US2790878A - High voltage contactor - Google Patents

Description

April 30, 1957 c. A. LlsTER HIGH VOLTAGE coNTAcToR Filed sept. 15, 1954 6 Sheets-Sheet 1 sa 38 JNVENTOR. k CHARLES A. L ISTER Il' I l A* ATTORNEYS.

as la 8' April 30, 1957 c. A. LlsTER 2,790,878

` HIGH VOLTAGE: coNTACToR Filed Sept. l5, 1954 6 Sheets-Sheet 2 /-Z 5 l v INVENTOR.

CHARLES LISTE?.

April 30, 1957 c. A. I ISTER 2,790,878

HIGH VOLTAGE coNTAcToR Filed Sept. l5, 1954 6 Sheets-Sheet 3 Z08l `l C@ o! /l I l rre- 74 11 19a INVENTOR. 2D 18 9 CHARLES/A. LETER M, ATTORNEYS.

April 30, 1957 c. A. LlsTl-:R

HIGH VOLTAGE coNTAcToR 6 Sheets-Sheet 4 Filed Sept. l5. 1954 INVENTOR. CHARLES A. LETER April 30, 1957 c. A. L lsTER HIGH VOLTAGE coNTAcToR 6 Sheets-Sheet, 5

Filed Sept. 1.5, 1954 ISI TIG

209 ZOQ INVENTOR.

CHARLES A. LLB-TEE ATTORNEYS.

April 30, 1957 C. A. USTER 2,790,878

HIGH VOLTAGE CONTACTOR Filed Sept. 15, 1954 6 Sheets-Sheet 6 l INVENTOR. 7 CHARLES A. USTEP.

Lk ATTORNEYS.

United States Patent O HIGH VOLTAGE CoN'rAcroR Charles A. Lister, Shaker Heights, Ohio, assigner, by mesne assignments, to Square D Company, Detroit, Mich., a corporation of Michigan Application September 1S, 1954, Serial No. 456,245

Claims. (Cl. 20d- 147) This invention relates to electromagnetically operated contactors and more particularly to non-oil-immersed contactors suitable for repeatedly switching circuits carrying large alternating currents at moderately high voltages and for interrupting such circuits under fault conditions even when the available three-phase short-circuit capacity of circuits is as high as 50,000 kilovolt-arnperes.

Until recently, contactors, used in moderately high voltage alternating current circuits were nearly all of the oil-immersed type. Increased knowledge of alternating current arcing phenomenon `at voltages within the range of 2000 to 6000 volts, however, has made it possible to interrupt successfully in air the arcs formed in such moderately high voltage circuits. Nevertheless, there has not heretofore been available a contactor capable of interrupting in air a fault current where the symmetrical portion of the fault current corresponds to 50,000 kilovolt-amperes and the direct current component is any value possible with the particular symmetrical portion. Consequently, it has been necessary to use oil-immersed contactors or contactors backed up with current-limiting fuses whenever the available short-circuit capacity of the circuit approaches 50,000 kilovolt-amperes. In order to be competitive with oil-immersed contactors, non oil-immersed or air-break contactors for use at voltages within the range mentioned and in circuits of such large available fault capacity must comprise a compact structure for effecting separation of the contacts thereby to draw an arc therebetween and simple means for moving the are into an adequate arc-extinguishing structure which also must be of relatively small dimensions.

It is an object of this invention to provide an improved air-brake contacter for use in alternating current circuits of such moderately high voltage.

Another object is to provide an alternating current, air-break contactor, for use at moderately high voltages, which can interrupt fault current when the symmetrical portion of the fault current corresponds to 50,000 kilovolt-amperes and the direct current component is any value possible with the particular symmetrical portion and which is comparable in space requirements and cost with oil-immersed equipment of the same rating.

Another object is to provide a moderately high voltage, air-break contactor of high interrupting capacity so designed and constructed that removal and replacement of parts is more easily accomplished than in prior air-break contractors of comparable voltage rating.

Another object is to provide an air-break contacter comprising a novel group of sub-assemblies arranged for ease of mounting on a rigid frame work to form a complete air-break contactar.

Another object is to provide an air-break contactor having a rigid frame structure the cross-supports of which serve as mounting means for substantially lall parts of the contactor.

Another object is to provide an improved multi-pole contactor in which each of the poles as well as the mag- 2,790,878 Patented Apr. 3l), 1957 ICC netic operating means are removable without disturbing other parts of the contactor.

Another object is to provide a moderately high voltage, air-brake contacter having improved means for attaching and anchoring incoming and outgoing leads.

Another object is to provide improved magnetic Operating means for an air-break Contactor.

Another object is to provide improved means for operating the control circuit contacts of an air-break contactor.

Another object s to provide an alternating current, airbreak contactor having improved means for creating a blowout eld.

Another object is to provide an air-break contacter which includes improved means to prevent opening of its contacts as a result of forces created by large fault currents.

In order to be competitive with oil-immersed contactors in moderately high Voltage alternating current circuits of large available fault capacity, air-break contactors must be capable of interrupting a fault current when the symmetrical portion of the fault current corresponds to 25,000 or 50,000 kilovolt-amperes and the direct current component is any value possible with the particular symmetrical portion. The contactor to be described has been tested and has been found capable of successfully interrupting such fault currents. A readily modified and less expensive arc chute may be used when the contacter is required to interrupt only 25,000 kilovolt-amperes.

A contacter in accordance with this invention comprises a trame structure having a plurality of cross supports on which are mounted a base for a magnetic operating means and a plurality of bases carrying identical blowout and stationary contact assemblies. A movable armature and a plurality of movable power contact assemblies are mounted in spaced relation on an operating shaft supported by bearings carried by end frames. The conductors carrying current to the movable contacts are so arranged that forces created by currents owing in those conductors are opposed in a manner such that they cannot cause the contacts to separate. A tie rod from the armature to an auxiliary shaft provides positive operation of circuit control contacts. Arc chutes for each pole are readily demounted and each comprises a plurality of spaced insulating cooling plates disposed between a pair of arc runners, the plates being so shaped as to define a slot for arc entry. An insulating housing rests on the cross supports and provides barriers between the several poles.

Further objects and advantages of this invention will become apparent from the following description wherein reference is made to the drawings in which:

Fig. l is `a front elevation of a contactor embodying the invention and arranged to be operated by a direct current magnet;

Figs. 2 and 3 are side and rear elevations, respectively, of the contacter of Fig. l;

4 is an enlarged front View of the operating magnet and stationary control circuit contacts land of the coorerating armature and movable control circuit contacts of the contactor of Figs. 1,12 and 3 partly in section as indicated by the line 1i riot Fig. 2;

Fig. 5 is an enlarged sectional View taken generally `along the line S--' of Fig. l;

Fig. 6 is a wiring diagram of a circuit for the operating coil of the contactor of Figs. l, 2 and 3;

Fig. 7 is an enlarged sectional view taken generally along the line 7--7 of Fig. l but with parts associated with the operating magnet removed for clarity;

Figs. 8, 9, l0 and ll are fragmentary sectional views taken generally along the lines 8-8, 9 9, 1010 and 11-11, respectively, of Fig. 7;

afferrare Figs. l2 and 13 are perspective views of the cooling plates; and

Fig. 14 shows a modified magnet structure for use with alternating current.

Referring rst to Figs. l, 2 and 3, a contacter embodying the invention includes a frame comprising right and left hand side plates 11 and 12 preferably formed from steel, a front cross support 14, and top and bottom cross supports 15 and 16. Each of the side plates 11 and 12 has an in-turned base flange 18 provided with suitable openings for mounting bolts and has an upper portion 19 of its front edge face tapered upwardly toward the rear so that the upper portion of each side plate is narrower than the lower portion.

The front cross support 14 is preferably a metal channel having depending side walls 20 and tip-turned terminal anges 21 suitably secured on the inner surfaces of the side plates 11 and 12, respectively, at thc lower front portions thereof. The top and bottom cross supports 15 and 16 are preferably metal channels having pairs of rearwardly directed side walls 22 and 24, respectively, and pairs of forwardly directed terminal flanges 25 and 26, respectively.

The terminal flanges 25 of the top cross support 15 are suitably secured on the inner surfaces of the side plates 11 and 12, respectively, near the top edges of the plates approximately midway between the rear edges of the plates and the top of the tapered portions 19. To facilitate mounting and transporting of the contacter, a pair of perforated hangers 28 may be suitably fastened on the outer surfaces of the side walls 11 and 12, respectively, opposite the respective flanges 25. The terminal flanges 26 of the bottom cross support 16 are suitably secured on the inner surfaces of the side plates 11 and 12, respectively, just above the respective in-turned flanges 18. The web portions of the cross supports 25 and 26 are vertically aligned.

The frame 10 has few parts, permits ready inspection, repair and replacement of the operating parts of the contactor, is easily assembled, and yet is strong and rigid. The cross support 14, 15 and 16 not only impart rigidity but7 as will become apparent, also serve as mounting means for the operating parts of the contactor. By merely selecting the length of the cross supports, the frame 10 can accommodate efficiently any reasonable number of poles.

Suitably secured at their top and bottom portions in horizontally spaced relation on the front faces of the web portions of the cross supports 15 and 16, respectively, are a plurality of elongated insulating bases or panels 29 each of which supports a blowout and stationary power contact assembly 30 (Figs. 7 and l0). An insulating base or panel 31 is suitably secured at its top and bottom portions to the frame supports 15 and 16, respectively, at the rear thereof and supports on its lower portion a direct current operating magnet 32 (Figs. 4 and 5) and on its upper porti-on a group of stationary control circuit con tacts 34.

It is to be noted that any one of the bases 29 and the base 31 are easily mounted on and removed from the cross supports 15 and 16 without disturbing the other bases. The mounting of the bases 29 on the front and the base 31 at the rear vof the cross supports 15 andv 16 disposes the bases 29 and 31 in an advantageous position for a compact arrangement of the operating parts.

An operating shaft 35 extends across the lower front portion of the frame 10 and has a squared portion intermediate of cylindrical end portions 36 and 38. The end portions 36 and 38 are received in respective bearings 39, preferably of the self-aligning spherical type, mounted on the outer surfaces of the side plates 11 and 12, respecw tively. The end portion 36 extends for a considerable distance beyond its associated one of the bearings 39 to permit connection of a mechanical interlock (not shown) with an adjacent contactor or with a door latch of a protective housing. The shaft 35 serves as a pivot axis for and supports in spaced relation a plurality of identical movable power contact assemblies 40 (Fig. 7) which cooperate with the blowout and stationary contact assemblies 30, respectively, and also supports an armature and movable control circuit Contact assembly 41 (Figs. 4 and 5) which cooperates with the operating magnet 32 and the group of stationary control circuit contacts 34. A plurality of anti-blowolf assemblies 42 (Figs. 7 and 9) are mounted in horizontally spaced relation on the cross support 14 in front of the shaft 35 and are associated with the movable power contact assemblies 40, respectively.

Arc chutes 44 are provided for the pairs of power contacts, respectively, and a barrier or housing 45 surrounds all of the power contacts and the arc chutes 44.

As shown best in Fig. 7, a preferred lead clamp 46 for a plurality of incoming flexible conductors or leads 48 comprises an elongated base member 49 of suitable insulating material secured 1to the outer face of the lower side Wall 22 of the top frame support 15 and an elongated closure member 50 of similar material bolted to the rear edge face of the base member 49. The members 49 and 50 have complementary semi-circular recesses which, when the members are in assembled position, define openings 51 each of which receives in clamped engagement one of the leads 48. The end portions of the leads 48 below 'the lead clamp 46 are secured to terminal blocks 52, respectively, which are fastened on the rear faces of the bases 29, respectively. The terminal blocks 52 are preferably pre-assembled as a part of the stationary contact and blowout assemblies 30, respectively, as will be described.

A preferred lead clamp 53 for a plurality of outgoing leads or conductors 54 comprises an elongated base member 55 of suitable insulating material secured on the upper face of the upper side wall 24 of the bottom frame support 16 and an elongated closure member 56 of similar material bolted to the top edge face of the base member 55. The members 55 and 56 have semi-circular recesses which, when the members are in assembled position, defined openings 57 each of which is adapted to receive in clamped engagement one of the leads 54. Front end portions of the leads 54 pass around the bases 29, respectively and are connected to the anti-blowoff assemblies 42, respectively. In the three pole contactor shown, a total of six clamping openings 57 are provided so that similar outgoing leads 54 from an adjacent contacter (not shown) for controlling the same lead may be held rigidly before passing around the panels 29 to be connected to the respective anti-blow-otf assemblies 42.

It is to be noted that the lead clamps 46 and 53 are readily accessible and easily demounted yet provide adequate clamping force for the leads. The fact that the cross supports of the frame are used as supports for the lead clamps greatly simplies the construction.

The operating magnet 32 is shown best in Figs. 4 and 5. The base 31 which carries the magnet 32 is preferably bolted to the frame supports 15 and 16 and is spaced from the rear edges thereof by cylindrical spacers 58 surrounding the respective mounting bolts. The operating magnet 32 comprises a .magnetic core plate 59 from which extend forwardly of the contacter and in vertically spaced relation a pair of magnetic cores 60 carrying operating coils 61, respectively, that are biased outwardly from the plate 59 against respective nonmagnetic core caps 63 by suitable liat springs 62 disposed between the plate 59 and the coils 61. The plate 59 and the cores 60 are secured to the base 31 by cap screws 64 which pass through respective aligned openings in the base 31 and the plate 59 and are received in tapped openings in the respective cores 60. The coils 61 are preferably connected in series with each other and cach has a pair of terminal leads 65. The leads 65 are electrically connected to the front end portions of respective terminal studs 66 passing through the base 31.

If desired, a suitable energy storing and dissipating circuit can be associated with the coils 61 to reduce arcing consequent upon opening of a supply circuit for the coilsA For this purpose a resistor 67 may be suitably mounted in spring clips 68 on the rear face of the panel 31 and below the resistor 67 a capacitor 69 may be held by a suitable metal clamp. As illustrated in Fig. 6, the resistor 67 and the capacitor 69 are connected in series with each other and the series connected resistor and capacitor are connected in parallel with the series-connected coils 61 to a circuit controlled by a switch 70 and supplied from a source 71 of direct current.

The armature and movable control circuit Contact assembly 41 is also best shown in Figs. 4 and 5 and comprises an armature 72 preferably in the form of a ilat plate of magnetic metal secured at its lower end portion to the squared portion of the operating shaft by a pair of horizontally spaced front clamps 74 and a pair of complementary rear clamps 75. The clamps 74 and 75 have respective angular grooves 76. The grooves 76 of the rear clamps 75 receive one corner of the shaft 35 and the grooves 76 of the front clamps 74 receive a diagonally opposite corner of the shaft 35. Cornplementary ones of the clamps 74 and 75 are secured to each other and to the armature 72 by a pair of cap screws 78.

As shown by solid lines in Fig. 5, the armature 72 normally rests due to gravity in an open position against a suitable stop mechanism 80 to be described. Upon energization of the coils 61, the armature 72 rocks counterclockwise (Fig. 5) from the open position to a closed position indicated by broken lines 79 turning the shaft 35 with it as indicated. When the coils 61 are deenergized, the armature 72 returns to its open position due to gravity and the pressure of contact springs to be described.

The vertically spaced arrangement of the cores 60 and associated coils 61 not only permits the contactor to be relatively narrow but provides a larger torque at the shaft 35 as the armature 72 approaches and reaches its closed position than could be obtained with a magnet of the same size having a single core or a pair of horizontally spaced cores.

In order to provide a direct and positive drive between the armature 72 and the movable control circuit contacts, an angle bracket 81 is preferably secured to the lower left-hand end portion (Fig. 4) of the armature 72 by a pair of the cap screws 78 and carries by means of a I bolt 82 a suitable rod-end bearing 84 for a vertically disposed tie-rod 85 pivotally connected at its upper end portion by a similar rod-end bearing 86 and associated bolt 88 to an angle bracket 89. The bracket 89 is preferably secured by one pair of a plurality of cap screws 90 to the left hand one of a pair of horizontally spaced clamp members 91. Each of the clamp members 91 has an angular groove receiving a corner of a squared portion of a shaft 92 and is complementary to and secured by a pair of the cap screws 90 to a clamp member 94 also having an angular groove for receiving a diagonally opposite corner of the shaft 92. The shaft 92 has cylindrical end portions received respectively in suitable bearings 95 carried at the outer end portions of respective horizontally spaced bearing posts 96 secured to the panel 31. When the armature 72 rocks as a result of energization and deenergization of the coils 61, the tie-rod 3S causes similar rocking movement of the shaft 92.

Each of the clamp members 94 has a tongue portion 97 inclined upwardly toward the base 31 and having fastened on its upwardly directed side face as by a pair of screws 98 an insulating movable control circuit contact carrier 99 and on its downwardly directed face an angle block 100 on the downwardly directed side face of which lli) 6 is secured as by another pair of screws 98 another of the carriers 99.

Each of the movable Contact carriers 99 carries within a transverse opening through its thickened free end portion a pair of identical conducting Contact bridges 102 biased apart by a helical spring 104 and suitably insulated from each other. Each of the contact bridges 102 carries a pair of spaced contact buttons which, upon rocking movement of the shaft 92 in response to rocking of the armature 72, engage and disengage complementary contact buttons 10S of the stationary control circuit contacts 34.

The stationary contact buttons 103 are carried by con tact brackets 109 each of which is detachably secured on a selected one of a plurality of studs 110 and 111 mounted in spaced relation on the panel 31. The studs 110 and 111 are identical except that the studs 110 are shorter than the studs 111. Each of the brackets 109 has contact bottons 108 on opposite sides thereof, respectively, which are selechtively placed in operative position depending upon whether the bracket is mounted on a stud 110 or on a stud 111 and depending upon whether it is for cooperation with an upper or lower one of the carriers 99. For example, if one of the brackets 109 is on an upper one of the studs 111, one of its contact buttons 108 is placed in normal closed position and, if moved to an upper one of the studs 110, the other one of its Contact buttons is positioned for normally open operation. Circuit control contacts of the type described are disclosed and claimed in Noyes Patent No. 2,5 85,824, issued February 12, 1952.

It is to be noted that the control circuit contacts are of very rugged construction, are positioned for easy access, and are operated through a positive linkage by Ythe armature 72 which in turn drives the main operating shaft 35.

Although any suitable stop mechanism may be used to arrest movement ofthe armature 72 andthe other movable parts of the contactor at the open position thereof, it should be one that prevents rebound. Rebound of the movable parts can cause restriking of an arc at the power contacts. The preferred stop mechanism to be described is disclosed and claimed in patent application Serial No. 436,372, lled J`une 14, 1954 in the name of Everett E. Noyes.

The stop mechanism 80 shown best iin Figs. 4 and 5 comprises a ilat mounting plate 112 suitably secured on the inner surface of the front portion of the side plate 11 and carrying a horizontally disposed and inwardly directed cylindrical stud 114 and a pair of horizontally disposed and inwardly directed spaced pins 115 and 116. An elongated sleeve 117' preferably made of canvas-base Bakelite land rotatably mounted on the stud 114 has a generally square cross section except that the intersection of two of its side faces is rounded ofl` as at 118. A counterweight 119 preferably in the form of a iiat plato land bolted to one face of the sleeve 117 is held by gravity against the pin 11S and maintains the rounded portion 118 in the broken line position shown in Fig. 5 when the armature 72 is in its attracted position indicated at 79. Upon release of the armature 72 caused by deenergization of the coils 61, gravity and contact springs to be described cause the armature 72 to rock clockwise as viewed in Fig. 5. The kinetic energy of the moving parts of the contactor is relatively large and if the armature '72 were to strike a fixed stop it would rebound. This rebounding is prevented by the stop mechanism 80 since, when the armature strikes the rounded portion 113, the sleeve 117 rotates counterclockwise on the stud 114 and rubs against the armature 72 absorbing some of the kinetic energy as friction and some as potential energy stored in the counterweight 119. The armature 72 comes to rest on a flat face of 75 the sleeve 117 opposite from the one to which the counterweight is attached. The pin 116 is engaged by the counterweight 119 to restrict the sleeve 117 from turning through too large an angle in the counterclockwise direction under unusual conditions.

Referring now principally to Figs. 7 and l0, each of the blowout and stationary power contact assemblies 30 comprises a pair of horizontally spaced laminated blowout ears 122 extending forwardly and rearwardly of their associated one of the panels 29. The ears 122 of each pair are notched at their rear end portions to receive with a press fit respective end portions ot an associated laminated blowout core 124 of substantially square cross-section. Since the .assemblies 3i) are identical, a description of one will sutlice. Each of the blowout ears 122 comprises a plurality of inner laminations 125 having a depending portion '1.26 in thc region of the power contacts to be described and a plurality of outer laminations 128 of shorter length and narrower width all riveted together. If desired, thc laininations 125 may be disposed on the inner side of a stiffcning lamination 129 shaped like the laminations 125 but of greater thickness and the laminations 1.28 may be disposed on the outer side of the lamination 129. The ears 122 are preferably secured near their rear end. portions to opposite sides, respectively, of their associated one of the` panels 29 by a pair of vertically spaced bolts 130 which pass through the panel 29 edgewise. A blowout coil 131 comprising a plurality of turns ot cdgcwound copper strap has an upper terminal extension 132 bolted to the terminal block 52 to which an associated one ot the incoming leads 48 is attached and has a lower terminal extension 134 con nected to a lug 135 loosely received. on a. stud 136 which passes through the associated panel 29 and holds a forwardly extending stationary contact bracket 138 in posi tion. The bracket 138 carries at its forward end a detachable power contact 13). A tubular insulator 140 has a central opening of substantially square eross-section receiving the core 124 and a cylindrical outer surface abutting the inner periphery of the coil 131. Adjacent turns of the coil 131 are insulated from each other by tlat flexible annular insulators 141 slitted so as to be readily received on the insulator' 140 between the convolutions. Similar insulators 141 are stacked along the insulator 140 at opposite ends of the coil 131.

Since the core 124 lits tightly into the notches in the ears 122, low losses and relatively high flux. densities are obtained. rifhe insulator 140 is of accurate length so that when the ears 122 engage the side faces of their associated one of the bases 29 they also engage the end faces of the insulator 149 and are thus held parallel. A pair of insulators 142 in the forni oi relatively thin sheets of iusu-lating material may be interposed between the re spective ears 122 and the ends of the insulator 140 and the side walls of the panel The insulators 142 have openings which receive the respective end portions of the core 124 and preferably extend beyond the top and bottom edges of the respective blowout ears 122 to provide barriers between live parts. A pair of endvvise directed shoulders 143 are formed at opposite ends of the core 124 at the rear tace thereof. Portions of the insulators 142 overlie the respective shoulders 143 and insulating blocks 144 are held against the outer surfaces f the insulators 142, respectively. The inner end portions of the blocks 144i are `held against the respective shoulders 143 by a stud. 145 passing through the insulator 140 and holding the core 1.24, the coil 131, and the in sulators 140, 141., 142 and 144 together as a unit prior to assembly of the contacter'. During assembly of the contactor, the terminal block 52 which is secured to the upper terminal extension 132 is atlixed to the panel 29 and the lower terminal extension 13d is then drawn forward by turning a nut on the stud 136 against the lug 135. The core 124 is thus forced tightly into the grooves in the ears 122. A second stud 146 passing through the ears 122 and the insulators 140, 141, and 142 is then inserted and draws the ears 122 tightly against the respective end faces of the insulator and the respective edge faces ot the panel 29 with the insulator 142 interposed between.

Each of the movable power contact assemblies 40, shown best in Figs. 7 and 8, comprises a main contact arm 150 having a pair of depending leg portions 151 defining an angular' recess therebetween for receiving one corner of a squared shank portion of an insulator 152 having .a squared axial opening receiving the shaft 35 and 'having cylindrical flanges 153 disposed on opposite sides of the` shank portion. An angle clamp 154 received on the diagonally opposite corner of the insulator 152 `from thc corner received by the leg portion 151 is bolted to the lower end faces of the leg portions. A spring clamp 155 secured to the upper end portion of the arm 150 carries a contact pressure spring 156 which biases in a counterclockwise direction (Fig. 7) an auxiliary contact arm 157 pivoted on a pin 158 carrier by the main arm 150. A movable power contact 159 is detachably mounted on the upper end portion of the auxiliary arm 157 for engagement with the stationary power contact 139.

Tihe closed position of the movable power contact assemblies 40 is indicated by broken lines in Fig. 7. When the shaft 35 rocks due to energization of the coils 61, each of the contact arms 150 moves from the solid line open position to the broken line closed position. During this movement the contents 139 and 159 of each pole engage cach other and the auxiliary arms 157 rotate about their pivot pins 158 compressing the associated one of the springs 156.

Power is carried to each of the movable power contacts 159 by a llexible conductor 160 forming part of one of the anti-blow-of assemblies 42. Since the assemblies 42 are identical, a description of one will suffice.

Each of the assemblies 42 comprises a flanged standof insulator 161 mounted on the front frame Support 14 and a metal post or pedestal 162 mounted on top of the insulator 161. The pedestal 162 has at its lower end portion a rearwardly directed and downwardly inclined tongue portion 164 to which is suitably bolted an end portion of one of the outgoing leads 54, and at its upper end portion an overhanging portion 165 from which depends a U-sbapcd connector 166 each leg of which is provided with a stiffening rib 168. An angled connector bar 169 having a thickened rear end portion is secured to the lower bight portion of the connector 166 and eX- tcnds rearwardly above and in spaced relation to the tongue portion 164. An end portion of one of the flexible conductors is secured to the upper face surface of the lthickened end portion of the connector bar 169. A pair ot insulating plates 17.1 are fastened on opposite sides, respectively, of the tongue portion 164 and the connector bar 169 to stiften the assembly.

A pair of conductor retainer plates 172 formed of insulating material are mounted on opposite sides of the pedestal 162 and pass between the legs ot the connector 166. The conductor 160 passes on the front side of a pair of vertically spaced bolts 174 which are suitably insulated and extend between the rear end portions of the plates 172.

When a contacter of the type described is used in an alternating current circuit ot' large available short circuit capacity, fault currents create large electromagnetic forces. The electromagnetic forces set up by such currents flowing in the Contact bracket 138 through the contacts 139 and 159 and through the conductor 160 of each pole tends to expand the loop thus formed by forcing the conductor 16() 'forwardly thereby to cause premature opening of the contacts 139 and 159. These forces of expansion are neutralized in the present construction by the anti-blOw-oi assemblies 42 just described. This is because thenconnector `166, vthe connector bar 169, and

evadere 9 the flexible conductor 160 of each assembly form a second loop the forces of which tend to force the conductor 160 rearwardly toward the base 29. Consequently, the forces tending to move the conductor 160 forwardly are substantially neutralized and there is `insuiiicient resuitant force to separate the contacts 139 and 159. The connector 166 also performs the additional function of centering the conductor 160. This is because the current tlowing in the spaced legs of the connector 166 reacts with that flowing in the conductor 160 and thereby tends to maintain the conductor 160 equidistant from the spaced legs of the connector 166.

Referring now to Figs. 7, 8, 9, and ll, each of the identical arc chutes 44 has a front wall 174, a rear wall 175, and a pair of side Walls 176. The side walls 176 are preferably formed from laminated plastic material having thin sheets of electrical insulation libre bonded to each side. Upper and lower pairs of reinforcing strap members 175 and 179 secured at opposite ends to the walls 171i and 175 extend across the outer surface of the respective side walls 176.

A front arc runner 180 formed from copper strap extends upwardly a short distance along and is secured to the inner side of the front wall 174 and has a rearwardly directed loop portion 181 extending over and in close proximity to the movable power contact 159 when the contact 159 is in its open position, The lower end portion of the arc runner 130 is bent rearwardly and defines a pointed blade portion 182 for reception under a spring clip 134imounted on the top of the pedestal 162. The pedestal 1G12 then serves to hold the arc chutes 44 in position and also serves to connect the arc runners 180 to the respect-ive outgoing leads 54. A rear arc runner 185 also formed from copper strap extends upwardly a short distance along and is secured to the inner side of the rear wall 175 and has a Iforwardly ldirected loop portion 186 extending over and in close proximity to the stationary Contact 139. The lower side of the loop portion 186 defines a pointed blade portion 18S received under a spring clip 189 carried by the bracket 138. A brace member 19@ imparts rigidity to the portion 186 of the arc runner 185.

Interitting channel-shaped members 190 and 191 of insulating material best shown in Fig. ll are interposed between the front arc runner 180 and the front wall 174 and have their side walls on opposite sides of the arc runner and extend nearly the entire length of the wall 174. A pair of insulating spacers 192 interposed between the front wall 174 and the respective side walls 176 extend inwardly on opposite sides of the channels 190 and 191. Spacers 194 are similarly interposed between the rear wall 175 and .the respective side walls 176.

A pair of lining members 194 of arc resisting material secured to the lower inner sides of the side Walls 17 6, respectively, deline by their upper edges respective shoulders 196 upon which rest a plurality of complementary arcing plates 198 and 199 shown best in Figs. 12 and 13. The lower end 'faces of the spacers 192 and 194 also engage the shoulders 196.

The arcing plates 19S have a slot 21N) one side of which is defined by a slanting portion 201 and the arcing plates 199 have a similar slot 202 one side of which is deiined by an oppositely slanting portion 203. The slot 200 merges at its upper end into a. narrow vertical slot 204 and the slot 202 merges in a similar slot 265. The slots 204 and 205 provide additional expansion space for the arc gasses and thereby eliminate burning of the plates 198 and 199 at the upper extremities of the slots 200 and 202. The plates 19S and 199 are complementary and are alternated when arranged in the are chute as shown in Fig. 7 so that the slots 200 and 202 and the slot extensions 204 and 205 in effect define a sinuous arc path. Ridge portions 205 on the edges of the plates 198 and 199 serve to space the central portions of the plates apart from each other.

If the contactor is to have an interrupting rating of 50,000 klovolt-amperes, rectangular extension plates 206 having the same cross-section as the plates 158 and 199 are mounted on top of the plates 198 and 199, respectively, thereby to provide additional cooling area for the arc gases. For a contacter to be rated at 25,00() kilovolt-amperes, the plates 193 and 199 are used without the extensions 206 and the are chute structures 44 are shortened accordingly. A pair of strap members 208 suitably fastened on the inner walls 176 after the plates 193 and 199, and the plates 206 if used, are in position serve to hold the plates in assembled position.

For the rating of 50,000 kilovolt-ampere, the vertical dimension from the bottom of the cross support 16 to the top of the cross support 15 is approximately two feet and six inches. In each figure, `all of the parts are drawn to the same scale so that the dimension of any part can be determined from the one dimension recited.

Each of the arc chutes 44 is received between a pair of the blowout ears 122 with the lower edge surfaces of the strap members 178 resting on the upper edge surface of the respective ears 122. A pair of suitable clamp members 2%9 pivoted at 209 on the outer side of the respective strap members 173 are turned downwardly over the outer face surfaces of. the respective ears 122 as shown to assist in holding the arc chutes 44 in position.

The housing t5 comprises a top wall 210, a front wall 211, and four spaced phase barriers 212 and thereby denes chambers for each of the poles of the contractor. A plurality of studs 213 and associated cylindrical spacers 214 hold the phase barriers 212 in spaced relation and metal corner clips 215 secure the top wall 210 to the front wall 211 and to the outer pair of the phase barriers. There are vno exposed metal parts within the housing. Each of the phase barriers 212 has a shoulder 216 (Fig. 7) which is disposed behind the upper ange 22 of the cross support 15. Preferably the cross support 15 is covered on its upper and front sides by a thin sheet of insulating material (not shown). The outer pair of the phase barriers 212 are received at their upper rear edge portion in grooved brackets 217 carried by the cross support 15 and at their front edge portion in similar brackets 217 carried by the `cross support 14. The housing 45 is open only at the rear so that arc gases emerging from the top of the arc chutes 41tare directed rear wardly and are exhausted at the back of the contactor.

In the modication of Fig. 14, an operating magnet 220 for use with alternating current may comprise a C-shaped laminated core 221 pivotally mounted centrally of its closed end on a pin 222 carried by a pair of horizontally spaced studs 224 extending forwardly from a base 225 similar to the base 31. A compression spring 226 in a thirnoleshaped spring socket 22 fastened on the front of the base 225 biases the core 221 clockwise about the pin 222 so that the lower face of the lower leg of the core bears against the upper end of an adjustable stop bolt 229 threaded in the outer end portion of a stop stud 231i and locked by an adjusting nut 231. The stud 230 is carried by the panel 225. The upper leg 232 of the core 221 carries a suitable coil 234 the leads 235 of which `are attached to respective horizontaliy spaced terminal studs 236 which pass through the panel 225. The coil 234 is held in position by a pair of horizontally spaced rlat springs 23S bearing on the front face of tr e coil 234 and depending from a spring bracket 239 bolted to the side plate 11. Each leg of the core 221 has a suitable shading coil 2% disposed in its end face.

An armature 2411 for cooperation with the operating magnet 220 comprises a plurality of laminations held in stacked relation by rivets and carried loosely between a pair of side plates 244 each having a forwardly off-set depending end portion 245. The respective inner faces of the portions 245 are secured to clamping members 246 which cooperate with respective clamping members 248 one of which carries a bracket 249 for supporting the rod end bearing 84 for the tie-rod 85 which operates movable control circuit contacts as in the principal embodiment.

Since the core 221 is resiliently held in position on its pivot 222 by the spring 226, and the stacked laminations of the armature 244 are free to move slightly with respect to the side plates 245, the core 221 and armature 2511 are free to assume a proper position when, upon energization of the coil 234, the core 221 is engaged by the armature 244. Because of this self-adjusting mounting for the core 221 and the armature 241, extreme accuracy in di rnensioning of parts is not required to insure quiet and efficient operation.

What I claim is:

l. A contacter for alternating current systems com-- prising a stationary contact, a coopcrable movable contact movable to an open circuit position in a direction forwardly of the stationary contact in a path defined laterally by generally upright parallel planes, n conductor means connected to and extending rearwardly of the contactor from the stationary Contact, a 'fixed conductor spaced forwardly from the movable Contact and in align ment generally with the path thereof, said fixed conductor having an upwardly extending portion and a depending portion which depends from the upper end of the upwardly extending portion and has its lower end portion below said movable Contact, a liexible conductor electrically connected at one end to the lower end portion of said depending portion and at the other end to said mov able contact, said depending portion, throughout a substantial portion of its length, being spaced rearwardly from said upwardly extending portion and being disposed, when the contacts are in closed position, forwardly from said flexible conductor, a conductor means connected to the lower end of the upwardly extending portion, whereby there are `formed two conducting loops which are in series with each other and are arranged physically so that the current-produced repulsive forces on the flexible conductor urging it in said opening and closing directions, respectively, are opposed to each other.

2. A contactor according to claim l characterized in that the conductor means which is connected to the lower end of the upwardly extending portion extends rearwardly therefrom below the level of the lower end of said depending portion.

3. A contactor in accordance with claim l characterized in that an arc runner is provided for the movable contact and has a portion disposed in arc receiving position with respect to said movable contact and has a lower end portion supported on and electrically connected to the upper end of said fixed conductor.

4. A contacter according to claim 3 characterized in that a second arc runner is provided for the stationary Contact and has a portion disposed arc receiving position with respect to said stationary contact and is electrically connected thereto.

5. A contacter according to clairn 4 characterized in that the conductor means connected to the stationary contact includes a blow-out coil, and ilux conducting means are provided for isolating said flux of the coil from said conductors while concentrating said flux so as to move arcs formed at the contacts onto and along the runners.

6. .A contacter according to claim 5 characterized in that said runners are disposed in an arc chute and are sccured to the front and rear portions thereof, respectively, said llux conducting means are ears for said blow-out coil, said chute is supported by said ears and is remov able cndwise of the chute forwardly of the contacts, the runner of the movable contact and the upper end of the fixed conductor having inter-engageable fastening means which are engageable by movement of chute rearwardly into operating position for constraining the `chute in said operating position and which are releasablc by movement of the chute forwardly.

7. A contactor according to claim l characterized in that said depending portion has a central opening extending lengthwise thereof and adapted to afford passage of the flexible conductor therethrough forwardly and rearwardly upon movement of the movable contact to open circuit position and closed circuit position, respectively.

8. A blowout structure for the purposes described comprising a pair of magnetic ears spaced apart iiatwise from each other and having notches, respectively, which are aligned with each other, each notch opening through an edge of its associated ear so as to receive with a press fit an end portion of a common core piece in direction laterally of the core piece, a coil surrounding the core piece, terminal extensions on the ends of the coil, means securing the cars to the support, means securing the termnnl extensions to the support in a position wherein the core piece is in the coil. and partially in the notches, with at least one of said extensions adjustably movable toward the support in a direction parallel to the lateral movement of the core piece into the notches, and means associated with said securing means for moving at least said one of said extensions toward the support thereby to move said one of said extensions into final position and thereby to press said core piece fully into said notches.

9. A contacter for alternating current systems comprising a stationary contact, a cooperable movable contact movable to an open circuit position in a direction forwardly oli' the stationary contact in a path dciined laterally by generally upright parallel planes, a generally upwardy extending fixed conductor spaced forwardy from the movable Contact and in alignment generally with the path thereof, a iiexible connector electrically connected at one end to said Vlixed conductor and at the other end to said movable contact, a irst arc runner for the movable contact having a portion disposed in are receiving position with respect to said movable contact, a second arc runner for the stationary Contact having a portion disposed in arc receiving position with respect to said stationary contact, an are chute including said tirst arc runner at the forward portion thereof and said second are runner at the rear portion thereof, and said iirst arc runner and the upper end of said fixed conductor having inter-engageablc fastening means for securing said rst arc runner to the upper end of said fixed conductor in electrically conducting relationship thereto.

l0. A contactor for alternating current systems coinprising a stationary contact, a conductor means connected to, and extending rearwardly of the contacter from, thc stationary contact, a movable contact cooperable with the stationary contact and movable to an open circuit position in a direction forwardly of the stationary contact in a path deiined laterally by generally upright paral` lel planes, a generally upwardy extending fixed conductor spaced forwardly from the movable contact and in alignment generally with the path thereof and having a lower rearward extension, a iiexiblc connector electrically connected at one end to said lower rearward extension and at thc other end to said movable Contact, said fixed conductor, throughout a substantial portion of its length above said lower rearward extension, being disposed, when the contacts are in closed position, forwardly from a substantial portion of said flexible connector, whereby two conducting loops which arc in series with each other arc formed and one of said loops includes said conductor means, said stationary and movable contacts, and said flexible connector, and the other of said loops includes said fixed conductor and said tiexible connector, a conductor means connected to the fixed conductor so that repulsive forces, produced by currents flowing in the loops, are in opposition to each other and urge the tiexible conductor in said opening and closing directions, respectively, an arc runner for the movable Contact havn ing a portion disposed in arc receiving position with respect to said movable contact, and inter-engageable fas- References Cited in the file of this patent UNITED STATES PATENTS 2,240,654 Jochem et al. May 6, 1941 14 l Healis Dec. 8, Pierce Sept. 19, Frese Sept. 16, Grepe Dec. 16, Wood et al. July 21,

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