US2691711A - Arc-quenching device for electric contactors - Google Patents

Description

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ARC-QUENCHING DEVICE FOR ELECTRIC CQ'N'IACTOR-S Filed March a, L951 3 sheets sheet 1 FEB WITNESSES: 45

ATTORNEY Oct. 12, 1954 D, ms 2,591,111

ARC-QUENCHING' DEVICE FOR. ELEQTRIC CON-'FACTOR-Si Filed March 8, 1951 3 Sheets-Sheet 2 WITNESSES: INVENTOR Delber'i Ellis.

ATTORNEY ELLIS ARC-QUENCHING nmvxcs FOR ELECTRIC CONTACTORS Filed March a, 1951 3 Sheets5heet 3 Fig.

INVENTOR Delberi Ellis.

ATTORNEY WITNESSES:

patented Get. 12, 11954 UNIED ARC-QUENCHING DEVICE F013, ELECTREC CGNTACTORS Application March 8, 1951, Serial No. 2l li61 (Cl. Zeb -1 1 i) 5 Claims. 1

This is a continuation-in-part of my copending patent application Serial No. 124,923, filed November 1, 1949, and assigned to the assignee of the present invention.

My invention relates to arc-quenching devices for electric contactors and more particularly to are box structures that contain mutually insulated metal plates or grids spaced from one another along the path of the interrupting arc to subdivide the arc and to promote its deionization.

The known are box structures of this type comprise an insulating arc box, usually of molded material, attached to the base of the electric contactor. The stationary contacts, to be interconnected or disconnected by the movable contact assembly of the contactor, are disposed within a cavity of the box, and the grid plates are individually inserted into grooves molded into the box material.

These known are box structures for quenching a current-interrupting arc in air have two stationary contacts disposed one above the other to cooperate with a movable contact bridge that in its closed position extends almost vertically when the arc box is mounted for operation. Only one grid stack is provided above the upper stationary contact to quench the upwardly blowing arc, while different and less effective arc-dividing means are provided beneath the lower stationary contact.

It is one of the objects of my invention to provide an arc-quenching device which can be more easily assembled than the known devices and permits checking the grid stacks before they are placed into the insulating housing of the arc box or otherwise mounted on the contactor.

Another object of my invention is to improve the current-interrupting and arc-quenching operation of air-exposed arc box devices of contactors, such as motor starters, panel-mounted relays and other switching devices, whose contact and arc-quenching means operate in air and must satisfy extremely limited space requirements. In this respect, it is a more specific object of the invention to secure a satisfactory arcquenching performance that is equally effective at the two arcing places between the ends of a movable contact and the two stationary contacts to be bridged by the movable contact.

In accordance with a feature of my invention, 1 provide insulating carrier means of molded material with which a stack of initially spaced grid plates of conductive material are molded together to form a single rigid unit.

According to another feature of the invention,

I provide the insulating body portion of an arc box with one or several separate inserts, each composed of an insulating carrier and a stack of grid plates that are firmly secured to the carrier to form a rigid unit therewith. These carriera-nd-grid inserts are manufactured as separate units and hence can be inspected or tested be fore they are placed into cavities of the arc box structure. The carrier means of the gridstack unit consist preferably of inorganic molded insulating material. For instance, the gridplates may be molded into the material before it is cured, or the carrier and grid plates may engage ahd lock each other by male and female joint elements.

According to another feature of the invention, and for the purpose of securing the above-men tioned improvement in arc-quenching performance of air-exposed contact devices, I provide a single arc box with two stacks of horizontally arranged and vertically spaced grid plates whose respective recesses are mutually aligned in each stack to form together a vertically extending groove which faces the groove of the other stack of the same are box.

These and other objects and features of the invention will be apparent from the following description of the embodiments illustrated on the drawings.

Figure 1 shows a part sectional view through an electromagnetic contactor with an arc box structure designed in accordance with the invention;

Fig. 2 is a cross section through the are box structure, the section being taken along the cut indicated in Fig. 1 by the dot-and dash line II-II;

Fig. 3 is a cross section of one of the grid plate inserts only, appertaining to the same are box structure, the section being taken along the plane denoted in Fig. 2 by the dot-and-dash line IIIIII;

Figs. 4 and 5 represent sectional views of modified grid plate inserts, respectively;

Fig. 6 is a partial front View on an arc structure according to the invention for a three pole contactor;

Figs. 7 through 10 illustrate another threepole arc-quenching device according to the invention, Fig. '7 being a cross section through the are box for one of the three poles, Fig. 3 a top view of the base portion of the are box, Fig. 9 a bottom view of the appertaining cover portion of the arc box, and Fig. 10 a side view of the assembled device;

Fig. 11 is a top view on the base portion of still another embodiment and Fig. 12 a bottom view of the appertaining cover portion of the arc box structure, this embodiment being designed as a single-pole unit; and

Fig. 13 shows three units according to Figs. 11 and 12 assembled together so as to form a threepole device.

The electromagnetic contactor shown in Fig. 1 has a base plate I on which all of the other contactor parts are mounted. Firmly attached to the base plate is a molded insulating body 2 to which is attached another molded insulating body 3. The two bodies form together an arc box structure which has a cross opening. This opening forms two cavities 4, 5 for the reception of grid plate inserts, and an intermediate chamber 6 for the contacts. Two stationary contacts 8 and l are, respectively, firmly secured to the molded insulating body 2 and the molded insulating body 3, and are connected with terminals for attachment to the circuit to be controlled by the contactor. The stationary contacts 1 and 8 are spaced from each other and extend into the respective cavities 4 and 5 and into the range of the recessed grid plates described below. A movable contact bridge 9 cooperates with the stationary contacts 1 and 8. The bridge is slidably mounted in a saddle if] under the bias of a contact pressure spring H which tends to hold the contact bridge 9 toward the seat portion or the saddle. The saddle is attached to an insulating cross bar l2 which may serve to actuate the auxiliary or interlock contacts (not shown) of the contactor. The cross bar I2 is firmly secured by a bracket l3 to the plunger-type armature M of the electromagnet whose coil is denoted by l5. The appertaining magnet frame I6 is secured to a structure I! which is firmly attached to the base plate I. The armature assembly is illustrated in the contact-closing position, i. e., under the energized condition of the electromagnet. When the magnet is deenergized, the armature 14 drops into the position shown in dotted lines and separates the movable contact bridge 9 from the stationary contacts I and 8 so that two arcs are drawn between the contact surfaces of the movable bridge 9 and the respective stationary contacts I and 8.

In order to subdivided and deionize these two arcs, two insert units are mounted one in the cavity 4 and the other in the cavity 5 of the arc box structure. These units are each composed of an insulating housing portion 2! and 2| and a number of grid plates 22 and 22. Two cross bars 23, 23' are attached to the arc box struc ture by screws 24 and 24 in order to fasten the respective grid plate inserts.

Both grid plate inserts may be of identical design. According to Figs. 2 and 3, the recessed metal plates 22 that form the grid stack of each insert are firmly joined with an insulating carrier 2| shaped as a housing of a. substantially U-shaped cross section. This housing consists of molded, preferably inorganic, material and covers the back and lateral edges of the inserts. The individual grid plates 22 are preferably joined with the material of the insert housing 2! at the time the housing is molded and before the housing is hardened. As a result, the individual inserts consist of rigid structural units which are placed, as a whole, into the corresponding cavities of the contactor arc box structure. It will, therefore, be apparent that the individual insert units can be inspected, checkedor tested independently of the contactors and before they are assembled with the other parts of the contactor. As a further result, time and labor involved in assembling the contactor are considerably reduced. Another advantage may result from the fact that, in the event of damage to the grid plate stacks caused after the contactor is assembled or due to abuse or overloading of the contactor, a repair is facilitated because each insert unit can readily be removed and replaced by a new unit without requiring the tedious insertion of individual and loose grid plates. The two bodies 2, 3 of the insulating box structure may consist of the molded inorganic material customary for such structures. However, the invention ofiers the further advantage that it permits making the enclosing box structure of plastic, hot molded, resinous or the like organic material.

When, as mentioned above, the grid plates are placed into the carrier material before the latter is cured or treated, no special fastening means and no particular design of the plates and carrier may be necessary to safely secure the plates to the carrier. However, if desired, the plates and carrier may be equipped with fastening elements, for instance as shown in Figs. 4 and 5. According to Fig. 4, the molded carrier 3! is firmly joined with the grid plates 32 by having the carrier material enter into openings 34, 35 or recesses of the plate. The insulating material 3! during the molding process is forced through the openings or recesses of the plates and, when cured, is rigidly joined with the plates. According to Fig. 5, the grid plates 42 have the recesses 44 into which the material of the carrier 4| enters during the molding process in order to secure the desired tight connection.

Fig. 5 shows also a modification of the insulating carrier means which in this embodiment consists of two separate retainers 4| disposed at opposite sides of the grid plates and spaced from each other so as to leave the contact side and the opposite back side open. The back of the device may be covered by a metal plate or a plate of insulating (for instance, molded inorganic) material. It is obvious that spaced retainers as simplified by Fig. 5 are not limited to the particular connections shown but are also applicable with connections of other designed devices according to the invention.

The invention is applicable to contactors of any pole number. Fig. 6, for instance, shows a front view of an arc box structure 46 for a three-pole switch. This structure has three front cavities 41, 48 and 49 to receive three insert units which are secured in the structure by means of a cross bar 50. Each of these insert units is designed in the manner described above with reference to Figs. 1 through 5. It will be recognized from the illustrated embodiments that a carrier-grid unit according to the invention represents such an arc-quenching device. That is, each of these units is basically a single-pole arc box. It will, therefore, be understood that such a unit is sufficiently complete in itself for being mounted on a contactor in any suitable manner and, if desired, without a separate enclosing box structure. Indeed, the insulating carrier or housing of the grids can be given an enlarged size so that it also takes the place of one or both of bodies 2, 3 thus resulting in a complete contact enclosure in which all essential parts arejoined together to a solid, coherent structure.

Aside from the above-mentioned features and advantages, the contactor according to Fig. 1 also embodies the features and improvements described presently.

As mentioned, in the conventional contactors for panel or wall mountin with an air-exposed and air-filled arc box containing deionizing grid plates, these plates extend vertically and are disposed only above the path of the arc to be quenched by the stack. In contrast thereto, the arc box structure according to the invention, as shown in Fig. 1, has two grid stacks on opposite sides of the air-filled interior space of the arc box, and the grid plates 22 and 22 of each stack extend horizontally and are vertically spaced from each other. Thus, the mutually aligned recesses of the plates in each stack form together a vertically extending groove which faces the groove of the other stack. The stationary contacts '5 and 8 have their respective contact faces located between the two stacks and straddled by the respective stack grooves; and the vertically movable contact bridge 9 has its contact faces also straddled by the grooves in all positions of the bridge 9 so that the entire path of vertical bridge movement lies within the vertical extent of the two stacks.

In such a device, the two arcs drawn between the stationary contacts '5, 8 and the contact faces of the bridge 9 are exposed to the arc-extending and quenching effect from the initial moment of contact separation. The two arcs form part of a single loop circuit whose electrodynamic effect tends to blow both arcs away from each other and toward the respective grid stacks. For that reason, and because the horizontal arrangement I The arc-quenching device illustrated in Fig. 7 1

is similar to those previously described in that its arc box is equipped with two stacks of arc grids, which are spaced from each other within the arc box cavity structure and cooperate with stationary contacts and a contact bridge, whose respective contact surfaces extend in horizontal planes and are straddled by the grooves formed of the recesses in the grid plates of the two stacks. However, the two grid stacks according to Fig. 7 are not attached to respective insulating inserts separate from the insulating housing proper, but are immediately secured to insulating bodies which form the base portion and cover portion of the arc box structure, respectively.

More in detail, the device according to Fig. I has a mounting plate on which an insulating base portion 52 of an arc box is mounted. Seated on the base portion 52 is an insulating cover portion 53. Both portions together form a cavity St for the contact means and grid stacks.

This cavity is in communication with the am bient air and has an opening for the pass-age of a contact-actuating member 55, which may be designed and operated in the same manner as the member ill in the above-described embodiment of Fig. 1. Mounted on the member 55 and biased by a contact pressure spring (not illustrated in 7) a contact bridge 5i; to cooperate with stationary contacts 5? and 58. The stationary contacts are attached to respective terminals 59 and ti) and are firmly secured to-- gether with the terminals on the base portion 52 of the arc box. Disposed within the base portion 52 is a grid stack El whose individual grid plates have a recess similar to that of the grid plates described in connection with the preceding embodiments. The cover portion 53 contains a similar grid stack 62. The recessed portions of the two grid stacks straddle the contact surfaces of the stationary contacts and or the movable contact bridge, and, as mentioned, the path of movement of the contact bridge extends fully within the range or the grid stacks. As also explained, the horizontal arrangement of the contact surfaces and grid stacks has the effect that a substantially equal quenching function is imposed on both partial arcs that exist between the contact bridge and the two stationary contacts during the circuit-interrupting performance. This quenching effect is not predicated upon any particular fastening of the grid stacks in the respective portions of the insulating are box structure. However, the grid stacks may be firmly molded into the insulating material of the are I box portions as described previously.

The arc-quenching unit according to Fig. 7 may form part of a multipole structure as will be apparent from the three-pole arrangement shown in Figs. 8 and 9 in which one of the three arc-quenching units is denoted by the same reference numerals as used in Fig. 7 for correspond ing elements. According to Figs. 8 and 9, a single arc box base portion 52 has three aligned cavities, each equipped with a grid stack 6!. Each is provided with the two stationary contacts 57!, 58 and with the appertaining terminals 59 and 59, respectively. According to Fig. 9, the cover portion 53 of the arc box structure is designed in a similar manner, i. e., it has three aligned cavities matching those of the base portion, each cavity being equipped with a grid stack Arc-quenching devices according to the invention can be designed in such a manner that the quenching device for each individual pole forms an operative unit in itself which can be used for single-pole operation or can be assembled with similar units for multipole contactors or" any desired pole number. An embodiment of such a single-pole unit is illustrated in Figs. 11 and 12.

According to Fig. 11, the insulating base portion it of a single-pole arc box has a cavity which contains a grid stack 8i designed as described previously. This stack may be molded into the insulating material of the base portion 52 or it may be fastened to the base portion in any other suitable manner. Mounted on the base portion 52 are two stationary contacts I? and iii with apertaining terminals It and S9, respectively. The design and arrangement of these contacts and terminals correspond to those of the contacts and terminals shown in Fig. 7. The cover portion d3 of the same single-pole unit has a matching cavity with a grid stack 82 as is apparent from Fig. 12. When cover portion "it and base portion it? are assembled, two matching grooves til and iii form an opening through which the contact-actuating member enters into the interior of the are box structure.

As shown in Fig. 13, a plurality of single-pole units according to Figs. 11 and 12 can be mounted on a common base plate 92 to form a multipole interrupting device or any desired pole number. In Fig. 13, three units for a three-pole contactor are denoted by 93, 94 and 95. These units are aligned with one another on the base plate 92 so that the two grid stacks of each unit have their respective grid plates extending in horizontal planes.

It will be obvious to those skilled in the art that the invention permits various modifications other than those specifically referred to in the foregoing without departing from the gist of the invention and within the scope of its essential features set forth in the claims annexed hereto.

I claim as my invention:

1. A current-interrupting arc-quenching device, comprising an air-filled arc box in communication with ambient air, said are box comprising a base and a cover having aligned openings therein defining a horizontal passage through opposite ends of the arc box, a movable contact bridge disposed substantially centrally in said passage and having a given path of movement extending vertically when the device is operatively mounted, said. ridge extending horizontally and having respective contact faces at both ends, two stationary contacts having respective contact faces in said arc box engaged by said respective faces of said bridge when said bridge is at one end of said path, a pair of arc extinguisher units, each unit including an insulating housing and a stack of horizontally arranged and vertically spaced grid plates disposed in the respective housings, said respective arc extinguisher units fitting into said passage for opposite ends of said are box with the respective plates in spaced confronting relation on opposite sides of said contacts and extending along said entire path of bridge movement, the plates of each stack having respective mutually aligned recesses facing those of the plates of said other stack and straddling one of the respective contact faces of said bridge in all positions of said bridge along said path.

2. A current-interrupting arc-quenching device, comprising an arc box, said are box having a base and a cover having aligned openings therein defining a passage through opposite ends of the arc box, a pair of arc extinguisher units, each unit including an insulating housing and a stack of horizontally arranged and vertically spaced grid plates in the respective housings, said respective arc extinguisher units fitting into said passage from opposite ends of said are box with the respective plates in spaced confronting relation, the plates of each stack having respective mutually aligned recesses forming together a vertically extending groove, said groove of each stack facing that of the other stack, two horizontally spaced stationary contacts having respective contact faces between said stacks and straddled by said respective grooves, and a movable contact bridge having respective horizontally spaced contact faces engageable with said respective faces of said stationary contacts and straddled by said respective grooves.

3. A current-interrupting arc-quenching device comprising an arc box, said are box including a base and a cover having aligned openings therein defining a passage through opposite ends of the arc box, a air of arc extinguisher units, each unit including an insulating housing and a stack of horizontally arranged and vertically spaced grid plates in the respective housings, said respective arc extinguisher units fitting into said passage from opposite ends of said are box with the respective plates in spaced confronting relation, the plates of each stack having respective mutually aligned recesses forming together a vertically extending groove, said groove of each stack facing that of the other stack, two horizontally spaced stationary contacts having respective contact faces disposed in a common plane and between said stacks and straddled by said respective grooves, and a movable contact bridge having respective horizontally spaced contact faces engageable with said respective faces of said stationary contacts and straddled by said respective grooves, said bridge having a vertical path of movement smaller than the vertical extent of said stacks.

4. An arc box structure for electric contactors, comprising, a two-piece insulating arc box having a base portion and a cover portion, each of said portions having an opening therethrough from one end through the other, said openings being aligned when said cover portion is assembled on said base portion, a pair of arc extinguisher units, each unit comprising an insulating housing and a stack of grid plates secured in said housing, said respective housings being insertable from opposite ends of said are box into said respective openings with said grid plates of said respective units being disposed in spaced confronting relation, and means securing said respective housings in said respective openings.

5. An arc box structure for electric contactors, comprising, a two-piece insulating arc box having a base and a cover, each of said base and said cover having an opening therethrough from one end through the other, said openings being aligned when said cover is fitted to said base, a pair of are extinguisher units, each unit comprising an insulating housing and a stack of grid plates secured in said housing, said respective housings slidably fitting into said respective openings from opposite ends of said are box with said grid plates of said respective units being disposed in spaced confronting relation, a pair of stationary contacts mounted in said are box in respective positions adjacent and between said respective units, and a movable contact bridge for bridging said stationary contacts, said bridge moving along a path essentially at right angles to the plane of said grid plates between positions engaging and disengaging said stationary contacts.

References Cited in the file of this patent UNITED S'IAES PATENTS Number Name Date 2,239,031 Bierenfeld et al. Apr. 22, 1941 2,240,007 Power Apr. 29, 194] 2,244,061 Graves, Jr. June 3, 1941 2,363,606 Maseng Nov. 28, 1944 2,372,045 Armstrong Mar. 20, 1945 2,492,726 Ayers et a1. Dec. 27, 1949 2,551,822 Bingenheimer et a1. May 8, 1951 2,590,543 Kalaway Mar. 25, 1952

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