US2486300A

US2486300A - Electromagnetic trip circuit breaker

Info

Publication number: US2486300A
Application number: US542718A
Authority: US
Inventors: Lindstrom Ture; George G Grissinger
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1944-06-29
Filing date: 1944-06-29
Publication date: 1949-10-25
Anticipated expiration: 1966-10-25

Description

Oct. 25, 1949. r. LINDs-rRoM Er AL ELECTROMAGNETIC TRIP CIRCUIT BREAKER Filed June 29, 1944 Wim/E@ Patented Oct. 25, 1949 ELECTROMAGNETIC TRIP CIRCUIT BREAKER Ture Lindstrom, Edgewood, and George G. Grissinger, Wilkinsburg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 29, 1944, Serial No. 542,718

Claims. (Cl. 200-109) device including anv armature operable to trip the breaker with improved means for adjusting the armature biasing means. to thereby vary the minimum current required to instantaneously trip the breaker.

Another object of the invention is to provide a circuit breaker wherein an electromagnetic trip device having a movable armature biased against attraction and operable by said electromagnet to trip the breaker with improved means for manually adjusting the tension oi the biasing means to thereby vary thel minimum overload current required to trip the breaker.

The novel features that are considered char- 2 Lindstrom and assigned to the assignee of the present invention. For a more detailed description lof the construction and operation of the main circuit breaker, reference may be had to acteristic of the invention are set forth in particular in the appended claims. 'Ihe invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will best be understood from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawing, in which:

Figure 1 is a vertical sectional view of a threepole circuit breaker showing the operating mechanism and the trip device embodying the principles of the invention.

Fig. 2 is an enlarged sectional view of the trip device showing the improved adjusting device.

Fig. 3 is a sectional view of the trip device taken on line III- III of Fig. 2 and showing the adjusting device,

Fig. 4 is a iront elevational view showing the portion of the adjusting lever which projects outside the breaker casing, and

Fig. 5 is a fragmentary sectional View of the adjusting device.

Referring to Fig. l of the drawing, the circuit breaker illustrated is of the three-pole type and is of the same general construction as the circuit breaker fully described in United States Patent No. 2,083,304, issued June 8, 1937, to Ture the above-mentioned patent.

The circuit breaker comprises, in general, a casing II of I.molded insulating material having a removable cover I3 secured thereon, stationary contact means I5, cooperating movable contact means Il, an operating mechanism I9 and a unitary trip device 2l.

Three sets of stationary and movable contact means |5--II are provided forming the three poles oi the breaker. The movable contact means Il for the several poles are mounted on contact members 23 and the movable contact members 23 for the center pole are pivotally mounted on a movable switch member 25, and are biased toward the stationary contact means I5 relative to the switch member 25 by means of springs 21 carried by the switch member.

The switch member 25 is pivotally mounted by means of a pivot pin 29 on a U-shaped main frame 3l which also supports the circuit breaker operating mechanism I9. The switch members for the outer poles are connected to the center pole switch, member 25 for simultaneous movement therewith by means of a rigid tie bar 33 which extends transversely across the three poles of the breaker. Each switch member is securely clamped to the tie bar 33 by a clamp 35, and the switch members are insulated from the tie bar and from each other by means of an insulating sleeve 31 surrounding the tie bar 33.

The electrical circuits for the several poles of the breaker are the same for which reason only the circuit for the center pole will be described. This circuit extends from an upper terminal 45 through a conductor 41, the stationary and movable contact means I5Il, a flexible shunt conductor 49, a conductor 5I and an energizing conductor 53 for the trip device 2i to the lower terminal 55.

The operating lmechanism I9 (Fig. 1) is mounted in the main frame 3| and includes a toggle comprising a pair of toggle links 5l and 59 having one end pivotally connected to the center pole switch member 25, a carrier lever 5I for releasably restraining the other end of the toggle 51-59 in operative position, a channel-shaped operating :member 63, an overcenter spring for connecting the operating member 63 to the knee 61 of the toggle 51-59, and an operating handle 69.

The main frame 3| is disposed below the contact means and is rigidly secured to the base of the casing I I by means of screws il and 13. The screw 13 extends through the conductor 5| and serves to secure the conductor 5I as well as the frame 3| to the casing. One end of the toggle link 51 is pivotally connected to the center pole switch member 25 by a pivot pin 11 and the other end or the toggle link 51 is pivotally connected to one end of the toggle link 59 by the knee pivot pin 51.

The lower end of the overcenter spring unit is pivotally connected to the lower end of the operating member 63 by means of a pivot pin 8| and a pair of supporting ears S3 projecting from the operating member 53. The operating member 53 is pivotally supported on the main frame 3| by means of a pivot pin 85. The lower end of the toggle link 59 is pivotally connected to the carrier lever 6| by means of pivots 81 only one of which is shown.

The carrier 5| is pivotally in the main frame by means of a pivot pin 39 at the apex of the bell crank levers. Clockwise movement of the carrier lever is normally prevented by a latching lever 9| comprising a pair of spaced parallel levers which are joined by integral yokes 93 and 95 and pivotally mounted on a pivot pin 91 supported in the main frame 3|. The yoke 93 of the latching lever 9| normally engages the upper end of the carrier lever 6I and restrains the carrier lever in operative position. The free lower end of the latching lever 3| carries a pivoted latch engaging paWl S9 supported on the yoke 95 of the latching lever, the pawl 99 and the latching lever :'21 being normally restrained by the trip device 2 i.

When the trip device is operated the pawl 99 and the latching lever 3| are released thereby permitting counterclockwise movement of the latching lever under the biasing influence of the overcenter spring unit 55. This movement of the latching lever causes the yoke 93 to release the carrier lever 6| which is then moved clockwise about the pivot 89 by the overcenter spring unit 55 and the force exerted by the contact springs '21. This causes bodily movement and eventually collapse of the toggle 51-59 toward the base of the casing I I in simultaneous opening of the contacts for all or the poles of the breaker.

In order to reset the breaker following an automatic tripping operation, the operating handle 59 is moved in a clockwise direction to the off posiion. This operation of the handle causes the operating member 53 to engage and reset the carrier lever 6| and the latching lever SI to their latched positions. The contacts may then be closed by moving the operating handle |59 in a counterclockwise direction to the on position.

The circuit breaker may be opened manually by moving the operating handle S9 in a clockwise direction from its Figure l position to its extreme clockwise position. When the handle has been moved a short distance, a projection (not shown) on the operating member 53 engages the yoke 15 of the toggle link 51 and starts the knee 51 of the toggle 51-59 toward the base of the breaker at the same time the spring 35 moves across the center line of the toggle link 59 and now exerts a force in a direction to move the knee of the toggle toward the base. The movement of the several parts of the operating mechanism is now automatic and the contacts for all of the poles are opened simultaneously with a snap action.

The contacts are closed after they have been opened manually by moving the operating handle in a counterclockwise direction which carries the 4 line of action of the spring unit 55 over the center line of the toggle link 5S. The springs 65 then exert a force biasing the knee of the toggle outwardly from the base, causing straightening of the toggle and closing of the contacts of all of the poles with a snap action.

The trip device comprises a unitary structure the several elements of which are mounted on a panel |0| (Figs. 1 and 2) of insulating material removably mounted on the base of the casing The trip device is enclosed in a casing |02 and comprises generally a bimetal element |533 and an electromagnet |05 for each pole of the breaker. The conductor 53 forms a loop |51 which, near its left-hand end, is secured to a bracket |09 by means of rivets III. The rivets I|| also serve to rigidly secure one Aend of the bimetal element |03 to the conductor 53. The bimetal element |03 extends to the right substantially parallel to the upper leg of the loop |01 of the conductor 53 which serves as a heater element for the bimetal element. The bracket |09 is firmly secured to the panel IUI by means of bolts I|3 which pass through openings in the panel and in the bracket |39 thereby rigidly securing the conductor 53 and the bimetal element |03 to the panel. A trip bar |35 of insulating material is pivotally supported by means of brackets I I'I (only one being shown) which are suitably secured to the panel I0 I. The trip bar extends across all of the poles of the breaker and is adapted to be operated by the thermal trip device or the electromagnetic trip device of any pole to effect release of the operating mechanism and opening of the contacts. Secured to the trip bar ||5 is a latch member IIS which engages and restrains an intermediate latch I2 I. The latch I2I is pivotally mounted on a pin |23 in the bracket IIT and is provided with a latching portion which engages the pawl 99 and restrains the latching lever 9| and the operating mechanism in the closed position. Also secured to the trip bar II5 is an extension |25 having secured thereto near its free outer end a pin |21 which is adapted to cooperate with the bimetal I 03 to operate the trip bar.

Upon the occurrence of an overload current below, for instance 1000% of normal rated current in the circuit of any pole of the breaker, the bimetal element |03 associated with the affected pole is heated by the flow of excessive current through the loop |01 of the conductor 53 and when heated a predetermined amount deflects upwardly rotating the trip bar I|5 counterclockwise about its pivot point, This movement of the trip bar releases the latch I2I whereupon the for-ce of the operating springs 65 (Fig. 1) causes opening of the contacts in the previously described manner.

The breaker is tripped instantanteously upon the occurrence of overloads of 1000% 'or more of normal rated current, or on short circuits by means of the electromagnetic trip means |05. The electromagnet |05 comprises a fixed U-shaped core member |29 (Figs. l and 2) rigidly supported on the bracket |09, and a movable armature I3 I slidably mounted on a pair of spaced rods |33 (see also Fig. 3) secured to and projecting downwardly from the panel ISI. The armature |3| is biased to unattracted position by means of springs |35 surrounding the rods |33 and cornpressed between the ends of a bar |31 to which the armature is secured, and washers |39 on the lower ends of the rods |33. The washers |39 are supported by the legs I4I of a bifurcated adjusting lever |43 (Figs. 2, 3 and 4). The end of each of the legs 14| is formed to straddle the corresponding rod |33 to adjustably support the washers |39 and maintains the springs |35 in compression. The upper leg of the conductor loop |01 passes between the poleypieces of the U-shaped magnet core |23 and serves as an energizing means for the electromagnet.

Normal current flowing in the circuit of the breaker including the conductor 53, energizes the electromagnet |05 but not sufficient to attract and operate the armature |3| against the force of the biasing springs |35. Upon the occurrence of an overload current of 1000% or more of normal, or a short circuit, the electromagnet is energized sulciently to instantaneously attract and move the armature to the pole pieces of the core member |29. During this movement the armature I 3| engages a projecting member |45 secured to the trip bar I5 and thereby actuates the tripbar to release the` intermediate latch |2| and cause opening operation of the breaker mechanism in the manner previously described.

In orde-r to adjust the tension of the springs |35, the lever |15 is rs't drawn out until the end of the slot |13 engages the pin |65. The outer or handle end of the lever |15 is then moved outwardly away from the bracket |53 in order to disengage the pin |60 from the slot |1| after which the lever |15 is rotated clockwise (Figs. 2 and 5) about the pivot |05 to the desired position. The lever |15 is then released and the head of the pin |59 enters the appropriate slot |1| which retains the adjusting device in the position to which it is set. The force of the springs |35 pressing the arm |48 (Fig. 5) against the rounded end of the arm ||5| of the U-shaped lever |63 produces a force which tends to turn the lever |53 counterclockwise in the plane ofthe axis |65 of the lever. This presses the arm |51 of the lever |63 against the side .of the bracket |53 adjacent the lever, thus retaining the pin |60 in the selected slot |1|. The lever |15 is then slid inwardly over the pins IE5- |09 to the position shown in the drawing.

Assuming that the breaker is rated to carry a normal current load indenitely without actuating the trip device, the bimetal |03 may be calibrated to trip the breaker with an inverse time delay in response to overloads of, for example, between and 300% of the normal rated current. The electromagnetic trip device may be calibrated and adjusted to instantaneously trip the breaker on overloads of, for instance, between 300% and 1100% of rated current depending on the setting of the lever |43 and the corresponding tension placed on the springs |35. Assuming that the Itrip device is calibrated to the arbitrary values set forth above, with the lever |15 set to the low position, as shown in Figs. 2 and 4, the electromagnet will operate in response to an overload current of 300% or more of normal current to instantaneously trip the breaker. If the adjusting lever |15 is moved to the high position to correspondingly increase the force of the springs |35 biasing the armature against operation, the armature will not be attracted until the occurrence of an overload current of 1100% or more of normal. By adjusting the lever |15 to a point between the high and low positions, the magnet will function to instantaneously trip the breaker in rresponse to an overload current of -a minimum value corresponding to the particulassetting of the lever |15. It Will be apparent that the device may be set to cause instantaneous tripping 'of the breaker in response to minimum overloads of, for instance, 300%, 500%, 700%, 900% or 11.00% `of normal rated current. It will be understood that if the device is set to instantaneously trip out at a minimum overload of, for example, '700% of normal, the bimetal element |03 will function to trip the breaker after a time delay upon the occurrence of overload currents of any value between 100% and '700% of rated current, or between 100% of normal current 'and th'e particular minimum current value between 300% and 11.00% at which the device is set.

The low or minimum current value at which the magnet will operate to instantaneously trip the breaker -may be further adiusted by adding or removing Washers |39 (Fig. 5) thus increasing or reducing the initial tension of the springs |35 and the "lolw setting of the device. In order to remove or add washers |39, the cover |02 is removed an-d the operating lever |15-411 is 4moved counterclockwise beyond the low position until it strikes a stop |10 (Fig. 5) in which position the lever |413 has been moved a sumcient distance in a counterclockwise direction to clear the ends of the rods |33 and permit the removal of or the insertion of additional washers |39. The device is then adjusted lto the low setting. The cover |02 is replaced and sealed so that the adjustment cannot be tampered with.

While the invention has been disclosed in ac- 'cordance with the provisions of the patent statutes, it is to be understood that various changes and modifications in the structural details and arrangement of parts thereof may be made Without departing from some of the essential features of the invention. It is desired, therefore, 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, the combination of an armature operable to cause opening of Said circuit breaker, spring means arranged to bias said armature against operation, an electromagnet op.- erable in response to predetermined overload current conditions to operate said armature, a lever supporting said spring means, said lever being movable to vary the tension of said spring means to th'ereby determine the minimum overload current value required to operate said armature, and manual means comprising an adjustable lever engaging said supporting lever and operable when adjusted to move said supporting lever.

2. In a circuit breaker, the combination` of an armature operable to cause opening of said breaker, means supporting said armature for sliding movement, means comprising a pair of compression springs arranged -to bias said yarmature against operation, .an electromagnet operable in response to overload currents above a predetermined value to operate said armature, a lever having spaced projections engaging and supporting said compression springs, and a lever manually operable to move said supporting lever to vary the compression of said springs to thereby selectively determine the minimum overload current required to operate said electromagnet.

3. In a circuit breaker, the combination of an armature operable to cause opening of said breaker, spaced supports slidably supporting said armature, spring means surrounding said supports and disposed to bias said armature against operation, a pivoted lever having portions thereof engaging and supporting said spring means, said lever being adjustable to vary the tension of said springs, an electromagnet operable in response to overload currents of a `predetermined value toy operate said armature, and a manually adjustable lever movable to adjust said pivoted lever to selectively deter-mine the operating characteristic of said electromagnet,

4. In a circuit breaker, the combination of a trip member operable to effect opening of said circuit breaker, an armature movable to operate said trip member, a plurality of springs disposed to bias said armature against attractin, a support member common to all of said `springs adjustably supporting said springs, a manual lever having a cam portion engaging a portion of said support member, said manual lever being operable to adjust said support member to simultaneously vary the tension of all of said springs, and an electromagnet operable in response to overload currents to operate said armature to effect opening or" said circuit breaker.

5. In a circuit breaker, the combination of an armature operable to effect opening of said circuit breaker, spaced supports slidably supporting said armature, spring means disposed to bias said armature against operation, a pivoted lever having spaced portions thereof engaging and supporting said spring means, said lever being adjustable to vary the tension of said spring means, electromagnetic means operable in response to overload currents to operate said armature, a

manually adjustable lever movable to adjust said pivoted lever to thereby selectively determine the minimum overload current required to operate said electromagnetic means, and a projection on said manually adjustable lever engaging a fixed member to restrain said manually adjustable lever and said pivoted lever in the adjusted position, said spring means acting through said pivoted lever to maintain said restraining means in engagement with said fixed member.

6. In a circuit breaker, the combination of an electromagnet including a U-shaped magnet core, an armature operable in response to overload currents to effect opening of said circuit breaker and an energizing conductor extending between the legs of said core member for energizing said electromagnet, spring means disposed to bias said armature against operation, a pivoted lever having spaced legs straddling said conductor and supporting said spring means, and a manually adjustable member movable to adjust said lever and vary the tension oi said spring means to thereby vary the minimum overload current required to operate said armature.

7. In a circuit breaker, a trip device operable in response to overload currents to eiect opening of said circuit breaker comprising a sealed casing enclosing said trip device, a conductor having an energizing loop disposed in said casing, an electromagnet energized by said conductor, an armature operable by said electromagnet to release said operating mechanism, a pair of springs disposed to bias said armature against operation, a iorked lever straddling said loop and supporting said springs, a manually operable lever having a portion extending through an opening in said casing, and said manually operable lever engaging said forked lever and being operable to adjust said forked lever to vary the tension of said springs thereby varying the minimum overload required to operate the armature.

8. In a circuit breaker, the combination of trip device operable to effect opening of said circuit breaker comprising a sealed casing enclosing said trip device, a conductor having an energizing loop disposed in said casing, an electromagnet disposed in said casing between the legs of said loop to be energized thereby, an armature operable by said electromagnet, a pair of springs disposed one on each side of said loop biasing said armature against operation, a support lever mounted in said casing and having legs straddling said loop supporting said springs, a manual lever mounted in said casing and having a portion engaging said support lever, and an eX- tensible arm slidably mounted on said manual lever and extending through an opening in said casing and operable to adjust said support lever to thereby vary the tension oi said springs.

9. In a circuit breaker, the combination oi a tripping electromagnet including an armature operable in response to overload currents to effect automatic opening of said breaker, a pivoted lever, spring means compressed between one end of said pivoted lever and said armature biasing said armature against operation, said pivoted lever being positionable to selectively vary the compression of said spring means while said armature remains stationary to thereby vary the minimum overload current required to operate said armature, and a settable lever cooperating with said pivoted lever to selectively position said pivoted lever.

10. In a circuit breaker, the combination of a tripping electromagnet, a slidable armature operable to cause opening of said circuit breaker, said electromagnet being operable in response to overload currents to operate said armature, a pivoted member, a plurality of springs compressed between said pivoted member and said armature biasing said armature against operation, and a manual operator cooperating with said pivoted member and operable to adjustably position said pivoted member to thereby simultaneously vary the compression of all of said springs while the armature remains stationary to thereby vary the tripping point of the breaker.

TURE LINDSTROM. GEORGE G. GRISSINGER.

Cil

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS