US2545402A

US2545402A - Circuit breaker

Info

Publication number: US2545402A
Application number: US552997A
Authority: US
Inventors: Joseph D Wood
Original assignee: ITE Circuit Breaker Co
Current assignee: ITE Circuit Breaker Co
Priority date: 1944-09-07
Filing date: 1944-09-07
Publication date: 1951-03-13
Anticipated expiration: 1968-03-13

Description

March 13, 1951 .1. D. WOOD CIRCUIT BREAKER 2 Sheets-Sheet l Filed sept. 7. 1944 INVENTOR.

21 i'c. Z2 o. 22a

D w W D. H p m u n N n A March 13, 1951 1. D. woon 2,545,492

CIRCUIT BREAKER Filed Sept. 7, 1944 2 Sheets-Sheet 2 "D Ln IN VEN TOR.

JOSEPH D WOOD www ATTORNEY Patented Mar. 13, 1951 CIRCUIT B REAKER Joseph D. Wood, Upper Darby, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application september 7, 1944, serial No. 552,997A

(c1. zoo-ss) 3 Claims.

My present invention relates to circuit breakers, and more particularly to combined thermal magnetic circuit breakers which are adapted to be tripped with a time delay which varies inversely with the excess load placed thereon, but which are also arranged to trip instantaneously on short circuits or loads beyond a predetermined excess load.

Combined thermal magnetic circuit breakers are generally well known and frequently include some form of mechanism for operating the Contacts between open and closed position, a spring which biases a toggle mechanism toward a collapsed position to trip the contacts apart, and a latch which temporarily overcomes the action of the spring.

`The bi-metallic thermal element or the magnetic trip are arranged to operate this latch so that the action of the opening spring will no longer be defeated and so that the contacts may be separated.

Such thermal magnetic circuit breakers sometimes include simplified arc extinguishing means but rarely include arcing contacts since the current values at which they operate are relatively small.

The interrupters themselves are relatively inexpensive and the contacts, or for that matter, the Whole circuit breaker may be changed Without excessive cost.

Such terminal magnetic circuit breakers have tended, however, constantly toward greater and greater complexity as the commercial development of the art has proceeded, until the usual present day small thermal magnetic circuit breaker, while nevertheless remaining within an approximate over-all size no larger than previo is circuit breakers, has compacted the many additional elements thereof within the sameisizefcasing. These breakers .have thus become :delicate in operation; they fall readily out of adjustment; and maintenance or replacement is an important factor to be considered. I

My present invention contemplates a novel thermal magnetic circuit breaker for the protection of relatively small loads which maintains the compactness and simplicity of external operation which has previously been achieved, but which nevertheless is simplified and sturdy in oonstrucff tion and economical in manufacture and assembly. p

` My invention further contemplates a novel arrangement wherein the number of moving parts in the housing is substantially decreased and where the cverall number of parts within the housing is also substantially decreasedl delicate latches are obviated, and delicate adjustments are made unnecessary. Indeed for the most part, av circuit breaker housing for any particular capacity which is of the same size as the housingsV of prior circuit breakers having the Same capacity, is characterized in my invention by the amount of empty space within the housing itself.

This space may be filled with additional insulating elements or where the installation of a new switchboard makes this possible, the housing may be substantially reduced in size for the same capacity circuit breaker.

Accordingly, a primary object of my invention is the construction and formation of a novel thermal magnetic circuit breaker.

Another object of my invention is the formation of a circuit breaker having inverse time delay characteristics for excess loads below a predetermined value and instantaneous tripping characteristics for any excess load above the predetermined value.

Still another object of my invention is the formation of a thermal magnetic circuit breaker which is simple and sturdy in construction and in which delicate latches and moving parts are obviated.

These and many other objects of my invention will become apparent from the following description and drawings in which:

Figure 1 is a side view with the cover removed of my novel thermal magnetic circuit breaker showing the parts thereof in closed circuit position. I Y

Figure 1a is a plan view of the thermal unit of the circuit breaker of Figure l, taken from line Ia-Ia of Figure 1.l

Figure 2 is a view corresponding to those o Figures 1 and 3, showing the partsl of the circuit breaker re-set-preparatory to the circuit closing operation; and-1 l VFigure 3 is a side view of my novel thermal magneticfcircuit breaker showing the parts thereof in tripped condition.

Referring now to Figure 1, my novel thermal magnetic circuit breaker is enclosed in the insulating housing I0, the base II of which is adapted to be secured to a switchboard in any suitable manner, as for instance by connecting screws, through the openings I2 and I3 in the said base II, and in the terminals I4 and I5. Current enters through the lower terminal I4 which preferably is an L-shaped piece of suitable conductive material, the end of which passes through the slot I6 in the lower end of the houslng.-

Current then passes to the connector il which is secured to the terminal i4 in any suitable manner, as for instance by brazing; current then passes through the energizing coil i3 for the magnet I9. The magnet is secured to the interior of the wall oi the housing ill in any suitable manner. Current flows from the magnet coil i8 to the conductor Ila, the end 20 of which is secured to the lower leg 2l of the bi-metallic thermal element 22. Bi-rnetallic thermal element 22 is a U-shaped member having the customary construction. Current passes up one leg 22d of the bi-metallic thermal element 22, across the top of the U at 23, and down the other leg 22h to the terminal block 25 to which the opposite leg of the bi-metallic thermal member 22 is conductively secured at 26.

Current then passes from the terminal block 25 to the lower flexible contact support 28, through the contact support 28, to the vmain stationary contact 29 which is secured to the end of the flexible Contact support 28 in any suitable manner. The contact support 28 is mounted in a recess 35 of the base ii of the housing, and recess 35 is provided with Ia bore 3l in which is mounted the compression spring 32. Compression spring 32 drives the flexible contact support 28' of position; and spring 32 also drives the main` stationary contact 29 toward the main movable contact 35 to maintain adequate current carrying pressure.

Current then passes from the main stationary contact 29 to the main movable contact 35 on the contact bridge 36, through the contact bridge 36, to the movable arcing contact 3l and movable arcing horn 38, which are mounted on the opposite end of the contact bridge 36. Current then passes from the movable arcing contact 3'! to the stationary arcing contact ci) and stationary arcing horn 4|, which members are mounted on the end of the upper flexible contact carrying member 42. This member is exactly similar in construction to the lower iexible contact carrying member 28 and is mounted in the recess 43, the said recess having the bore 44 in which the compressing spring #l5 is positioned to drive the ilexible contact carrying member 42 toward the moving arcing contact to establish proper current carrying pressure between the arcing contacts.

The spring 45 also drives the flexible current carrying Imember 42 against the upper terminal member i5, which upper terminal member l5 prevents the Contact carrying member l2 from being pushed out by the spring. The upper terminal member i5 passes out through the slot "il in the top of the housing l adjacent the base in order that an appropriate connection ymay be made thereto.

The movement of the contact bridge 35 with respect to the housing and with respect to the stationary contact members is limited by the converging curved slots l) and 5 l.

A pin 52 carried by the bridge 36 at its lower end bears in the slot 5l and thus guides that end of the bridge when the same is brought into movement as hereinafter described. The pin 53 carried by the contact bridge at its upper end rides in the slot 5D of the housing and also guides that end of the bridge when the same is brought into movement.

An upper toggle consisting of the links Si) and 4 each other. The toggle link Bl is pivoted on the housing at the pin 64, while the toggle link 60 is pivoted on the contact bridge 36 by the pin 53. The knee-pin 52 moves over center when the circuit breaker is closed. That is, a tension spring 65 connects the opposite pins 5G and 53 of the toggle tending to collapse the toggle, as shown in Figure 2. When the circuit breaker is brought to the fully closed circuit position, the toggle is straightened against the tension of spring 65 and then the knee-pin 52 moves upwardly over center to a position where the spring 35 tends to collapse the toggle upwardly. This upward collapse of the toggle, however, is prevented by the fact that the link 60 of the toggle 2-52-6i bears against the end wall 53 oi the arc chute lil. Consequently, the toggle U-GZ--l by its movement over center positively maintains the arcing contacts 36 and 3l in engagement while the spring 45 on the upper Contact carrying member 52 ensures adequate contact pressure.

The lower end of the contact bridge 36 is also provided with a toggle consisting of the links l2 v and T3 connected by the knee-pin lil. The leit-v hand end of the left-hand link i2 is connected to the pin 52 at the lower end of the contact bridge 35, while the right-hand end of the righthand link I3 is connected to the stationary pin" 15 carried by the wall oi the housing.

spring 16 between pins 'i5 and 52 tends tocollapse the toggle. Ordinarily in the open condition of. the circuit breaker, where the

lower contacts

35 and 29 are open, the toggle collapses upwardlyv as shown in Figure 3. When the circuit breaker is fully closed, the knee-pin l@ of the toggle is moved downwardly to straighten the toggle' against the tension of the spring 'i6 and the said knee-pin 74 moves over center so that the collapsing force of the spring 'I6 on the toggle is a downward force. This downward collapsing force is resisted by the pin 'it carried by the housing which acts as a stop therefor.

Here again the contact 35 is maintained in current carrying relation with the stationary contact 29 in a positive manner by the over center position of the toggle l2-lll-l3 while appropriate current carrying engagement between contacts 39 and 25 is obtained by the compression spring 32 which urges the flexible contact carrying member 26 toward the movable contact 35.

A yoke 80, preferably of insulating material, is connected to the knee-pin 32 of the upper toggles. The yoke 8D is provided with a slot 8B at its upper end through which pin 52 passes. The normal position of the yoke 83 in the closed circuit position of the circuit breaker as shown in Figure 1 is one wherein the uppermost end of the slot 88 bears against the upper side of the knee-pin 62 of toggle 60--62--5L The lowest end of the yoke `8|l is provided with a ire-entrant flange 9@ which extends just below the end 23 of the bi-metallic element 22.

On the occurrence of excessive current conditions suiiicient to heat bi-inetallic element 22 to deflect the same downwardly, the end 23 of the bi-metallic element bears against the flange and pulls the yoke et downwardly. The upper end of slot 28 of the yoke then pulls the knee-pin 62 of the toggle {iQ-Z--i downwardly through center, and when the toggle passes through center so that the knee-pin is below the line of the spring 65, the tension spring collapses the toggle in the manner shown in Figure 2 and the arcing contacts 36. and 31 separate and inter-1v A tension rupt the current ow through the circuit breaker (see Figure 3). f

The yoke 8c is slidably positioned in the,r ousing 90 in any suitable manner, as for instance by being mounted in a slot in the wall of the housing or by the pin extending from the Wall of the housing into the long slot |0| of the yoke 8G (Figure 3). rlhe yoke 8! is free toV move downwardly once the toggle G-SZ-BI collapses so that the slot 8E therein offers no impediment to the opening of the arcing contacts.

When the arcing

contacts

36 and 31 separate, an aro is drawn between them and moves up on to the-arcing horns 38 and 4| and moves into the arc chute l0. The arc chute 'IU is of the type described in Patent No. 2,353,729 for Air Blast Arc Chute, issued July 18, 1944, to O.`Jensen. and consists of successive U-shaped plates 95 of relatively high electrical resistance. As the arc moves upwardly and is broken in series between these plates, the movement of the arc along these plates not only cools the arc but progressively introduces greater resistance in series with the arc, thus further hastening the interruption thereof.

The arc gases are then vented through the top opening 95 of the areJ chute 10. On the ocourrence of excess current conditions above a predetermined value, as for instance in the case of short circuits, the magnet i9 is sufficiently energized by the coil I8 to attract the armature 91 mounted on the bi-metallic element 22 and thus causes the end 23 of the lei-metallic element to be deilected downwardly to engage the flange 90 of the yoke 8|) to cause collapse of the toggle 60-62-2! and thus to cause the arcing contacts 36 and 3l to separate.

During the separation of the arcing contacts 36 and 3l, the

main contacts

35 and 29 remain connected not only because of the over center position of their toggle '|2-'|4-13 but also because the curves of the two slots 50 and 5| are such that the only position which

main contacts

35 and 29 may assume when the arcing contacts open is the closed position. main contacts 29 and S5 never carry interrupting current.

A connecting link l lo is provided between kneepins 52 and 'le of the upper and lower toggles. The connecting link |59 has an upper slot and a lower slot l I2 engaging respectively the upper knee-pin 52 and the lower knee-pin T4. The connecting link il is also provided with a pin 8| which is engaged by the slot 82 of the end 83 of the handle 84, which handle is rotatable about the pin 85.

In order now to re-set the arcingr contacts in closed position from the position of Figure 3 to the position of Figure 2, the end 84 of the handle is rotated downwardly invraclockwise direction. Through the slot 32 in the opposite end 83 of the handle the pin 8l of the connecting link H0 is forced upwardly. The lower end of slot il! now forces the knee-pin 62 of the toggle 60-52-5! upwardly against the tension of the spring S to straighten the toggle and finally to force the same throughA center sothat the tendency of the spring E5 is-to collapse it upwardly, this collapsing force being resisted by the wall 68 of the arc chute 'lo which wall bears against the link 60.

Thus, as shown in Figure 2, by the downward rotation of handle Sil, the arcing contacts are closed. During this upward movement of the connecting link H0, the lower end of the slot Consequently the l |12 in the connecting link ||0 engages the kneepin 'I4 of the toggle l2-14f-13 and breaks the same upwardly through center so that it collapses and opens the

main contacts

29 and 35.

During this upward movement of the toggle pin 62, the yoke te is carried upwardly also by the pin 62 in the slot 88 to re-position the yoke 89 for a subsequent tripping operation, also as shown in Figure 2.

When the members have reached the position of Figure 2, the handle 84 may now be rotated upwardly to close the

main contacts

29 and 35. This upward rotation of the handle 84 in a counterclockwise direction moves the opposite end 83 downwardly and hence the slot 82 moves the pin Bi of the connecting link lll! downwardly. The lower slot il2 in the connecting link now. engages the pin i!! or" the toggle 12--14--13 to straighten the toggle against the tension of spring l' and moves the knee-pin 'I4 through center so that the collapsing force of the spring 16 is one which would now tend to collapse the toggle downwardly; this downward :collapsing force is however resisted by reason of the fact that the link 'i3 of the toggle bears against the stop '18.

When this operation is completed, the circuit breaker parts are back once more in the position shown in Figure 1 where the circuit breaker is in closed circuit position.

The operation is entirely trip free since on closing of the

main contacts

29 and 35, the yoke 89 is free to move to collapse the toggle oli-624| even though the handle Sil is held upwardly. This is obvious from an inspection of Figure 3 where even though the handle 84 is in upward or closed position, the toggle @il-eZ-l has collapsed.

Should it be desired to open the circuit breaker manually, a downward rotation of the handle 84 from the position shown in Figure 1 to the position shown in Figure 2 will move the con necting link Ii!) upwardly until the lower end of slot H2 moves the knee-pin lli through center to collapse the toggle l'2-14-l3 and open the

contacts

29 and 35. Since this manual opening operation will occur under normal current oonditions, no arc extinguishing means need be provided for contacts 29 and S5. Arc extinguish ing means are required only for the contacts 26 and 3l which will interrupt excess loads.

A simple indication is provided for the condition oi the circuit breaker. The toggle 6| has a small extension |29 beyond the pin E@ which eX- tends slightly outside the front end of the housing ii. When the circuit breaker is in the fully closed circuit position of Figure l, the handle 84 is up and the extension |26) extends straight outrom the circuit breaker. The end |2| of the extension |29 ,may be marked with the word On When the circuit breaker trips to the position shownin Figure 2, although the handle 84 remains up, the extension |20 will have been rotated upwardly so that the surface |22 will become visible. This surface |22 may be marked with the word Tripped Even though the extension |26 may be in the On position, shownin Figure 2, the position of the handle 84 in the down position oi Figure 2 will show that the circuit breaker is oir. Consequently the upper position of the handle should `be marked On and the down position of the handle should be marked O' In the foregoing I have illustrated my invenation.v only .in connection with .preferred .simple embodiments thereof. The essence of the invention includes simplied, latchless and sturdy operating members for the circuit breaker, which members are readily accessible for replacement and repair. This simplicity and sturdiness, as contrasted with the many delicate moving parts and latching means of prior thermal magnetic circuit breakers, is a definite benent with respect to economical manufacture, assembly and maintenance.

All flexible pigtails which have often been a source of trouble in prior thermal magnetic circuit breakers have been eliminated by the use of the two flexible contact carrying members 29 and ft2, which are biased into appropriate position by the small compression springs il and 32, which springs themselves are fully protected since they are completely covered by the exible contact carrying members.

While these contact carrying members have been described. as flexible contact carrying members, it is obvious from the foregoing that they may preferably be rigid members, the mounting of which however, is fieXib-le, in that they are not positively held at either end but are biased into appropriate position by their respective'springs. This elimination of pigtails eliminates one of the primary reasons for wear and maintenance in prior thermal magnetic circuit breakers. This circuit breaker structure has been found to be practical in operation and unique in its freedom from necessity from maintenance and repair.

Since many variations and modifications of my invention will now be obvious to those skilled in the art, I prefer to be bound not by the specinc disclosures herein, but only by the appended claims. I claim:

l. In a circuit breaker, a, first stationary contact and a rst movable contact engageable therewith, a first toggle connected to said first movable contact, said rst toggle being over-set when said first movable contact engages said first stationary contact; a second stationary contact and a second movable contact; said first and second movable contacts being in series with and rigidly connected to each other; said circuit breaker having a first and a second terminal; said rst and second stationary contacts being connected respectively to said first and second terminals; a second toggle connected to said second movable contact, said second toggle being over-set when said second movable contact engages said second stationary contact; means automatically responsive to selected current conditions for drawing said first toggle through center and collapsing the same to move said rst movable contact away from said first stationary contact; a link connecting said toggles; and a manually operated member connected to said link for drawing said second toggle through center and. collapsing the same to move said second movable contact away from said second stationary Contact, and for thereafter operating said first toggle to eiiect engagement of said first mentioned cooperating contacts.

2. In a circuit breaker, a rst stationary con'- vtact and a first movable contact engageable 'therewith, a rst toggle connected to said rst movable contact, said first toggle being over-set when said rst movable contact engages said first stationary Contact; a second stationary contact and va second movable contact connected in series. with said first mentioned contacts; .said circuit breaker contact, said second toggle being over-set when 1 said second movable contact engages said second stationary contact; means automatically responsive to selected current conditions for drawing said rst toggle through center and collapsing the same to move said rst movable contact away from said rst stationary contact; a link connecting said toggles; and a manually operated member connected to said link for drawing said second toggle through center and collapsing the same to move said second movable contact away from said second stationary contact; and for thereafter. operating said first toggle to effect engagement of said rst mentioned cooperating contacts; said manual and automatic means being independently operable to open their respective contacts, and providing trip free action to said circuit breaker.

3. In a circuit breaker, a first stationary contact and a rst movable contact engageable therewith, a first toggle connected to said rst movable contact, said first toggle being over-set when said first movable contact engages said first stationary contact; a second stationary contact and a second movable contact connected in series with said first mentioned contacts; said circuit breaker having a first and a second terminal; said first and second stationary contacts being connected respectively to said first and second terminals; a second toggle connected to said second movable contact, said second toggle being over-set when said second movable contact engages said second stationary contact; means automatically responsive to. selected current conditions for drawing said first toggle through center and collapsing the same to move said first movable contact away from said first stationary contact; a link connecting said toggles, slots in said link, pins on said toggles movable in said slots, and manually operative means connected to said link for drawing said second toggle through center and collapsing the same to move said second movable contact away from said second stationary contact; and for thereafter operating said rst toggle overcenter to eiiect engagement of said first mentioned contacts; said manual and automatic means being independently operable to open their respective contacts; and said toggles being connected to said link through said movable pins in said slots m said link whereby said automatic means are operable to trip said circuit breaker open while said manual means is held against opening to effect trip free operation thereof.

JOSEPH D. WOOD.

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

, UNITED STATES PATENTS Number Name Date 661,771 Rucker Nov. 13, 1900 1,720,263 Chandler July 9, 1929 1,772,442 Hanny Aug. 5, 1930 2,122,693 Maseng- July 5, 1938 FoRErGN PATENTS Number Country Date 66,678` Germany Jan. 18, 1893 244,548 Great Britain Dec. 24, 1925