces the trip arm 185. The shafts 212 and 222 have been moved out of position in the exploded view for the sake of clarity. Actually, t1 e shaft 222 pierces the triparm 155 at point 297.. The longitudinal axis of;shaft 222 is-.. essen tially parallel to the longitudinal axis of shaft212and milled shaft 170.

When the roller 193 is moved, straightening the toggle, it causes the crank 211 to rotate compressing spring 220. The roller clears the top of prop latch 213 letting the crank rotate in the opposite direction until the prop latch surface 213 is directly beneath and supporting the roller 193. The other arm 214 of prop latch 211 bears against the shaft 222 preventing further rotation of the crank 211 so that the latch surface 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 prop latch 211 moves the arm214away from the. shaft 222 until the roller 193 clears the top of prop latch 213. Then the reverse rotation of the crank 211 occurs until the arm 214 again bearsagainst the shaft 212.

Thus, when the toggle is straightened and the circuit breaker closed, the prop latch 211 locks the toggle 194-195 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 rotations of roller 179 against the arm 190, as described above, is returned to its normal position by means of a crank 230. The crank 231) 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 2311 supports 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 231i to rotate. The rotation of crank 23% causes the roller 233 to meet the indentation 232 returning the crank 181 to its normal position.

' The circuit breaker may also be closed by closing means 301i, 241 as disclosed in copending application Serial No.

383,714, filed October 2, 1953.

As heretofore noted, the circuit breaker is provided with a time delayitrip armature 142 and an instantaneous trip armature 143 which function in a manner well known in the art as, for example, described in copending application Serial No. 254,359, filed November 1, 1951. 7

Also as heretofore noted, the circuit breaker is provided with a current limiting unit which is both an interrupting device and a trip unit. The current limiting device 10 has a fusible element with a plurality of reduced cross-sectional areas and is surrounded by quartz crystal. The unit is also provided with a striker pin 11 which is normally inoperative.

The construction whereby the stored energy for the striker pin 11 is released upon thesrupturing of a fusible element, is shown in copending application Serial No. 316,221, filed October 22, 1952, and Serial No. 461,378, filed October 11, 1954.

The current limiting device 10 has electrical terminals 12 and 13 by which it is connected inelectrical series with the cooperating contactsv 6tl61 of the phase or pole with which it is associated. Thus, for example, as seen in the figures, the current limiting device 10 is removably retained within theclip terminal means 14-15. Thus, for each pole of the circuit breaker, the current will flow from the source through the current limiting device 10 through the cooperating contacts 60-61 to the load. Each current limiting device 10 is positioned so that its striker pin is in close proximity to the lever '16. A common bar 18 is provided with an extension lever 16a, 16b, 16c respectively extending therefrom for each pole of the circuit breaker. The common bar 18 is pivoted around fixed pivot 19 .and the extension lever 16 is rigidly attached thereto.

136F213 threadably engaging the-end sections 22-24 so that the effective length of the rod can be adjusted 4 by altering the threaded engagement between'the three members;

The top end of the rod 20 has a member 23 pivotally mounted thereon at point 24'. The member 23 contains openings to receive the screws 25 and 26. A plate 27 is positioned on one side of the common tripper bar 170 and the screws 25-26 which extend through the plate 27 are in threadable engagement with the plate 27'. Hence, the plate 27 is effectively bolted to the common tripper bar 170.

On the occurrence of a severe short-circuit current, the current limiting device will rupture thereby interrupting the current flow in the phase with which it is associated. The ruptured portion of the current limiting device 10 will permit a spring to release stored energy so that the striker pin 11 will be driven upwardly thereby rotating its associated extension bar 16 in a counterclockwise direction around the fixed pivot 19. This rotation will pull the rod 20 downwardly thereby causing the left-hand end of the plate 27 to rotate downwardly.

This motion will cause the common tripper bar 170 to be rotated in a counterclockwise direction to thereby release the latch 177-186. Thus, the striker pin 10 is operatively connected to the common tripper bar 170 by means of linkage mechanism 16-20.

By providing a long arm of the extension lever 16 on the right of pivot 19 and a relatively short arm on the left of this pivot, it is possible to multiply the force on the striker pin 11. Thus, even though a relatively large force is required to rotate the common tripper bar 170, a relatively small force driving the striker pin upwardly will be multiplied through linkage mechanism 16-20 so that a sufiicient force is imparted to the plate 27 to rotate the common tripper bar 170 in a counterclockwise direction to release the latch 177-186.

Hence, with my novel arrangement, a force multiplying means is provided through linkage mechanism so that a relatively small spring can be used in connection with the current limiting device 10 and still obtain sutficient force to rotate the common tripper bar and release the latch of the circuit breaker.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my inven tion 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. A circuit protective arrangement comprised of a multipole circuit breaker and a current limiting device associated with each pole thereof; each pole of said circuit breaker having a pair of cooperating contacts and a first trip means; said first trip means operatively connected to a common tripper bar to effect simultaneous disengagement of the cooperating contacts associated with each pole of said circuit breaker; said first trip device rendered operative on the occurrence of a fault current below a first predetermined current magnitude; each of said pair of cooperating contacts having a current limiting device connected in electrical series therewith; said current limiting device effective to interrupt current flow above said first predetermined current magnitude; said current limiting device having a striker pin normally held in an inoperative position; a mechanical device operatively connecting each of said striker pins to said common tripper bar; said mechanical device being comprised of an auxiliary common tripper bar and a linkage; said auxiliary common tripper bar having relatively long extensions extending in a direction and positioned to be engaged respectively by said striker pin of one of said current limiting devices associated therewith; said auxiliary common tripper bar having a relatively short extension; said short extension being operatively connected to said common tripper bar by said linkage; said auxiliary common tripper bar along with its plurality of long extensions and short extension serving as a force multiplying means for said current limiting devices.

2. A circuit protective arrangement comprised of a multipole circuit breaker and a current limiting device associated with each pole thereof; each pole of said circuit breaker having a pair of cooperating contacts and a first trip means; said first trip means operatively connected to a common tripper bar to efiect simultaneous disengagement of the cooperating contacts associated with each pole of said circuit breaker; said first trip device rendered operative on the occurrence of a fault current below a first predetermined current magnitude; each of said pair of cooperating contacts having a current limiting device connected in electrical series therewith; said current limiting device effective to interrupt current flow above a first predetermined current magnitude; said current limiting device having a striker pin normally held in an inoperative position; mechanical means operatively connected between said striker pin and said common tripper bar; said striker pin operatively connected to rotate said common tripper bar through said mechanical means when said current limiting device interrupts said circuit; said mechanical means being comprised of an auxiliary common tripper bar and a linkage member to multiply the force of said striker pin to a magnitude sufficient to rotate said common tripper bar; said auxiliary common tripper bar having a plurality of long extensions corresponding to the number of poles of said circuit breaker and having one of said current limiting devices associated respectively with each of said long extensions; a short extension from said auxiliary common tripper bar, one end of said linkage connected to said common tripper bar and the other end of said linkage connected to said short extension; said linkage being adjustable in length.

3. A multi-pole automatic circuit interrupter being comprised of pairs of cooperating contacts, manual control means, operating mechanism and trip elements; said operating mechanism containing a common tripper bar; a current limiting device associated with each pair of said cooperating contacts; said pairs of cooperating contacts having an engaged and disengaged position; said manual control means, said trip elements and said current limiting devices being operative through said common tripper bar of said operating mechanism to effect movement of said pairs of cooperating contacts from said engaged position to said disengaged position; each of said current limiting devices having a stored energy means releasable on the occurrence of a predetermined fault current; an auxiliary common tripper bar; said auxiliary common tripper bar having a plurality of long extensions and a short extension; said short extension from said auxiliary common tripper bar connected to said common tripper bar by a linkage; said linkage being adjustable; said plurality of long extensions from said auxiliary common tripper bar each being positioned respectively for engagement by said stored energy device of said current limiting device associated therewith; each of said current limiting devices operative to move said common tripper bar through said long extension, said auxiliary common tripper bar, said short extension and said adjustable linkage.

References Cited in the file of this patent UNITED STATES PATENTS 2,306,153 Biermanns et al Dec. 22, 1942 2,330,690 Dannenberg Sept. 28, 1943 2,473,196 Dannenberg June 14, 1949

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