US2709731A - Circuit breaker - Google Patents

Description

May 31, 1955 J. a. M' CNEILL 2,709,731

I CIRCUIT BREAKER Filed Aug. 26, 1953 cs Sheets-Sheet 1 '1 I "l Fig.l. l9

A27 425 43! 425 427 425 I8! l w i I I )H; J L Egg 4 Insulation Insulation 249 WITNESSES: 2 5 INVENTOR May 31, 1955 J. B. MaCNEILL 2,709,731

v CIRCUIT BREAKER Filed Aug. 26, 1953 K-Sheets-Sheet 2 WITNESSES:

2s 24| 245 24 INVENTOR Ls John BMucNeiH.

United States Patent CIRCUIT BREAKER John B. MacNeill, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 26, 1953, Serial No, 376,667

9 Claims. (Cl. 200-108) This invention relates to circuit breakers and more particularly to circuit breakers of the type used for controlling moderate power distribution circuits.

in certain circuit breaker applications, for instance, where a circuit breaker is to be applied in a selective tripping system as a source breaker or as a bus tie or group feeder breaker, the breaker is equipped with an overcurrent trip device which trips the braker with a time delay on all values of overload currents up to the interrupting capacity of the breaker. With the breaker latched in the closed position, the breaker will carry such excessive overload currents for some time without damage to the breaker and will then interrupt the circuit.

If an attempt is made to close the breaker against a fault current on the line the breaker would likely be severely damaged. The reason for this is that the large magnetic forces which tend to blow the contacts apart are greater than the force applied by the closing mechanism to close the contacts. Merely providing greater closing force does not solve the problem because the greater closing force would, when closing the breaker with a normal current on the line, cause damage to the breaker.

An object of the invention is to provide a circuit breaker having a trip device embodying time delay tripping means and means for tripping the breaker instantaneously only when the breaker is closed with a fault on the line.

Another object of the invention is to provide a circuit breaker embodying time delay and instantaneous tripping means with means for disabling the instantaneous tripping means except during a closing operation.

Another object of the invention is to provide a circuit breaker having a normally ineffective instantaneous trip means with means for rendering the instantaneous trip means effective only during a closing operation of the breaker.

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

Figure 1 is an elevational view partly in section of a circuit breaker embodying the principles of the invention, the circuit breaker being shown during a closing operation with the parts in the positions they assume at the instant the arcing contacts touch.

Fig. 2 is a sectional view taken on line 11-711 of Fig. 1 showing the instantaneous trip disabling mechanism.

Pig. 3 is a vertical sectional view through the trip device.

Fig. 4 is a sectional plan view of the time delay device taken substantially along line lV-lV of Fig. 3.

Fig. 5 is a fragmentary sectional view taken on line VV of Fig. 4 showing the short-time delay valve device and the adjusting means therefor.

The invention is illustrated as applied to a circuit breaker of the type fully disclosed in copending application Serial No. 141,136, filed January 28, 1950, by John B. MacNeill, Fritz E. Florschutz, Ture Liudstrom and Bernard G. Tremblay and assigned to the assignee of this application.

Referring to Fig. 1 of the drawings, the circuit breaker includes a plurality of pole units each comprising a contact structure indicated generally at H, and an overcurrent trip device indicated generally at 13. The contact structure and the trip device for each pole unit are mounted on a separate insulating base 15 which is rigidly secured to a metal panel 17. Since the pole units are alike, only the center pole unit is illustrated and described.

The insulating base 15 for the center pole unit is secured to the panel 17 by means of screws 19 threadedly engaging metal inserts 21 molded integral with the insulating base 15.

The contact structure 11 conrrises a stationary main contact 23 and a stationary arcing contact 25, both of which are secured on the inner end of a terminal conductor 27 which extends through suitable openings in the insulating base 15 and in the metal panel 17.

Cooperating with the stationary main and arcing contacts 23 and 25, respectively, is a movable main contact 33 and a movable arcing contact 35. The movable main contact 33 is mounted on a pivoted cont t carrying member 37 and the movable arcing contact 3;: is suitably mounted on the contact carrying member 3'7.

The Contact carrying member 37 is pivotaliy mounted by means of a pivot pin 41 on the upper or free end of a generally channel-shaped switch arm having its two sides pivoted by means of separate pivot pins 45 on spaced brackets 47 mounted on the base 25.

The contact carrying member 37 is electrically connected by means of a flexible conductor 51 to the energizing coil of the trip device 13 to be later described. A spring 57 compressed between the lower end of the contact carrying member 37 and a spring seat in the insulating base 15 provides contact pressure in the closed position of the breaker and also biases the contact structure in opening direction.

The movable contact structure is normally maintained in the closed position by an operating mechanism indicated generally at 61 (Fig. I) mounted in a U-shaped frame 63. The frame 63 comprises spaced side members 65 (only one being shown) and a connecting cross member 67. The frame 63 is supported on a platform 69 which forms the cross member of a main bracket comprising a pair of spaced side members 71 (only one being shown) joined at their outer ends by the cross member or platform 69. The platform extends across the width of the breaker and the side members 71 are rigidly secured to the metal panel 17 on the outsides oi the two outer pole units.

The operating mechanism includes a lever 73 pivotally mounted on a pivot pin 75 supported in the side member 65 of the frame 63. The lever 73 comprises a pair of spaced levers joined by a cross member "7'7 and between them support a rod 79 which extends across all three poles of the breaker. The rod 79 is operatively connected by means of an insulating connecting member 8;? to the pivot pin 41 in the free end of the switch member 43 on which the movable contact member 3'7 is mounted. There is a connecting member 81 for each pole of the breaker connecting the rod 7 9 to the moving contact structure for each pole unit so that upon operation of the rod 79 the movable contact structures for all three poles move in unison.

' An operating linkage comprising toggle links '53, ant 37 is provided to hold the lever '73 and CUE y the movable contacts in the closed position and to operate the movable contacts to open and closed positions. The toggle link 83 is pivotally connected to the lever 73 by a pivot pin 89 and the toggle link 85 is connected by a knee pivot pin 91 to the toggle link 83 and by a knee pivot pin 93 to the toggle link 87. The toggle link 87 is pivotally mounted on a fixed pivot 97 in the frame 63 and has a cam member 95 thereon.

The linkage 83, 85, 87 comprises two toggles one of which 83, 85 functions as a tripping toggle and the other 85, 37 as a closing toggle. The tripping toggle 83, 85 is normally slightly underset above a line drawn through the pivot pins 39, 93 and the closing toggle 85, 87 is normally underset below a line drawn through the pivots 91, 97, the closing toggle 85, 87 being shown in Fig. I in the position it assumes during a closing operation just as the arcing contacts 35, touch.

The tripping toggle 83, is normally biased in a direction to cause its collapse by a component of the spring 57 which biases the movable contact structures for the several poles of the breaker in opening direction and biases the connecting members 81 toward the left (Fig. l). The tripping toggle 83, 35 is normally prevented from collapsing by means of a main latch member 99 pivoted on the pivot pin and connected by a link 101 to the knee pin 91 of the trippirv toggle, the link 101 being connected to the latch member 99 by a pivot pin 193.

The main latch 99 is held in latching position by an intermediate latch lever 165 pivoted on a pin 107 supported in the frame 63. The latch lever carries a latch roller 111 which normally engages the main latch 99 to releasably restrain the latter in holding position. The latch lever 105 at its lower end carries a latch member 1113 engaging a light-load latch 115 mounted on a channel-shaped member 117 pivotally mounted on a pin 119 supported in the frame 63. The latch lever 105 and the member 117 are biased to their latching positions by a spring 121 tensioned between the parts as shown in Fig. 1. Rigidly mounted on the right hand end of the channel-shaped member 117 is a trip bar 123 which extends across all of the poles of the breaker and has secured thereto an insulating bracket 125 for each pole of the breaker. Each of the brackets 125 has a headed screw 127 adjustably mounted therein for cooperating with the trip device 13 for the corresponding pole unit in a manner to be later described.

As long as the main latch 99 is held in latching position by the latching mechanism just described, the tripping toggle 33, 85 will, through the link 101, be held in the position shown in which the breaker contacts are held in the closed position. The closing toggle 8587 is normally biased in a direction to cause its collapse by a spring 129 but is normally prevented from collapsing by a shouldered support member .131 pivoted on the pin 107 and biased by a spring 133 into supporting engagement with the knee pin 93 of the closing toggle. As shown in Fig. l the breaker is near the end of a closing operation and as the fully closed position is reached the shoulder on the support member 131 will drop under the knee pin 93 and hold the closing toggle in thrust transmitting position to hold the breaker contacts closed.

Rigidly secured to the front plate or cross member 67 of the frame 63 is a bearing member 135 in which is rotatably mounted a handle shaft 137 to the outer end of which is secured an operating handle (not shown). Secured to the inner end of the shaft 137 is a cam member 149 which has the dual function of engaging the free end of the channel-shaped member 117 to manually trip the breaker upon movement of the handle in one direction and of engaging the cam 95 on the closing toggle 85, 87 to manually close the breaker upon movement of the handle in the opposite direction. The cam member 149 and the handle are biased in both directions toa central position in a well known manner by means of a spring 145.

Assuming the circuit breaker to be in the closed and latched position with the support member 131 supporting the closing toggle 85, 87 in its extended thrust transmitting position, the breaker is tripped open by manually rotating the handle shaft in the proper direction. During this movement the cam member 149 engages and actuates the channel-shaped member 117 to disengage the latch member 115 from the latch 113 whereupon the force exerted by the springs 57 biasing the switch arms 4-3 in opening direction and transmitted through the connecting members 81, the rod 79 and the lever 73, causes the tripping toggle 83, 85 to collapse upwardly and effects opening movement of the movable contacts for all of the poles of the breaker.

The closing toggle 85, 87 does not immediately collapse following release of the latch mechanism since it is held by the support 131. During the collapsing movement of the tripping toggle 83, 85 the toggle link 85 rotates counterclockwise about the pivot pin 93 causing an ear 153 formed on the link 85 to engage and move the support member 131 to disengage the shoulder thereon from beneath the pin 93 whereupon the toggle 85, 87 collapses downwardly under the bias of the spring 129 and the weight of the moving armature of a closing solenoid, which will be described later. Collapse of the closing toggle 85, 87 causes resetting of the tripping toggle 83, 555 to thrust transmitting positions and resetting of the latching mechanism to latching positions. The mechanism is now in condition for a closing operation.

The contacts are closed either manually by operation of the shaft 137 by the handle or by operation of a closing solenoid indicated generally at 159. In order to close the contacts manually, the shaft 137 is rotated in the direction opposite to the direction it is rotated to manually trip the breaker. This operation of the shaft 137 engages the cam member 149 with the cam 95 on the closing toggle link 87 and straightens the closing toggle 85, 87. Since, at this time, the knee of the tripping toggle 83, S5 is restrained by the latching mechanism, the thrust of straightening the closing toggle 35, 87 is transmitted through the tripping toggle to rotate the lever '73 in a clockwise direction to close the contacts. As the knee pin 93 of the closing toggle 85, 87 arrives at the fully closed position the support 131 is moved by the spring 133 into supporting engagement with the knee pin 93 to maintain the contacts closed.

The circuit breaker is closed automatically by energi- Zation of the closing solenoid 159 which is effected either manually or automatically by closing a suitable switch (not shown). The solenoid 159 comprises a fixed magnet yoke 161 and a fixed core member 169 supported on brackets 163 secured to the underside of the platform 69. A movable armature 171 is attached to the lower end of an operating rod'173 which extends upwardly and has its upper end pivotally connected to the knee pivot pin 93 of the closing toggle 85, 87. An energizing coil 1'75 wound on an insulating spool is supported on the fixed magnet yoke 161.

In the closed position of the breaker the armature 171 i is held in its raised position slightly above the position shown in Fig. 1. When the breaker is tripped open the closing toggle 85, 87 collapses permitting the armature 171 to assume its lower or unattracted position. Thereafter, upon energization of the coil 175, the armature 171 is attracted upwardly straightening the toggle 85, 37 and neous tripping armature 192. The, bolt 183 which secures the upper end of the magnet yoke 181 to the base also secures the lower end of the flexible conductor 51 to the upper turn of the winding 139. The lower end of the winding 189 has a conducting lug 193 electrically and mechanically secured thereto and this lug is secured to a conducting terminal 195 and to the base 15 by means of a bolt 197. The energizing winding 189 is thus electrically connected in series relation in the circuit through the breaker which circuit extends from the terminal 27, the 1 main and arcing contacts 23, 33 and 25, 35, the contact member 37, flexible conductors 51, energizing coil 189 of the trip magnet to the terminal 195. Upon energization of the tripping magnet the armature 191 is attracted upwardly and actuates a trip rod 199 Which engages the headed screw 127 to operate the trip bar 123 and trip the breaker.

The movable armature 191 comprises an upper cupshaped member 2191 and a lower tubular member 203 both of magnetic material and rigidly secured together. The member 291 has a central opening therein and is adapted to slide over a sleeve 295 surrounding the trip rod 199. The sleeve 295 is limited in its upward movement relative to the trip rod 199 by means of a spring clip 207 seated in an annular groove in the trip rod. A spring 299 coiled about the trip rod 199 is compressed between the lower end of the sleeve 205 and the bottom of a counterbore 211 in the lower element 203 of the movable armature.

The fixed core member 187 (Fig. 3) is clamped to the upper leg of the magnet yoke 181 by means of a thimble 139 the bore of which acts as a guide for a tubular extension 141 on the instantaneous trip armature 192. The tubular extension 141 has a collar 143 on the upper end thereof and an inwardly extending flange 147 also on the upper end of the extension 141 acts as a guide for the trip rod 199. A conical coil spring 151 compressed be tween the armature 192 and the bottom of the fixed core member 187 biases the armature 192 to its unattracted position.

The trip rod 199 is moved upwardly to trip the breaker under the control of the time delay device 179 which comprises a flexible diaphragm 213 (Fig. 3) attached to the lower end of the trip rod 199 and valve means for admitting air to the space below the diaphragm at various rates to provide diiierent amounts of time delay in the operation of the trip rod. The flexible diaphragm 213 is disposed in a chamber 215 formed in an upper housing member 217 and a lower housing member 219, both of the housing members being formed of molded insulating material. The outer edge of the diaphragm 213 is clamped between the housing members 217 and 219, together with a sealing gasket 221 to thereby form an air-tight seal. The housing members are secured together and rigidly secured to the lower leg of the magnet yoke 181 by means of bolts 223 (Figs. 3 and 4). The central portion of the diaphragm 213 is clamped between upper and lower clamp members 225 and 227 respectively, the upper clamp memher 225 having an annular projection 229 extending downwardly through an opening in the lower clamp member 227 and formed over against the lower face of the latter to form an air-tight seal.

Secured to the lower end of the trip rod 199 is a sleeve 231 having a flange 233 thereon rigidly secured to the upper clamping member 225. The lower portion 293 of the movable armature extends downwardly through an opening in the upper wall of the chamber 215 above the diaphragm 213 and is seated on the upper face of the clamping member 225 being biased thereagainst by the spring 269.

Since the spaces above and below the diaphragm 213 are completely sealed oil from each other and the space above the diaphragm is at atmospheric pressure, any force tending to raise the trip rod 199 will be restrained by the partial vacuum below the diaphragm. In order to control the rate of tripping movement of the trip rod 199 valve devices indicated generally at 235 (Fig. 3) and 237 (Fig. 5) are provided to admit air to the space below the diaphragm 213 at different rates to provide a long time delay and a short time delay respectively in the operation of the trip rod.

The central bottom portion of the housing member 219 is molded to form a valve seat 241 in the shape of an inverted truncated cone. Surrounding the valve seat 241 is a tubular metallic member 243 molded into the housing member 219 and threaded internally to receive a valve 245 having a conical opening therein for cooperating with the valve seat 241. The valve 245 is provided with a flange 247 for supporting an adjusting knob 249 of insulating material which is biased thereagainst by a spring 251 coiled about the tubular member 243 and compressed between the bottom of the housing member 219 and the upper surface of the knob 249. A flange 253 on the knob 249 cooperates with a flange 255 on the housing member 219 to support a filter 257 for filtering the air admitted to the chamber 215 below rhe diaphragm. A passage 259 is provided along the threaded surface of the valve 245 and a passage 261 extends axially through the valve seat 241 to admit air to the chamber 215 below the diaphragm. Rotation of the knob 249 rotates the valve 245 which moves the valve axially of the valve seat 241 to vary the rate of admission. of air to the chamber below the diaphragm thereby varying the amount of time delay provided in the operation of the trip device.

The short time delay valve device 237 (Fig. 5) controls a passage for admitting air from the chamber 215 above the diaphragm 213 to the space below the diaphragm at a rate to provide a short time delay in the order of alternating current cycles in the tripping of the circuit breaker. The valve device 237 comprises a tubular valve element 273 (Fig. 5) disposed in an opening 275 in the housing member 217 and having an enlarged head portion seated in an opening 279 in the housing member 219. The valve element 273 is provided with a valve seat and a valve 281, slidable in the tubular valve element 273 normally cooperates with the valve seat to close a communication with opposite sides of the diaphragm. The valve element 273 is provided with an axial passage 233 in which is disposed a tapered projection 285 on the valve 281 and which is normally closed by the valve 281. The head 277 of the valve element 273 is provided with horizontal passages 287 disposed at right angles to each other. A passage 289 in the housing member 217 communicates the chamber 215 above the diaphragm 213 with the opening 275 above the valve seat and a passage 291 in the housing member 219 communicates the chamber 2.15 below the diaphragm 213 with passages 287 in the portion 277 of the valve element 281. The valve ele ment 273 is held in place by a plug 292 threaded into the opening 279 in the housing member 219.

it will be seen that upward or opening movement of the valve 281 will open the passage 283 and establish a communication from the upper side to the lower side of the diaphragm 213 through the passages 289, 283, 287 and 291. The valve 281 is actuated to open position by means of an armature 293 (Figs. 4 and 5) which is biased to unattracted position by a spring 294 and which is attracted upwardly by the tripping magnet 177 when the magnet is energized by overload circuits in an intermediate range of overloads of, for instance, 200% to 1000% of normal rated current. An opening 296 (Fig. 5) in the lower leg of the magnet yoke 181 provides an air gap for the magnetic circuit through the armature 293. The armature 293 is provided with laterally extending projections 295 (Fig. 4) which are seated in recesses 297 in the upper portion of the housing member 217 to pivotally support the armature. A bracket 299 (Figs. 4 and 5) secured to the armature 293 has a semi-circular opening 333 (Fig. 4) therein which engages in a notch 305 in the upper end of the valve so that upon actuation of the armature 293 the bracket 299 engages a substantially semi-circular head 307 on the valve 281 and mov s the valve to open position. This opens the previously described communication and permits air to pass from the chamber 215 above the diaphragm 213 to the space below the diaphragm to control the tripping movement of the trip rod 199 (Fig. 3). The rate of flow of air to the space below the diaphragm, and consequently the rate of tripping movement of the trip rod, is controlled by the amount of opening of the valve 281.

The extent of opening movement of the valve 231 is adjustably controlled by means of an adjustable S- shaped member 309 (Fig. The upper portion 311 of the S-shaped member comprises an adjustable stop disposed in the path of tripping movement of the free end of the armature 293 to limit the upward movement of the armature 293 and the extent of opening of the valve 281. The center cross bar 313 of the Se-shaPed member 309 has a threaded opening therein which is engaged by a reduced threaded portion 315 of an adjusting screw 317, so that upon rotation of the screw the S-shaped member 309 will be moved up or down, depending on the direction of rotation of the screw, to provide for greater or lesser movement of the armature 293 and, hence, greater or lesser opening movement of the valve 281.

The screw 317 extends through an opening in a cross member 321 of insulating material and has an insulating knob 319 secured to its lower end. The cross member 321 is secured to the underside of the housing member 217 by means of screws 323 only one of which is shown. An enlarged threaded portion 335 of the adjusting screw 317 passes through a clearance opening in the lower portion of the S-shaped member and threadedly engages an indicating member 337. A pointer 339 at the outer end of the member 337 extends through a vertical slot 340 in an index plate 341 supported at its lower end on the cross member 321 and having its upper end secured to a cross member 343 integral with the housing member 217.

The pickup point, that is, the magnitude of overload current required to actuate the armature 293 may be varied by varying the tension of the spring 294. The upper end of the spring 294 is attached to the armature 293 and the lower end of the spring is attached to a movable member 391 (Fig. 4) which threadedly engages an adjusting screw 395. The screw 395 is rotatably mounted in the cross member 321 and has an adjusting knob (not shown) on the lower end thereof below the cross member 321. R0- tation of the screw 395 will move the member 391 up or down to vary the tension of the spring 294, thus varying the pickup point of the armature 293. The movable member 391 is provided with a pointer 393 extending through a vertical slot in the index plate to prevent rotation of the movable member and to indicate the setting of the device.

Similarly the pickup point for the movable armature 191 (Fig. 3) of the tripping electromagnet 177 may be adjusted. The armature 191 is biased to its unattracted position by means of springs 405 (Figs. 3 and 4) having their upper ends attached to a U-shaped yoke 40"] which has its two legs pivotally supported in spaced, grooved studs 409 supported on the housing member 217 substantially as shown in Figs. 3 and 4. The right hand end of the yoke 407 engages an annular groove 413 (Fig. 3) in the lower member 203 of the armature 191, The lower ends of the springs 405 are attached to a movable member 415 which is threadably engaged by an adjusting screw 417. The lower end of the adjusting screw 417 is rotat- It will be understood that the scale plate 341 bears indicia adjacent the several pointers indicating the settings of the several adjusting devices.

The trip device operates with time delays of diiferent durations in two ranges of overcurrents below a predetermined magnitude. These ranges of overcurrents may be arbitrarily defined as, for example, a low range up to 500% or 600% of normal rated current, and a high range between 500% or 600% and 1000% of normal rated current. The circuit breaker will also trip open instantaneously in response to excessive currents above 1000% of normal rated current, or short circuit currents, but only during a closing operation when the breaker closes in against such a fault current, since means, to be hereinafter described, is provided to defeat instantaneous tripping except during a closing operation of the breaker.

Upon the occurrence of an overcurrent in the low range the tripping electromagnet becomes energized and attracts the armature 191 (Fig. 3) upwardly. The armature acts through the spring 209 and the sleeve 205 to produce an upward thrust on the trip rod 199, the movement of the trip rod being retarded by the partial vacuum below the diaphragm 213. The trip rod 199 moves up slowly in tripping direction as air is drawn into the space below the diaphragm through the long time delay valve 235 until the upper end of the trip rod engages the headed screw 127 (Fig. 1) and actuates the latch mechanism to eiiect tripping of the breaker in the manner previously described. The time delay provided by the long time delay valve device 235 is in the order of seconds and may be varied by adjusting the valve 241, 245 as set forth previously. A spring biased bypass valve 425 (Fig. 3) controls a passage through the diaphragm 213 to provide for quick restoration of the armature 191, the trip rod 119 and the diaphragm 219 to their normal positions following a tripping operation.

An overcurrent in the high range of overcurrents, but below 1000% of normal rated current, energizes the tripping electromagnet 177 sufficiently to attract the valve actuating armature 293 (Fig. 5) upwardly against the adjustable stop 311 opening the short time delay valve 281. This admits air to the space below the diaphragm 213 at an increased rate and provides a relatively short time delay in the order cycles in the operation of the trip device.

As previously set forth the armature 192 is provided to instantaneously trip the breaker open in response to excessive fault currents or short circuit currents. It was also pointed out previously that the circuit breaker in certain locations in a selective tripping system is capable of carrying excessive currents for a certain length of time without damage to the breaker, the length of time the circuit breaker is to carry such excessive overload currents being determined by the setting of the short time delay device. The critical time in the operation of the breaker when damage is most likely to occur is in closing the breaker in against an excessive fault current or short circuit current. For this reason it is desirable to defeat the operation of the instantaneous trip armature 192 at all times except during closing operations and until the breaker is fully closed.

The means for defeating the operation of the instantaneous trip armature 192 comprises a latch or interposer 42 5 (Figs. 1, 2 and 3), there being an interposer 425 for the trip device of each pole of the breaker as shown in Fig. 2. The interposers are mounted on a rock shaft 427 mounted in brackets 429 which in turn are supported on the upper legs of the associated magnet yoke 181. An' arm 431 attached to the shaft 427 is pivotally connected at its free end to a link 433 which extends upwardly. At its upper end the link 433 is connected by means of a pin and slot connection 435-437 to a bracket 439 secured to the cross member 77 joining the levers 73 of the breaker operating mechanism. A spring 441 connected under tension between the pin 435 on the bracket 439 and a pin 443 on the link 433 normally maintains the lower end of the slot 437 against the pin 435 but permits overtravel of the lever 73 in the opening direction.

In the closed position of the circuit breaker the interposer is held in the position shown in Fig. 3 by the linkage just described in which position the interposer lies in the path of the collar 143 and blocks tripping movement of the instantaneous tripping armature. Thus, instantaneous tripping of the breaker when the breaker is standing in closed position is defeated. However, should an excessive fault current or a short circuit current occur with the breaker closed it will be tripped open by the armature 191 under the control of the time delay device and the short time delay valve (Fig. 5) in the manner previously described with a time delay in the order of alternating current cycles.

When the breaker is opened either manually or by operation of the trip device the toggle linkage 83, 85, 37 collapses rotating the lever 73 together with the bracket 439 counterclockwise about the pivot 75 to open the contacts. This movement of the bracket 439 draws the link 433 upwardly and rocks the shaft 427 counterclockwise moving allof the interposers out of the path of tripping movement of the corresponding collars 143 thus freeing the instantaneous trip armature 192 for each of the poles for operation during the following closing operation.

The circuit breaker is shown in Fig. l at the point during a closing operation when the arcing contacts have just touched. If, at this time, that is, when the contacts touch during the closing operation, there is a heavy overload or short circuit current on the line, the trip device will be energized sufficiently to actuate the instantaneous tripping armature 192. Since, at this time, the interposer 425 is not in position to block movement of the armature 192 the armature will be actuated to instantaneously trip the breaker open.

If, when the arcing contacts touch, there is no overload current or an overload current of insufficient magnitude on the line to attract the armature 192 the breaker will go to the fully closed and latched position moving the interposer 425 (Figs. 1 and 3) into the path of tripping movement of the armature 192 thus defeating instantaneous tripping while the breaker is in the closed position.

The interposer 425 in no way interferes with the operation of the trip device when the device functions in response to overload currents of lower value, that is, overload currents which effect a long time delay or short time delay in the operation of the device.

It will be seen that the invention provides a circuit breaker that is normally tripped open with a time delay and is tripped open instantaneously only during a closing operation.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

I claim as my invention:

1. In a circuit breaker having separable contacts and operating means therefor, a member movable to effect separation of said contacts, an electromagnetic trip device comprising an energizing winding, a first armature operative when said winding is energized by overload currents to move said movable member, a time delay device for providing a time delay in the operation of said movable member by said first armature, a second armature operative when said winding is energized by overload currents above a predetermined value to move said movable member, and an interposer connected to be operated by said operating means during a closing operation and op- 10 erated after the contacts touch to a position to prevent operation of said second armature.

2. In a circuit breaker having separable contacts and operating means therefor, 21 member movable to effect separation of said contacts, an electromagnetic trip de vice comprising a single energizing winding, a first armature operative when said single winding is energized by overload currents to move said movable member, a time delay device for providing a time delay in the operation of said movable member by said first armature, a second armature operative when said single winding is energized by overload currents above a predetermined value to move said movable member, and an interposer connected to be operated by said operating means during a closing operation and operated after the contacts touch to a position to prevent operation of said second armature.

3. In a circuit breaker having separable contacts and operating means therefor, a movable member movable to effect separation of said contacts, an electromagnetic trip device comprising an energizing winding, a pair of armatures movable within said winding, each of said armatures being movable to engage and move said movable member to effect separation of said contacts, a time delay device for effecting a time delay in the tripping operation of one of said armatures, and a member positioned by said operating means during a closing operation after the contacts touch to prevent movement of said second armature.

4. In a circuit breaker comprising relatively movable contact means and operating means therefor, a movable member movable to cause opening of said contact means, an electromagnetic trip device comprising an energizing winding, a first armature movable within said winding, a trip rod movable by said first armature for engaging and moving said movable member, a time delay device for effecting a predetermined time delay in the operation of said trip rod, a second armature movable within said winding for engaging and moving said movable member, and an interposer connected to be moved by said operating means during a closing operation and operative only after the contacts engage to prevent tripping movement of said second armature.

5. In a circuit breaker comprising relatively movable contact means and operating means therefor, a movable member movable to cause opening of said contact means, an electromagnetic trip device comprising an energizing Winding, a first armature movable within said winding, a trip rod movable by said first armature for engaging and moving said movable member, a time delay device for effecting a predetermined time delay in the operation of said trip rod, means responsive to predetermined energization of said Winding for decreasing the amount of time delay in the operation of said trip rod, a second armature movable Within said winding for engaging and moving said movable member, and an interposer connected to be moved by said operating means during a closing operation and operative only after the contacts engage to prevent tripping movement of said second armature.

6. In a circuit breaker having relatively movable contact means and operating means therefor, a movable member movable to efiect opening of said contact means, an electromagnetic trip device comprising an energizing Winding, a pair of armatures disposed in axial align ment Within said winding, a trip rod movable by one of said armatures for engaging and moving said movable member, a time delay device connected to effect a time delay in the tripping movement of said trip rod, the other of said pair of armatures being operable to engage and instantaneously move said movable member, and means responsive to the position of said operating means at a predetermined point in the closing movement thereof for preventing movement of said other armature.

7. In a circuit breaker having separable contacts, movable means movable to effect separation of said contacts, an electromagnetic trip device comprising an energizing winding, an armature'operative when said winding is energized in response to overload currents for moving said movable means, a time delay device providing a time delay in the operation of said movable means by said armature, another armature operative when said winding is energized in response to overload currents above a predetermined value to instantaneously move said movable means, and mechanism connected to be positioned according to the position of said contacts preventing operation of said other armature while said contacts are in engagement.

8. In a circuit breaker having separable contacts, movable means movable to effect disengagement of said contacts, an electromagnetic trip device comprising an energizing winding, an armature operative when said winding is energized in response to overload currents for moving said movable means, a time delay device providing a relatively longtime delay in the operation of said movable means by said armature when said winding is energized in response to overload currents of relative low value, said time delay device providing a relatively short time delay in the operation of said movable means by said armature when said winding is energized in response to overload currents of high value, another armature operative only when said winding is energized in response to overload currents of high value to instantaneously move said movable means, and mechanism responsive to the position of said contacts preventing operation of said other armature while said contacts are in engagement.

9. In a circuit breaker having separable contacts, movable means movable to etfect disengagement of said contacts, an electromagnetic trip device comprising an en ergizing winding, an armature operative when said winding is energized in response to overload currents for moving said movable means, a time delay device for effecting a relatively long time delay in the operation of said movable means by said armature when said winding is en ergized by overload currents below a predetermined value, a control element operable when said winding is energized in response to overload currents above said predetermined value to cause said time delay device to effect a relatively short time delay in the operation of said movable means by said armature, another armature operative only when said winding is energized in response to overload currents above said predetermined value to instantaneously move said movable means, and mechanism responsive to the position of said contacts preventing operation of said other armature when said contacts are in engagement.

References Cited in the file of this patent UNITED STATES PATENTS 2,669,623 MacNeill et al Feb. 16, 1954 FOREIGN PATENTS 2,047 Great Britain Feb. 1, 1900 796,774 France Ian. 27, i936

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