US2291466A - Circuit breaker - Google Patents

Description

July 28, 1942. l.. J. GOLDBERG 2,291,466

CIRCUIT BREAKER Original Filed July 17, 1940 2 Sheets-Sheet 1 l lllll INH inventor:

Leon J.Gold.b Pg,

His tzowrvwey.4

.July 28, 1942- L.. J. GOLDBERG CIRCUIT BREKER 2 Sheets-Sheet 2 Inventor:

Leon J. Goldbefcg,

Original Filed July 17. 1940 bww/14,7 e. MV/M Hi s Attorney.

Patented July 28, 1942 CIRCUIT BBEAKER Leon J. Goldberg, Schenectady,

General Electric Company,

New York Original application Jul 345,969. Divided and this application May l5,

1941, Serial No. 393,552

(Cl. 2ML-147) 12 Claims.

My invention relates to circuit breakers, more particularly to electromagnetically operated circuit breakers or contactors, and has for its object a simple, reliable and compact blow-out coil and arc chute structure for circuit breakers.

This application is a division of my copending application, Serial No. 345.969, led July 17, 1940, for Circuit breaker, in which application I have claimed the circuit breaker contact structure disclosed in this application.

In my copending application, Serial No. 393,551, filed May 15, 1941, for Electromagnet, I have claimed the electromagnet described in this application.

In carrying out my present invention I provide a blow-out coil, stationary contact and pole piece assembly which is enclosed in an arc chute structure fitting over it as contrasted with the conventional arrangement of larger size in which the pole pieces are on the outside of the arc chute. Also, I provide further enclosure means for preventing arcing over between current conducting parts comprising insulating barriers on the operating shaft for the movable contacts, which barriers fit closely into complementary concave arcuate surfaces on the arc chutes. By

' means of this structure, I provide a very compact arrangement of the current conducting parts while maintaining adequate electric insulation between them.

For a more complete understanding of my invention, reference should be had to the accompanying drawings in which Fig. l is a fragmentary plan view of a contactor embodying my invention; Fig. 2 is a side elevation view of the device shown in Fig. 1 looking toward the right hand; Fig. 3 is afragmentary view in section taken along the line 3-3 of Fig. 1 looking in the direction of the arrows; Fig. 4 is a view mainly in section taken along the line 4-4 of Fig. 1 looking in the direction of the arrows; Fig. 5 is a fragmentary view of the arc chute and insulating base; Fig. 6 is an exploded view of the stationary contact and blow-.out coil assembly; Fig. 7 is a view in perspective of the stationary magnet core, and shading coils disassembled therefrom; Fig. 8 is a fragmentary side elevation view showing the movable contacts turned to permit removal of the stationary contact; while Fig. 9 is an elevation view of an arc chute provided with a modified form of my invention; Fig.

10 is a detail view of the core of the blowout coil. Referring to the drawings, in one form of my invention. the switch parts are mounted on a steel base plate I0 which can be secured upright 55 N. Y., assignor to a corporation of y 17, 1940, Serial No.

to a suitable panel or other support. A stationary magnet frame II (Fig. rI) is secured by brackets I2 and` I3 to the support I0 by means of suitable screws (not shown) a layer of electrically insulating material (not shown) being provided between the brackets I2 and I3 and the support and the screws being electrically insulated from the support. Also secured directly to the support I0 is a base member I4 (Fig. 5)

made of a suitable electrically insulating material such as a molded phenolic condensation product, having its right-hand side, as seen in Fig. l, secured to the plate III over the bracket I2 by means of a bolt I5 passing through the two parts. A spring clamp I6 (Fig. 3) is provided underneath the head of the bolt to take up irregularities in I0 or I4 instead of allowing either I9 0r I4 to bend to compensate for these irregularities. One other bolt, not shown, near the left hand side of I4 is also provided to secure the supports III and I4 rigidly together, a layer of insulating material Il being provided between them. On its side adjacent the support I0, the support I4 is provided with a large recess I9 in which lies the heads of screws or bolts hereinafter referred to in detail for securing various switch parts to the other side or front of the insulating base I4, the layer of insulation Il further insulating these heads from the metal support Ill.

As shown, the circuit breaker is a three-circuit device such as for a three-phase circuit, the de tails for one circuit only, i. e., one stationary and one movable contact, being shown in detail.

Each stationary contact 20 (Fig. 8) is mounted on an electrically conducting, non-magnetic supporting member 2l, preferably made of copper, and secured thereto by means of a screw 22 passing through a slot 23 in the end of the contact adjacent the insulating base I4. Preferably a boss (not shown) is provided on the member 2I around the screw 22 for engaging la corresponding recess on the contact 20 so as to further position the contact.

As shown in Fig. 4, the stationary contact supporting member 2l is secured by screws 25 to the insulating base I4, It is provided with a length 2S (Fig. 6) extending outward at right angles to the base I4 and with a portion extending upward as seen in Fig. 4 and slightly curved back toward the base in conformity with the curvature of a blow-out coil 21 but spaced from the blow-out coil. This blow-out coil, mounted inside or behind the member 2| is formed from a strap of electrically conducting material, such as copper, which is wound edgewise into a coil. One end 21a (Fig. 6) of the coil ls welded directly to the contact supporting member 2| while its other end is welded to a terminal strap 23 which is secured to the support I4 by a screw 29. A magnet iron core 30 extends axially of the blowout coil and pole piece plates 3| and 32 made of magnet iron are welded to the ends of this core. In the assembly of the Plates 3| and 32, they are bent or shaped to rest tightly against the edges or sides of the supporting member 2| and are secured and pressed suitably in place while they are welded to the core member 30.

'I'hus the blow-out coil 21, the core 30, the pole pieces 3| and 32, and the support 2| are securely assembled together by welding into a unitary construction. The ends 3|a and 32a. (Fig. 6) of the pole pieces project slightly beyond the member 2| at the lower end of the upright portion of the member 2| so as to bring the flux passing between these ends of the pole pieces in the region of the contact surface on the stationary contact which lies between these projecting ends, as seen in Fig. 4. It will be noted. however, that the pole pieces extend upward, as seen in Fig. 4, beyond the upper end of the stationary contact 20 but substantialhf flush with the outer surface of the member 2| so as to form a magnetic field between the poles along the upper region of the member 2|. This magnetic neld moves the end of the arc upward along the member 2| so as to increase the length of the arc and tend to extinguish it.

As shown, the upwardly extending portion of the contact support 2| is cut away at each side to form recesses 3|b and 32b into which the magnetic plates 3| and 32 fit. The plates and the recesses 3|b and 32h are co-extensive, as shown in the drawings. with this upwardly extending portion of the contact support 2| throughout the greater portion of its length beginning at its lower end adjacent the contact making portion of the stationary contact 20. Thus, the plates 3| and 32 fit in the recesses 3|b and 32h which are substantially the same depth as the thickness of the plates so as to be substantially flush with the sides of the contact support 2|. The stationary contact 20 is narrower than the support 2| and is of such width that it fits loosely between the projecting ends 3|a and 32a of the magnetic plates. Moreover. the plates 3| and 32 extend substantially at right angles with the axis of the blow-out coil, and their upper portions terminate substantially flush with the outer face or front of the contact support.

A distinguishing feature of this assembly of the stationary contact, blow-out coil and other parts is its compactness, l. e. it is only slightly wider in a direction parallel with the axis of the core than the width of the contact 20.

.The movable contact 33 (Fig. 4) which is a substantially straight strap of conducting material, such as copper, is mounted on an irregularly shaped rotatable member or shaft 34 having its ends pivotally mounted on metal supporting brackets 35 and 36 secured to the supporting plate I0. 'I'his rotatable shaft or member 34 is made of a suitable electrically insulating material, such as a molded phenolic resin. At each end, it is preferably provided with a tubular portion 36a (Fig. 8) fitting over a cylindrical bearing member 36h carried by the brackets 35 and 38 so as to support the member 34 for rotation about a predetermined axis parallel with the support I0.

As shown in Fig. 4, the support 34 is provided with an arm or bracket 31 against which the movable contact 33 is pressed by a helical spring 33, the opposite end of the spring being secured to a cross bar 39 forming a part of the support 34. Also the bracket 31 is provided with a wedge shaped bearing projection 40 which engages a notch in the adjacent side of the contact 33 and forms a pivot bearing for the contact. 'I'he spring 3l bears on the contact on an area between the bearing 40 and the end 31a of the bracket 31 so as to hold the contact on the bearing which is adjacent the lower end of the contact, as seen in Fig. 4, and to press the contact against the end of the bracket 31, shown as a cross bar 31a forming a part of the supporting member 34. Preferably the upper end of the contact 33 is provided with a slightly curved contact making portion 4| which prevents making current on s sharp edge when 33 engages with 2li.

The movable contact 33 is so mounted on the bracket 31 that the three points, its point of initial engagement with the stationary contact, its pivot on the bearing 40, and the center or axis 42 of the shaft 34 are on a straight line and lie in a common plane. With this arrangement, the two contacts engage without sliding action, but when the movable armature 43 secured to the member 34 seats or seals on the stationary magnet core a slight sliding action is produced between the contacts. This minimum sliding action reduces the wear on the contacts and prolonga their life. Also the small amount of sliding action that takes place occurs on the current carrying engaging surfaces of the contacts whereby these surfaces are maintained clean.

Moreover, the stationary contact 2li, as seen in Fig. 4. has its upper contacting portion, which is straight, in substantially parallel relation with the movable contact but converging toward its end slightly toward the movable contact. By reason of this arrangement, the line of engagement between the two contacts starts near the upper ends of the two as they first touch and then moves downward as the movable contact rolls slightly on the stationary contact. This action minimizes bouncing of the contacts and thereby minimizes any tendency for the contacts to weld together during their engaging action. Also the lowering movement of the line of contact tends to break any incipient welds between the contacts. Moreover, by reason of the plane contacting surface of the stationary contact and the similar plane surface of the movable contact, except for the bend at the upper end of the movable contact, and the bend at the lower part of the stationary contact, the line of engagement between the two is given a maximum movement downward, as seen in Fig. 4.

Another feature of the movable contact 33 is the extension 44 (Fig. 4) on its lower end below the pivot 40 which extension provides suiiicient mass to prevent vibration or bouncing of the movable contact during the opening movement. It will be understood that when the supporting member 34 is moved in a clockwise direction, as seen in Fig. 4, from the closed to the open position, the upper end 31a of the bracket 31 strikes the movable contact a sharp blow, and because a considerable portion oi the mass of the movable contact lies above the end of the bracket, there is a tendency for the contact to turn in a counterclockwise direction about the upper end of the bracket as a pivot, the lower end leaving the bearing 40. Such action would result in wear on the bearing 40 and, moreover, produce irregular opening movement of the contact. It might even cause the movable contact to reengage the stationary contact after it has moved away slightly from the/stationary contact. The extra. mass 44 of material on the lower end of the movable contact eliminates this irregular action by balancing the mass of the movable contact on each side of the upper end of the bracket 31 which engages the movable contact with a blow. In fact, this mass 44 tends to cause the movable contact to pivot about its bearing 40 when the blow is given it. The contact, therefore, does not leave its bearing and-moreover, the opening movement of its upper end is accelerated.- This is adistinct advantage when the ,gap between the contacts is small for it overcomes the tendency for the arc to remain stationary and burn the contacts.

As seen in Figs. 1 and 3, the U-shaped magnet armature 43 is mounted between the sides of a channel shaped metal arm 45, the lower end of which is secured to the insulating shaft or support 34 by screws 45h. The lower end 46 of the armature 43 extends through an aperture 41 in the bottom or cross portion arm 45 and is pro- ,vided with a slot 48 loosely embracing the lower edge of the aperture. The upper end 49 of the armature extends through a slot or opening between the sides of the arm 45. A second bearing for the armature in addition to that provided by the slot 48 is provided by an extruded rounded projection 45a on the arm 45 which engages the armature at a point equidistant from the armature pole faces. Movement of the armature on the arm 45 is, furthermore, limited in a clockwise direction, as seen in Fig. 3, about the bearing 45a by a bolt 50 extending between the sides of the arm 45, this bolt being surrounded by an insulating fiber cylinder I (Fig. l) which is engaged by the upper end of the armature. The bolt 50 is also insulated from 45 at one end, thereby preventing 45 and 50 from forming a closed electric circuit around the armature. Aperture 41 extends to the end of 45 as shown by 41a, thereby preventing the lower part of 45 I from forming a closed electric circuit around the armature. Moreover, the bolt 50 forms a stop to limit the clockwise movement of the support 34, the bolt coming to rest against an arm 52 secured to a strap 53, made of a non-magnetic material such as brass, extending through the operating `coil 54 and secured by a screw 55 to the stationary magnet core II.

This suspension for the armature 43 provided freedom for the armature to align itself on the pole faces of the stationary core regardless of slight manufacturing inaccuracies in the support for the armature and the mounting of the stationary core. The armature is loosely supported at each en d but with small clearances, which provides for a small amount of universal pivotal movement on the bearing projection 45a. Moreover, the pole facesl of the stationary core are located in a plane passing through the axis of rotation of the support 34 by reason of which sliding of the armature on the stationary core and resulting abrasive action is minimized. This sliding action is also minimized by the support for the armature at its lower end with slight clearances whereby the lower end is free to move but slightly toward the stationary core during the opening or closing movement. The weight of the armature is supported on the lower ,wall of the aperture 41.

As shown in Fig, 3, the pole shader 56 on the upper leg of the magnet extends through the operating coil 54 and has a portion exterior of the coil substantially as large as the other portion. Also, as shown in Fig. '1, this exterior portion 51 has a reduced cross section so that the preponderant amount of heat is generated in this portion outside of the coil. It will be understood that the remaining portion of the shader inside the coil has a cross section too large to provide the required amount of electrical resistance. Also a U-shaped spring 58 is provided in the slot 60 in the pole face whereby the pole shader is kept from resting on the bottom of the slot. This arrangement prevents the shock of the armature striking' the stationary core from being transmitted to the shader and breakage of the shader by metal fatigue. To further minimize the eilect of these shocks, the shader is made of very light material such as aluminum or an aluminum alloy. The pole shader is furthermore secured by projections 6I provided in it which projections lie in a notch 62 in the stationary core and are held therein by the strap 53 extending over the notch.

The pole shader 63 on the lower leg, which is not subjected to the severe shocks of the upper leg, extends toward the outside of the stationary core and lies in a notch 64. It is secured in this notch by a U-shaped spring 65 (Fig. 3) having its ends secured in holes 66 (only one of which is shown) in the supporting brackets I2 and I3.

A single piece molded arc chute 61 covers all three pairs of switch contacts including the blowout coils and blow-out pole pieces. This chute is molded from a suitable electrically insulating material such as an asbestos compound. As shown in Fig. 5, the arc chute is provided with chambers or recesses defined by walls 68 which recesses receive the pairs of switch contacts. Moreover, the insulating base I4 is provided with walls 69 between. the pairs of stationary contacts. These walls dovetail in tightly tting relation with the walls on the arc chute '81, dovetail joints 10 and 10a being provided. Also each recess in the arc chute leads outward through a restricted arc extinguishing opening 1I in which the arc is extinguished quickly.

tact supporting members 2l, the pole pieces and the members 2l are the electrically conducting parts nearest each other. Consequently the maximum insulating requirements are presented by these parts, which are completely electrically insulated by a single one of the walls B8 of the arc chute. Moreover, barriers 12, Figs. l and 4, are provided on the rotatable support 34 on each side of each movable contact 33. These barriers have edges 13 which are arcuate with the axis of support 34 as a center and are in closely spaced relation with similar complementary concave arcuate edges 14 on the chute B1.

Also this rotatable member is provided with barriers shunts 16 leading to the movable contacts.

As shown, in Fig. 4, the arc chute B1 is hung on an upper cross bar or ledge 11 forming an integral part of the insulating base I4, and hooks 15 between the flexible conducting over the upper end of the contact support 2|. The arc chute is provided with projections 18 which extend downward behind or on the righthand side of the cross bar 11 as seen in Fig. 4 between this cross bar l1 and the upper projecting end of the stationary contact supporting member 2l. Therefore, the arc chute can be slipped in place or removed very readily.

Provision is made for preventing the complete removal of the screws 22 (Fig. 8) from the member 2|. To' provide access to the screw 22 for the removal or adjustment of the stationary contact, the member 34 is turned in a clockwise direction to the position shown in Fig. 8. the arc chute 6l having been removed and also the stop 52 for the armature. In this position of the member 34, a projection 18 on the member lies justbehind the screw 22 so that the screw can be turned out only until its head engages the stop 19, as indicated in Fig. 8. This completely releases the stationary contact 28 but the screw remains in engagement and supported by the member 2|. This stop 18 prevents complete removal of the screw from the member 2| and thereby avoids loss of the screw and the tedious process of rethreading it in the member 2|.

The flexible shunts 'I6 are made of braided copper wire but for compactness instead of having terminals at each end, the ends are dipped in hot tin or solder to form solid terminals 16a and 1Gb. Also the terminal 16h (Fig. 4) is extended and turned back away from the movable contact 4| to form an arcing horn. When the switch is opened the arc is stretched between the upper end of the supporting member 2| and this arcing horn provided by the extension of the terminal 1Gb.

The operating coil 54 (Fig. 3) is seated upon a sponge rubber ring 8|) which in turn rests at one side against a bracket 8| secured to the stationary magnet core by the screw 55 and on the opposite side against the stationary magnet core. The stop 52 is forked and extended back and downward against the outer end of the coil 54 to form a holding projection 82 on each side of the strap 53 engaging the front or outer end of the coil and holding the coil against the rubber ring 80. It will be observed that the removal of the part 42 by removal of the screw 83 makes accessible for removal the coil 54, and the stationary and movable contacts.

Moreover, the coil 54 is mounted by positioning of the bracket 8| in a tilted position downwards, as seen in Fig. 3, with respect to the leg of the stationary core that it encircles. This positioning of the coil and also the projection of the coil toward the right-hand beyond the end of the stationary core pole face into the air gap makes the magnetic ilux more e'ective in applying a pulling force to the armature.

As shown in Fig. 3, the rotatable operating member 34 is provided with a projection 84 which, when the switch is closed engages and moves downward an operating rod 85 for a bridging interlock contact 86 which is biased to the open position by a compression spring 81. This bridging contact 86 is mounted, as shown, so that its contact faces are at an .angle with the faces oi the stationary contacts and, as a result, make contact with a rolling wiping action.

Also other operating projections similar to the projection 84 are provided on the member 34 for the operation if required of additional interlock switches or time delay interlock switches and also to provide for the mechanical interlocking member.

It will be understood that the openings 'Il in the arc chute 81 extend through the arc chute member from the exterior into communication with the recesses between the walls 88. When the circuit breaker has two or more poles, as in the device disclosed. the possibility exists ot the arcs lplaying through the openings 1| for such a distance on the exterior oi' the arc chute that they will come together and short circuit the .poles of the circuit breaker. For the purpose of preventing this, I have in Fig. 9 showed a modied form of my invention in which each o1' the openings in the arc chute is subdivided by projections or barriers forming relatively short openings which are in staggered relation with each other. As shown, the two outside openings are each subdivided by two arc splitting barriers 88 and 88 to -Iorm three relatively short openings 80, 8|, and 82. The central opening is provided Iwith only one arc splitting barrier 83 which subdivides it into two openings 84 and 85 of substantially equal length. It will be observed that the openings 84 and 85 are in staggered relation with the openings 88, 8|, and 82.

The use oi the barriers not extent to which the arcs play externally oi' the arc chute, but also by reason of the staggered relation prevents the high points of two adjacent arcs from being adjacent each other. Or, in other words, the arrangement increases the distance between the high points o1' the arcs and thereby increases their electrically insulating relation with respect to each other.

While I have shown a particular embodiment of my invention, it will be understood. of course, that I do not wish to be limited thereto, since many modifications maybe made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent oi' the United States, is:

1. A circuit breaker comprising a base made oi' electrically insulating material, a stationary ccntact mounted on said base, a movably mounted contact cooperating with said stationary contact, a rotatably mounted support made of electrically insulating material for said movable contact. an are chute made oi' electrically insulating material having side barrier walls on opposite sides of said contacts cooperating with said base to enclose said contacts, electrically insulating barriers formed with arcuate edges mounted on said only reduces the rotatable support on opposite sides of said movable contact, said side barrier walls on said arc chute having complementary concave curved edges in closely spaced relation with said arcuate edges oi said rotatable barrier walls.

2. A circuit breaker comprising a base made of electrically insulating material, a stationary contact mounted on said base, an iron core with pole pieces associated with said stationary contact, a movably mounted contact coopera with said stationary contact, a rotatably mounted support made of electrically insulating material for said movable contact, an arc chute made of electrically insulating material having side :barrier walls on opposite sides of said contactsy cooperating with said base to enclose said contacts and said pole pieces, electrically insulating barriers formed with arcuate edges mounted on said rotatable support on opposite sides of said movable contact` said side barrier walls on said arc chute having complementary concave curved edges in closely spaced relation with said arcuate edges of said rotatable barrier walls.

3. A circuit breaker comprising a base made of electricaly insulating material, a contact support made of electrically conducting non-magnetic material secured at its lower end to said .base and bent upward in spaced relation with said base, a core of magnetic material inside said support so as to be partly surrounded thereby, a pair of pole pieces made of magnetic material for said core on opposite sides of said support and in engagement with said support, a stationary contact carried by said support, a movably mounted contact cooperatingr with said stationary contact, and an arc chute member having side barrier walls on opposite sides of said pole pieces and said contact support closely adjacent thereto and cooperating with said base so as to enclose said contact support, said pole pieces and said contacts.

4. A circuit breaker comprising a base made of electrically insulating material, a contact support made of electrically conducting non-magnetic material secured at its lower end to said base and bent upward in spaced relation with said base, a terminal conductor secured to said base adjacent said contact support, a blow-out coil inside said support so as to be partly surrounded thereby and having its ends secured to said terminal member and said support in electrically conducting relation therewith, a pair of pole pieces made of magnetic material for said blow-out coil on opposite sides of said support and in engagement with said support, a stationary contact carried by said support, a movably mounted contact cooperating with said pole Ipieces and said stationary contact, and an arc chute member having side barrier walls on opposide sides of said contact support closely adjacent thereto and cooperating with said base so as to enclose said contact support, said pole pieces and said contacts.

5. A circuit breaker comprising a base made of electrically insulating material, a blow-out coil mounted on said base, a pair of pole pieces for said blow-out coil. a stationary contact adjacent said blow-out coil, a -movably mounted Contact cooperating with said stationary contact, a rotatably mounted support made of electrically insulating material for said movable contact, an arc chute member made of electrically insulating material having side barrier walls on opposite sides of said pole pieces and cooperating with said base to enclose said blow-out coil, said pole pieces and said contacts, and rotatable barriers made of electrically insulating material on said rotatable support on opposite sides of said movable contact, said barriers being formed with arcuate edges, and said side barirer walls on said arc chute having complementary curved edges in closely spaced relation with said arcuate edges of said rotatable barrier walls.

6. A circuit breaker comprising a base made of electrically insulating material, a contact support made of electrically conducting non-magnetic Lif) tact support, a blow-out coil inside said curved portion of said support so as to be partly surrounded thereby and having its ends secured to said terminal member and said support in electrically conducting relation therewith, a pair of pole pieces made of magnetic material for said blow-out coil on opposite sides of said support and in engagement with said support, a stationary contact carried by said support, a movably mounted contact cooperating with said stationary contact, a rotatably mounted support made of electrically insulating material for said movable. contact, an arc chute member made of electrically insulating material having side barrier walls on opposite sides of said pole pieces and said contact support cooperating with said base to enclose said contact support, said pole pieces and said contacts, and rotatable barriers made of electrically insulating material on said rotatable support on opposite sides of said movable contact, said barriers being formed with arcuate edges, and said side barrier walls on said arc chute having complementary curved edges in closely spaced relation wtih said arcuate edges of said rotatable barrier Walls.

7. A circuit breaker comprising a plurality oi. pairs of relatively movable contacts arranged in substantially side by side relation, a unitary arc chute member tting over said plurality of pairs of contacts and providing a single barrier wall between adjacent pairs of contacts, said arc chute member being provided with a plurality of openings opposite each of said pairs of contacts, the arc chute openings for each pair of contacts being staggered with relation to the openings for each adjacent pair of contacts.

8. A circuit breaker comprising a base made of electrically insulating material, a contact support made of electrically conducting non-magnetic material secured at its lower end to said base and extending upward into a curved form, stationary contact means on the outer side of said contact support at its lower end, a blowout coil inside the curvature of said contact support having its ends secured to said support and said base whereby said blow-out coil is supported in spaced relation with said contact support, a core member made of magnetic material extending axially through said blow-out coil, a plate made of magnetic material secured to each end of said core member, said plates extending substantially at right angles with the axis of said blow-out coil into engagement with opposite sides of said contact support and extending from a point adjacent said contact means upward over a substantial portion of the upwardly extending length of said contact support, and a cooperating contact mounted for movement into enmaterial secured at its lower end to said base and having a substantially curved portion in spaced relation with said base, a terminal conductor secured to said base adjacent said congagement with 'said stationary contact means.

9. A circuit breaker comprising a base made of electrically insulating material, a Contact support made of electrically conducting non-magnetic material secured at its lower end to said base and extending upward into a curved form, stationary contact means on the outer side of said contact support at its lower end, a blow-out coil inside the curvature of said contact support having its ends secured to said support and said base whereby said blow-out coil is supported in spaced relation with said .contact support, said contact support having a, portion cut away at each side to form a recess on each side extending throughout a substantial portion of the upwardly extending length of said contact support,

a core member made of magnetic material ex-y wardly extending length of said contact support,

and a cooperating contact mounted for movement into engagement with said stationary contact means.

10. A circuit breaker comprising a base made oi' electricalhr insulating material, a contact support made oi electrically conducting non-magnetic material secured at its lower end to said base and extending upward into a curved form, a. blow-out coil inside the curvature of said contact support having its ends secured to said support and said base whereby said blow-out coil is supported in spaced relation with said contact support, said contact support having a portion cut away at each side to form a recess on each side extending throughout a substantial portion of the upwardly extending length of said contact support, a core member made oi' magnetic material extending axially through said blow-out coil, a plate made oi' magnetic material secured to each end of said core member, said plates extending substantially ai; right angles with the axis of said blow-out coil and fitting in said recesses, portions on the lower ends of said plates projecting beyond the front of said contact support, a stationary contact secured to said contact support between said projecting portions oi said plates, and a cooperating contact mounted for movement into engagement with said stationary contact.

1l. A circuit breaker comprising a base made of electrically insulating material, a pair oi contact supports made of electrically conducting non-magnetic material having their lower ends secured to said base in spaced relation with each other and each extending upward into a curved form, stationary contact means on the outer side of each of said contact supports at its lower end, a blow-out coil inside the curvature of each of said contact supports having its ends secured to said contact support and said base, a core member made of magnetic material extending axially through each oi' said blow-out coils. a pair of plates made o! magnetic material secured to the ends ci' each oi said core members. each pair of said plates extending substantially at right angles with the axis of the associated blow-out coil into engagement with opposite sides oi the associated contact support and terminating adjacent said contact means. a cooperating contact mounted for movement into engagement with each of said stationary contact means. a unitary arc chute member made of electrically insulating material fitting over said plurality of stationary and movable contacts and provided with a single electrically insulating barrier wall between said contact supports.

12. A circuit breaker comprising a base made of electrically insulating material, a pair of oontact supports made of electrically conducting non-magnetic material having their lower ends secured to said base in spaced relation with each other and each extending upward into a curved form, stationary contact means on the outer side of each of said contact supports at its lower end. a blow-out coll inside the curvature of each ot said contact supports having its ends secured to said contact support and said base, a core member made oi' magnetic material extending axially through each of said blow-out coils. a pair of plates made oi' magnetic material secured to the ends of each of said core members, each pair oi said plates extending substantially at right angles with the axis o! the associated blow-out coil into engagement with opposite sides of the associated contact support, a cooperating contact mounted for movement into engagement with each of said stationary contact means, a unitary arc chute member made of electrically insulating material fitting over said plurality of stationary and movable contacts and provided with a single electrically insulating barrier wall between said contact supports, said arc chute being provided with a plurality oi openings opposite each oi said contact supports, the openings opposite each oi said supports being in staggered relation with the openings opposite the other contact support.

LEON J. GOLDBERG.

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