US2036250A - Relay - Google Patents

Description

4 Sheets-Sheet l RELAY G. C. ARMSTRONG ET AL Filed July 30, 1932 April 7, 1936.

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RELAY Filed July 30, 1932 4 Sheets-Sheet 2 April 7, 1936.

April 7, 1936.

G. C. ARMSTRONG El' AL RELAY Filed July 30, 1932 4 Sheets-Sheet 5 ATTORNEY 4 Sheets-Sheet l.-

`April 7, 1936. G. c. ARMSTRONG Er A1.

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m llw f Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE RELAY Application July 30, 1932, Serial No. 626,594

18 Claims.

Our invention relates to relays, and more particularly to relays of the line-starter type that are especally designed to cooperate with electric devices protected by safety features.

An object of our invention is the provision of a relay of the class indicated that shall be reliable and compact, and be economically manufactured and installed.

Another object of our invention is to prevent the closing of the contact members of a relay when the magnetizing winding of the relay is deenergized.

A still further object of our invention is to so construct and arrange the base or support of a relay that the base constitutes a part of the enclosure for the relay and may be mounted with or without conduit fittings of any kind. n

A still further object of our invention is to so construct and so mount the arc chute of a contactor that its movable contact members may be carried thereby, thus eliminating the usual crossbar upon which the movable contact members are mounted and making it impossible to operate the relay with the arc chute removed.

It is also an object of our invention to provide for operating a relay or contactor by a set of push-buttons, and for independently actuating the contact ngers of the push-buttons by thermal elements, which, when heated to a predetermined value, interrupt the circuit for energizing the magnetizing winding of the relay or contacter and thereby disconnect the load from the supply source.

It is likewise an object of our invention to provide an interlock operable by the closure of the contact members of a relay for constraining the contact lingers of a start push-button in a closedcircuit position when the pressure on the start push-button is released.

Other objects and a fuller understanding of our invention may be had by referring to the following specification, taken in connection with the accompanying drawings, in which:

Figure 1 is a front elevational view, partly in section, of a relay embodying the features of our invention, the cover being removed to show the structural features thereof;

Fig. 2 is a bottom plan view of our relay with the cover removed to show the structural features thereof;

Fig. 3 is a cross-sectional view of our relay taken along the line III-III of Fig. 1 looking toward the left and showing the cover in place;

Fig. 4 is a cross-sectional view, similar to the view of Fig. 3, of our relay but taken along the line IV-IV of Fig. 1;

Fig. 5 is a fragmentary cross-sectional view of the arc chute, and illustrates, particularly, the releasable connection between the actuating lever and the arc chute;

Fig. 6 is a fragmentary view, partly in section, of our relay, and illustrates, particularly, the contact fingers of the start push-button, in combination with an electrical interlock that is actuated by the arc chute, and the thermal element which insures overload protection for one phase;

Fig. 7 is a fragmentary view of our relay, and illustrates, particularly, the contact lingers of the re-set push-button, in combination with the thermal element that insures overload protection for another phase;

Fig. 8 is a perspective view of the contact fingers for the start push-button, ir.- combination with the mechanical interlock that is operated by the arc chute and the thermal element which insures overload protection;

Fig. 9 is a diagrammatic view of the electrical connections for our relay;

Fig. 10 is a front elevational view of our relay shown mounted with conduit fittings;

Fig. 11 is a side elevational view of our relay with the conduit fittings shown in cross-section in order to distinguish them from the cover of the relay, and

Fig. 12 is a bottomplan view of our relay, part of the conduit fitting being cut away to show the thin or weakened sections along the bottom edge of the support upon which the relay is mounted.

With particular reference to the drawings, our relay or contactor comprises, in general, a base or support I upon which the various parts of the relay are mounted, a plurality of stationary contact members II carried by the support I0, a magnetizable core having three legs 3 I, 32 and 33, a magnetizable winding 24 surrounding the middle leg 32, an armature 34, a pivotally mounted arc chute I 1, a plurality of movable contact members I2 resiliently mounted upon the arc chute, a start pushbutton6l and a re-set push-button 62.

The arc chute I'I is preferably constructed in the form of a unitary structure, andis provided with separate compartments for each set of contact members I I a-nd'I2. The inner walls of each compartment of the arc chute are provided with substantially parallel ribs I8 and the top of each of the compartments is provided with openings I9 through which the hot gases may escape. The ellect of the ribs I8 is such that they hasten the extinguishment of the arc, a provision which materially lengthens the life of the contact members. As illustrated, the sides 20 of the arc chute I1 depend downwardlyand are pivotally connected at a pivot-point 2I to the side members 23 that are mounted upon opposite sides ofthe support III. 'I'he front of the arc chute II is provided with projecting edges II8 and resilient springs I5 for carrying the movable contact members I2 are mounted on these edgesby means of bolt I6. I

contact members II and I2. As a further means A' for lengthening the life of the contact members and to reduce the heating resulting from contact resistance, their engaging surfaces may be-provided with silver or other suitable metal which is very little affected by the intense heat of the arc.

As shown best in Fig. 1, the sides of the shoes I3 are provided with outwardly extending tabs I4. Accordingly, when the arc chute I1 is actuated to the open circuit position (see Fig. 4) the .central rib I8 engages the outwardly .extending tabs I4, and thereby constrains the movable contact member I2 to the open-circuit position. However, when the arc chute I1 is actuated to the closed-circuit position (see Fig. 3), the movable contact member I2 rmly engages the sta.

tionary contact member I -I, as the central rib I8 is slightly in advance of the stationary contact member I2 and it thereby no longer engages the "outward extending tabs I4. From the foregoing,

it is observed that the arc chutel I1 not only serves the purpose of an arc chute, but likewise constitutes a support for the movable contact member I2. Thisl construction eliminates the usual crossbar upon which the movable contact member I2 `is mounted. Furthermore, this construction makes it impossible to operate the relay with the arc chute removed, a requirement specified for safety purposes.

AAs shown in `Figs. 1, 3 and 4, the stationary contact members II may be suitably mounted upon the upper portion of the support III. Therefore, when'wirlng or installing the relay the conductor leads may be brought through suitable openings near the top edge of the support I and be directlyl connected to the stationary contacts Il. Each of the movable contact members I2 is individually connected, by means of iiexible conductors IIIII, to the upper ends of conductor bars 13, 84, 81, and 88 that are mounted in suitable channels provided therefor on the lower portion of the support `I0 (see Fig. 1). Accordingly, when wiring and installing the relay the conductor leads for the movable contacts I2 may be brought through suitable openings near the bottom edge of the support III and be connected to' the lower ends of the conductor bars.

- As illustrated best in Figs. 3 and 4, the magnetizable core that actuates the armature 34 is The magnetizable winding 24 is of the "selfsustained type and is adapted to surround the central leg 32. The upper end of the rectangular tube upon which the winding is wound extends beyond the winding, and one pair of the opposite sides thereof are cut away so that the remaining pair of opposite sides straddles the top central portion of the magnetizable core (see Figs. 3 and 4). The winding 24 is then retained in position by a screw 5II which passes through the upper extended ends of the rectangular tube and the top central portion of the magnetizable core. A mounting of this type is very simple and economical to construct and install in that it requires no retaining clips or wedging blocks of any kind to hold the magnetizable winding in position.

The mounting of the armature 34 and the manner in which it is inter-connected with the arc chute I1, is a radical departure from the conventional manner heretofore practiced in the art. As illustrated, the armature 34 is mechanically connected to the arc chute I1 by means of a pivotally mounted member 36 and an inter-connecting link 39. 'I'he pivotally mounted member 36 is pivoted at a pivot-point 38, and comprises two spaced members, the lower portion of which straddles the armature 34 and the upper portion of which straddles the leg 3 3 of the magnetizable core. The upper ends of the spaced members are brought together and pivotally connected to the inter-connecting link y39 at a pivotpoint 42. A stop 46 is provided upon the upper surface of the magnetizable core to limit the iorward movement of the pivotally mounted member 36. As illustrated, the central portion of the armature 34 is pivotally connected at a pivotpoint 35 to the lower ends of the spaced pivotally mounted member 36. Therefore, by means of this construction the armature 34 moves not only upwardly, when attracted by the main core, but also outwardly in a longitudinal direction, causing the pivot-point 35 to describe an arcuate path. The rear end of the armature 34 is provided with a latch or hook 4I adapted to engage a projecting or obstructing portion of the support III, when the magnetizable winding 24 is deenergized (see Fig. 4). The pivot-point 35 is slightly to the left of the centerof gravity of the armature 34 so that the rearward end of the armature, when the magnetizable winding 24 is deenergized, always drops by means of gravity andengages the obstruction 40 of the support III. In this position, should the relay be unduly jarred or should an accidental force be applied in a clockwise direction to the arc chute I1, the latching engagement would constrain the longitudinal movement of the armature 34, and thus prevent the closure of the contact members II and I2. 1t will be noted that. each armature is provided with suitable shading coils 31.

For the purp'ose of releasing the latch 4I of the armature 34,* when the magnetizable winding 24 ,is energized, we provide for making the air gap between the leg 33 and the rear end of the armature less than the air gap between the leg 3I and the forward end of'the armature. Consequently when the winding 24 is energized, the

rear end of the armature 34 is iirst attracted upwardly and, just as soon as the latch 4I clears the obstruction 4II, the amature 34 is allowed to move forwardly in a longitudinal direction, and

thus actuate the arc chute I1 to the closed-circuit rearwardly at the same time, causing the pivotpoint 35 to describe an arcuate path, until the latch 4| again engages the obstruction 40. As is readily apparent, with this type of armature mounting, no additional parts are required for obstructing the closing of the contact members when the magnetizable Winding 24 is deenergized.

As shown in Figs. 4 and 5, the forward end of the inter-connecting link 39 is releasably connected to the arc chute I1, so that the arc chute may be readily tipped forwardly for wiring the relay or for inspecting of the contact members thereof. As shown best in Fig. 5, the projecting edge I8 of the arc chute I1 is provided with a transverse recess for receiving a pin 43. Pivotally connected to the pin 43, and straddling the outer end of the inter-connecting link 39, is a clip 44 having inwardly projecting resilient tabs 45 which engage a slot 50 when the clip 44 is in the locked position. When releasing the outer end of the inter-connecting link 39 from the arc chute I1, it is only necessary to grasp the clip 44 and withdraw it until the inwardly projecting tabs 45 clear the slot 50'. The pin 43 may then be raised out of its recess for releasing the arc chute I1.

The relay is operated by a start push-button 6| which engages a set of contact lingers 63 and 64, and a reset push-button 62 which engages a set of contact fingers 16 and 11. (See Figs. 6 and 7) With reference to Fig. 6, the contact fingers 63 and 64 are normally constrained in the opencircuit position, and they are disposed to be separately and independently operated by means of a mechanical interlock 14- actuated by one of the sides 20 of the arc chute I1 and a thermal element 69 that is responsive to the current flowing through one ofthe sets of contact members II and I2.

The electrical interlock lever 14 comprises a linger that is connected to the lower end of the left-hand side 20 of the arc chute. Consequently, when the arc chute I1 is in the open-circuit position, being the position shown in Figs. 2 and 6, the electrical interlock lever 14 is positioned at a slight distance from the Contact finger 64. However, when the arc chute I1 is actuated to the closed-circuit position by first depressing the start push-button 6| and energizing the magnetizable winding 24 the electrical interlock lever 14 moves upwardly and constrains the lower contact finger 64 to engage the contact finger 63, even though the pressure on the start button 6I has been released. With reference to Fig. 1, the contact fingers 16 and 11 arel normally constrained to their closed-circuit positions and are disposed to be separately and independently operated by means of a thermal element 8| that is responsive to the current flowing through one of the sets of contact members and I2. Upon the outer end of the contact finger 11 is mounted an upwardly projecting member 18, which, when the re-set push-button is depressed, breaks the,

electrical contact between the contact fingers 16 and 11.y In this respect, the re-set push-button 62 also constitutes a stop push-button, because, when the relay is in a closed-circuit position it may be readily tripped or opened by merely depressing the re-set push-button. Inasmuch as the mounting and construction of the set of contact fingers for the start and re-set pushbuttons are similar, a description with respect to thestart push-button only will be given.

As is best shown in Fig. 8, the lower contact linger 64 is constructed of an irregular-shaped,

thin piece of resilient material and may be connected to the side member 23 by means of the nuts 66 or other suitable means. The upper finger 63 is connected to a spring-actuated clip, pivotally mounted at a pivot-point 65. Depending from the spring-actuated clip is a block member 61 in which is inserted, in the lower end thereof, a flat engaging member 68. Mounted in front of the engaging member 68 is a thermal element 69 with its free end contacting the engaging member 68. A heating element 10, which is connected in circuit relation with one of the sets of contact members II and I2, is mounted above the thermal element 69. In this manner, when the thermal element 69 is heated to a predetermined temperature its free end swings downwardly and clears the lower end of the engaging member 68, and thus allows the spring that surrounds the pivotpin 65 to bias the lower end of the engaging member 68 on top of the thermal element 69. Also, at the same time, the contact member 63 swings upwardly and breaks the electrical engagement with the contact finger 64, even though the electrical interlock lever 14 is biasing the contact finger 64 upwardly.

As shown best in Fig. 9, the heating element 10 for the start push button 6| is connected in series-circuit relation with the set of contact members II and I2 on the left of the relay, and the heating element for the re-set push button 62 is connected in series-circuit relation with the set of contacts and I2 on the right of the relay. This circuit arrangement, together with the circuit connections for the magnetizable winding 24 are shown diagrammatically in Fig. 9.

With respect to the heating element 10 that is associated with the start push-button 6I, the current iiowing through the conductor I 0I also fiows through the heating element 10 to the terminal and thence through the flexible conductor |00, and the set of contact members and I2 on the left side of the relay to the outgoing conductor. Simliarly, with respect to the heating element 80 for the reset push-button, the current flowing through the conductor I 02, flows through the heating element to the terminal 86 and thence through the flexible conductor |00, and the set of contact members II and I2 on the right side of the relay to the outgoing conductor. The magnetizing Winding 24 is connected in shunt circuit-relation with the two heating units 10 and 80. Hence, the current for operating the magnetizing winding 24, after leaving the terminal 95, flows through a ilexible conductor 93, the contact iingers 63 and 64, (assuming that they are closed), the flexible conductor 92, the winding 24, the flexible conductor 9|, the Contact fingers 16 and 11, and the flexible conductor 81 to the terminal 86.

In explaining, the operation of the relay, let it be assumed that the conductors are energized and that the arc chute I1 is in the open-circuit position. In order to energize the magnetizable winding 24 the push-button 6I is depressed. Just as soon as the contact member 63 engages the contact member 64, the shunt circuit is completed for energizing the magnetizable winding 24. The arc chute I1 is, accordingly, actuated in a clockwise direction to the closed-circuit position. In this position of the arc chute I1, the electrical interlock lever 14 is actuated upwardly and constrains the contact finger 64 to firmly engage the contact member 63, even though the push-button 6| is no longer depressed. Accordingly, the relay remains continuously energized.

However, should an overload condition prevail i'or a predetermined length 0I time, either one or both of the thermal elements 69 or 8l may respond to interrupt the circuit that energizes the magnetizable winding 24. In the event that both of the thermal elements respond simultaneously to interrupt the circuit that energizes the magnetizable winding 24, or in the'event that only the thermal lelement 8| that is associated with the re-set push button 62 responds to interrupt the circuit that energizes the magnetizable winding 24, it is necessary for the operator to rst depress the re-set push-button 62 before depressing the push-button 6| for reenergizing the magnetizable Winding 24. However, in the event that only the thermal element 69 that is associated with the start push-button 6I responds to interrupt the circuit for energizing the magnetizable Winding 24, it is only necessary for the operator to depress the push-button BI to reenergize the lmagnetizable winding 24.

In practice, the general procedure is to always depress the reset push-button 62, after the relay is tripped by an overload condition, because, when the cover is on the relay, the ope'rator has no way of telling whether one `or both of the thermal elements have responded.

As shown in Figs. 3, 4, 10, 11 and 12, the relay is provided with a cover 22, which is adapted to engage a notched-recess around the perimeter of the support I0. The cover 22 may be secured to the base I in any suitable manner. As illustrated, a threaded screw, having a retaining disc 48 and a knob 49, is provided to readily engage a threaded-opening in a bracket 41 that is mechanically connected to the magnetizing core. By this construction, the support. I0 also comprises a portion of the enclosure for the relay. The back of -the support I0 is suitably recessed in order to provide available space for the conductor leads when'mounting the relay. In mounting the relay upon a panel or wall, or upon a machine tool bracket or leg in which the wiring is concealed, the conductor leads may be brought through a hole in the Wall or thepanel concealed v by the relay and thence through the openings near the top and-bottom edges of the support I0 and be connected to the contact terminals of the relay without the use of conduit fittings of any kind.

For conduit wiring, suiable attachments. such as those shown in Figs. 10, 11 and 12, are provided. In Fig. 11, the conduit attachments are shown in cross-section vto distinguish them from the cover 22 and the support I0 of the relay. 'I'he conduit attachments comprise, in general, a housing II'I that is disposed to engage the top of the cover 22, and a similar housing |I that is disposed to engage the bottom oi the cover 22.

with a ridge for securing the conduit attachments II'I and I I5 in a ilxed position.

The plate |2| maybe fastenedto the back of the support IUl by the bolt -and'nut |24.

In order to accommodate both types of mounting, the upper 1 and lower edges of the support |0 are provided with weakened portions |25 (see Fig. 12). For the conduit wiring, the weakened 'portions |25 are knocked out so that the conductor leads. upon leaving the conduit attachments III and II'I, may' pass through the knocked-out The top and the bottom of the cover 22 are provided as illustrative and not in a limiting sense.

We claim as our invention:

1. In combination, a magnetizable' member, a

winding for said magnetizable member, an armature adapted to be actuated by the flux oi.' the magnetizable member, means for causing the armature to move longitudinally relative to the magnetizable member, and means for restraining said longitudinal movement.

2. In a relay having a movable contact member, a magnetizable member, a Winding for saidy magnetizable member, an armature adapted to be actuated by the iiux of the magnetizable member, a pivotally mounted member interconnecting the armature and the movable contact member. a latch operable by the armature, said armature being so pivotally connected to the pivotally mounted member that the latch is released when the armature is attracted by the magnetizabley member.

3. In a relay having a movable contact member, in combination, a magnetizable member, a-

winding for said magnetizable member, an armature adapted to be actuated by the ux of the magnetizable member, a pivotally mounted member inter-connecting the armature and the movable contact member, an obstruction, and means for so connecting the armature to the pivotally mounted member that the armature engages the obstruction when the said winding is deenergized and clears the obstruction when the said winding is energized.

4. In a ,relay having a movable contact member, in combination, a magnetizable core having three legs, a winding mounted upon" the middle leg, an armature adapted to be actuated by the flux of the magnetizable core, a pivotally mounted member interconnecting the armature, and the movable contact member, said armature being pivotally connected at near its mid-portion to one end of the pivotally mounted member, latching means provided on one end of the armature to restrain the armature from moving longitudinally, and means for causing the attractive force of the magnetic flux to be greater on the end of the armature that is provided with the latching 5 means.

5. In a relay having amovable contact member, in combination, a magnetizable core having three legs, a winding'mounted upon'vthe middle leg, an armature ladapted to be actuated by the flux o! the magnetizable core, a pivotally mounted member interconnecting the armature and the movable contact member, said armature being pivotally connected at nearits mid-portion to one end of the pivotally mounted member,.an obstruction, one endv of said armature.- being provided with a notch to engage said obstruction to restrain the armature from moving longitudinally, and means for causing 'the attractive force of they magnetic flux to be greater on the end o i the armature that is provided withY the notch.

6. In combination, .a magnetizable member having two ends, a winding for said magnetizable member, an armature adaptedA to be attracted to- Ward the two ends of the magnetizable member, means for moving the armature in a direction other than the direction that it is attracted by the magnetizable member, and means for restraining the said other directional movements of the armature when the said winding is deenergized.

7. In a relay having a magnetizable core and an yarmature actuated thereby, in combination, a stationary contact member, a movable contact member, a pivotally-mounted arc chute for housing the contact members, said arc chute providing a support for the movable contact member, means for resiliently securing the movable contact member to the arc chute, and means interconnecting the arc chute and the said armature, said means comprising a pivotally-mounted member one end of which supports the armature and the other end being secured to the arc chute.

8. In a relay having a magnetizable core and an armature actuated thereby, in combination, a plurality of stationary and movable contact members, a pivotally mounted arc chute having separate compartments for housing each set of contact members, each of said compartments i having ribbed surfaces to aid in extinguishing the arc, means ior resiliently mounting the movable contact members upon the arc chute to be supported and actuated thereby, and means interconnecting the arc chute and the said armature comprising a pivotally-mounted b ell crank lever one end of which is pivotally secured to the armature and the opposite end being linked to 'the arc chute.

9. A relay comprising, in combination, a support, a plurality of stationary contact members mounted upon the support, a plurality of movable contact members, an arc chute having separate compartments for housing each set of the contact members, means for pivotally mounting the arc chute upon the support, means for resiliently mounting the movable contact members upon the arc chute, a magnetizable core having three legs, a winding mounted upon the middle leg, an armature adapted to be actuated by the ilux of the magnetizable core, a pivotally mounted member interconnecting the armature and the arc chute, said armature being pivotally connected at its central portion to one end of the pivotally mounted member, latching means provided on one end of the armature to restrain the armature from moving longitudinally, and means ,for causing the attractive force of the magnetic flux to be greater on the end of the armature that is provided with the latching means.

10. In combination, a magnetizable core having a plurality of legs, a magnetizing winding ior the core, an armature member constituting a movable part of the core and having latch means on one end thereof, a pivotally-mounted bell crank actuating lever disposed to be operated by the armature, said armature being pivotally secured near its mid-portion to the bell crank lever in such manner as to cause the latch means to engage when the magnetizing winding is deenergized and to automatically unlatch when the Winding is energized.

11. A control device comprising a plurality .of stationary contact members, a plurality of cooperating movable contact members, a pivotallymounted arc chute for enclosing said contact members, said movable contact members being resiliently secured to the arc chute to be supported and moved thereby, an electromagnet having an armature for actuating the arc chute and movable contact members, and a mechanical linkage connecting the armature to the arc chute and supporting the armature in working position, whereby upon energization of the electromagnet the armature is caused to actuate the arc chute, and consequently, the movable contact members into engagement with the stationary contact members.

l2. A control device comprising a plurality of stationary contact members, a plurality of cooperating movable contact members, a pivotallymounted arc chute for enclosing said contact members, saidmovable contact members being' resiliently secured to the arc chute to be supported and moved thereby, an electromagnet having an armature for actuating the arc chute and movable contact members, and a mechanical linkage connecting the armature to the arc chute and supporting the armature in working position, saidarmature being provided at one end with a latch disposed to ,engage an. obstruction when the electromagnet is deenergized and to automatically disengage the obstruction when lthe electromagnet becomes energized.

13. A circuit controlling device comprising a base member, a plurality of stationary contact members supported by the base member, an arc chute pivotally mounted for movement toward and away from the stationary contact members, a plurality of movable contact members carried by the arc chute disposed to engage with the stationary contact members, an electromagnet provided with an armature for actuating the arc chute, a bell crank lever pivotally supported by the base member, said armature being pivotally secured to and supported by one end of the bell crank lever, and a link connecting the other end of said bell crank lever to the arc chute.

i4. A circuit controlling device comprising a base member, a plurality of stationary contact members supported by the base member, an arc chute pivotally mounted for movement toward and away from the stationary contact members, a plurality of movable contact members carried by the arc chute disposed to engage with the stationary contact members, an electromagnet provided with an armature for actuating the arc chute, a bell crank lever pivotally supported by the base member, said armature being pivotally secured to and supported by one end of the bell crank lever, a link member pivotally secured to the opposite end of the bell crank member, and means detachably connecting the link member to the arc chute.

l5. A circuit controlling device comprising a base member, a plurality of stationery contact members supported by the base menloer, an arc chute pivotally mounted for movement toward and away from the stationary contact members, a plurality of movable contact members carried by the arc chute disposed to engage with the stationary contact members, an electromagnet provided with an armature for actuating the arc chute, a bell crank lever pivotally supported by the base member, said armature being provided with a latch portion aty one end disposed to engage an obstruction on the base, and pivotally secured to one end of the bell crank lever so that the latch will engage when the electromagnet is deenergized and disengage when the electromagnet becomes energized, and a link member connecting the opposite end of the bell crank member to the arc chute.

16. A circuit controlling device comprising a plurality of stationary contact members, a plurality of cooperating movable contact members, a pivotaliy-mounted arc chute device enclosing said contact members, said movable contact members being supported by the arc chute, an electromagnet having an armature for actuating the arc chute, a mechanical linkage interposed between the armature and the arc chute, switch means operable to establish an energizing circuit for the electromagnet, and means actuated in accordance with the movement of the arc chute for holding said switch means in the closed position.

17. A circuit controlling device comprising a plurality of stationary contact members, a plurality of cooperating movable contact members, a

pivotally-mounted arc chute device enclosing said contact members, said movable contact members being resiliently supported by the arc chute, an electromagnet having an armature for actuating the arc chute, a mechanical linkage interposed between the armature and the arc chute, normally-open contact members for controlling the energization of the electromagnet, means operable to close said contact members. and means actuated by the movement of the arc chute in response to the energization of the electromagnet for retaining said contact members in the close position.

18. A circuit controlling device comprising a plurality of stationary contact members, a plurality of cooperating movable contact members, a pivotally-mounted arc chute device enclosing said contact members, said movable contact members being attached to and movable with the arc chute, an electromagnet having an armature for actuating the arc chute, a mechanical linkage interposed between the armature and the arc chute, switch means operable to establish an energizing circuit for the electromagnet. means actuated by the arc chute for holding the switch means in the closed position, and normallyclosed switch means interposed in the energizing circuit for the electromagnet, said switch means being operable to deenergize the electromagnet.

GEORGE C. ARMSTRONG. DELBERT ELLIS. l

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