US2873330A - Contactors - Google Patents

Description

United States Patent CONTACTORS Joseph J. Gribble, Fox Point, Wis., assignor to Square D Company, Detroit, Mich., a corporation of Michigan Application September 14, 1955, Serial No. 534,227 2 Claims. (Cl. 200-144) g The present invention relates to contactors and more particularly to contactors having a relatively high capacity requiring arcing barriers between two or more adjacent poles.

An object of the present invention is the provision of a contactor having an increased current interrupting capacity.

Another object is to provide a yoke or movable contact support means which increases the 'current interrupting capacity of a contactor.

A further object of the invention is the provision of double break contact structure in which arcing is produced at one point which is enclosed by a cover block utilizing a minimum amount of material.

Still another object is to provide a contactor having the foregoing qualities and convertible from normally open position to a normally 'closed position.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

Figure 1 is a front view of the contactor partially in section of a preferred embodiment of the invention.

Figure 2 is a cross sectional view of the contactor taken along the line 22 of Figure 1 in the direction shown.

Figure 3 shows a section of the contactor taken along the line 3-3 of Figure 1 in the direction indicated.

Figure 4 is a pictorial view of the cover block.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Figures 1 to 3 which illustrate a preferred embodiment, a contactor 6 supported on a mounting plate 8. The contactor is a modified .form of an air circuit breaker requiring an auxiliary source of power or apparatus, e. g., solenoid or latching means for holding the contactor in closed position. The principal parts of the contactor include an insulating base, contact operating means, and the contacts which coact to complete or to interrupt a circuit. The contactor section includes a double break contact structure having a pair of stationary contacts or brackets '9 and 10 mounted in opposing relation to a movable contact bridge 12 having a pair of corresponding contact sections on a supporting strap. The stationary contacts or brackets 9 and 10 are mounted on an insulating base block 13 in arc chutes or chambers 14 by means of terminal straps 15,16 and secured to the insulating block 13 by screws 17 and A four pole contactor has been illustrated in which the section taken along section line 2 and shown in Figure 2 discloses a normally closed contact; and the cross section taken along the line 3 shown in Figure 3 discloses a normally open contact structure.

' Referring more particularly to Figure 3, in which the normally open 'contacts are shown; a double break ice circuit interrupter is shown having L-shaped stationary contact brackets 19 and 20 mounted on the insulating base block 13 in the arc chute or chamber 22. The contacts on the stationary brackets 19 and 20 are located in opposing relation to contacts on the movable bridge 23 formed from a section of conductive strap which completes the circuit between the line and load stationarycontacts of the contact support straps 19 and 20 respectively. The stationary contact support straps are secured in position by terminal straps 26 and 27 which are fastened to the insulating block 13 by screws 17 and 18. Since the contacts are subject to wear suitable fastening means such as screws 24 and 25 are provided for removably attaching the contact straps to the terminal straps 26 and 27. l The movable bridge is also subject to wear and replacement and is therefore removably retained in position by a movable contact operator or spring guide 28 and helical spring 29 which are mounted on the yoke 30 and secured to an abutment thereon by a screw 33. On the ends of the terminal straps 26 and 27, load and line terminals 34 and 35, respectively, are provided, and suitably positioned for convenient access from the outside of the' insulating block 13.

In comparing the normally closed pole illustrated in Figure 2, and the normally open pole in Figure 3, it is found that the load terminal straps 15 and 26 are identical. However, the load contact support straps 19 and 20 differ in length of the supporting legs and location of the contacts to provide an opposing contact surface for the movable bridge contacts. In the nor mally closed structure of Figure 2, the movable bridge 12 is biased against the stationary contacts by a helical spring 37 which seats'on a suitable abutment provided on the insulating block 13 in the upper part of the chamber directly above the spring guide 28.

The line contact bracket 10 is connected to the terminal strap 16 and has an extension projecting into the chamber and a contact on the upper surface which is disposed in opposing relation to the corresponding movable bridge contact, cooperating with the load contact to statically load the spring 37 and position the bridge 12 across the stationary contacts, and thereby incorporate a double break circuit structure. The terminal strap 16 extends upwardly and out of the arc chute 14, projecting into an open chamber for the line terminals 38 betweenbarriers 39 separating the poles of the contactor 6.

Referring to the normally open pole of the contactor shown inFigure 3, it is seen that the movable bridge is supported below the stationary contacts by the spring guide 28, providing a contact gap between stationary and movable contacts and a spring 29 compressed upon energization of the contact operating means shown in Figures 1 and 2. The L-shaped stationary contact strap 19 is positioned in a channel 40 in the insulating block 13 and fastened to the line terminal strap 27 which extends laterally into a terminal chamber 43 bounded on either side by are barriers 39 separating the line terminals from the adjacent poles.

An L-shaped insulating block 13 is provided having arc chutes or chambers 14, 22, 31 and 32 and terminal chambers 43 housing the contact and terminal structure of the respective poles.

The contacts are mounted on the base block in the arc chutes or chambers which serve to confine an arc and separate the poles from each other thereby minimizing the danger of striking an arc from one pole to the contact structure of another pole and short circuiting the respective lines. The insulating block 13 is made from are resisting insulating material wherein the arc extinction takes place as a result of extensionof the are along the surface of the arc chute or cavity. Metal inserts may be molded in the arc chute to assist in extinguishing the arcj-and-"a certain amount of arc blowout is obtained 'by theconfiguration of the line contacts of Figure 3 due to the magnetic field setup about the conductors tending to stretch the arc and force it against the walls of the chute thereby enhancing the cooling efiect.

The leg of the L-shaped base block forming chambers or are chutes 14, 22', 31 and 32 is placed against the mounting plate 8 and includes a back surface 44 for securing the load straps and stationary contact straps, closing the end of the chamber of the are chute and insulating the conducting parts from the mounting plate. The are barriers '39 project laterally from the back sur face 44, the upper portion forming the other leg of the L along with the portion of the block connecting the arc barriers and serving as a base for mounting the terminal straps. As shown in Figures 2- and 3, vertical slots 45 and 46' are formed in the portions of the block connecting' barriers 39, permitting the terminal straps or contact brackets to project from the chamber and external access to terminals 25 and 34.

In order to confine an are forming during the interruption of the front or line contacts, a removable cover block 47 is secured over the open end of the chambers 14, 22, 31 and 32 to confine the ionization caused by the arcing of the contacts, and wherein the vertical barriers 48 along with the vertical longitudinal front and bottom walls 49 and 50 form individual" cavities for each pole. The'cov'er plate. is secured to the vertical barriers by means of screws 52 extending through barriers 48' of the cover plate and seating in threaded openings provided in the barriers '39 along the adjacent vertical leg of the insulating block 13.

Under heavy current use the cover plate of the conta'ctor 6 is made of. tie-ionizing material which acts to accelerate the de-ionization of the gases formed in the cavity. In comparison with the insulating materials used in the insulating block 13, the de-ionizing material used in the cover plate 4-7 is much morecostly. Since the deionizing eifect occurs only adjacent to the arc and is required only at the line contacts where the most severe arc occurs, the ale-ionizing material should only embody the cavities adjacent the line contacts to encompass the are formed during contact interruption.

The bottom wall 50 is cut back from the end of the arc barriers 48 and extends forward along the center line of the arc chamber forming slots adjacent to the barriers to accommodate the yoke arc barriers 21. Open channels are formed in the ends of the arc barriers to mate with the end flanges or abutments of the arc barriers of the insulating base block. 13. As illustrated in Figures 2 and 3, the cavity forms a semi-circle along the cross section to provide a continuous surface for the are formed between the contact bridge 23 and the stationary line contact, of the bracket 19.

The operating means is shown in Figures 1 and 2 and comprises an E-shaped stationary magnet 55 secured to the mounting plate 8; a coil 56, positioned around the center projection having control or energizing terminals 57; and an armature 58 entirely outside the coil and movable against the striking surface 59 of the core or stationary magnet 55. A U-shaped actuating beam 60 is pivotally connected to the armature -3 by a pivot pin 61 at the lower end thereof and adapted to ride along the surface of a support or retaining bracket 62 under the influence of the movement of the armature 58. The yoke 30' is secured tothe upper end of the beam 60 and includes a plurality of yoke arc barriers, one of each being adjacent either transverse side of spring guides 28 except the outside guide which has only one insulating barrier, to isolate the ionization formed during an interrupting period from adjacent chambers and insulate 4 the bridge contact and spring guide from the adjacent pole for the length of travel of the yoke.-

The primary function of the yoke 30 is to actuate the movable contact structure and couple the contact operators or guides 28 to the armature 58 or actuating beam 60. The operating means is retained in position by the retaining bracket 62 having-a slotted end portion slidably positioned over a downwardly projecting member 42 integral with the actuating beam 60. As shown in Figure 2 the upper end of'the retaining bracket includes a vertical projecting flange seating in a slot formed in the under surfaceof theyoke30. The bracket 62 may be detached from the actuating beam or operating means by moving the bracket downwardly until the'respective slots are disengaged. The operating means or actuating beam 69 is retained in operating position by the bracket 62 wherein said bracket remains stationary and is secured by screws 63 which are threaded into openings provided in the adjacent leg of the stationary magnet 55.

Operation The normally closed contacts of Figure 2 are opened upon energization of the coil 56 attracting the armature 58 which strikes thesealing surface 59 of the core 55; moving the actuating beam 62, yoke 30 and the spring guide 28 vertically a distance equal to the gap between the armature and stationary magnet. The spring guide strikes the bridge contact compressing the spring 37 opening the circuit between the line and. load contacts: Upon de' energization. of the coil. 56;, the armature; and remainder of the operating means including the spring guide 28, resumes the position shown in Figure 2 closing the circuit between the line and the-load.

The normally open contacts structure of Figure 3- may be closed in a similar manner as described in the opening of the contacts in Figure 2, however in this instance the bridge contact 23 is retained by' the spring guide 28, and upon energizing of the coil and subsequentmovement of the armature; the spring guide and the bridge contacts move upwardly in. a vertical direction closing the corresponding contacts between the movable bridge and stationary line and load contact straps.

During a circuit interruption period an are formed et-ween. the line contact and the opposing movable contact on the contact bridge 23 is extinguished by being blowninto cavity. 54along the surface thereof and in addition, if the cover is made of de-ionizing material, the heat of the arc will partially decompose the surface of the material combining with, the gases formed to deionize the area adjacent the contacts.

While certain preferred embodiments ofthe invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the. art and the invention is. to be given its broadest possible inter;- pretation within, the terms of the following claims.

What is claimed is:

1. In a contactor of the character described, the combination comprising; an insulating base providing a sup.- port for spaced pairs of stationary line and load contacts, a movable contact for each pair of line and load contacts arranged for engagement therewith, means including an insulating yoke for moving said movable contacts into and from engagement With the stationary line and load contacts, a separate insulating block securable to said base said separable block being formed of deionizing material, said block having a substantially fiat bottom surface with slots therein arranged to provide spaced separated internal chambers for enclosing the. line contacts and providing an opening for exposing the. load contacts and'an arcuate wall in saidchambers arranged for directing ionizing gases. away from the line contacts and from said chamber when the movable contacts move from engagement therewith and spaced barriers on the 5 yoke arranged for extending through the slots for directing the ionizing gases from adjacent line contacts.

2. In a contactor of the character described, the combination comprising; an insulating base providing a support for a plurality of pairs of exposed stationary line and load contacts which are arranged on the support so the line contacts are laterally spaced on the support, a movable contact member including a yoke of insulating material carrying movable contacts arranged to provide a bridging engagement between the respective parts of line and load contacts, a separate insulating block securable to the base having spaced chambers therein arranged for enclosing and separating the line contacts from each other and to provide an opening for permitting the load contacts to remain substantially exposed, said separate insulating block being formed of de-ionizing material and the said chambers therein being constructed References Cited in the tile of this patent UNITED STATES PATENTS 2,304,972 Van Valkenburg et a1. Dec. 15, 1942 2,319,906 Rowe May 25, 1943 2,394,090 McFarland Feb. 5, 1946 2,448,659 Aitken Sept. 7, 1948 2,492,726 Ayers et al. Dec. 27, 1949 2,773,948 Pelz et a1. Dec. 11, 1956

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