US3403239A

US3403239A - Electromagnetically-operated air-break, clapper-type high-voltage contactor

Info

Publication number: US3403239A
Application number: US457977A
Authority: US
Inventors: Robert M Schramm; Richard F Ptak; David L Swindler
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1965-05-24
Filing date: 1965-05-24
Publication date: 1968-09-24
Anticipated expiration: 1985-09-24
Also published as: GB1116993A

Description

Sept. 24, 1968 R M SCHRAMM ET AL I 3,403,239

ELECTROMAGNETICALLY-OPERATED, AIR-BREAK, CLAPPER-TYPE HIGH-VOLTAGE CONTACTOR Filed May 24, 1965 5 Sheets-Sheet 1 2 2 "o g G\ x Wag/6722375 I fienzillickremm jzcwr'd 17.3 3046 Squad/er p 1968 R M. SCHRAMM ET AL 3,403,239

R-TYPE ELECTROMAGNETICALLYOPERATED, AIR-BREAK, CLAPPE Filed May '24, 196E HIGH-VOLTAGE GONTACTOR 5 Sheets-Sheet 2 N I I W5 i .flguzrzdkfl Sept. 24, 1968 R. M. SCHRAMM ET AL 3,403,239

3 ELECTROMAGNETICALLY-OPERATED, AIILBREAK, CLAPPER-TYPE I I 3 HIGH VOLTAGE CONTACTOR Filed May 24, 1965 '5 Sheets-Sheet S I Sept. 24, 1968 R M SCHRAMM ET AL 3,403,239

ELECTROMAGNETICALLY-OPERATED, AIR-BREAK, CLAPPER-TYPE HIGH-VOLTAGE.- CONTACTOR Filed May 24, 1965. 5 Sheets-Sheet 4 Sept. 24, 1968 R. M SCHRAMM ET AL 3,403,239

ELECTROMAGNETICALLY-OPERATED, AIR-BREAK, CLAPPER-TYPE HIGH-VOLTAGE CO NTACTOR Filed May 24, 1965 5 Sheets-Sheet 5 United States Patent ABSTRACT OF THE DISCLOSURE The contactor has provision for mounting currentlimiting fuses disposed vertically on its front side, and has rear-mounted plugin-termina1s. For each pole of the contactor, power is brought to each contact pair from its associated terminal through a horizontally-disposed power bus assembly and thence through its associated currentlimiting fuse. Each pole of the contactor is further provided with a blow-out assembly and a removable are chute for constraining and extinguishing the arc. Addi tionally, arc constraint is facilitated by the power bus assemblies, each of which includes an elongated conductor which provides a divided current path around its associated arc chute.

This invention relates to electromagnetically operated contactors and more particularly to air-break contactors suitable for repeatedly switching polyphase circuits carrying large alternating currents at moderately high voltages and for interrupting such circuits under fault conditions even when the available short-circuit capacity of the circuits is as high as 50,000 kilovolt-amperes, unfused, and up to a maximum of 415,000 kilovolt-amperes with current limiting fuses presently available.

Contactors used in moderately high voltage alternating current circuits have been of the oil-immersed and airbreak types. Up to a few years ago, there had not been available a contactor capable of interrupting in air a fault current where the symmetrical portion of the fault current corresponded to 50,000 kilovolt-amperes and the direct current component was at any possible value determined by the ratio of reactance to resistance. Consequently, it had been necessary to use oil-immersed contactors or contactors backed up with current-limiting fuses when ever the available short-circuit capacity of the circuit approached 50,000 kilovolt-amperes.

With increased knowledge of alternating current arcing phenomenon at voltages within the range of 2000 to 5000 volts, however, it became possible to interrupt successfully in air the arcs formed in such moderately high voltage circuits.

In order to compete with oil-immersed contactors, it was necessary that non-oil-immersed or air-break contactors for use at voltages within the range mentioned and in circuits of such large available fault capacity comprise a 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. Examples of such prior art air-break contactors which met the foregoing requirements are illustrated and described in Patents Nos. 2,790,878 and 3,017,481, issued in the name of Charles A. Lister on Apr. 30, 1957, and Jan. 16, 1962, respectively, to the assignee of the present invention.

Although these high voltage air-break contactors have been used successfully for several years, they are relatively difiicult and expensive to build and are larger than is desirable for optimum installation requirements. Also when these prior art contactors are used in combination with current-limiting fuses, the fuses are generally located 3,403,239 Patented Sept. 24, 1968 in a separate enclosure and are, therefore, relatively inaccessible. When attempts were made, in some designs, to locate the fuses on or near the contactor, the fuses had to be positioned at the rear or on top of the contactor so that the contactor had to be partially withdrawn from its enclosure to gain full access to the fuses. In contactors according to the present invention, provision is made to mount fuses on the front face of the contactor.

Thus, the present contactor need not be withdrawn from its enclosure to inspect or replace fuses. The contactor is provided, however, with wheels or rollers and with electrical disconnects to permit convenient withdrawal of the contactor in order to facilitate inspection of the contacts or maintenance and repair.

Because space is often at a premium in electrical control installations, it is desirable to be able to vertically align two or more contactors within a single enclosure. The large size of the prior art contactors, however, makes it impractical to place more than two fully-rated contactors in vertical alignment within a single enclosure. Using contactors of the present invention, it is possible and convenient to vertically position three fully-rated contactors within a cabinet only ninety inches high.

In the prior art contactors, transformers which apply control voltage for the operating magnet of the contactor are generally mounted separately from the contactor because of the unavailability of mounting space on the contactor itself. In the present invention, control transformers are mounted directly on the contactor as a component part thereof.

Prior art contactors, in order tosuccessfully interrupt fault currents, were commonly provided with large and cumbersome arc chutes which were constructed of a multiplicity of individual pieces. In contactors in accordance with this invention, the use of a relatively short two-piece arc chute is made possible because of the are constriction provided by electromagnetic forces set up by the flow of current in a novel conducting path about the arc chute.

The contactor of this invention also provides a novel movable contact structure whereby the movable contact for each pole may be conveniently and individually adjusted so that, in operation, all of the movable contacts engage their associated stationary contacts concurrently.

It is an object of this invention to provide an improved draw-out, air-break contactor for use in alternating current circuits of moderately high voltage.

Another object is to provide an 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 contactors of comparable voltage and interrupting rating.

A further object is to provide an air-break contactor having provision for receiving current-limiting fuses on the front face thereof.

Still another object is to provide an improved multipole air-break contactor in which elongated current conductors provide novel divided current paths around the respective arc chutes of the contactor.

Another object is to provide an air-break contactor having a control voltage transformer incorporated as a component part of the contactor.

An additional object is to provide an alternating current air-break contactor having improved movable power contact assemblies.

A more detailed object is to provide a contactor for use in alternating current circuits comprising a stationary contact, a movable contact movable between a closed and an open circuit position with respect to the stationary contact in a path disposed forwardly of the stationary contact, a fixed conductor means spaced forwardly from the movable contact and in alignment generally with the path, a flexible conductor electrically connected at one end to the fixed conductor means and at the other end to the movable contact, an elongated conductor extending from the rear to the front of the contactor and disposed above the contacts in substantial vertical alignment with said path, first fuse retaining means supported on the fixed conductor means and opening forwardly of the fixed conductor means, second fuse retaining means supported on the elongated conductor at the forward end thereof and opening forwardly of the elongated conductor, the first and second fuse retaining means being substantially vertically aligned with respect to each other so as to be adapted for carrying a fuse in substantially a vertical position between the retaining means forwardly of the contacts, electrical circuit completing means for the stationary contact disposed at the rear thereof, and electrical circuit cornpleting means for the elongated conductor, positioned at the rearward end thereof.

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

FIG. 1 is a front perspective view of a contactor embodying the present invention;

FIG. 2 is a rear perspective view of the contactor of FIG. 1;

FIG. 3 is a front elevation of the contactor of FIG. 1, two of the three power fuses being removed and other structure being removed or cut away to show additional detail;

FIG. 4 and FIG. 5 are crosssectional views taken generally along the lines 44 and 55, respectively, of FIG. 3;

FIG. 6 is a perspective view of one of the elongated conductors shown in FIGS. 1, 2, 3 and 4.

FIG. 7 is a top perspective view of one of the arc chutes of the contactor; and

FIG. 8 is a fragmentary perspective view of a movable power contact assembly shown in cross-section in FIG. 4.

Referring to FIGS. 1 through 4, a contactor embodying the invention includes a frame 10 comprising left and right hand side plates 11 and 12, respectively, preferably formed from steel, a front cross support 14, and bottom and top rear cross supports 15 and 16, respectively. Each of the side plates 11 and 12 has a 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 up-turned end flanges 21 suitably secured on the inner surfaces of the side plates 11 and 12, respectively, at the lower front portions thereof. The bottom rear cross support 15 is preferably a metal channel having a pair of rearwardly directed side walls 22 and a pair of forwardly directed end flanges 23, respectively. The end flanges 23 (FIGS. 4 and 5) of the bottom rear cross support 15 are suitably secured on the inner surfaces of the side plates 11 and 12, respectively. As shown best in FIG. 2, the top rear cross support 16 is a channel preferably molded of glass polyester and having a pair of rearwardly directed side walls 24. Vertical strengthening ribs 25 and a plurality of pairs of raised guides 26 are molded integrally with the support 16. The support 16 and the guides 26, together, serve as an upper support and locating means for a plurality of phase barriers 27, the function of which will be later described. In addition, the guides 26 provide increased electrical clearance between adjacent power disconnect stab terminals to be later described. The support 16 has a pair of end flanges 28 suitably secured on the inner surfaces of the side plates 11 and 12, respectively, near the top edges of the plates. The

supports

15 and 16 are vertically aligned.

The frame 10 thus 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 supports 14, 15, and 16 not only impart rigidity, but, as will become apparent, also serve as mounting means for the operating parts of the contactor.

To facilitate mounting and transporting of the contactor, suitable apertures 11a and 12a may be provided in the side walls 11 and 12, respectively, near the top edge thereof. Pairs of wheels 11c and may also be mounted on the side walls 11 and 12, respectively, adjacent the bottom edge thereof, to facilitate withdrawing the contactor from its enclosure (not shown) for inspection or maintenance.

Suitably secured at their top and bottom portion in horizontally spaced relation on the front faces of the web portions of the rear 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 and an elongated conductor and power bus assembly 30a (FIGS. 2 and 4). An insulating base or panel 31 is suitably secured at its bottom and top portions to the rear cross supports 15 and 16, respectively, at the rear thereof. The panel 31 supports on a lower portion of its front face a direct current operating magnet assembly 32 (FIGS. 3 and 5) and on an upper portion of its front face a mounting plate 33 adapted to receive a control transformer and fuse assembly 34 to be described later.

It is to be noted that any one of the

bases

29 and 31 are easily mounted on and removed from the

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 of the

supports

15 and 16 disposes the bases 29 and the base 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 37, The end portions 36 and 37 are received in respective bearings 38 (FIG. 3), preferably of the self-aligning spherical type, mounted on the inner surfaces of the side plates 11 and 12, respectively. The end portion 36 extends for a short distance beyond its associated one of the bearings 38 and has an interlock arm 39 (FIG. 2) mounted thereon to permit connection of a mechanical interlock means (not shown) with an adjacent upper or lower contactor or with a door latch of a protective housing.

The shaft 35 serves as a pivotal axis for, and supports in spaced relation, a plurality of identical movable power contact assemblies 40 (FIG. 4) which cooperate with the blowout and stationary contact assemblies 30, respectively. The shaft 35 also supports an armature and control circuit operator assembly 41 (FIGS. 1, 3, and 5) which cooperates with the operating magnet assembly 32 and with a group of control circuit switch units 42. A plurality of pedestal and insulator assemblies 43 (FIGS. 1, 3, and 4) are mounted in horizontally spaced relation on the front cross support 14 in front of the shaft 35 and are associated with the movable power contact assemblies 40, respectively.

A plurality of arc chutes 44 are provided for the poles of the contactor, respectively, and the phase barriers 27 provide insulation between adjacent poles.

The operating magnet assembly 32 is shown best in FIGS. 3 and 5. The base 31 which carries the magnet assembly 32 is preferably bolted to the rear cross supports 15 and 16 and is spaced from the rear edges thereof by cylindrical spacers 58 surrounding the respective mounting bolts. The magnet assembly 32 comprises a generally U-shaped magnetic frame 59 from the bight portion of which extends, forwardly of the contactor and in vertically spaced relation to the legs of the frame 59, a magnetic core 60 carrying an operating coil 61. The frame 59' and the core 60 are secured to the base 31 by a cap screw 62 which passes through respective aligned openings inthe base 31 and the frame 59 and is received in a tapped opening in the core 60. A flat spring 62a, disposed between the frame 59 and the operating coil 61, biases the coil 61 forwardly from the bight portion of the frame 59 against an inner core cap 63 and an outer non-magnetic spacer 64 secured to the core 60 at the forward end thereof by a suitable bolt. The coil 61 has a pair of terminal leads 65 which are electrically connected to terminals on a combined terminal block and rectifier assembly 66.

If desired, a suitable voltage reducing circuit can be provided to reduce the voltage at the coil 61 consequent upon operation of the armature and control circuit operator assembly 41 into a sealed position with respect to the core 60. For this purpose a resistor 67 may be mounted by a through bolt 68 on the side plate 12. The resistor 67 is connected in series with the coil 61 and in parallel with a normally-closed contact of a push-button operated switch 70.

The armature and control circuit operator assembly 41, as best shown in FIG. 5 comprises an armature 72 preferably in the form of a fiat plate of ferrous metal secured at its lower end portion to the squared portion of the operating shaft 35 by suitable bolts.

As shown in FIGS. 1 and 5, the armature 72 normally rests, due to gravity, in an open position against a bight portion of a U-shaped stop plate 80 secured to the upper leg of the frame 59 by suitable bolts. Upon energization of the coil 61, the armature 72 rocks counterclockwise from the open position to a closed position, indicated in FIG. 5 by broken lines 81, turning the shaft 35 with it as indicated. When the coil 61 is deenergized, the armature 72 returns to its open position due to gravity and the pressure of contact springs to be described.

In order to provide means for operating the control circuit switch units 42, an arm 82 is secured to the shaft 35 (FIG. 5) as by a pair of cap screws 83. When the armature 72 rocks as a result of energization and deenergization of the coil 61, the arm 82 is caused to cooperate with self-restoring push-button operators 84 of the group of conventional control circuit switch units 42.

The control circuit switch units 42 are mounted by screw fasteners on a support bracket 86 (FIGS. 1 and 5) which is secured by bolts 87 to the right side plate 12. The

bracket 86 is disposed generally horizontally and normal to the side plate 12 and is positioned, as shown in FIGS. 1, 3, and 5, so that the push-button operators 84 of the contact units 42 can cooperate with the arm 82 as previously described. It is to be noted that the control circuit switch units are positioned for easy access. Connections from the switch units 42 may be made by means of a cable or wire harness 42a to either one or both of a pair of plug receptacles 89.

Electrical power for the operating coil 61 is supplied to the combined terminal block and rectifier assembly 66 by a control transformer 90 (FIG. 5) which is a part of the control transformer and fuse assembly 34. The assembly 34 comprises, in addition to the transformer 90, a pair of insulating channel members 91 each of which supports a pair of control fuse clips 92 for retaining a fuse 93 in parallel spaced relation on the front face of each of the channels 91. The primary of the transformer 90 is connected through the fuses 93 to two of the power bus assemblies 30a as indicated best in FIG. 1. The lowervoltage secondary of the transformer 90 may be connected through terminals in one or the other of the plug receptacles 89 to an external push button (not shown).

Referring now principally to FIGS. 2, 4, and 6, each of the elongated conductor and power bus assemblies 30a includes an elongated conductor 101 comprising preferably two suitably formed copper leg portions or sections 102 and 103. Each of the sections 102 and 103 is secured at one end by bolt fasteners to a fuse clip mounting block 104. The other end portions of the sections 102 and 103 are inturned and are joined together by bolt and nut fasteners 105. A blade portion 106 of the section 102 projects beyond the end of the section 103 and serves as a power stab terminal for the contactor. As is evident from FIGS. 2 and 6, a rectangular opening is defined in the assembly 30a between the sections 102 and 103 and the block 104. Each of the assemblies 30a also has a pair of insulating spacers 108, suitably secured, one to each of the sections 102 and 103, by insulating screw fasteners such as nylon screws 109. The spacers 108 serve as positioning guides for the phase barriers 27 as will be described later.

Referring now principally to FIGS. 1, 2, and 4, each of the blowout and stationary power contact assemblies 30 comprises a pair of flux conducting horizontally spaced laminated blowout ears 122 formed of ferrous metal and extending forwardly and rearwardly of their associated one of the panels 29. Since the assemblies 30 are identical, a description of one will suffice. Each of the blowout ears 122 comprises a plurality of laminations all riveted together and having a lower portion 126 in the region of the power contacts tapered upwardly toward the front so that the forward portion of each ear is narrower than the rear portion. Each of the ears 122 has a portion removed therefrom so as to define, in each ear, a generally trapezoidal opening aligned generally lengthwise of the ear so that, when the contactor is connected to a source of power, blowout flux is effectively concentrated across the power contacts to be described and the lower portion of the arc chutes 44. The ears 122 are preferably secured near their rear end portions (FIG. 2) 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 of insulated edgewound copper strap has an upper terminal bolted to an electrically conductive angle bracket 132 which is mechanically and electrically received in the forward portion of jaws of a power terminal contact jaw 133. The rearward portion of the contact jaw 133 together with the blade portion 106 of the assembly 30a serve as means whereby each pole of the contactor can be conveniently connected to external power conductors of an electrical panel 135. The blowout coil 131 also has a lower terminal extension 134 connected by suitable bolt fasteners to a forwardly extending stationary contact bracket 138 which is secured to its associated panel 29 by a through bolt 140. The bracket 138 carries, at its forward end, a detachable power contact 141. A magnetic core 142 of spirally-Wound insulated ferrous metal strip is received coaxially within the coil 131 and abuts the inner periphery thereof. Adjacent turns of the coil 131 are insulated from each other by insulation (not shown) carried by the proper strap comprising the coil. A pair of insulators 143 are positioned at opposite ends of the core 142 between the core and its associated blow-out ears to prevent magnetic shortcircuiting of the turns of the spirally wound core.

The rear end portions of the ears 122 are held together by a stud 145 passing centrally through and holding the core 142, the coil 131, and the insulators 143 together as a unit prior to assembly of the contactor.

Each of the movable power contact assemblies 40, shown best in FIGS. 4 and 8, comprises an elongated electrically non-conductive contact arm pivotally mounted at its lower end by a pin 151 on an insulator 152 having a shank portion with an axial opening therein for non-rotatably receiving the shaft 35 and having cylindrical flanges 153 disposed in spaced-apart relation on the shank portion. A contact pressure spring 155, secured at one end to the upper end portion of the arm 150 and at the other end to the insulator 152, biases the contact arm in a counter-clockwise direction (FIG. 4) toward the insulator 152. A movable power contact 159 is detachably mounted on the upper end portion of the contact arm 150 for engagement with an associated one of the stationary power contacts 141.

The closed position of the movable power cntact assemblies 40 is indicated by broken lines in FIG. 4. When the shaft 35 rocks due to energization of the coil 61, each of the contact arms 150 moves from the solid line open position to the broken lineclosed position. During this movement the contacts 141 and 159 of each pole engage each other and the contact arms 150 rotate about their pivot pins 151 against the bias of the associated one of the springs 155. Adjustable stop means comprising an adjustable screw 156 carried in a threaded insert retained in the contact arm 150 provides means for selectively adjusting the positional relationship of each of the contact arms 150 with respect to its associated insulator 152 so that, in operation, all of the movable contacts engage their associated stationary contacts concurrently.

Power is carried to each of the movable power contacts 159 by a flexible conductor 160 forming part of one of the pedestal and insulator assemblies 43. Because the assemblies 43 are identical, a description of one will suflice.

Each of the assemblies 43 comprises a flanged standoff insulator 161, mounted on the front frame support 14, and a fixed conductor means such as a metal post or pedestal 162 mounted on top of the insulator 161 and having generally flat or planar front and rear face portions. An end portion of one of the flexible conductors 160 is suitably bolted to the flat rear face portion of the pedestal 162. Fuse retaining means such as the lower fuse clip 164 is suitably bolted to the front face portion of the pedestal.

An upper fuse clip 165, similar to the clip 164, is bolted to the fuse clip mounting block 104 which was described. in connection with the elongated conductor 101. As best shown in FIG. 4, the lower and upper fuse clips 164 and 165 are substantially vertically aligned with respect to each other so that a fuse, such as the fuse 166, may be carried by the clips in substantially a vertical position forwardly of the contacts and at the front of the contactor.

When a contactor of the type described is used in an alternating current circuit of 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 141 and 159, and through a portion of the conductor 160, for each pole, tend to expand the loop thus formed by forcing the movable contact forwardly thereby to cause premature opening of the contacts 141 and 159. These forces of expansion are neutralized in the present construction by the downwardly depending loops of the flexible conductors 160. This is because the flexible con ductor 160 of each pole forms a second loop, the forces of which tend to force the loop of the conductor 160 to expand thereby to urge the movable contact of that pole rearwardly toward the base 29. Consequently, the forces tending to move the contact 159 forwardly are substantially neutralized and there is insuflicient resultant force to prematurely separate the contacts 141 and 159.

Referring now to FIGS. 1 through 4 and 8, each of the arc chutes 44 comprises two identical portions 174. The portions 174 of the arc chutes 44 are preferably molded from arc-resisting material and have a plurality of relatively thin arcing plates 177 molded integrally therewith lengthwise of the arc chute. The arcing plates 177, which are tapered throughout substantially their entire length and beveled at their lower end portions, are disposed in the portions 174 of the arc chute 44 so that, when the chute is assembled, the arcing plates 177 define, in effect, a sinuous arc path which becomes longer upwardly of the chute 44 to aid in breaking up electrical arcs introduced therein.

A pair of identical arc runners 180 (FIG. 4) formed from copper strap is secured in each of the arc chutes 44 by suitable recesses in the end wall portions of the chutes. Each of the arc runners 180 has an inwardly directed loop portion 181 extending over and in close proximity, respectively, to the contacts 141 and 159 of its pole when the contact 159 thereof is in its open position. The lower end portion of each arc runner 180 terminates in a pointed blade portion 182 for reception, respectively, under a spring clip 184 for its pole mounted on the rear face portion of the pedestal 162 and on the upper surface of the bracket 138.

Each of the arc chutes 44 is received, through the rectangular opening in the power bus assembly 30a, between the associated pair of the blow-out ears 122 with lower edge surfaces 185 of the arc chutes resting on the upper edge surfaces of the associated pedestal 162 and bracket 138, respectively. As best illustrated in FIGS. 1 and 7, finger grip extensions 174a are provided at the upper edge of each arc chute 44 to facilitate their removal and handling.

In operation, the electromagnetic forces established by current flow through each of the elongated conductor and power bus assemblies 301: tend to direct and constrict the are formed upon separation of the associated pair of contacts 141 and 159 so that the arc is confined and dissipated entirely within the arc chute 44 for that pole.

As previously mentioned, the spaced phase barriers 27 (-FIGS. 1 and 2) separate each of the poles of the contactor. Each of the phase barriers 27 has a shoulder which is disposed behind the upper side wall 24 of the rear cross support 16. At their lower front edge portion, the barriers 27 are received in respective grooved brackets carried by the front cross support 14. At their upper front edge portion, the barriers 27 are positioned between the adjacent insulating spacers 108.

If desired, an additional set of electrical stab terminals and power buses 191 can be added to the contactor to supply fused power to other contactors in a complex starter system. As illustrated in FIGS. 1 and 2, the stab terminals and power buses 191 extend, respectively, through openings 29a molded integrally with the elongated panels 29. At their forward end, the buses 191 are electrically connected, respectively, to the conducting pedestals 162.

Having thus described our invention, we claim:

1. A contactor for use in alternating current circuits comprising:

(a) a stationary contact,

(b) a movable contact movable between a closed and an open circuit position with respect to said stationary contact in a path disposed forwardly of said stationary contact,

(c) an arc chute removably disposed in are receiving relation to said contacts,

(d) fixed conductor means spaced forwardly from the movable contact and in alignment generally with said path,

-(e) a flexible conductor electrically connected at one end to said fixed conductor means and at the other end to said movable contact,

(f) an elongated conductor extending from the rear to the front of the contactor and disposed above said contacts in substantial vertical alignment with said path,

(g) said elongated conductor having a bifurcated portion comprising a first leg portion and a second leg portion which are joined at respective opposite ends to define a rectangular opening therebetween, said arc chute being disposed within and removable through said opening,

(h) first fuse retaining means supported on said fixed conductor means and opening forwardly of said fixed conductor means,

(i) second fuse retaining means supported on said elongated conductor at the forward end thereof and opening forwardly of said elongated conductor,

(j) said first and second fuse retaining means being substantially vertically aligned with respect to each other so as to be adapted for carrying a fuse in substantially a vertical position between said retaining means forwardly of said contacts,

(k) electrical circuit completing means for said stationary contact disposed at the rear thereof, and

(l) electrical circuit completing means for said elongated conductor, positioned at the rearward end thereof.

2. A contactor according to claim 1 characterized in that said flexible conductor forms a single conducting loop disposed downwardly from said fixed conductor means and said movable contact whereby, when current flows in said loop, the current-produced forces on said loop urge said contacts to their closed-circuit position.

3. A contactor in accordance with claim 1 characterized in that a pair of arc runners is provided, one electrically connected to said movable contact and one electrically connected to said stationary contact, each runner having a portion disposed above and in are receiving position with respect to its associated contact.

4. A contactor in accordance with claim 3 wherein said are runners are identical.

5. A contactor according to claim 3 wherein said electrical circuit completing means for said stationary contact includes a blowout coil and flux conducting means operative to concentrate flux produced by current in said coil so as to move arcs formed at the contacts onto and upwardly along said are runners, said flux conducting means comprising:

(a) a core within said coil,

(b) a pair of magnetic ears in flux conducting relation with opposite ends of said core, respectively, and extending forwardly of said core and coil in spaced relation to each other and having portions removed therefrom, respectively, so as to define, in each ear, an openingdior further concentrating said flux.

6. A contactor in accordance with claim 5 wherein said core is a spirally wound core.

7. A contactor in accordance with claim 3 characterized in that said runners are disposed in said are chute, said are chute being supported by said fixed conductor means and said circuit completing means for said stationary contact, the upper end of the fixed conductor means and the runner associated with the movable contact having interengageable fastening means, the electrical circuit completing means for the stationary contact and the runner associated with the stationary contact having similar interengageable fastening means, both interengageable fastening means being engagea'ble by move mnt of the chute downwardly into operating position and being releasable by movement of the chute upwardly out of operating position.

8. A contactor in accordance with claim 7 wherein said are chute comprises a pair of identical molded portions.

9. A contactor according to claim 1 characterized in that said movable contact is carried by operating means 0 including:

(a) an insulator having a shank portion with an axial opening therein and having cylindrical flanges disposed on opposite sides of said shank portion,

(b) an operating shaft rotatably mounted in said frame and non-rotatably received in the opening of said insulator,

(c) an electrically non-conductive contact arm pivotally mounted on said insulator for pivoting about an axis parallel to the longitudinal axis of said operating shaft,

(d) resilient means normally biasing said contact arm toward said insulator, and

(e) adjustable stop means for selectively adjusting the positional relationship of said contact arm with respect to said insulator.

References Cited UNITED STATES PATENTS 1,306,344 6/1919 Krantz 317114 2,338,715 1/1944 Graves 200-147 2,750,476 6/ 1956 Latour 200-147 3,155,801 11/1964 Pokorny 200-147 ROBERT S. MACON, Primary Examiner.