US2811607A

US2811607A - Circuit breaker

Info

Publication number: US2811607A
Application number: US411474A
Authority: US
Inventors: Hiller D Dorfman; Francis L Gelzheiser
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1954-02-19
Filing date: 1954-02-19
Publication date: 1957-10-29
Anticipated expiration: 1974-10-29

Description

Oct. 29, 1957 H. D. DORFMAN ET AL 5 Sheets-Sheet 1 I5 5 Insulation s1 95 u WITNESSES: i 2 INVENTORS Hiller D. Dorfmon 8 Francis L. Gelzheise 3 Sheets-Sheet 2 Oct. 29, 1957 Filed Feb. 19, 1954 n .m .l 7 9 m 9 77 m m 92 We m 3 7 3 3 1 6 7 7 g 9 6 F 35 3 7 "w 5 I HQ 6 3 Hg 9. 1\

7 I T 7 3 5 I. 4 5 7 2 9 1957 H. D. DORFMAN ETAL 2811607 CIRCUIT BREAKER United States Patent Q CIRCUIT BREAKER Hiller D. Dorfrnan and Francis L. Gelzheiser, Beaver, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 19, 1954, Serial No. 411,474

23 Claims. (Cl. 200-116) This invention relates to circuit breakers, and, more particularly, to multi-pole circuit breakers which are manually opened and closed, and which are opened antomatically upon the occurrence of an overload current in any pole of the breaker.

An object of the invention is to provide a circuit breaker having a housing comprising a base and a cover in which many of the parts of the breakers are mounted in the cover, with other parts mounted on the base.

Another object of the invention is to provide a multipole circuit breaker having an operating handle extending into each of the poles of the breaker with the contact arms for the several poles individually supported on the handle.

Another object of the invention is to provide a multipole circuit breaker having an insulating housing comprising a base and cover in which the movable parts are mounted in individual compartments in the cover and held in place when the base is put in position.

Another object of the invention is to provide a multipole circuit breaker having an insulating housing comprising a base and a cover in which an operating handle extends into each pole of the breaker to support and operate a contact arm in each pole, and a releasable member extending into each pole operable when released to effect individual opening operation of the contact arm for each pole.

A further object of the invention is to improve the assembly and lower the cost of circuit breakers of compact construction by having the movable contact member pivoted within the cover and extending downwardly into the base and electrically connected to a bimetal element on a terminal strip also positioned in the cover.

Another feature of the invention lies in the provision of a multi-pole breaker having a plurality of pivoted trip members connected together by an insulating cross bar substantially at the pivot axis of the trip member, with only a single latch holding all of the trip members. More specifically, the cross bar extends through one or more partitions between the pole units and substantially closes the one or more openings through which it extends.

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

in said drawings:

Figure l is a top plan view, partly in section, of a circuit breaker embodying the principles of the invention, the sectioned part being taken along line II of Fig. 2.

Fig. 2 is a vertical sectional view through the center pole taken on line II-II of Fig. 1 looking in the direction indicated by the arrows.

Fig. 3 is a vertical sectional View through an outer pole of the breaker taken on line III-III of Fig. 1 looking in the direction indicated by the arrows.

Fi g. 4 is a perspective view of the operating handle.

ice

Fig. 5 is a perspective view of the common releasable member.

Fig. 6 is a vertical transverse sectional view taken substantially along line VI-VI of Fig. 2 and looking in the direction of the arrows.

Fig. 7 is an end elevational view of the circuit breaker, the housing being partly broken away to show the trip device.

Referring to Figs. 1 and 2 of the drawings, the circuit breaker generally comprises a two-piece housing of molded insulating material comprising a base 11 and a cover 13, stationary contacts 15 and movable contacts 17 for each pole of the breaker, operating mechanism 19 and a trip device 21. The housing is divided into three separate compartments by means of matching

barriers

23 and 25 molded integral respectively with the base 11 and cover 13. While a 3-pole breaker is specifically described, the invention may be utilized in 2-pole breakers by merely omitting one of the outer compartments and the parts therein.

The stationary contacts 15 for each compartment are mounted on the inner ends of conductor strips 27, each of which extends through an opening in the adjacent end wall of the base 11 and has a line terminal connector 29 at its outer end for connecting the breaker to an electrical circuit. The stationary contact strips 27 are merely inserted in recesses in the base 11 and are held in place by the lower edge of the cover 13. The moving contact 17 for each pole is rigidly secured to a U-shaped switch or contact arm 31. The three contact arms 31 are operated to open and closed positions by the operating mechanism 19 to open and close the circuit.

The operating mechanism 19 comprises an operating member 32 having an operating lever 33 for each pole of the breaker and an operating handle 35, an overcenter spring 37 and a releasable trip meber 39. The operating member 32 including the handle 35 and the operating levers 33 for the several poles comprise a single member of molded insulating material so that operation of the handle simultaneously moves all of the levers 33. Molded on the operating member 32 are bearing surfaces 41 for pivotally supporting the member on the barriers 25 or on other bearing portions in the cover 13. The barriers 25 are provide-d with slots 43 for receiving and positioning the operating member 32. After the operating member in inserted into the slots 43, support and closure members 45 of insulating material are insorted in the slots 43 and suitably secured therein. When the base 11 is applied to the cover 13, the members 45 are secured in place by the upper edge of the base. The upper ends of the members 45 have a semi-circular notch engaging and supporting the lower sides of the bearing portions 41 so that the several poles are well isolated.

The releasable trip member 39 (Fig. 5) comprises a spring support lever or trip arm 47 for each pole of the breaker, each of the spring support or trip levers being secured adjacent its pivot axis to a tie rod or cross bar 49 of molded insulating material for unitary movement. The tie rod is provided with bearing portions 51 (Figs. 5 and 6) for supporting the releasable trip member 39 in the barriers 25 or on other bearing portions of the cover 13. The spring support or trip lever 47 for the center pole of the breaker extends toward the right (Figs. 2 and 5) and has a latch end 53 which is normally engaged by and releasably held by a single latch of the trip device (to be later described) to releasably hold all of the trip arms of the releasable trip member in operative position.

Each of the levers 33 (Figs. 3, 4 and 6) is bifurcated and the spaced legs 55 thereof are provided with notches 57 in which are seated the legs 59 of the U-shaped switch members 31 Thus the switch members 31 are pivoted at their upper ends in the notches 57 within the cavity in the cover 13 and their lower ends carrying the moving contacts 17 extend downwardly across the joint between the base and cover and into the cavity in the base to engage the stationary contacts 15. The stationary contacts are adjacent one end of the base and their contact surfaces face generally toward the otherend of the base so as to engage the movable contacts 17 on the lower ends of the switch members. This construction positions the switch members generally perpendicular to the joint between the base and cover and to the bottom of the base, and has the advantage that the length of the baseis kept to a minimum. The switch members 31 are held in place by the overcenter springs 37 which are connected under tension between the switch members 31 and the corresponding spring supports 47 of the releasable member 39 (Fig. In the position shown in Figs. 2 and 3 the springs 37 bias the switch members 31 to the closed position. v

The circuit breaker is opened manually by moving the operating member 32 (Fig. 2) by the handle 35 clockwise from the on position to the oh position. Dur ing this movement the inner ends of the switch arms31 are; carried over to the left of theline of action of the overcenter springs 37 whereupon the springs; move the Switch arms 31 to the open position with a snap action. The movable contacts 17 on the lower ends of the switch arms 31 face the stationary contacts adjacent one end of the base and move away from the stationary contacts in a direction generally along the bottom portion of the base. The contacts are closed by reverse movement of the operating. member 32, that is, from the ofi posi: tion to the on position. During this movement the inner ends of the switch members 31 for the several poles are moved over to the right of the line of action of the overcenter springs which then move the switch members to the closed position with a snap action.

An arc extinguisher 61 (Figs. 2, 3 and 6) is placed in a recess or arc chamber in the base 11 for eachpole of the breaker tov quickly extinguish the are drawn when the circuit is interrupted. The are extinguishers are held in the recesses by the lower edge of the cover 13, and may be of any suitable type, the one illustrated comprising-a series of spaced magnetic plates into which the arc is drawn and quickly extinguished. V

The circuit breaker is tripped open automatically in re'sponseto overload currents by operation of the trip device 21. The trip device comprises a trip bar 63 of molded insulating material pivotally supported in the cover 13 and extending across all of the poles of the breaker. The trip bar 63 is supported in a manner similar tothe operating member 32', that is, slots 65 (Figs. 2 and 7) are provided in portions of the cover 13, such as in the barriers 25, for receiving bearing portions 67 of the trip bar 63 and support and barrier members 69 may then be inserted in the slots 65 to support the trip bar 63 in place. Rigidly secured to the trip bar 63 in each pole of the breaker is a U-shaped member 71 (Figs. 2, 3 and 7) which extends into the base 11 of the breaker and has a reverse bend 73 therein, the end of said bend having an insulating button 72 thereon for cooperating with a bimetal element 75 of which there is one for each pole of the breaker.

Each bimetal element is connected by means of a flexible conductor 76 to the switch arm 31 in the correspondirig compartment and is rigidly mounted at its upper end on the inner end of a conductor 77 which is secured by means of a screw 79 to the cover 13 and which extends out through an opening in the end wall of the cover where it is provided with a load terminal connector 81 for gennectin'g an electrical load to the poles of the breaker. Thus, the parts of the sub-assembly unit comprising the terminal conductor 77, bimetal 75, flexible conductor 76,

switch arm 31 and movable contact 17 may all be welded or brazed together to provide a solid current path through the breaker with no sliding joints, and the complete unit may be mounted in the cover through the bottom thereof with the movable contact 17 extending downwardly to engage the stationary contact 15 in the recess on the base when the base and cover are put together.

The U-shaped member 71 for one pole (preferably the center pole if the breaker has three poles) has a latch 83 rigidly secured thereto which normally cooperates with the single latch end 53' of the plurality of releasable or trip members 47 to releasably restrain the whole releasable member 39 (Fig. 5) and the springs 37 for each of the poles in operative position. The trip bar 63 and the members 71 for each of the poles are biased by means of a spring 85 (Figs. 2 and 7) to the position shown in Figs. 2 and 3. The spring 85 is coiled about the trip bar 63 in the center pole compartment and has its bight bearing against the cover 13 and the two ends are hooked into openings in the legs of the U-shaped member 71 for the center pole as shown in Fig. 7.

Also forming a part of the trip device 21 is an elec-. tromagnetic trip means comprising a magnet yoke 87 (Figs. 2, 3 and 7) rigidly secured to the bimetal element 75 and an armature 89 rigidly mounted on the U-shaped member 71, or may be a part of it. v a V Adjusting means comprising ascrew 91 and a nut 93 is provided for adjusting the inner end of each of the conductors 77 to thereby adjust the bimetal element and hence the tripping pointof the breaker. By manipulating the screw 91 the amount of movement of the bimetal to cause release between the latch 83 and the latch end 53 of the releasable member for the center pole is varied thereby varying the tripping point of each of the bimetal elements 75. v

Upon the occurrence of an overload current in any pole of the breaker of, forinstance, up to 1000% of normal rated current, the bimetal element '75 for the afi ected pole becomes heated by the current flowing therein and, when heated a predetermined amount, bends toward the right (Figs. 2 and 3). When this occurs the free end. of the bimetal element acts through the insulating button 72 to movsuie adjacent 'end of the U-shaped member 71 therewith, thus rotating the trip bar 63 and disengaging the latch 83 from the latch end 53 of the releasable member 47 for the center pole of the breaker, thusr'eleasing the entire releasable structure 39(Fig. 5). As secessthe releasable member is released the springs 37 for all of the poles ofj the breaker rotate the releasable structure 39 including the spring support or trip member 47 for each of the poles in a clockwise direction to the position shown by set and dash lines in Fig. 2 when it is arrested by the end 53 of the releasable member for the center pel'c striking a. projection 95 on the base 11 ofth'e housing. This action carries the lines of action of the overcenter springs 37 for all of the poles of the breaker over to the right of their associated switch members 31; the springs 37 then moving the switch members to the open position with a snap action. Whenthe springs 37 move overce'ri'ter, they bias the operating member 32 and the handle 35 to an intermediate indicating position in which it is shownin Fig 2 in dot and dash lines; The operating lever and handle are stopped in the dot and dash line position (Fig; 2) by the engagement of the legs 55 of the levers in each compartment withpins 97 in the associated spring supports 47.

Before the contacts can be closed following an automatic opening it is necessary to reset and relatch the mechanism. This is accomplished by moving the handle 35 and the levers 33 clockwise from the trip indicatin'g position to a position slightly beyond the" as position. Dbiin'g this movement the regs 55 of the levers 33 act through the pins 97 and restorethe whole releasable structure 39 (Figs. 2, 3 and- 5') to the latched position. The contacts are then="closed in the previously described manner by movement of handle 35 and the lever 33 to the on position.

Upon the occurrence in any pole of the breaker of heavy overload current of, for example, 1000% or more of normal rated current or a short circuit current, the armature 89 is attracted to its magnet yoke 87 actuating the trip bar 63 to instantaneously trip the breaker.

It will be seen that there is provided a multi-pole circuit breaker in which all of the operating parts are mounted in the cover. All of the parts are readily assembled from the bottom of the cover and, with the exception of the bimetal element, none of the moving parts are positively fastened to the cover, the housing forming the sole support for the members without the use of any metal frames. The manual operating lever extends into each compartment for supporting and actuating the several switch members. The releasable structure extends into each compartment to support and, when released, to actuate the overcenter springs to effect automatic opening movement of the several switch members, and the trip bar extends into each of the compartments to be operated by any one of the trip devices to release the releasable structure.

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

We claim as our invention:

1. A multi-pole circuit breaker having a housing divided into compartments, relatively movable contacts in each compartment, a movable switch arm in each compartment having one of said contacts thereon, a common operating lever extending into a plurality of said compartments, said operating lever having a portion in each of said plurality of compartments operatively supporting one end of the movable switch arm in the compartment, a common releasable member extending into said plurality of compartments and having a support lever secured thereto in each compartment, an overcenter spring in each compartment connected under tension between the movable switch arm and said support lever in each compartment, said common releasable member when released effecting overcenter action of all of said overcenter springs to cause automatic opening movement of all of said switch arms, and a trip device operable in response to abnormal circuit conditions to release said common releasable member.

2. A multi-pole circuit breaker comprising a housing of molded insulating material divided into a plurality of separate compartments, relatively movable contacts in each of a plurality of compartments, a movable switch arm in each compartment having one of said contacts secured thereon, a common operating lever of one piece molded insulating material extending into each of said plurality of compartments, said operating lever having an integral portion in each compartment operatively supporting said switch arms, a common releasable member comprising an insulating member extending into said plurality of compartments, said common releasable member having a support lever secured thereto in each of said compartments, an overcenter spring in each compartment having one end connected to the support lever and the other end connected to the movable switch member, said common releasable member when released effecting overcenter movement of all or" said overcenter openings to cause automatic spring movement of all of said movable switch arms.

3. A multi-pole circuit breaker having an insulating housing comprising a base and a cover, said base and said cover having one or more matching barriers forming a plurality of compartments, stationary contact means mounted in said base in each of said compartments, a movable switch arm in each compartment and having a movable contact cooperating with one of said stationary contacts, a common operating lever mounted in said cover and extending into a plurality of said compartments, said operating lever having an integral portion in each of said plurality of compartments operatively supporting one end of said movable switch arms, a common releasable member mounted in said cover and extending into said plurality of compartments, said releasable member having a lever secured thereto in each compartment, an overcenter spring in each compartment having one end attached to said lever and the other end attached to said movable switch arm, said common releasable member when released effecting overcenter action of all of said overcenter springs to cause automatic opening movement of all of said switch arms, a common trip member mounted in said cover and extending into said plurality of compartments operable to release said common releasable member, and a separate trip device in each of said compartments mounted in said cover and operable in response to overload currents to actuate said common trip bar.

4. A multi-pole circuit breaker having an insulating housing comprising a base and a cover, said base and said cover having one or more matching barriers forming a plurality of compartments, stationary contact means mounted in said base in each of said compartments, 3. movable switch arm in each compartment and having a movable contact for cooperating with one of said stationary contacts, a common operating lever mounted in said cover and extending into a plurality of said compartments, said operating lever having an integral portion in each of said plurality of compartments operatively supporting one end of said movable switch arms, a common releasable mem ber mounted in said cover and extending into said plurality of compartments, said releasable member having a lever secured thereto in each compartment, an overcenter spring in each compartment having one end secured to said lever and the other end secured to said movable switch arm, said common releasable member when released effecting overcenter action of all of said overcenter springs to cause automatic opening movement of all of said switch arms, a common trip member extending into said plurality of compartments and operable to release said common releasable member, and a separate trip device in each of said compartments mounted in said cover and operable in response to overload currents to actuate said common trip bar, and said switch arms, said common operating lever, said common releasable mem ber, and said separate trip devices all being assembled in said cover.

5. A circuit breaker having an insulating housing comprising a base having a bottom portion and upwardly extending side and end walls, and a cover having a top portion with a handle opening therein and side and end walls extending downwardly to meet the side and end walls of said base, a stationary contact mounted in said base, a movable switch arm mounted within said cover and extending below the lower edge of said cover and having a movable contact thereon for cooperating with said stationary contact in the base, an operating lever pivoted within the cover and having a handle portion extending through the opening in the top of the cover for manual actuation of said switch arm, a pivoted releasable member supported within said cover, an overcenter spring biasing said releasable member to move to released position and biasing said switch arm to move to open and closed positions, said releasable member when released causing said overcenter spring to effect automatic opening of said contacts, and a current-responsive element supported solely by said cover and operated in response to overload currents to cause release of said releasable member.

6. A circuit breaker having an insulating housing comprising a base having a bottom portion and upwardly ex tending side and end Walls, and a cover having a top portion with a handle opening therein and side and end walls extending downwardly to meet the side and end walls of said base, a stationary contact mounted in said base, a movable switch arm mounted in said cover and extending below the lower edge of said cover and having a movable contact thereon for cooperating with said stationary contact for drawing an are, an arc chamber in said base in which the arc is extinguished, an operating lever supported pivotally within said cover and having a handle portion extending throughv the opening in the top of said cover for manually moving said switch arm, a releasable member supported at a pivot axis within said cover; an overcenter spring applying a biasing force to said releasable member and to said movable switch arm, said releasable member when released being moved by said overcenter spring to effect automatic opening of said contact's, a current-responsive,element mounted on said cover and extending downwardly therefrom into said base and operated in response to overload currents to cause release of said releasable member, said switch arm, said operating lever, said releasable member and said current-responsive element all being assembled with said cover. w

7 A multi-polc circuit breaker having a housing having a plurality of compartments, relatively movable contacts in each compartment, a movable switch arm in each compartment having one of said contacts thereon, a common operating lever extending into a plurality of said compartments, said operating lever having a portion in each compartment operatively supporting one end of the movable switch arms, a common releasable member extending into said compartments and having a support lever thereon in each compartment; one of said support levers being longer than the other of said levers, an overcenter spring in each compartment having one end attached to the movable switch arm and the other end attached to the support lever in the compartment, a common trip member extending into each compartment, a lever in each compartment operable by said trip member, latch means on one of said levers engaging said one support lever and releasably restraining said releasable member in operative position, and a trip device in each compartment responsive to overload currents for actuating said common trip member to release said common releasable member.

8. A multi-pole circuit breaker having a housing divided into compartments, relatively movable contacts in each compartment, a movable switch arm in each compartment having one of said contacts thereon, a common operating lever extending into a plurality of said compartmoms and supporting said movable switch arms, a pivoted releasable trip arm in each of a plurality of said compartments, a cross bar p'ortion connecting said trip arms for common pivotal movement, said cross bar portion being positioned substantially at the pivot axis of said trip arms, a trip device norm'allyengaging one of said trip arms and thereby holding all of said trip arms stationary while said switch arms are each moved to open and close the circuit upon actuation of said common operating lever extending into said compartments, a spring in each of a plurality of said compartments and each spring being connected between the trip arm and the movable switch arm and biasing one of said switch arms to move to open position upon pivotal movement of said trip arms when released by said trip device.

9. A multi-pole circuit breaker having a housing divided by one or more barrier walls into compartments, relatively movable contacts in each compartment, a movable switch arm in each compartment having one of said contacts thereon, a common operating lever extending into a plurality of said compartments, a pivoted trip arm in each of a plurality of said compartments, a cross bar portion connecting said trip arms for common pivotal movement, said cross bar portion being positioned substantially at the pivot axis of said trip arms, there being an opening through each of said one or more barrier walls, said cross bar portion connecting the trip arms having one or more portions each substantially closing 8 one of the'openings in the one or more barrier walls, a. trip device normally engaging one or said tiip amassed thereby holding all of said trip arms stationar said switch arms are each moved to open and close the circuit upon actuation of said marries operating. lever extending into said compartments, 5. spring match of a. plurality of said compartments and each spring biasing one of saidswitch arms to move to open position ri en pivotal movement of said trip arms when ieleased by said trip device. g I l 10. A multi-pole circuit breaker having a housing di vided into compartments, said housing ineliidiiiga cover having one or more barriers extending downwardly from the top thereof and a base having one or more barriers extending upwardly from the bottom thereof, relatively movable contacts in each compartment,- an individually movable switch arm in each compartment having one of said contacts thereon, a common operating lever extending into a plurality of said compartments and supporting said movable'switch arms, a pivoted releasable trip arm in each of a plurality of said compartments, a cross bar portion connecting said trip arms for common pivotal movement, said cross bar portion being positioned substantially at the pivot axis of said trip arms and said pivot axis being positioned substantially at the junction of the barriers onthe base and cover, a trip device normally engaging one of said trip arms and thereby holding all of said trip; arms stationary while said switch arms are each moved to open and close the circuit upon actuation of said common operating lever extending. into said compartments; aspring in each of a plurality of said compartments connected between the movable switch arm and the trip arm and each spring biasing one of said switch arms; to move to open position upon pivotal movement of said trip arms when released by said trip device. I p

11. A- multi-pole circuit breaker having a housing divided into compartments, relatively movable contacts in each compartment, a movable switch arm in each compartment having one of said contacts thereon, a common operating lever extending into a plurality of said compartments and supporting said movable switch arms, a pivoted releasable trip arm in each of a plurality of said compartments, a cross bar portion connecting said trip arms for common pivotal movement, said cross bar portion being positioned substantially at the pivot axis of said trip arms, a trip device normally engaging one of said trip arms and thereby holding all of said trip arms stationary while said switch arms are each moved to open and close the circuit upon actuation of said common operating lever extending into said compartments, a spring in each of a plurality of said compartments connected between the movable switch arm and the trip arm and each spring biasing one of said switch arms to move to open position upon pivotal movement of said trip arms when released by said trip device, and each of the same said springs also individually biasing one of said switch arms to move with a snap action upon the aforesaid actuation of the common operating lever extending into each compartment, and each of the same said springs also biasing the said trip arms and said cross bar portion to move to released position.

12. in a circuit breaker, a cover having a top portion with a handle opening therein and downwardly extending side and end walls, a base having side and end walls extending upwardly to meet side and end walls of the cover, an operating lever mounted in said cover and having a handle portion extending through the opening in the cover, a connected assembly unit mounted up in the cover and including a load terminal strip mounted on the coyer and having a bimetal element mounted thereon, a'flexible conductor connected at one end to said bimetal element at a point spaced from the part thereof mounted on the terminal strip and a movable contact member connected to the other end of the flexible connector, said movable contact member being pivotally mounted adjacent its upper end within the cover and extending downwardly below the lower edge of the cover and into the base, a stationary contact adjacent the base, and an arc chamber in the base in which the are between the stationary contact and the lower end of the movable contact member is established.

13. In a circuit breaker, a cover having a top portion with a handle opening therein and downwardly extending side and end walls, a base having side and end walls extending upwardly to meet side and end walls of the cover, an operating lever having a handle portion extending through the opening in the cover, a connected assembly unit mounted up in the cover and including a load terminal strip mounted on the cover and having a bimetal element mounted thereon, a flexible conductor connected at one end to said bimetal element at a point spaced from the part thereof mounted on the terminal strip and a movable contact member connected to the other end of the flexible connector, a spring-biased trip arm pivotally mounted in the cover and normally held stationary during operation of the breaker by manual movement of the operating lever, said trip arm mounted in the cover being releasable upon movement of the bimetal element mounted on the cover by the load terminal strip, said movable contact member being pivotally mounted adjacent its upper end within the cover and extending downwardly below the lower edge of the cover and into the base, a line terminal member mounted on the base and having mounted thereon a stationary contact, and an arc chamber in the base in which the are between the stationary contact and the lower end of the movable contact member is established.

14. in a multi-pole circuit breaker, a cover of molded insulating material having a top portion with a single handle opening therein, downwardly extending side and end walls and a downwardly extending barrier portion providing a plurality of pole unit spaces in the cover, a base of molded insulating material having side and end walls and a barrier portion extending upwardly toward the side and end walls and barrier portion of the cover, an operating lever arm for each of a plurality of the pole units and a single handle portion connected together for common movement in the cover, a trip arm for each of a plurality of the pole units, said trip arms being connected together for common movement and being pivoted on one or more of the downwardly extending portions of the cover, a trip device having a single latch portion normally holding all of said trip arms stationary during manual movement of said operating lever arms by the handle portion, a plurality of separate switch arms each individually pivoted in one of the pole unit spaces, a plurality of contacts each engageable by one of said switch arms, a plurality of springs each individually connected to one of the switch arms and biasing its switch arm to move to open position upon release of the trip arms by the trip device.

15. in a multi-pole circuit breaker, a cover of molded insulating material having a top portion with a single handle opening therein, downwardly extending side and end walls and a downwardly extending barrier portion providing a plurality of pole unit spaces in the cover, a base of molded insulating material having side and end walls and a barrier portion extending upwardly toward the side and end walls and barrier portion of the cover, an operating lever arm for each of a plurality of the pole units and a single handle portion connected together for common movement in the cover, a trip arm for each of a plurality of the pole units, said trip arms being connected together for common movement and being pivoted on one or more of the downwardly extending portions of the cover, a trip device having a single latch portion normally holding all of said trip arms stationary during manual movement of said operating lever arms by the handle portion, a plurality of separate switch arms each individually pivoted at its upper end within the cover in one of the pole unit spaces, a plurality of contacts each engageable by a contact portion on the lower end of one of said switch arms and each of said contacts being positioned in a separate space in the base, a plurality of springs each individually connected to one of the switch arms and biasing its switch arm to move to open position upon release of the trip arms by the trip device.

16. In a multi-pole circuit breaker, a cover of molded insulating material having a top portion with a single handle opening therein, downwardly extending side and end walls and a downwardly extending barrier portion providing a plurality of pole unit spaces in the cover, a base of molded insulating material having side and end walls and a barrier portion extending upwardly toward the side and end walls and barrier portion of the cover, an operating lever arm for each of a plurality of the pole units and a single handle portion connected together for common movement and supported by the molded insulating material in the cover, a trip arm for each of a plurality of the pole units, said trip arms being connected together for common movement and being pivoted on one or more of the downwardly extending portions of the cover, said trip arms being connected together by a cross-bar portion positioned substantially at the pivot axis of the trip arms and said pivot axis being positioned substantially at the junction between the base and cover, a trip device having a single latch portion engaging one of said latch arms and thereby normally holding all of said trip arms stationary during manual movement of said operating lever arms by the handle portion, a plurality of separate switch arms each individually pivoted at its upper end within the cover in one of the pole unit spaces, a plurality of contacts each engageable by a contact portion on the lower end of one of said switch arms and each of said contacts being positioned in a separate space in the base, a plurality of springs each individually connected to one of the switch arms and biasing its switch arm to move to open posi tion upon release of the trip arms by the trip device and a plurality of separated arc chambers in the base in each of which the arc is established between one of said contacts and the contact portion on the lower end of one of the switch arms.

17. A circuit breaker having an insulating housing comprising a base having a bottom portion and upwardly extending side and end walls, and a cover having a top portion with a handle opening therein and side and end walls extending downwardly to meet the side and end walls of said base, a stationary contact mounted in said base, a movable current carrying switch arm pivotally mounted within said cover and extending downwardly below the lower edge of said cover and having a movable contact thereon for cooperating with the stationary contact, an operating lever mounted in said cover and having a handle extending through the opening in said cover, a pivoted releasable member supported in said cover, an overcenter spring having one end attached to said releasable member and the other end attached to said movable switch arm, said releasable member when released changing the line of action of said overcenter spring to eifect automatic opening of said contacts, and a current-responsive element supported solely by said cover and operated in response to overload currents to cause release of said releasable member.

18. In a multipole circuit breaker, an enclosing housing comprising a base having upwardly extending side and end walls and a cover having downwardly extending side and end walls, a terminal strip extending into said cover and mounted on one end wall thereof, separable contacts for each pole, means releasable to efiiect automatic opening of said contacts, a trip member mounted in said cover and Corinna]: to an of said pores, latch meansin one of said poles normally engaging andre'str'aining. said releasable means, a trip device in each pole operable in response to certain overload currents to actuate s'ai'd tri member comprising a bimetai element having one en supported on said terminal strip on said cover and the other end free, the free end of said bimetal element extending downwardly toward said base to effect movement of said trip member and release of said releasable member, an armature foieach pole each being movable to actuate said common trip member, and a magnet yoke rer each pole attracting one of said armatures and moving said common trip member to erect release or said -r'el'easable member. p

\ I9. In a multipol'e circuit breaker, a hoiisi'ng erman ing a base and a cover, separable contact means for each pole, means releasable to eifect separation of ransom-act means, a conducting member for each pole extending into said housing and rigidly secured go said cover, a trip device for each pole comprising a himetal element having one end rigidly mounted on said conducting member on said cover and the other end free, a trip member common to all of said poles and mounted in said cover, a latch on said common trip member normally engaging and restraining said releasable means, thermal bending of any one of said bimetal elements actuating said trip member to cause release of said releasable means, an armature for each pole each being movable to actuate said trip member, and a magnet yoke for each pole mounted on the bimetal element and each attracting one of said armatures and actuating said trip member to effect release of said releasable means.

20. In a multi-pole circuit breaker, an insulating housing comprising a base having a bottom portion and up wardly extending side and end walls and a cover having a top portion with a handle opening therein and side and end walls extending downwardly toward the side and end walls of the base, a plurality of terminal members mounted on the base adjacent one end thereof and each having a stationary contact thereon positioned in the base, one or more barrier portions in the base between said stationary contacts and forming a plurality of arc chambers in the base, a plurality of movable switch arms pivotally mounted within the cover and extending downwardly into the base and each having at its lower end a contact movable in one of the arc chambers in the base in a direction generally along the bottom portion of the base to engage and disengage one of the stationary contacts in the base, operating means mounted within the cover and including a handle portion extending out through the handle opening in the top of the cover, a plurality of terminal strips mounted on the end of the cover at the opposite end of the breaker from the stationary contacts, each of said terminal strips having an inner portion extending upwardly into the cover and secured to the end wall thereof, a plurality of current responsive elements each connected to one of the terminal strips up in the cover and extending downwardly below the lower edge of the cover into the base, a plurality of flexible conductors each electrically connecting the lower portion of one of the current responsive elements within the base to one of the movable contacts on one of the switch arms pivotally mounted within the cover, and trip means actuatable by said current responsive elements to cause said operating means mounted in the cover to cause opening movement of the switch arms and interruption of the circuit in the arc chambers in the base.

21. In a multi-pole circuit breaker, an insulating housing comprising a base having a bottom portion and upwardly extending side and end walls and a cover having a top portion with a handle opening therein and side and end walls extending downwardly toward the side and end walls of the base, a plurality of terminal members mount ed on the base adjacent one end thereof and each having a stationary contact thereon positioned in the base, one; or mere barrier portions in the base between said stationary contacts and forming a plurality of arc chame" in the base, a plurality of movable switch arms pivotally mounted within the cover and extending downwardly into the base and each having at its lower end a contact nliovable in one of the arc chambers in the base in a direction generally along the bottom portion of the base to engage and disengage one of the stationary contacts the base, operating means mounted within the saverand including a handle portion extending out through the handle opening in the top of the cover, a plurality of terminal strips mounted on the end of the cover at the opposite end of the breaker from the stationany contacts, each of said terminal strips having an inner portion extending upwardly into the cover and secured to the end wall thereof, a plurality of current responsive elements each connected to one of the terminal strips up in the cover and extending downwardly below the lower edge of the cover into the base, a plurality of flexible conductors each electrically connecting the lower portionof one of the current responsive elements within the base to one of the movable contacts on one of the switch arms pivotally mounted within the cover, said operating means including a releasable trip member having a single latch portion releasable to cause all of the switch arms to move to disengaged position, a pivoted trip ba'r carried with the cover and extending across all of the poles of the breaker, said trip bar having thereon portions extending down into the base adjacent the lower end of each current responsive element so as to be actuated upon predetermined movement of any one of the current responsive elements, and a single latch portion carried with said trip bar and movable to cause release of said releasable trip member.

22. In a circuit breaker, a housing of insulating material including a base and a cover, said base having a cavity extending down thcreinto, said cover having a cavity extending up thereinto from its under side and having a handle opening in its top, and lower edge portions of the cover engaging upper edge portions of the base to form the housing, a stationary contact member inserted in the cavity in the base from the top thereof adjacent one end of the base and having its contact surface facing generally toward the other end of the base, a movable switch arm and operating mechanism therefor inserted in the cavity in the cover from the under side thereof and said operating mechanism including a handle projecting upwardl y'through the opening in the top of the cover, said movable switch arm being supported at its upper end within the cavity in the cover and having a contact surface adjacent its lower end within the cavity in the base with said contact surface facing generally toward the end of the base having the stationary contact, said movable switch arm in one of its positions having the direction of its length extending generally normal to the direction of the joint between the lower edges of the cover and the upper edges of the base, current responsive tripping means positioned adjacent the end of the breaker opposite the stationary contact member partly within the cavity in the cover and partly within the cavity in the base and operable to cause the operating mechanism to move the switch member to disengage the contacts, and said base and cover when positioned together holding said operating mechanism up in the cover and said stationary contact down in the base.

23. In a rnulti-pole circuit breaker, a housing including a base and a cover each of molded insulating material, said base having a cavity extending downwardly toward the bottom thereof, said cover having a cavity extending up thereinto from its under side and having a single handle opening in its top, and lower portions of the cover engaging upper portions of the base at a joint extending generally in the same direction as the top of the cover, a

plurality of stationary contact members spaced across one end of the base and each having a contact surface in the cavity in the base with each contact surface facing generally toward the other end of the base, a plurality of movable switch arms and operating mechanism therefor inserted in the cavity in the cover from the under side thereof and said operating mechanism including only a single handle portion projecting upwardly through the opening in the top of the cover for manually actuating all poles of the breaker, said plurality of movable switch arms having their upper ends positioned up in the cavity in the cover, each of said plurality of movable switch arms having its lower end extending downwardly into the cavity within the base and having a contact surface adjacent its lower end within the cavity in the base, each of said contact surfaces on the switch arms facing generally toward the end of the base adjacent which the stationary contacts are positioned, each of said movable switch arms in one of its positions having the general direction of its length extending across the joint between the base e and the cover generally perpendicularly thereto, a plurality of terminal strips extending into the cover and References Cited in the file of this patent UNITED STATES PATENTS 1,955,327 Dorfman Apr. 17, 1934 2,050,285 Dorfman Aug. 11, 1936 2,107,246 Jackson Feb. 1, 1938 2,279,737 Jennings Apr. 14, 1942 2,302,551 Jackson Nov. 17, 1942 2,367,382 Taylor Ian. 16, 1945 2,619,561 Swingle Nov. 25, 1952 2,656,440 Dorfman Oct. 20, 1953 2,668,206 Edmunds Feb. 2, 1954 2,673,264 Cole Mar. 23, 1954 2,678,359 Brurnfield May 11, 1954