US3300607A - Electrical connector with a helical conductor overload circuit breaker - Google Patents

Description

3,300,607 ELECTRICAL CONNECTOR WITH A HELICAL CONDUCTOR Jan. 24, 1967 K. M. DELAFRANGE OVERLOAD CIRCUIT BREAKER Filed Nov. 29, 1965 \\r H Nww 1 rr I II I I! N! l a g 1 3 6 7 1 a. a

IN VENTOR ATTORNEY United States Patent 3,300,607 ELECTRICAL CONNECTOR WITH A HELICAL CONDUCTOR OVERLOAD CIRCUIT BREAKER Kenneth M. Delafrange, 96 Washington Ave., Westwood, NJ. 07675 Filed Nov. 29, 1965, Ser. No. 510,266 Claims. (Cl. 200-1155) This application is a continuation-in-part of application No. 346,780, filed Feb. 24, 1964.

This invention relates to improvements in electrical connectors protective against overloading electric conductors in wiring systems of buildings and other uses. More particularly, it relates to electrical connectors interposed between input circuit wiring from an electric power source and branch output circuits connected thereto and to appliances or other power translating devices.

While there are other causations of failure and damage from overloading distribution circuits in installed wiring systems, by far the most common overload causation is that of detachable connection of current consuming means with branch supply circuits of the system at terminal connector outlets. This invention contemplates control of such circuits against overloading which often results in fires and other damage occasioned by overloading the connections at such terminal outlets.

It is, therefore, an object of the invention to provide electrical connector devices which, in use, will protect electric current supply wiring ia-gainst abnormal heating and damage from overload conditions.

A [further object is provision of electrical connectors providing branch output circuit extensions with at least one of the conductor means therethrough constituting also a thermal responsive overload circuit breaker operable under overload conditions to break the circuit, and this combined with means controlling circuit restitution.

The foregoing and further objects and advantages of the invention will be apparent from the following specification and the drawings forming a part thereof wherein FIGURE 1 is a side view of a three way branch plug connector embodiment of the invention, partly broken away, showing in a conductor means therethrough a spiral conductor operated circuit breaker.

FIGURE 2 is a partly broken front view of the structure of FIG. 1 showing also in cross section means for controlling circuit restitution.

FIGURE 3 is a top view, partly broken, of a multiple tap terminal outlet wall receptacle embodiment of the invention.

FIGURES 4 and 5 are fragmentary enlarged perspective views respectively of the circuit breaker reclosing control means of FIGS. 2 and 3.

In FIGURES 1 and 2 of the drawing, a plural conductor multiple circuit attachment plug 1 provides two side and one bottom branch output circuit connector receptacles in each of which are provided in conventional manner two spaced and independent contacts 2 engageable by plug contacts passing through spaced slots in the insulating body of the structure. Contacts 2 are parts of separate contact assemblies each inclusive of a conductor bar 3 and electrical connections to associated respective projecting connector blade contacts 4 and 5 for circuit continuation through plug 1 by insertion of the blades into a terminal outlet of a wiring system. Blade contact 4 and its associated connection and contact assembly may be permanently connected in customary manner and are not illustrated in detail. Blade 5-, however, is structurally different, having its end portion bent to provide anchoring and spring bearing flange portion 6, and further differs structurally from conventional contacts by its incorporation as a terminal part of a normally closed conductive cutout 3,300,607 Patented Jan. 24, 1967 directly in circuit between blade contact 5 and its conductively associated bus bar 3 and a contact thereon in each of the output circuit receptacles.

Contact 5 has fixed thereto at its inner flanged end portion a helical wire spring form conductor 7 with the connected end coil of the spring underlying and bearing against flange portion 6. Conductor 7 carries in fixed connection therewith at its free end a transverse contact bar 8 having at its free end a contact 9 fixed thereto. Conductive bar 3 of the branch contact assembly has connected thereto an upstanding conductor bar support 10 having its free end angularly 'bent and provided with fixed contact 11 so as to overlie and normally engage contact 9 on bar 8, this normal engagement being maintained under calculated tension of spring form conductor sufiicient to normally hold the contacts 9 and 11 in closed position. The helical conductor 7 has a high coefiicient of expansion and is made of high temperature metal alloy retentive of strength when heated and differing conductively and in performance under current flow therethrough from its associated conductors which are relatively soft and of conventional low resistance character. Nickelchrome alloys are found to be best and Nichrome wire is used in conductor 7 it having been found to have the most desirable operational characteristics under passage of current therethrough when in helical spring form, and, the gauge of the wire is predetermined by the maximum current value at which protective cutout operation is desired and in which minimum of impedance is involved.

The connector of the foregoing description is designed to operate in the following manner. Inserted into a terminal outlet connected with a power source, normal operation is simply that of providing branch output circuit or circuits from source. However, if there is or are connected therewith current consuming means of greater load capacity than that for which the connector is designed, the added resultant current flow quickly changes the static condition of the helical spring form conductor 7 causing it to heat and very quickly expand in linear movement to break engagement of contacts 9 and 11, thus opening.

the circuit. The quick opening of the breaker contacts minimizes heat storage in circuit wiring.

Cooling of the conductor 7 eventually causes the spring to return the contacts into engagement to restore the circuit. The intermittent operation is controlled, however, to enable correction of causation fault before restoration of the circuit. This control is accomplished by a lockout insulator member 31 slidable in a guide recess 32. This insulator is a small light weight molded body having an angular finger hold extension extending outwardly of the connector through a slot in the body communicating with the guide recess. At one end the body is enlarged and provided with a borehole type of recess having there in an end portion of a light helical spring 33 the other end of the spring engaging the connector body at one end of the guide recess. Forwardly of the enlarged portion of the body, the insulator is reduced in thickness to substantially that of the movable contact of the circuit breaker against which it normally engages under tension of the spring 33. The free end of the slide engaging the bar 8 and its contact is curved to minimize frictional en gagement with the movable contact when the breaker operates. When an overload causes expansion of the spring form conductor to open the contacts 9 and 11, the insulator slide under pressure of the spring 33 is caused to slide over the fixed contact where it remains until retracted by manual operation of the slide against the pressure of the spring. In its projected position, the spring form conductor is prevented from reclosing the breaker contacts by interposition of the insulating body therebetween. The lockout is automatic on operation of the breaker and restoration of the circuit requires manual retr traction of the slide. The spring conductor having cooled engages the slide under tension of the spring conductor so that when the slide is retracted against its spring the contacts snap closed and the slide is left in its normal 'end engagement with the movable contact for another safety projection in case of another overload. FIGS. 4 and 5 show this normal relation of the parts.

In an embodiment of the invention in FIG. 3 a wall type terminal receptacle or outlet 14 having branch outlets 15 and 16 is shown connected to power service wires 17 and 18 through the binding terminals 19 and 20 and multiple tap connections are provided at the outlets by pairs of contacts 22 connected to and supported by conductor bars such as 21. One of these bars 21 is provided with an angularly bent extension flange 23 at one end mounting if desired a contact 24. Adjacent the bar 21, insulated therefrom and substantially parallel thereto, a helical spring form wire conductor 26 similar to that hereinbefore described, and of Nichrome wire, is fixed at one end to binding terminal portion 20 by suitable fastening 27 and carries at its free end the transverse conducting switch bar 28 mounting contact 29 normally overlying and in contact with the contact 24 on conductor bar 21. Conductor 26 is disposed in a guide recess '30 in the insulation body of the outlet with its free end switch bar 28 and contact 29 disposed in an enlarged chamber portion of the recess 30 providing free movement of contact 29 into and out of contact with the contact 24 is response to linear movement of expansion of the conductor 26 in heating and cooling.

The operation of the circuit breaker is substantially as previously described in connection with the structure of FIG. 2, namely, the cutout switch remains normally closed as illustrated in FIG. 3 when output circuit loads connected to outlets 15 and/or 16 draw current within the predetermined range for which the arrangement is designed. However, when the attachment plug connected output circuits connected with the outlets are inclusive of power translating means using current greater than that for which the connectors are designed, this overload causes abnormal heating of the conductor 26 causing it to expand linearly to separate the contacts 24 and 29 to open the circuit from the supply lines, thus preventing overheating of such lines. When this happens, cooling of the spring form conductor follows causing it to again to move to close contacts 24 and 29. However, this closure is prevented by a control means combined with the breaker. This control means comprises an insulating slide member 34 having at one end portion thereof an angular finger hold extending outwardly of the outlet structure and through any cover plate therefor, not shown. The for ward end of this slide is curved and in normal operation of the outlet connector under proper current load engages the switch bar 28 under tension of a small leaf spring 35 having a free end extending through a hole in the slide and its other end anchored and fu'lcrumed in conforming slot in the outlet body and body portions defining a recess permitting swinging movement of the free spring end under its tension. On one side of the slide there is provided a contact 36 flush or very slightly raised above the surface of the slide. This contact does not extend to the end of the slide but has a rearward upwardly extending angular extension to engage in its forward or projected position a conductor contact electrical connector 37 disposed in the insulating body of the outlet to extend rearwardly where it is connected to lead connection 38 leading to one side contact of light 39, the other circuit connection of which is not shown but is connected to the other through contact connections.

The operation of the structure is substantially as before described in connection with FIG. 2, namely, when the breaker contacts are closed, the slide engages the movable contact under tension of the spring to be projected between the contacts when the breaker contacs open under overload conditions. It will remain in the projected position insulating the contacts from eachother until theslide is manually retracted against tension of the spring, as hereinbefore described, to allow the contacts to close and condition the structure for further overload operation. However, when the structure has cause of operation, the slide carrying the contact on its face makes connection with the contact of conductor 37 thus closing a shunt circuit inclusive of the indicator light or other signal or control circuit. The thermal responsive conductive means in the connectors are normally so designed as to be operative as cutouts at current values slightly below those Which would result in blown out main fuses and the like.

It will be apparent from the foregoing description of the embodiments of the invention selected for illustration that the connectors will prove protective of wiring systems using ordinary terminal outlets, and, that the use of the connectors illustrated will be protective of wiring installations where ordinary plug connected loads without the protective control feature therein are connected to the outlets. The invention is not limited to connectors with connecting contacts of the exact kind illustrated for other well known plug-in and socket contacts may be employed.

While the invention has been described in connection with specific embodiments of the invention, the words employed are those of description and not of limitation for structural modifications within the purview of the appended claims are contemplated without departure from the true scope and spirit of the invention.

I claim:

1. In combination with multiple terminal conductors of an electric power input circuit, a current overload control connector device connected with said conductors and having attachment plu'g receiving contacts adapted for separable connection with associated attachment plug contacts in a power consuming output circuit extension, said connector having an insulating housing and separate electric current conductive assemblies including said plug receiving contacts therein, one of said conductive assemblies having directly embodied therein a thermal circuit breaker comprising a fixed contact and a movable contact normally engaged therewith and mounted on a free end of a helical spring form conductor fixed at its other end against movement, said helical spring form conductor normally maintaining the contacts in engagement within a predetermined normal load current flow range but subject to linear expansion to separate the contacts under heat generated in the helical conductor by flow therein of an overload current above said range, and means for controlling reclosing of the breaker contacts after separation under overload, said means including a movable insulator member normally pressed edgewise against a side portion of the movable contact in its closed contact position to be automatically projected between the breaker contacts when opened and having an extension outwardly of the connector for manually retracting said member to permit closure of the contacts.

2. The structural combination as defined in claim 1 characterized by a nickel-chrome alloy spring form circuit breaker conductor.

3. The structural combination as defined in claim 1 wherein the said means for controlling reclosing of the breaker contacts includes an insulator slide member slidable'in a guide recess in the insulating housing and bearing at one end against the movable contact and tensioned spring means holding said slide member in engagement with the movable contact for projection by the spring means between the contacts when opened by overload.

4. The structural combination defined by claim 1 characterized by inclusionof shunt circuit connections including a terminal contact adjacent said insulator-member and the insulator member having on the movable breaker con- 5. The structural combination defined by claim 1 chartact and the shunt circuit terminal contact in the retracted acterized by inclusion of a pilot light, shunt circuit conposition of the insulator member. nections to said light including a terminal contact adjacent said insulator member and the insulator member hav- References Cited y the Examine! ing on the movable contact side thereof a spanning con- 5 FOREIGN PATENTS ductive contact engaged with the shunt circuit terminal contact and the movable breaker contact when the in- 465424 5/1950 Canada member proli'ded f between l BERNARD A. GILHEANY, Primary Examiner. breaker contacts, said spanmng conductive contact being out of connective jointure with the movable breaker con- 10 H. A. LEWITTER, Assistant Examiner.

Claims (1)

1. IN COMBINATION WITH MULTIPLE TERMINAL CONDUCTORS OF AN ELECTRIC POWER INPUT CIRCUIT, A CURRENT OVERLOAD CONTROL CONNECTOR DEVICE CONNECTED WITH SAID CONDUCTORS AND HAVING ATTACHMENT PLUG RECEIVING CONTACTS ADAPTED FOR SEPARABLE CONNECTION WITH ASSOCIATED ATTACHMENT PLUG CONTACTS IN A POWER CONSUMING OUTPUT CIRCUIT EXTENSION, SAID CONNECTOR HAVING AN INSULATING HOUSING AND SEPARATE ELECTRIC CURRENT CONDUCTIVE ASSEMBLIES INCLUDING SAID PLUG RECEIVING CONTACTS THEREIN, ONE OF SAID CONDUCTIVE ASSEMBLIES HAVING DIRECTLY EMBODIED THEREIN A THERMAL CIRCUIT BREAKER COMPRISING A FIXED CONTACT AND A MOVABLE CONTACT NORMALLY ENGAGED THEREWITH AND MOUNTED ON A FREE END OF A HELICAL SPRING FORM CONDUCTOR FIXED AT ITS OTHER END AGAINST MOVEMENT, SAID HELICAL SPRING FORM CONDUCTOR NORMALLY MAINTAINING THE CONTACTS IN ENGAGEMENT WITHIN A PREDETERMINED NORMAL LOAD CURRENT FLOW RANGE BUT SUBJECT TO LINEAR EXPANSION TO SEPARATE THE CONTACTS UNDER HEAT GENERATED IN THE HELICAL CONDUCTOR BY FLOW THEREIN OF AN OVERLOAD CURRENT ABOVE SAID RANGE, AND MEANS FOR CONTROLLING RECLOSING OF THE BREAKER CONTACTS AFTER SEPARATION UNDER OVERLOAD, SAID MEANS INCLUDING A MOVABLE INSULATOR MEMBER NORMALLY PRESSED EDGEWISE AGAINST A SIDE PORTION OF THE MOVABLE CONTACT IN ITS CLOSED CONTACT POSITION TO BE AUTOMATICALLY PROJECTED BETWEEN THE BREAKER CONTACTS WHEN OPENED AND HAVING AN EXTENSION OUTWARDLY OF THE CONNECTOR FOR MANUALLY RETRACTING SAID MEMBER TO PERMIT CLOSURE OF THE CONTACTS.

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