US2611013A

US2611013A - Electromagnetic trip device

Info

Publication number: US2611013A
Application number: US629662A
Authority: US
Inventors: Lindstrom Ture; Sandin Jerome; Herbert L Rawlins
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1945-11-19
Filing date: 1945-11-19
Publication date: 1952-09-16
Anticipated expiration: 1969-09-16

Description

Sept' 16, 1952 T. L lNnsrRoM ET Al. 2,611,0`i3

ELECTROMAGNETIC TRIP DEVICE Patented Sept. 16, 1952 UNITED STATES PATENT OFFICE ELECTROMAGNETIC TRIP DEVICE Pennsylvania Application November 19, 1945, Serial No. 629,662

9 Claims.

This invention relates to circuit breakers, and more particularly, to overload `trip devices for controlling the automatic operation of circuit breakers.

One object of the invention is to provide a circuit breaker embodying an improved trip device which is of simple construction, reliable in operation and inexpensive to manufacture.

Another object of the invention is to provide a circuit breaker embodying a novel trip device operable to trip the breaker after a relatively long time delay in response to overload currents of relatively lOw value, after a relatively short time delay in response to overload currents of intermediate value up to a predetermined value and instantaneously in response to overloads above said predetermined value.

Another object of the invention is to provide a circuit breaker embodying a novel trip device having a plurality of time delay devices one of which controls the trip device to trip the breaker in response to relatively high overload currents, and another of which time delay devices controls the trip device to trip the breaker in response to relatively low overload currents.

Another object of the invention is to provide a circuit breaker embodying a novel trip device according to the preceding paragraph wherein one of the time delay devices comprises a sealed casing movable to trip the breaker and containing a body of liquid, said casing having a core member disposed therein and movable relatively thereto to control the tripping movement of said casing, and another of said time delay devices comprises a mechanical escapement for controlling the movement of the casing.

The novel features that are considered characteristic of this invention are Vset forth in particular in the appended claims. The invention itself, however, both as to structure and operation together with additional objects and advantages thereof, will be best understood from the following detailed description of one embodiment thereof when read in conjunction withthe accompanying drawings, in which:

Figure l is a side-elevational view, partly in section, of a circuit breaker embodying the invention, Y y y Fig. 2 is an enlargedsectional view of the trip device taken substantially on line II-II of Fig. 3 and looking in the direction of the arrows Fig. 3 is a bottom view of the trip device,y

Fig. 4 is a detail view showing the escapement ratchet wheel and the inertia device,

Fig. 5 is a skeletonized View showing the fixed and movable core members and armatures in their relative positions but omitting the springs and sealed casing to more clearly illustrate the air gaps in the magnetic ciriuit, and

Fig. 6 is a detail vertica1 view taken on line VI-VI in Fig. 2 and showing the Calibrating spring toggle.

Referring to Figure 1 of the drawings, the reference numeral I I designates a base of strong insulating material which supports the various parts of the circuit breaker. A pair of terminals I3 and I5 are suitably secured to the base and each terminal has one or more connecting studs I9 which extend through the back of the base I I and serve to electrically connect the breaker to the circuit which it controls.

The upper terminal I3 has a contact block 2l of rigid conducting material secured thereto; and a rigid contact block 23 secured to the base is electrically connected to the lower terminal I5 through the energizing winding of the trip device of the breaker, which will be hereinafter described.

The contact means and mechanism of the circuit breaker illustrated are similar to the circuit breaker fully disclosed in Patent No. 2,214,471 issued September 10, 1940, to Leon R. Ludwig and Merle E. Horn, and assigned to the assignee of the present invention. Hence only a. brief description of these parts will be given in this application.

The main

stationary contacts

25 and 21 are rigidly secured to the contact blocks 2I and 23, respectively; and the auxiliary stationary contacts 29 and 3I are secured to a triangularlyshaped contact platform 33 of conducting material which is mounted on the upper portion of the block 2 I for limited tilting and rocking movement by means of pins 35 projecting from the opposite sides of the platform which engage in slots 3l provided in a pair of side walls 39 secured to the block 2I The platform 33 is biased outwardly from the base II by a. plurality of springs 4I and 43, and outward movement of the platform is limited by the' engagement of the pins 35 with the outer ends of the slots 3l and by stop projections 45 carried by the platform adjacent its upper end. The platform 33 and, consequently, the auxiliary contacts 29 and 3| are electrically connected to the terminal I3 by means of a flexible shunt conductor 41.

The movable contact means of the circuit breaker comprises a channel-shaped contact arm 49 of conducting material which is rigidly secured to a pivoted switch member 5I by means of a plulink 89.

rality of screws 53. The contact arm 49 carries a main lcontact bridging member 55 for bridging the

main contacts

25 and 21, and an auxiliary contact member 51 for engaging the stationary auxiliary contacts 29 and 3|, the auxiliary contact member 51 being secured to the upper end of the channel-shaped contact arm 49 by a plurality of screws 59.

The main contact bridging member 55 is4` formed of rigid conducting material, and is loose-v ly mounted on the contact arm 49 for limited movement relative to the contact arm toward and away from the

main contacts

25 and 21 by means of a pair of studs 6| secured to the contact carrying arm 49, only one stud being shown. A pair of coil springs (not shown) encircle the studs 9|, and are disposed between the contact carrying arm 49 and the bridging member 55 for biasing the bridging member toward the stationary

main contacts

25 and 21 with a predetermined force. The ends of the bridging member 55 are beveled to lie parallel with the beveled edges of the contact blocks 2| and 23, and have a pair of contacts 61 secured thereto for engaging the main

sta tionary contacts

25 and 21.

The auxiliary contact member 51 is formed of rigid conducting material, and has an intermediate contact 69 and an arcing contact 1| secured thereto for engaging the intermediate and arcing contacts 29 and 3| of the stationary contact means. f

A flexible shunt conductor 13 electrically connects the auxiliary contact arm 49 to the main stationary contact block 23. The flexible conductor 13 has its upper end secured to the contact arm 49 by the lower bolts 53. The lower end of the exible shunt conductor 13 is secured to the lower contact block 23 by means of a boit 11. Y Y

The switch member has a yoke-shaped lower endwhich is pivotally mounted between the side walls of a main frame 19 by means of the pivot pin 3|. The switch member 5| is movable about its pivot axis to open and closedv circuit positions to open and close the contactY means of the breaker by means of an operating mechanism indicated generally at 83.

The operating mechanism 83 is supported by the main frame 19 and comprises an actuating lever 85 pivoted on a pin B1 carried by the frame, and is connected to the switch member 5| byv a An operatingmember 9| is also pivoted on the pin 81 for movement about the same axis as the actuating lever 85. The actuating lever 85 is normally and releasably connected to the operating member 9| for movement thereby by means of a pair of latches-93 and 95, which are pivotally mounted on the lever 95 at 91 Yand 99, respectively. The latch 93 engages a rollei1v |9| carried by the operating member 9|, Vand this latch is, in turn, held in latching positionby the auxiliary latch 95. The operating member 9| is adapted to be releasably held in closed 'circuit position by means of a main holding latch |93 pivoted Vat ||9, which releasably engagesi the roller ISI. The auxiliary latch 95 is provided WithV a curved tailpiece |95 by means of which it isreleased to cause release of the latch 93" and consequent tripping of the circuit breaker by the release of the actuating lever 85 fromits connection With the operating member 9|. When released the actuating member 95 moves in a counterclockwise direction about tliepivot axis 81,Y causing opening of the movable contact means. Duringithis movement, 1 a cam surface |01 of the lever 85 engages the rounded nose of the main holding latch |93, Vmoving the holding latch to released position to effect release of the operating member 9| The switch member 5I and the actuating lever 95 are biased to open position by means of a pair of accelerating springs |99 (only one being shown), Which are connected at their upper ends to the switch member 5| and at their lower ends to the sides of the main frame 19.

To close the circuit breaker after it has been tripped open, the operating member 9| is iirst moved in a counterclockwise direction about the pivot axis 81 to the open position to effect resetting of the latches and reestablishment of the releasable connection between the actuating lever 85 and the operating member 9|. After the connection is thus established, the operating member 9| is moved in a clockwise direction to closed position by means of a handle to effect closing of the contact means of the breaker. TheA clockwise or closing movement oi the operating member 9| is limited by a portion 92 thereof striking a xed stop 94 on the frame 19. When the parts have been moved to closed position, the main holding latch |93 reengages the roller |0| to hold the operating member in closed position. The stop 94 is located to permit a slight overtravel of the member 9| to insure proper engagement of the latch |93 with the roller I0 It will be noted that the construction of the operating mechanism is such that the movable contact `means is trip-free of the operating member 9|;

that is, when the breaker is tripped, the contact means move to open position irrespective of the position of the operating member 9|.

The mounting arrangement of the contact means is such that during opening of the breaker the main bridging member 55 is iirst separated from the

stationary contacts

25 and 21, while the auxiliary contacts remain in engagement by reason of the outward movement of the contact platform 33 under the iniiuencev of the biasing springs 4| and 43. After` the bridging member 55 has separated a predetermined distance from the main stationary contacts, the

intermediate contacts

29 and 69 begin to separate. This takes place as soon as the pins 35 engage the ends of the slots 31. ADuring this time,lthe arcing contacts 3| and 1| remain in engagement due to the rocking movement of the contact platform 33. After the intermediate contacts have separated a predetermined distance, the arcing contacts 3| and 1| begin to separate. During closing, the contacts engage in the reverse order, as will readily be understood. It will thus be seen that the arc formed during separation of the contacts is drawn only between the arcing contacts 3| and 1|.

The circuit breaker `is adapted to be tripped Open either manually, or automatically, in response to predetermined overload conditions in the circuit, by means of a trip device indicated generally at ||5. u

The trip device comprises a trip lever ||1 which is pivotally mounted'intermediate its ends on the-frame 19 by means of a pivot pin |9, and an electromagnetic trip means, indicated `generally at |2|, whichis operable inl response to the predetermined overload conditionsgto move the trip lever ||1 to tripping position to cause autofdiately above the tripping electromagnet |2| to be engaged and moved by a plunger of the electromagnet to effect automatic tripping of the breaker. The arm |23 of the trip lever is provided with a projection |25 which is adapted to engage the curved tailpiece |05 of the auxiliary latch 95 to move this latch to released position upon movement of the trip lever to tripping position. The other arm of the trip lever ||1 forms a handle |21 whereby the trip lever may be manually moved to tripping position to effect manual opening of the circuit breaker. A spring |29 connects the arm |23 of the trip lever ||1 to an extension of the main holding latch |03 so that the spring thus serves to bias the main holding latch to latching position and the trip lever to its normal inoperative position, as shown in Fig. 1.

The movable core structure |33 comprises a sealed casing |5| (Fig. 2) of non-magnetic material having a portion |53 of reduced diameter at its lower end and having an armature |55 secured to the bottom of the reduced portion. The armature |55 is secured to the casing |5| Iby means of a portion of the bottom of the casing extending through an opening in the central portion of the armature and being riveted over against the inside of the armature as at |51. The upper end of the casing |5| is closed by means of a fianged disc |59 the flange of which is brazed or soldered to the inner surface of the casing. The central portion of the disc |59 is provided with an integral inwardly extending tube |6| for the purpose of filling the casing with a suitable liquid to the proper level, there being a space in the upper end of the tube which may be filled with a suitable gas. After the fluid is placed in the casing a screw |63 is inserted tightly into the tube 6| and brazed therein thus hermetically sealing the casing |5 Disposed within the sealed casing |5| is a core member |65 of magnetic material which is biased upwardly by means of a spring |61 against the filler tube |6| which acts as a stop therefor. The spring |61 is compressed between a shoulder formed in the casing |5| by the reduced portion vbushing |13 also of magnetic material is screwed into an opening in the lower leg of the magnet yoke. The bushings |1| and |13 are provided with guide rings |14 of non-magnetic material to guide the sealed casing |5| in its vertical reciprocal movement. The bushings |1| and |13 also form a part of the magnetic circuit as will be hereinafter more fully brought out.

The flange on the collar |81 extends inwardly an extent sufficient to engage and support a cylindrical armature |93 which extends in nested relation in the cylindrical space between the reduced portion |53 of the sealed casing |5| and the cylinder |85. The armature |93 is biased downwardly away from the sealed casing |5| and against the ange of the collar |81 by means of a spring |95 compressed between the bottom of the armature |55 and an adjustable spring seat |91 which is supported on a threaded plug |99 screwed into a tapped opening in the lower end of the armature |93. The plug |99 is provided with a screw driver slot across its bottom surface whereby it is rotatable in the threaded opening in the armature |93 to move the spring seat |91 up and down to thereby adjust the tension of the spring the purpose of which adjustment will be fully set forth hereinafter. The plug |99 is provided with a groove extending diametrically across its upper side whichis engaged by a projection 20| which may, for conveniences, comprise a rod welded to the under side of the spring seat |91.

When the plug |99 is rotated in either direction the rod 20| is forced upwardly and when the plug has rotated the rod is forced` back into the groove by the force of the spring |95. The spring seat |91 is prevented from rotating during this adjustment by an end thereof extending into a slot 203 in the wall of the armature |93.

As will be fully described hereinafter in the description of the operation of the trip device, the core member |65 and the control of the passage of fluid past the core member provides a long time delay when the device is operated in response to overload currents of relatively low value of, for instance, up to 300% of normal rated current. Means is also provided whereby a relatively short time delay is effected when the device is operated in response to overload currents in an intermediate range, for example, between.

I 300% and 1000% of normal rated current. This means comprises a mechanical escapement device indicated. generally at 205.

....Referring to Figs 2 and 3, integral with the "armature |93 and extending downwardly there- .fromlFigt 2) is-a pair of spaced projections 201 which between'tl'iem4 carry a pin `299. The pin '9is'engaged by open slots 2H in`a pair of spaced arms`2|3forming one arm .off a lever. 2|5 -pivoted on a'xed pivo'tpin 2|1 :supported in theside walls 2|9 .of a frame 22|. A roller 220 is mounted'on a pin 222 supported-'between the `arms 2|3 forcooperation with the collar |81 -as :will be fully described later. The-frame 22| is -suitably supported on the lower leg of the magnet yoke |3| by-means of the screw stud |91 anda pair of screws 223 (only one being shown).

The other arm of the lever 2|5 comprises a .mas's'225 having .a projection 221 integral therearm 225 of the lever 2|5. y

, Theother arm of thev lever 233 comprises, a segment gear 231 whichmeshes with a vpinion 239. mounted for rotation ona shaft 24| supported in the side walls 2|9 of the frame. The ,pinion239 is secured to one end of a sleeve 243 surrounding the' shaft, 24| and having its other vend secured to an escapement ratchet wheel 245. vAn inertia member 241 mounted von a shaft 249 cooperates with the teeth on the periphery of the ratchet wheel 245 and has a mass 25| secured thereto by means of rivets 25.3 only oneof which .is shown..

.. yThe lever 2|5 (Fig. 2) vis biased against clockwise movement by meansof a calibratingspring 255; having its upper end hooked over a movable stud 251.slidablefverticallyin a slot in the magnet -`-yoke `13| andin a corresponding `slot ina scale platez 25S.- .T'ne scale plate 25S is suitably secured ...toi the. magnet yokev as Aby screws (not shown). The-stud 251 is clamped Yto thescale plate in its. .adjusted position vby a thumb nut 26 .The scale `pl'aten259 is provided with a suitable. scale (not shown) arranged vertically adjacent the path of movement of the stud 251 and a pointer (also not shown) is provided movable with `the stud251 and thumb nut 25| which cooperates with the scalev to indicate the setting tov whichitfhe device is The lower end. of. the spring 255 is 'hooked over the knee pin y263 of a toggle comprising

toggle Elinks

255 and 261, the toggle being disposed in a cut-out portion of the mass22'5'. The'toggle link 265 is mounted on'afixed pivot 259 supported in the side walls 2 I9 of the frame 22| and the toggle 'link'261 is connected to the lever 2| 5 by means of "a pin 21|. 'The knee end ofeach of the toggle iii-irs 1255 and ser is bifureatedgans `theatre ofthe linkV 255 extends between other forks'of the" link 251. lThe lower endof'the s`pringfv255 is hooked Y. around the knee pin 253 between the forks of the link'255 and the .forks of the togglelinl; V2|51 eX- tend beyond the knee pin wherethey engage the ends ,of a pin 213 in the linkf to maintain the ltoggle zes-:251 slightly emersa-.below a 1in-e core member against the stop ll.

suit particular requirements.

drawn through the centers of the pins 269 and The trip drive functions within two ranges of overload currents below a predetermined value to trip the breaker after a relatively long time delay in the lower range of overload currents, with a relatively short time delay in the intermediate range` of overload currents and instantaneously in response to overload currents above the predetermined value, or on short circuits. These ranges of overload currents may be arbitrarily defined as up to 300% of normalrated current for the low range, 300% to l000% of rated current for the intermediate range, and l000% or more of rated current for the instantaneous tripping range.

- The limits of the intermediate range of overloads set forth are to be considered merely by way of example and these` may be varied considerably to For instance, by therprovision of stronger or weaker springs. en-

' tirely different sets of values may be established.

There are three main'air gaps in the magnetic circuit indicated at A, B and C, which are more clearly shown in Fig. 5. It will be observed that the lower sharp edge of the bushing 11| which forms a part of the magnetic circuit and the upper edge of the enlarged portion |69 of the core member which forms the air gap A lie in substantially the same horizontal plane, when these parts are in their normal positions withthe These edges are shaped to produce an extremely high .magnetic flux density in the air gap A. The air gap B comprises two magnetic circuits bl and b2 (Fig. 5). The air gap B produces the tripping force for long time delay tripping in response to overload currents in the low range of overload currents up to approximately 500% of normal rated current.

When a persistent overload occurs in the low range of overload current values, for instance,

1,50% of normal current, the magnetic circuit is energized but, due to the extreme high Vdensity iiux across the air gap A, the core member. 65 will be held in substantially the position shown in Figs. 2 and 5 while the magnetic ux in the air gap B starts to move the armatures |55 and |93 upwardly. At this current value, the upward pull ofthe armature |93, through the spring is added to the upward pull of the armature 155.

YThis pull of the armature |93 is insufficient to of the uid below the core member |65 causes the ball check valve |11 to close forcing the fluid through the restricted passage '|83 thus providing a relatively long time delay on overload currents within the low range of values. During long time delay tripping operations, the vpreviously described escapement device 205 is operated but since the operation is slow the esca-pement device Aoers relatively little resistance to operation. Y

Before v.the sealed `casing can star-t its upward the tripping v"tripping movement, itis necessary that the forces in the magnetic circuit be great enough to overcome the tension of the calibrating spring 255. When the forces are sufficient to overcome the spring 255 the movable core structure, acting through the pin 209 and the arm 213, rotates the lever 215 clockwise about its pivot 2|1. This action causes collapse of the toggle 265-261 and reduces the effective force of the spring 255 resisting operation of the lever 215.

After the circuit is opened by opening of the breaker contacts and the winding |31 is deenergized, the movable core structure 133 is returned to its normal position against the stop 89 by gravity aided by the spring 255. The spring |61 at the same time causes opening of the check valve 1111 permitting a free flow of fluid to the space below the core member |65 and restores the core member upwardly to its normal position against the stop |61.

The operation of the device is somewhat different on overload currents in the intermediate range, that is, between 300% and`1000% of normal current. When the winding |31 is energized by an overload current in the intermediate range, of, for instance, 800% of normal current, the armature |93 is attracted with sufiicient force Yto overcome the spring |95 and quickly close the air gap b1 (Fig. 5). This would result in substantially instantaneous tripping if the armature |93 were not otherwise restrained. It is desirable that the time delay on intermediate overloads be much shorter than on overloads in the low range of values but greater than the instantaneous tripping. To this end the armature 193 is restrained by the mechanical escapement device 205. When the armature |93 starts to move upwardly it acts through the pin- 209 to rotate the lever 215 in a clockwise direction. The lever 215 through the spring 229 (Fig. 1) rotates the segmental lever 233 which, in turn, rotates the pinion 239 and the ratchet wheel 245 (Figs. 2 and 4) in a counterclockwise direction under the control of the inertia member 241 which retards the upward movement of the armature |93.

The pull of the armature .|55 in response to overloads in the intermediate range is not great enough to displace the `core member 165 relative to the fixed core member, consequently the core member, in the absence of other forces, would remain substantially stationary while the sealed casing 15| moved very slowly in tripping direction being retarded by the now of iiuid through the oriiice |83. This would provide a relatively long time delay in response to overload currents in the intermediate range. In order to provide short time delay tripping in the intermediate range of overload currents, other'means are provided to actuate the sealed casing in tripping direction. This means comprises the lever 2 15 and the roller 220. When the lever 215 is rotated in a clockwise direction by upward movement of the armature 93, the roller 220 engages the collar |81 and moves the tube |51 upwardly therewith. It will be observed that the roller 220 is disposed on the arm 213 at approximately one-half the distance from fulcrum 2 11 as the pin 209, consequently the armature |93, acting through the pin 209, lever 215 and the roller 220 applies twice the force to move the tube than is applied directly by the armature and moves the tube at approximately one-half the speed of the armature |93. This provides for gradual closing of the air gap b1 and insures that the device will not function to trip the breaker until the ratchet wheel 245 escapes the inertia member 241.

The ratchet wheel 245 is provided with teeth about a portion of its periphery as can be clearly seen in Figs. 2 and 4 of the drawings. As viewed in Figs, 2 and 4, the ratchet wheel is rotated in a counterclockwise direction and the duration of the short time delay tripping in response to overloads in the intermediate range is measured by the time required for the last tooth on the ratchet wheel to escape the inertia member 241.

The time at which the armature 193 will start to move upwardly in tripping direction in response to overload currents in the intermediate range may be varied by varying the tension-of the spring |95. This is accomplished by rotating the threaded plug |99 (Fig. 2) to increase or decrease the compression of the spring |95.

The duration of the short time delay tripping may be varied by changing the position of the ratchet wheel 245 relative to the inertia member 241 so that a greater or lesser number of teeth are required to pass the inertia, device before tripping occurs. A further adjustment of the ratchet wheel is provided for accurately adjusting the duration of the short time delay tripping. This adjustment includes the adjusting screw 236 (Fig. l). As previously described, the spring 229 is given an initial tension and the arm 23| of the segmental lever 233 is spaced from the arm 225 of the lever 215 by means of the spacer rod 235. Since the lever 215 is biased to its normal position, as shown in Figs. l and 2, by the spring 255 and toggle 2165-261, it will be obvious that by turning the screw 236 the position of the segmental lever 233 may be varied relative to the position of the lever 215 in either direction depending on the direction the screw 236 is turned. The segmental lever 233 acting through the pinion 239 and sleeve 243 correspondingly moves the ratchet wheel 245 relative to the inertia device 241. The degree of movement of the ratchet wheel by adjustment of the screw 236 is relatively small to provide for Vernier adjustment of the short time delay tripping. The screw 236 is locked in its adjusted position by means of a lock nut 215 The movable core structure and the escapement time delay device are restored to their normal positions following a short time delay tripping operation by the weight of the movable core structure and spring 255 and toggle 265-261.

When an overload current of 1000% or more, or a short circuit occurs the entire movable core structure acts as a solenoid and functions to instantaneously trip the breaker. Under this circuit condition, the movable core structure operates the lever 215 (Fig. 2) but stretches kthe spring 229 (Fig. 1) without operating the escapement device 205. The movable core structure is restored to its normal position following an instantaneous tripping operation by the

springs

255 and 229 assisted by the weight of the core structure.

The invention provides an improved trip device for a circuit breaker having a time delay means comprising a time delay element sealed in a casing containing a body of fluid for controlling the tripping operation on overload currents in the low range of overload current values, a second time delay device comprising a mechanicalA escapement device for controlling the tripping operation on overload currents in the intermediate range of overload current values, the trip device functioning to instantaneously trip the breaker independently oi both of said time` delay devices in response to overload currents- 11 above the intermediate range of overload currents. or on short circuits.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and inodications may be made in the structural ldetails and combination of elements disclosed without departing from somefof the essential features of the invention. Itis, therefore, desired that the language of the appended claims be given as reasonably broad interpretation as the prior art permits.

We claim as our invention:

l. In a circuit breaker, a trip device comprising an energizing Winding, a fixed magnet yoke having a portion of reduced cross section, a sealed casing movable to effect a tipping operation, a first armature at one end of said casing for moving said casing upon energization of said trip device by certain overload currents, aA iirst time delay means'comprising a magnetizable member disposed in said casing and having a portion of reduced cross section,meansbiasing said magnetizable member to a normal position wherein the portionof reduced cross section cooperates with the portion of reduced cross section of said magnet yoke to forman "air gap of high 'density flux, said'air gaprestraining said magnetizable member against movement'when said trip device is energized by said certain overload currents to thereby retard movement of said casing with a relatively long time delay, a second armatureV in axial alignment With said first arrriature for moving said casing upon energization of said trip device by certain'other overload currents, and a secondtime 'delay means comprising a mechanical escapement device connected to said second armature operable when said trip .device is energized by said certain other overload currents to retard movement of said casing Witha relatively short time delay.

2. -In a circuit breaker, a trip device comprising an energizing vwinding, a fixed magnet yoke having a portion of reducedcross section, a sealed casing movable Within said magnet yoke to effect a tripping operation, a nrst armature at one end of said casing movable upon energiaation oi said trip device by overload currents of certain value to'move'said casing, a time delay device comprising a magnetizable member disposed in said sealed-casing and having aportion at one end thereof of reduced crosssection, means biasing said magnetizable member to a normal position wherein said portion o-reduced cross section cooperates With the portion of reduced'cross section of said magnet yoke to form an air gap of high density rluX, said air gap restraining said magnetizable member against movement when said trip device is'energized by said overload currents of certain value to thereby retard movement of said casing With a relatively long time delay, a second armature in axial alignment with said first armature for moving said casing When said trip device is energized by overload currents of certain other value, a mechanical esca-pement device for retarding movement of said second armature with asrelatively short time delay, a ieverhaving one end connected to said second armature for operating said mechanical escapement device. and means permitting movement of said casing by said second armature independently of said time delay device to effect an instantaneous tripping operation. Y

3. In a circuit breaker, a trip device comprising an energizing Winding, a fixed magnet yoke having a portion of reducedcross section, a Sealed casing movable Within said magnet yoke to effect a tripping operation, a first armature at one end of said casing movable upon energization of said trip device by overloadcurrents or certain value to move said casing, a time delay device comprising a magnetizable member disposed in said sealed casing and having a portion at one end thereof of reduced cross section, means biasing said magnetizable member to a normal position wherein said portion of reduced cross section cooperates with the portion of reduced cross section of said magnet yoke Yto form an air gap of high density flux, said air gap restraining said magnetizable member against movement when said trip device is energized by said overload currents of certain value to thereby retard movement of said casing with a relatively long time delay, a second armature in axial alignment with said iirst armature for moving said casing when said trip device is venergized byoverload currents of certain otherr value, a mechanical escapeinent device-for retarding movement of said second armature with a relatively short time delay, a lever having one end connected to said second armature for operating said mechanical escapement device, means on said lever vfor engaging and moving said casing when said trip device is energized by overload currents of said certain othervaIue, and meanspermitting movement of said casing by said second armature independently ofA said time delay device to effect al1-instantaneous tripping operation.

4. In a circuit breaker, an electromagnetic trip device comprising an energizingr winding, a fixed magnet yoke having a portion of reduced cross section, a sealed casing movable Within said Winding to eiect a tripping operation, a rst armature at one end of said casing for moving said casing in response to VVcertain abnormal circuit conditions in said Winding, a iirst time delay means comprising a magnetizable member in said sealed casing biased to a normal position adjacent the other end of said casing, one end of said magnetizable member forming an air gap with said iirst armature and having a portion of reduced cross section cooperating with the portion of said magnet yoke toA form an air gap of khigh density iiux for restraining said magnetizable member against movement relative to said magnet yoke to thereby retard"m'ovement of said casing, a second armature movable relative to said first armature in response to certain other abnormal circuit conditions in vsaid Winding to move said casing, a second time delay device connected to said second armature for retardng movement of said second armature When said second armature is moved in response to said certain other abnormal conditions, and spring means between said first and second armatures for permitting movement of said second armature relative to said rst armature when said second armature is moved in response to said certain other conditions.

5. In a circuit breaker, an electromagnetic trip device comprising an energizing Winding, a lfixed magnet yoke having a portion of reduced cross section, a sealed casing movable Within. said winding to eiTect a tripping operation, a rst armature at one end of said casing for moving said casing in response to certain abnormal circuit conditions in said winding, a rst time delay means comprising a magnetizable member in said sealed casing biased to anormal position adjacent the other end of said casing, one end of said magnetizable member forming an air gap with said rst armature and having a portion of reduced cross section cooperating with the portion of said magnet yoke to form an air gap of high density iiux for restraining said magnetizablemember against movement relative to saidmagnet yoke to thereby retard movement of said casing, a second armature movable relative to said first armature in response to certain other abnormal circuit conditions in said winding to move said casing, a second time delay device connected to said second armature for retarding movement of said second armature when said second armature is moved in response to said certain other abnormal conditions, and spring means between said rst and second armatures for permitting movement of said second armature relative to said rst armature when said second armature is moved in response to said certain other conditions, and means for adjusting the tension of said spring to vary the minimum abnormal condition required to move said second armature relative to said first armature.

6. In a circuit breaker, an electromagnetic trip device comprising an energizing winding, a Xed U-shaped magnet yoke, a sealed casing movable within said winding to cause a tripping operation of said trip device, a rst armature disposed at one end of said casing for moving said casing upon energization of said trip device by certain overload currents below a predetermined value, a first time delay device comprising a magnetizable member disposed in said sealed casing and biased to the other end of said casing to form an air gap with said magnet yoke, said air gap restraining said magnetizable member against movement when said trip device is energized by said certain overload currents to retard movement of said casing with a relatively long time delay, a second armature disposed outside said casing and movable within said winding for moving said casing upon energization of said trip device by certain other overload currents below said predetermined value, a second time delay device comprising a mechanical escapement operatively connected to said second armature and operable when said trip device is energized by said certain other overload currents to retard movement of said casing with a relatively short time delay, a spring between said first and second armatures permitting movement of said second armature relative to said rst armature to reduce the air gap therebetween when said second armature is moved in response to said certain other overload currents below said predetermined value, and a spring between said second time delay device and said second armature to permit movement of said casing by said second armature independently of both of said time delay devices to thereby eiect instantaneous operation of said trip device.

7. In a circuit breaker, an electromagnetic trip device comprising an energizing winding, a fixed magnet yoke, a sealed casing movable within said winding to cause a tripping operation, a rst armature disposed at one end of said casing for moving said casing upon energization of said trip device by overload currents of certain value, a magnetizable member disposed in said sealed casing and biased to the other end of said casing to form an air gap with said magnet yoke whereby said magnetizable member is restrained against movement when said trip device is energized by said overload currents of a certain value to retard movement of said casing with a relatively long time delay, a tubular armature movable within said winding for moving said sealed casing upon energization of said trip device by overload currents of a certain other value, a mechanical escapement device operatively connected to said tubular armature and operable when said trip device is energized by overload currents of said other value to retard movement of said tubular armature with a relatively short time delay, a'spring in said tubular armature disposed between said first armature and said tubular armature for permitting movement of said tubular armature relative to said first armature when said tubular armature is moved in response to said overload current of certain other value, and adjusting means for adjusting the tension of said spring to vary the minimum overload current required to move said tubular armature relative to said rst armature.

8. In a circuit breaker, an electromagnetic trip device comprising an energizing winding, a magnet yoke, a sealed casing movable within said winding to cause a tripping operation of said device, a first armature at one end of said casing for moving said casing upon energization of said trip device by certain overload currents below a predetermined value, a rst time delay device comprising a magnetizable member in said casing biased to the other end of said casing to form an air gap with said magnet yoke, said magnetizable member being held against movement by energization of the trip device by said certain overload currents to retard movement of said casing, a second armature also movable within said winding for moving said casing upon energization of said trip device by certain other overload currents below said predetermined value, a spring between said rst and second armatures permitting movement of said second armature relative to said rst armature, a second time delay device for retarding movement of said second armature, a lever having one end connected to said second armature for operating said second time delay device, and a spring between said second time delay device and said lever permitting movement of said casing by said second armature independently of both of said time delay devices to effect an instantaneous tripping operation upon energization of said trip device by overload currents above said predetermined value.

9. In a circuit breaker, an electromagnetic trip device comprising an energizing winding, a magnet yoke, a sealed casing movable within said Winding to cause a tripping operation, a rst armature at one end of said casing for moving said casing upon energization of said trip device by certain overload currents below a predetermined value, a rst time delay device comprising a magnetizable member in said casing biased to one end of said casing to form an air gap with said magnet yoke, said magnetizable member being held against movement by energization of said trip device by said certain overload currents to retard movement of said casing, a second armature also movable within said winding for moving said casing upon energization of said trip device by certain other overload currents below said predetermined value, a spring between said iirst and second armatures permitting movement of said second armature relative to said rst armature, a second time delay device comprising a mechanical escapement for retarding movement of said second armature, a lever operable by said second armature for operating said mechanical escapement, and a spring between said lever and said mechanical escapement permitting movement of said casing by said Vsecond armature independently of said rst and second time delay devices to eiect -an instantaneous tripping operation'upon energization of said trip device by overload currents above said predetermined value.

,Y y TURE LINDSTROM.

JEROME SANDIN. HERBERT L. RAWLINS.

. REFERENCES CITED Y Y The ollowingl references are of record in the 111e of this patenti' f Number