US1862158A - Electric switch and opening and closing circuits therefor - Google Patents

Description

June 7, 1932. 1,862,158

ELECTRIC SWITCH AND OPENING AND CLOSING CIRCUITS THEREFOR G. w. o KEEFFE 2 Sheets-Sheet 1' Filed Feb. 17. 1950 I Jhven'ivm ELECTRIG SWITCH AND OPENING AND CLOSING CIRCUITS THEREFOR Filed Feb. 17. 1930 2 Sheets-Sheet 2 Imus-717021 Patented June 7, 1932 umrao srA'rl-zs PATENT OFFICE GEORGE W. OIEEFFE OF MILTON, MASSACHUSETTS, ASSIGNOB CONDIT ELECTRICAL EANUFACTUBING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A CORPORA- TION OI MASSACHUSETTS ELECTRIC SWITCH AND OPENING AND CLOSING CIRCUITS THHEI'OR Application filed February 17, 1930. Serial No. 428,908.

This invention relates to electric switches suitable for'the control of small power, as motor, circuits and articularly to switches of this type having e ectrically actuated cls- [fling means which also constitute means to hold the switch closed when once it has been closed. The switch closing and holding means is included in a control or ilot circuit which is arranged to be electrically connected with IQ the power circuit by the closing of the switch, whereby the control circuit is automatically energized and de-energized in response to closing and opening of the switch.

It is a rule of the underwriters code that 1 when the switch is open there shall be no potential between ground and any phase conductoron the load side of the switch. To satisfy this requirement in switches of this I type it has been the general practice either to provide the main switch with an auxiliar switch that opens and closes the pilot circuit in response to closing and opening movements of the main switch or to connect one side of the pilot circuit with the movable 95 switch member, as the brush, by a flexible conducting braid. The use of an auxiliary switch involves additional contacts and, for

this reason alone, is objectionable. Flexible leads must be carefully insulated from adja- 39 cent switch mechanism and from the switch casin and, in a compact enclosed electric switc this is often diflicult. A further objection is the danger that sooner or later the braid will break due to repeated flexure thereof during the operation of the switch and 1 short circuit the switch circuit.

It is an object. of this invention to provide an improved construction for an electrically operated switch wherein the pilot circuit including the switch closing and holding means is automatically energized andde-ener 'zed by the closing and openin of the switc o It is a further ob ect o the invention to provide a multi-break switch having spaced stationary contacts comprising line terminals of the switch and an insulated intermediate stationary contact member constituting the pilot circuit terminal of the switch WhlCl'l is arranged to beelectrically connected with a line terminal upon closing of the switch.

A still further object is to provide an enclosed electrically operated switch having an insulating terminal supporting plate at the top thereof which constitutes a support for the line and pilot circuit terminals of the switch, all of which terminals are disposed on the upper face thereof.

A further object is to provide a switch wherein the movable contact members are supported on an insulating plate carried in m a movable frame, which plate is free from flexible connectors and can be freely removed from the frame.

A yet further object of the invention is the provismn of an improved electrically opere5 atecl switch having its pilot circuit automatical ly energized and de-energized from the mam switch circuit by the closing and opening of the switch and having a movable contact structure which is free from positive electrical connection with its support and which is freely removable therefrom.

A still further object is generally to improve the construction and operation of electrically operated switches. '15

Fig. 1 is a perspective rear view of an electTIC SWltClI embodying the invention.

F g. 2 is a sectional elevation through a SlIl le phase of the switch taken on line 2-2 of ig. 1. -so

Fig. 3 is a wiring dia ram of the control circuits of the switch, t e contact members and relay of one phase conductor only being shown.

The switch here shown is contained within an enclosing casing (Fig. 2) having the fixed back portion 10 comprlsin the support for the switch and the removabfi: front portion 12 which is hinged to and constitutes a front closure for the back 10. An attaching bracket 14 is secured, as welded, to the inner face of the back portion 10 and has forwardly extended and oppositely reflexed flanges 16 on which the switch is adapted to be removably secured and a forwardly extended plate as 18 which is located between said spaced flanges 16 and is dis ed behind the operating mechanism of t e switch. 7

- The flanges 16-of said .bracket'are spaced from the back walls of the casing and are closely adjacent the side walls thereof and cooperate with the casing to form vertical wire ducts, the forwardly extended plate 18 constituting an intermediate barrier to obstruct the assa e of the wires between said flan es an in t e vicinity of the switch operating mechanism, thus to prevent the conductors from coming in contact with the mechanism. I

The switch includes the left and right hand sideplates20and22,respectively. Saidplates are rovided at the top with pairs of inwardly-directed reflexed ears 24 upon which the stationary contact carrier 26 is secured, and at the bottom front edge with inwardly-reflexed ears 28 which have inwardly-directed ofiset portions 30, shown dotted in Fig. 2. The horizontally disposed M-shaped core 34 of the operating and holding electromagnet is fixedly located upon the similar faces of said ofiset portions 30 and is secured permanently thereto by rivets 32. Said core 34 and said stationary contact carrier 26 constitute the means for securing said side plates in spaced relation. Said side plates are also formed at the rear bottom edges thereof with outwardly-reflexed flanges 36 which are adapted to rest upon flanges 16 of said su porting bracket and are secured removab y thereon by holding screws 38.

The stationary contact carrier 26 consists of a ri d plate of insulating material and is provid a d on its under face with three sets of stationary contact members 40, 40a and 40b by to old the contact bars in position. end contact members arranged in spaced relation and in a line extending from the front to the rear of the plate. Three lines of contact members A, B, and C are herein provided, one for each phase circuit through the switch, and said lines are arranged in spaced relation across the plate and are insulated each from the other by said plate. Each contact member consists of a copper bar at the ends and on the under faces of which are provided expressed, spheroidally-shaped bosses, or contacts 42. The stationary contact members of the sets are received in transverse parallel grooves44formed in the under side of said carrier plate whereby the contact members are held permanently in ali ment. Each of said contact bars is provitfe d with a central internally screw threaded passage 46 into which attaching bolts 48 that pass through said plate 26 from the to are removably screw threaded, wh e rlee 40 and 40b are adapted to be connected to the line conductors of the power circuit. To this end, a terminal plate 50 is received in the ends of each of said slots 44 under the contact members 40 and 40b. Said plates have upstandin ears 52 which overlie the front and side e ges of said carrier-plate and are screws 54 for the circuit leads. Each of the plates 50 is secured to the carrier plate by a notch 84 in the bottom face 0 provided with attaching screw 55 independently of the contact attach-- ing bolts 48. The intermediate contact members 40a are secured in the slots 44 by attachin screws 56 similar to attaching screws 48. or purposes which will subsequently appear, the intermediate contact member 400 of one of the phases is provided with aterminal connector 58, which is clamped beneath the head of screw 56 and is consequently electrically connected with the contact member 40a. As shown most clearly in Fig. 1, the terminal connector 58 is associated with an end phase, as phase A, of the switch although it could be associated equally well with the center phase, if desired.

The movable contact members are mounted on a carrier 60 which comprises a flat plate of insulating material similar to that of the stationary contact carrier 26f Said carrier 60 is provided with three horizontally spaced sets of contact members, each set of which consists of two spaced contact members 62 and 62a which have contact bosses 64 formed in the top faces thereof similar to the bosses 42 of the stationary contact members. Said movable contact members are located beneath the stationary contact members and in position each to engage an inner boss of the outer contact members 40 and 40b and a separate boss of the common inner contact member 40a thusto complete the circuit between the contact members 40 and 40b and to provide four points of circuit interruption in series for each phase of the switch. Each movable contact member is resiliently mounted in a recess 66 in the top face of the contact carrier 60 on vertical pins 68 which are slidably received in said contact carrier 60.

The .contact carrier 60 is removably supported in a holding frame 7 0 that is verticaly movable to open and close the switch. Said holding .frame consists of a horizontal metal plate 72 having upwardly refiexed and parallel end walls 74 and inturned horizontal edges 76 which constitute tracks which are received within horizontal grooves 78 along the ends of said movable contact carrier 60. The carrier 60 with its contact members can be withdrawn along saidhorizontal track and removed entirely from the switch, since by provision hereinafter to be described the movable contact members constitute a simple bridging member having, no fixed electrical connectlon with the switch or its control mechanism. A leaf spring 80 which is secured to said holdin frame 70 by a rivet 82 at one end thereo is arran ed to enter a said contact carrier 60 thus to secure the carrier removably in place with its contact members aligned wit theeoo rating stationary contact members. Inter ocking means are provided to prevent the withdrawal of the contact carrier when it is in the switch closed position. Said interlocking means includes the inwardu.

ly-reflexed ears 86 carried at the top of side ,purpose with pairs of inwardly directed parallel ears 88 at both their front and rear edges which ears are loosely received in spaced. vertical slots 90 formed in the upstanding end walls of said frame whereby to guide the frame for vertical movement into and out of switch closing position. Said frame is reciprocated by operating mechanism that "is duplicated at each end of the frame. The hottom plate 72 of the frame at each side thereof is provided with centrally-located, downwardly-reflexed ears 92 (Fig. 2) .each of which ears is pivotally connected to the upper end of a vertical link 94. Said link is pivoted at its lower end to the horizontally extended arm 96 of a bell crank lever which is pivoted on a pin 98 carried by its adj accnt side plate at the rear thereof. The vertical leg 106 of said bell crank lever is pivoted by a pin 102 to one end of the toggle link 104, the free end of which is pivoted to the reduced end 166 of a pin 108 which pin has an enlarged section 110 that extends loosely through a verticallyextended arm 112 of an armature supporting frame. Each of said side plates 20 and 22 is provided with normally struck-out parallel arms 114 Fig. 2) which have inwardly-directed spaced ends 116 that are paralled with said side plates and which terminate in the parallel, confronting faces 118 forming a vertical slot 120 therebetween. The pin is vertically movable in said slot and the confronting faces 118 which comprise the side walls of said slot serve to guide said pin and the lower end of link 103 for straight-line vertical movement. Said side plates are also provided with a set of struck-out inwardly-directed ears 122 which are disposed beneath and are vertically aligned with the edges 118 of slot 120 and constitute additional guiding means for the arms 112 of the armature frame. 1

It will be evident that when the links 104 are straightened into a horizontal position and the arms 112 are raised, that the movable contact carrier 60 will be elevated to its switch closed position wherein the contact members 64 thereof will be in engagement withthe cooperating fixed contact members and will complete the circuit through the switch.

Said. arms 112 are connected at their lower ends bya horizontal strap 124 which supports an armature 126 for a switch closing electromagnet comprising the core 34 and the energizing coil 130. Said armature is provided with side plates 132 which extend beyond the ends of the armature and oven lie the angularlydnclined lower end portions 134 of arms 112. The energizing winding of said operating electromagnet is adapted to be energized to raise the armature 126 thereof to close the switch and is also adapt ed to remain energized and in its elevated switch closing position for so long as the switch remains closed.

A relay panel 136 is located at the front of the switch beneath the movable contact carrier 60 and is attached by suitable screws to inwardly-extended ears 140 of said side plates 20 and 22. Said panel is composed of a suitable insulating material, as bakelite and is provided with upper terminals 142 for the two outer phases A and C which are in the form of spring clips suitable for "re- 'ceiving the cylindrical end ferrules of the usual cartridge type relay 156. Similar lower terminal members 144 are provided directly beneath said terminals 142. The upper terminals 142 are electrically connected by means of their attaching screws 138 with rigid straps 146 of conducting material which extend through the switch in the space between the duplicated operating mechanisms therefor and are connected at their ends with the stationary terminals 52 of the rearmost stationary contact members 406 of the A and C phases. The middle phase of the "switch is provided with a terminal conductor 150 on said relay panel which is connected by a similar strap 146 with the fixed contact member 40?) of phase B, which terminalconstitutes one of the phase terminals of the auxiliary control circuit thereinafter to be described. A pair 01 intermediate terminal clips 152 are provided on said panel for the two outer phases of the switch, the terminals of each pair being spaced apart on said panel and insulated thereby from each other.

Suitable overload responsive means as the thermal relays 156 are-received in the line terminal clips, 142 and 144 and the pilot terminals 152, and are adapted to open the switch upon overload by opening the pilot circuit including the winding 130 of the holding electromagnet, as is common practice.

In Fig. 3, is shown a. wiring diagram for a single phase, as phase A, of the switch and illustrating the connections for the control or pilot circuit, only the contact members and overload relay of this phase conductor being shown. As diagrammatically shown, the switch includes the stationary contact bars 40 and 40a and 406, the movable contact bars 62 and 62a and the switch closing electromagnet including the core 34, the armature 126. and the energizing winding 130 therefor. Said switch is arranged to control the load" circuit comprising the conductors 158 and 160 which maybe, for example, connectedwith an electric motor, not shown.

Ill

hilt) BIB ' An overload relay 156 has a heating coil 162 thereof included in series in conductor 160' s of the invention.

thus tobe energized by the current flowin in the load circuit. Said relay is provide with intermediate terminals 151 and 153 which are insulated from said heating coil and which are normally electrically connected by means of a thermally expansible element 164 which, however upon being sufliciently heated by current flowin in said heating coil is adapted to flex an open the circuit between said terminals.

Said switch closing electromagnet winding 130 is included in a pilot, or control, circuit which is established across the line side of the circuit 158, 160 by the closing of the switch,

whereby to constantly energlze the coil and maintain the switch closed. Said pilot circuit also includes the terminals 151 and 153 of the thermal relay in series therewith, thus to provide for automatically openin the pilot circuit to de-energize said coil an open the switch upon overload. Said pilot circuit comprises the conductor 166, which is connected with one side of the line, contacts 151, 153 of said thermal relay, electromagnet coil 130, a normally closed switch 170, and a conductor 172 which is connected with terminal 58 of the middle stationary contact member 40a which when the switch is closed is energized from the other side of the line, thus to complete a holding coil circuit which is automatically energized and de-energized by corresponding closing and opening movements of the switch. The holding coil circuit can be interrupted when desired by opening the normally closed switch 17 0 or, upon overload, by the operation of the thermal element 164 to interrupt the holding coil circuit. A normally' open switch 174v is provided, which shunts the conductor 172 and which is connected in the line ahead of the main switch, by which the holding coil circuit can be energized to'close the switch and complete the holding coil circuit above described, thus to leave the switch closed.

By the provision of the conductor 172 which is connected with the intermediate stationary terminal 40a, it will be evident that when, the normally closed switch170 is depressed to open the holding coil circuit, the switch will open; and the switch will stay open regardless of the release of said switch 170 until the holding coil 130 is again energized by depressing the normally open switch 174. Thus, the arrangement above described provides an electrically controlled switch that is entirely free from troublesome auxiliary switches and flexible leads in its control, or pilot, circuit and in which the phase conductors on the load side of the switch are entirely disconnected from the energized con-. ductors on the line side of the switch when the switch is open.

Various changes may be made in the construction and arrangement of the contact members without departing from the scope The switch herein illustrated is described and claimed in my copending application filed January 24, 1929, Serial No. 334,7 83.

I claim:

1. The combination of a switch having'two outer and an intermediate insulated contact member which control the power current traversing the switch two movable insulated contact members both engageable with said intermediate and a separate outer stationary contact member, switch operating mechanism including an actuating coil, means for initially energizing said coil to close the switch, and a circuit including said intermediate stationary contact member to hold said coil energized after the switch has closed.

2. The combination of a switch having two outer and an intermediate insulated contact member which control the power current traversing the switch, two movable insulated contact members both engageable with said intermediate and a separate outer stationary contact member, switch operating mechanism including an actuatingcoil, a circuit includin a normally-open closing switch for initia ly energizing said coil and closing the switch, a holding circuit which includes said coil and the intermediate stationary contact member for shunting said closing switch and holding said coil energized when the switch 3. The combination of a switch for connecting portions of power circuit conductors having cooperatin' stationary and movable contact members or connecting portions oi one power conductor and three insulated stationary contact members and two insulated movablecontactmembersfor connecting portions of the other conductor, said three stationary contact members consisting of an intermedi'ate insulated contact member and two outer contact members which are connected to the portions of their respective power conductor, said two movable contact members both engaging the intermediate contact member andva separate outer contact member, switch operating mechanism including an electromagnet having an actuating winding which is adapted to be energized to close the switch and to remain energized to hold the switch closed, and control apparatus therefor including a control circuit which is connected between said intermediate contact member and the first conductor and includes said actuating winding and a normallyclosed circuit-opening controller for de-energizing said winding and opening the switch when it is closed, and a second circuit which is in series with said winding and circuitopening controller and is connected with said second conductor and includes a normallyopen circuit-closing controller which shunts said intermediate contactmember and its cooperatin movable contact member and energizes-sai winding for closing the switch when it is open, the closing of the circuit through said intermediate contact member thus subsequently maintaining the switch closed.

4. An electric switch having insulated stationary contact members including spaced terminal contact members and an intermediate contact member which control'the power current traversin the switch, a movable bridging member or electrically connectin all of said stationary contact members w ereby to complete the circuit through the switch, means for electrically o crating said movable brid ing member inc uding a closing coil which is adapted to be energized when the switch is closed to hold the switch in closed position, and a control circuit for said closing coil having one end thereof electrically connected to said intermediate stationary contact member.

5. A multi-break electric switch having fixed and aligned contact members including a pair of spaced terminal contacts and an intermediate normally insulated contact which control the power current traversing the switch, a movable bridging member arranged to electrically connect and disconnect said stationary contact members, electrically operated means for closing said switch including an electromagnet whlch is energized from the circuit to be controlled, said electromagnet also constituting means to hold the switch in switch closed position when once it has been closed, and a control circuit for said electromagnet having one terminal thereof connected with one side of said main circuit and having its other terminal electrically connected wit the other side of said main circuit at said intermediate stationary contact member.

In testimony whereof, I have signed my name to this specification.

GEORGE OKEEFFE.

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