Safe break terminator

April 2, 1968

E. A. LINK

3,376,541

SAFE BREAK TERMINATOR

Filed March 11, 1966

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Attorney

United States Patent Office ^{3 376 541}

Patented Apr. 2, 1968

3,376,541 . SAFE BREAK TERMINATOR Edwin A. Link, Waukesha, Wis., assignor to

RFE Corporation, Waukesha, Wis.

Filed Mar. 11, 1966, Ser. No. 533,462

Claims. (Cl. 339—61)

ABSTRACT OF THE DISCLOSURE

Disclosed herein is an electrical connector including a first and second member one of which is made of an elastic material with each member having an electrically conductive part with each part adapted to be connected to the other and an electrically conductive layer on said one elastic member to shield the connection.

.The present invention relates to improvements in electrical connectors for high voltage electric cables, and is more particularly applicable to load break current interrupters used in terminating such cables.

Load break current interrupters of the type contemplated herein are generally described in my co-pending application Ser. No. 343,527, filed Feb. 10, 1964. This type of current interrupter is designed specifically to eliminate the hazard of electric arc on disconnection of the high voltage cables.

However, on termination of the high voltage cable a charge will be exposed on the surface of the terminator of sufficient strength to shock the operator if he accidentally comes into contact with it due to the capacitance and conductance of the insulating material. Shielding has therefore been proposed for the terminator so as to interpose a ground or neutral potential between the operator and the high, voltage present in the current carrying parts. External shields which are presently being used have created, a further problem on termination. During the interrupting cycle, ionized gases are expelled and if of sufficient amount it is possible for a restrike arc to be established between a base shield and the male or female part. This would result in a short circuit between the current carrying parts and the grounded shield.

. The primary object of the present invention is to provide an electrical connector for a high voltage cable which is externally shielded from the high electrical voltages normally encountered in such connection and thus be safe to handle and operate.

Another object of the present invention is to provide an improved electrical connector having an outer conductive shield which is insulated from possible restrike arcs which can occur on disconnection.

Another object of the present invention is to provide an improved electrical connector having a grounded layer between the operator and the hot conductor to protect the operator from the hot conductor.

. A still further object of the present invention is to provide an improved method for fabricating an electrical connector for a high voltage cable having an electrically conductive shield.

These objects are accomplished using an electrical connector having an electrically conductive member embedded in a resilient connector housing with the conductive member projecting into a connection recess in the housing with an electrically non-conductive follower secured to the end of the conductive member. The receptacle for this connector is provided with an insulated sleeve immediately in front of an electrically conductive sleeve both of which are embedded in an electrically nonconductive housing. The connector housing and receptacle housing are both provided with an electrically con2 ductive shield, which is either molded, painted or sprayed onto, the housings or the housings are dipped into the conductive material, with the shield being connected to the grounded sheath of the cable to thereby form a continua5 tion of the stress cone at the cable termination. This shield terminates near the open end of the housing and is insulated at the end by molding an additional layer of insulating material at the end of the housing and folding the additional material at the end of the housing over the out10 side surface of the shield. The end of the shield is then embedded within the connector housing material where it will not be exposed to the ionized gases created on disconnection of the cable.

Other objects and advantages will become more readily 15 apparent from the following detailed description when read in connection with the accompanying drawing in which a cross-section view of a plug and receptacle is shown.

The electrical connector shown is particularly adapted 2o for use with a ground level type transformer, but it should be obvious that the basic principle of the application is not so limited. The concept of this electrical connector can be used in any application where it is desirable to reduce or eliminate high electric stresses at the connec25 tion and also eliminate the hazard of establishing an uncontrolled electrical arc when breaking or disconnecting high voltage electrical cables.

Referring to the drawing, the electrical termination shown includes a plug assembly 10 and a receptacle as30 sembly 12. The plug assembly includes a hood 14 which is molded from a resilient insulated material such as an elastomer or rubber, and is provided with , an electrical connection recess 16 and a cable termination recess 18. These recesses are shown transverse to each other but 35 they could be co-axially arranged if desired. A hook eye 20 may be provided on the housing to aid in disconnecting the plug from the receptacle.

Since the housing is made of resilient material, by pulling on the hook eye the housing will elongate and 40 reiease from the receptacle with a snap action as more clearly defined below.

A conductive shield 50 is provided on the outer surface of the hood. This shield may be molded onto the hood or the hood can be coated with the shield by dipping, 45 painting or spraying. The conductive material used to form the hood includes either lampblack, graphite or carbon black which is combined with a binder, a resin or an elastomer similar to or identical to the elastomer used to form the hood. The following is an example of a for50 mula of the conductive material:

Nordel 1040 (binder)100

Zinc oxide 5

Conductex S.C. (Columbia Carbon Corp.)100

Flexon 865 20

Ethyl tellurac ” j

Sulphur _____________________________~j

Methyl zimate j

Thiurian M____ _ , ₆₀ mbts------------------ξζξξςξξξξς:ς:ς:ςξξςς 2

Z 6040 silane_________________ -iz

This mix is dissolved in a solution of xylene and ethyl hexylacetate dispersed in a mill to form a solution which is applied to the hood by dipping.

6a The end of the coating near the end of the hood is insulated by turning the end 54 of the housing back upon the conductive material as seen in the drawing. This is accomplished by molding the hood so that it is longer ^than. ^re9^uirec! at the connection recess end. When the coating is applied to the hood it is terminated short of the end of the hood a distance sufficient to allow the end

3,376,541

In connecting the plug assembly and receptacle assembly, insulated member 48 is inserted in sleeve 60 and the bushing aligned with the connection recess of the hood. The plug assembly is then pushed onto the receptacle until the reduced diameter section of the conductive sleeve engages conductive member 42. The inner end of the bushing will then be seated in the connection recess of the hood with the rib seated in the groove of the bushing. The connection between the conductive members will be shielded from high electric stresses by the conductive coating on the outer surface of the housing which is connected to and grounded by the conductive sleeve of the cable. The operator will thereby be protected from the cable at all times.

When the plug asembly is withdrawn from the receptacle, a gap will occur between the electrically conductive member and the electrically conductive sleeve across which a high voltage arc is normally established. The insulated member will be drawn into the insulated 20 sleeve lengthening the gap in the space between, the. insulated member and the insulated sleeve thus extinguishing the arc and interrupting current flow. Because some ionized gases are formed during the interruption a restrike arc might also occur‘between the stress relief 25 coating and the female connection (56) but this is prevented by the overlapping of the hood over the shield to insulate the end of the conductive shield.

Although only one embodiment of the present invention has been shown and described, it should be apparent 30 that various changes and modifications can be made herewith without departure from the scope of the appended claims.