US2107821A - Automatic switch for electric service lines - Google Patents

Description

Feb. 8, 1938. l E FARRELL 2,107,821

AUTOMATIC SWITCH FOR ELECTRIC SERVICE LINES Filed Oct. 1 8, 1934 gmc/YM JosphEZFa/rrel l x. MW

Patented Feb. 8, 1938 UNITED STATES PATE-NT OFFICE Joseph E. Farrell, Washington, D. C., assigner to Automotive Devices Corporation, Washington, D. C., a corporation of Delaware Application October 18, 1934, Serial No. 748,959

11 Claims.

This invention relates to a device for normally maintaining an electrical service line circuit closed. but which automatically functions upon the existence of unusual conditions in the line, such as surges resulting from a short or overload, to automatically open the circuit for the purpose of protecting electrical apparatus included therein.

A general object of the invention is to provide a novel device intended to obviate the use of a fuse of the type including a .strip of metallic alloy which melts or breaks upon the occurrence of the unusual condition in the line and which is generally unsatisfactory for numerous reasons.

- not only a waste of the article itself but frequently requires much time and labor to locate where many circuits are involved, and also causes inconvenience and delay due to loss of the circuit while the replacement is made. Therefore, the present invention contemplates an improved device of the electromagnetic switch type which may be used indefinitely after it is once installed by merely manually resetting the switch portion thereof to restore the circuit after it has been automatically opened to safeguardV the line.

While electro-magnetic devices of this general type have heretofore been used, nevertheless many of them are open to the objection that they do not reliably function and are particularly objectionable because after they have functioned to open the line circuit, the switch terminals are left unguarded or unprotected so that in the event that a subsequent unusual surge occurs in the line, an arc is produced between the exposed switch terminals due to the fact that they are only separated by an air gap. Also, many devices heretofore used have been open to the objection that the manual resetting means may be operated to bring the switch contacts intoengaging relation while the short or other unusual condition still exists in the line with the result that if it is attempted to manually hold the switch in its closed position in an eifort to reset it while still subjected -to unusually high voltage, arcing will also occur which will not only destroy the switch contacts but in some cases produce an arc of such high intensity that it will flash beyond the limits of the device and burn 0r otherwise injure the hand of the party endeavoring to reset the switch.

Accordingly, the invention contemplates as one of its essential elements a construction wherein a barrier of insulation is automatically and positively interposed between the switch contacts when the device is called upon to function to open the line thereby eliminating an air gap between the switch contacts and keeping them adequately separated and insulated until conditions are such as properly to permit 'of restoring the circuit.

A further and distinctive object of the inven-I tion is to provide a novel arrangement whereby after the device has once functioned to open the line, the barrier of insulation will not only be maintained or kept between the separated switch contacts but it will be impossible to manually reset the switch until after the unusual condition in the line has been remedied. That is to say, the movement of the resetting means in an attempt to reclose the switch will be idle so long as the unusual condition persists. In that connection, the invention contemplates as a part of the resetting means a pair of insulated movably related elements, one of which carries a manual resetting handle while the other carries the insulation barrier for separating the contacts, and as long as the unusual condition exists in the line, these two members will be disconnected so that the manually shiftable element may be moved independently of the insulation barrier or cut-olf, and only when the unusual condition ceases to exist in the line will it be possible for these two members to be automatically coupled or connected to effect the resetting and reclosing of the switch.

kA further object of the invention is to provide a simple, compact and reliable construction which lendsl itself to an embodiment that facilitates manufacture and assembly and which because of its simplicity and substantial construction will function indefinitely without being removed or disconnected from the line circuit.

With the above and other objects in view which will more readily appear as the nature of the invention is better understood, the invention consists in the novel features ci construction, combination and arrangement of parts', hereinafter more fully described, illustrated in the accompanying drawing and dened in the appended claims.

A preferred and practical embodiment of the invention is shown in the accompanying draw ing, in which:- ,j

, Figure l is a side elevation of the improved device;

Figure 2 is a top plan view thereof.-

Figure 3 is a vertical cross-sectional view i taken on the line 2--3 of Figure 2.

tion shown in the drawing, the same essentiallyincludes in its organization a supporting assembly designated generally as A, a switch housing carried thereby and designated generally as B, the latter being fitted with a cover C which is held to the housing by a flanged ring or equivaient means D.

Referring first to the supporting assembly A it may be pointed out that the same essentially includes a pair of main circuit terminals I and 2 which may be respectively in the form of a metallic shell and a center contact 2. The metallic shell I or its equivalent preferably houses an electromagnet 3, suitably insulated therefrom, and having at one end thereof an insulation plate or washer 4 while the opposite end abuts against one side of the cupped or recessed switch housing or base B. The center contact 2 is preferably in the form of a bolt whose shank 2l provides a core for the magnet and whose head 2b is intended to ilt within a recess 5 at the base of the housing so that when a rivet, or its equivalent, 2c is fitted to the opposite end, the said center contact will hold the parts I, 2, l and B in assembled relation. One end of the coil of the magnet 3 is in contact with the combined center contact land core member 2 as indicated at :c While the other end of the wire forming the magnet coil is led upwardly through the bottom of the switch housing B to a suitable conductor member 8 positioned and exposed at the face of the shoulder 1 within the switch housing. As shown in Figures 3 and 5, a portion of the metal shell constituting the circuit terminal I may be extended upwardly as indicated at 8 and bent over or otherwise secured as indicated at l* in the shoulder 1. The end 8* of the screw shell may, of itself, constitute one of the switch contacts, but in the assembly shown, it is preferred to have the said end Il engage with a stationary switch contact 9 intended to cooperate with a movable switch contact III carried by a spring switch lever II which is preferably formed as a part of a metallic switch frame designated generally as F.

The switch, of which the parts 9, IU and I I are a part, is designated generally as S, and these parts, together with their supports and control members are preferably arranged and assembled as a unit which may be fitted into the hollow or recessed portion of the switch housing B, above the shoulder 1, so as to rest on the latter when the parts are assembled, and be held in place by the cover C.

Referring further to the switch unit S it will be observed that the metal switch frame F which includes the yieldable spring switch lever II also comprises a body portion having a rounded rear wall I2 integral with the arms of the switch lever and is also provided with a bottom wall Il having the depending perforated ears Il and the 'altr/,ssi

upwardly extending rear wall Il. This formation provides in eifect a socket for receiving an insulating supporting plate I6. This plate is provided with a slot I1 and having its end opposite the socket terminating at and abutting against one of the sides of the switch contact 9 as will be apparent from Figures 3 and 5. The upper surface of the insulation plate I8 is therefore ush with the upper surface of the contact 9 for the purpose which will presently appear.

Mounted on the upper surface of the supporting plate Il are a pair of nested telescopically related insulating members which are intended to be connected vor disconnected automatically as conditions require. These insulating members are respectively a sliding contact separator and *barrier block G and a reclosing or resetting yoke H. Both are normally restrained spring actuated members, automatically released.' and manually reset.

The barrier block G is formed with a body Il having at its forward end an insulating toe Il which constitutes the barrier adapted to be interposedbetween the switch contacts 2 and Il when the circuit is open. The rear face of the block is provided with a seat for receiving a coil spring 2l whose opposite end engages with the wall I5 of the switch frame. The body of the block is also provided with a central recess or cavity 2I having an opening in the bottom thereof and adapted to receive a detent or latch 22 which is normally urged upwardly by a spring 23 confined between the underside of the head of the latch and the base of the cavity while the shank of the latch projects through the opening in the bottom of the recess or cavity and extends through the slot I1 to receive a nut 2l. This nut is slidably interlocked with the sides of a slot 2l in an armature member 2l. The latter is pivoted as at 21 to the ears Il of the switch frame and the spring-22 ofthe latch urges the armature member away from the head 2" of the combined center contact and-magnet core 2-2, and also urges the latch toward socket 2l of member H.

The sliding barrier block G is nested within the resetting yoke H which includes an insulation body 2l having a handle 2l adapted to project through a slot 2| in the cover C and is also provided with the side walls 22 whose bottom edges rest on the plate Il to surround and house the sliding switch block G. The body 29 is also provided with a rear wall 32 having an opening for permitting the passage therethrough of the spring 2l, the said wall also constituting an abutment for one end of the coil spring 24 confined between the wall 23 and the wall I5 of the switch lever frame. The spring 34 is of larger diameter than the spring 20 so that the latter is nested within the former. The inside face of the upper wall portion of the body 29 is provided with the keeper recess or socket 2s intended to receive the detent or head 22 of the armature controlled latch. When the detent or latch head 22 is engaged in the socket 2l as shown in Figure 3, it will be apparent that the members G and H will be interlocked and may be moved together. On the other hand, when the amature 26 is attracted to the head 2b of the combined core and center contact 2-2 as shown in Figure 5, the parts G and H will be free to move independently of each other.

For the purpose of holding the members G and H in their retracted podtion, when interlocked by the detent 22, the forward end of the upper wall of the body 29 of the resetting yoke is provided with a shoulder Il for engagingwith the upwardly extending bail shaped strap II* on the switch lever as, will be observed from Figure 3. Thus, when the device is in use and normal oonditions exist in the line, it will be apparent that lthe parts assume the position shown in Figure 3 wherein the part II* of the switch lever is engaged with the shoulder 2l of the resetting yoke. Likewise, the members G and H will be interlocked by the detent 22 and the armature 20 will be urged upwardly by the spring 22.

Upon the occurrence of a short or overload in the circuit including the present device, the magnet M will be activated and will attract the armature 28 against the tension oi.' the spring 22. This movement o! the amature will pull the latch or detent 22 downwardly and release the barrier block G from its interlocking engagement with the manually controlled resetting member H and the spring 2li will push the barrier block G forwardly so that the insulating toe Il will be thrust between the switch contacts 8 and It. The spring switch lever II is normally biased to the closed position so that contacts 9 and Ill are normally engaged. However, when the short or overload occurs the block G may move forward, after release from the member H by the withdrawal of the detent 22, due to the fact that the detent 22 at its shank portion can freely slide in the slot 25 of the armature member. When the insulating ban'ier or toe I9 raises or lifts the spring switch contact I0, it also elevates the upper arched portion of the strip I Il so as to remove the same from obstructing relation to the shoulder 25 on the resetting yoke H. Therefore, when I Il is moved out of the path of l5, the spring 3l can push the member H to the position shown in Figure 5. In this figure, the parts G and H are in the same relative position that they are in Figure 3 except thatthe insulating barrier or toe I of member G is interposed between contacts 9 and Ill and no current can pass between these contacts.

I! the undesirable condition persists in the line, it will be apparent that the armature 26 will be pulled to its downward position each time the handle 30 is moved from the full line position in Figure to the dotted line position because the circuit is re-closed between contacts 9 and I0. When this condition exists, it will be apparent that the resetting yoke H is disengaged from the slidable block G so that in event the handle 30 is.

moved from the full line position to the dotted line position shown in Figure 5, its movement will be idle so far as resetting is concerned and the spring Il will push the member G back to its former position between contacts 9 and III, and which is the off position of the switch.

On the other hand, if the short, or overload in the line is only of temporary duration and the armature 28 is released, it will be apparent that the spring 23 will return the armature to its normal position and consequently the detent 22 will move upwardly into the socket 28. Thus, the parts G and H will be interconnected again and by moving the handle from the full line position in Figure 5 to the dotted line position, it will be apparent that the insulating barrier I9 may be withdrawn from between the contacts 9 and I0 and the spring switch lever II will move downwardly to re-establish the circuit. Likewise, when the resetting yoke -H is retracted, the upper portion of the strap I I* will again become seated in the shoulder so that the entire actuating assembly consisting of the parts G and H will be held poised in their reset position.

Upon the subsequent occurrence o! a short or overload in the line, the latch or detent 22 will be pulled/downwardly and the spring 20 will thrust the block G forwardly to separate the contacts 9 and III and the circuit will be open. Resetting may be eecd again as previously described, and these operations may be repeated indeiinitely if desired.

From; the foregoing it will be apparent that a distinctive feature of the invention resides in providing means whereby the switch contacts will be positively separated and blocked by a. barrier of insulation immediately upon the opening of the circuit. As long as the undesirable condition persists in the line. this insulation barrier will remain in place and manipulation of the resetting means cannot permanently remove the barrier from its obstructing relation to the switch contacts. On the other hand, if the unusual condition automatically expires as quickly as it automatically occurred, then, the device may be reset manually for further use. As long as the insulation barrier remains between the contacts, subsequent surges o! high voltage current will produce no harmful result on the apparatus or on the attendant, thereby increasing the safety factor inherent in the device and substantially eliminating all hazards incident to the circuit being closed while the short persists inthe line.

Without further description it is thought that the features and advantages of the invention will be readily apparent to those skilled in the art, and it will of course be understood that changes in the form, proportion and minor details of construction may be resorted to, without departing from the spirit of the invention and scope of the ap- Y pended claims.

for unlocking the manual and automatic means and rendering said manual means incapable of being reset by the restraining means while abnormal conditions exist in the line.

2. In an automatic device for protecting electrical service lines, a pair of normally engaged switch contacts, separate spring urged manual and automatic insulation elements for controlling said contacts, means for normally interlocking said manual and automatic elements, restraining means effective while said elementsare interlocked, means associated with said automatic element for separating and insulating said contacts, and magnetic means for unlocking said manual and automatic elements and rendering said restraining means ineffective while abnormal conditions exist in the line, whereby the manual element can not be reset.

3'. In an automatic device for protecting electrical service lines, switch contacts one of which is normally spring biased to engage the other, and means for controlling said ilrst named contact, said means including a slidable insulation barrier and-a manually operated reelosing member, spring means for urging said members in one direction, means for normally interlocking said of the reclosing member while it is disconnected.

from the insulation member.

4. In an automatic device ior protecting electrical service lines, switch contacts one oi' which is normally spring biased to engage the other, and means for controlling said rst named contact, said means including a switch opening insulation member and a manually operated reclosing member, means for normally interlocking said members, means for restraining said members while intcriocked, and electro-magnetically operated means for releasing said members from said restraining means thereby to open the switch contacts and simultaneously render the reclosing member inoperative while the electromagnetic means is capable of being actuated by a persisting overload in the line.

5. An automatic switch for protecting electric service lines including a pair of switch contacts, an electro-magnet in circuit with one switch contact, a pair of superimposed nested and slidably related spring actuated insulation members, locking means for normally restraining the said members, means attracted by said electro-magnet upon the occurrence of an overload in the i line for releasing said locking means whereby one of the members may slide to separate the switch contacts while the other is set free to slide idle with respect to the first mentioned member as long as said means may be attracted by the electro-magnet.

6. In a device of the class described, apair of switch contacts, one of which is movable with reference to the other, an electromagnet in circuit with one of said contacts, shiitable superimposed control members oi insulation material for said movable contact, springs for urging said members in one direction, an armature in operative relation to the electromagnet, spring latch means connected with said armature for coupling and uncoupling said control members, and cooperating means on the movable contact and one of the control members for maintaining the same in normal position While connected by the latch.

7. In a device of the class described, a pair oi switch contacts, one of' which is movable with reference to the other, an electromagnet in circuit imth one of said contacts, shiftable control members for said movable contact, one of said members having an insulating toe adapted to be projected between said contacts, means for urging both of said control members in one direction, a spring latch carried by said member having the insulating toe, a socket in the other control member for receiving said latch, an armature in operative relation to the electromagnet, and means for slidabiy connecting said latch with the armature.

8. In a device of the class described, a pair of switch contacts, one of which is movable with reference to the other, an electromagnet in circuit with one oi said contacts, a pair of shiitable telescopically related control members, one of which is provided with an insulating toe adapted to be projected between said switch contacts, and the other oi which is provided with a shoulder i'or engaging with said movable contact, means for urging said control members in one direction, a latch carried by the control member having the insulating toe and adapted to engage with s socket in the member having the shoulder, a spring for normally urging the latch into the socket, an armature member in operatlve'relation to the magnet, and means for slidabiy connecting the latch and the amature.

9. In a device of the class described, a pair oi switch contacts, one o! which is movable with reference to the other, an electromagnet in circuit with one of said contacts, a pair oi shiftable telescopically related control members, one of which is provided with an insulating toe adapted to be projected between saidswitch contacts, and the other oi which is provided with a shoulder and a socket, a latch for engaging with a socket in the member having the shoulder, a spring for normally urging the latch into the socket, an armature member having a slot, and a member carried by the latch and having a slidable guiding engagement in the slot oi the armature member.

10. In a device of the lclass described, a pair of switch contacts, one of which is stationary and the other of which is movable, an electromagnet in circuit with one of said contacts, said movable contact including a spring arm having a contact portion normally adapted to engage with the stationary contact, restraining means on the movable contact, a pair oi' shiitable control members, a shoulder on one of said members, means for urging said control members toward the contacts, an insulating member carried by one oi.' said control members andadapted to be slidabiy proiectedlbetween the iixed and movable switch contacts to separate the same and elevate the movable contact whereby the restraining means thereof will be liited clear oi the shoulder of the other ot said control members, latch means for interconnecting said control members, and an armature member slidabiy interlocked with said latch means.

l1. In a device oi' the class described, a stationary switch contact, a movable switch contact, said movable switch contact being normally engaged with the fixed contact, an electromagnet in circuit with one oi said contacts, a pair oi shiitably mounted control members, latch means ior releasably interlocking said members, means i'or urging said control members in one direction, insulation carried by one of said members adapted to be projected between said ilxed and movable switch contacts to open the switch, a handle on one of said control members, restraining means on the movable switch member for engaging the control member having the handle, an armature operatively related to the electromagnet and adapted to actuate said latch means upon the occurrence of an overload in the line circuit thereby to disconnect said control mem-v bers and permit the insulation toe to be projected between said xed and movable switch contacts and to displace the restraining means of the movable contact out oi the path oi' the control member having a handle whereby manipulation oi the latter will render the control members ineiIective as long as the magnet attracts the armature.

JOSEPH E. FARRELL.

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