GB2119178A

GB2119178A - Electrical connectors having improved resistance to electrical breakdown

Info

Publication number: GB2119178A
Application number: GB08209961A
Authority: GB
Inventors: Geoffrey Lambert West
Original assignee: Plessey Co Ltd
Current assignee: Plessey Co Ltd
Priority date: 1982-04-03
Filing date: 1982-04-03
Publication date: 1983-11-09

Abstract

An electrical connector comprises plug and socket parts 1,2 having generally cylindrical insulating body members 3,4 one of which has an axially extending central boss 5 of generally frusto-conical form defined by a re-entrant annular cavity 6 for receiving a tapered wall section 7 of the other member whereby the two members engage one another to provide an extended re-entrant tracking path 8. The plug and socket parts are constructed and arranged so that, as the body member 3,4 are pressed together, any air which becomes trapped within the connector is forced into an electrically unstressed cavity 10 between the forward end of the plug pin 11 and the closed end of the co-operating socket member. <IMAGE>

Description

SPECIFICATION Improvements relating to electrical connectors This invention relates to electrical connectors and is more especially concerned with high voltage (EHT) connectors suitable for use in radar transmitter and x-ray machine cabling.

In the case of known constructions of high voltage electrical connectors the tracking path between co-operating surfaces of plug and socket body parts of the connector may be relatively short with the consequential risk of electrical breakdown or tracking along such paths due to the manufacturing surface imperfections and the ingress of dirt and moisture etc. into the connector. Another drawback with known connectors is that air tends to be trapped in high electrical stress areas within the connector as the plug and socket parts of the connector are pressed together.

According to the present invention there is provided an electrical connector suitable for high voltage applications comprising plug and socket parts having generally cylindrical insulating body members one of which has an axially extending central boss of generally frusto-conical form defined by a re-entrant annular cavity provided in the member for receiving a tapered wall section of the other member whereby the two members engage one another to provide an extended re-entrant tracking path and the plug and socket parts including conductive pin and socket members embodied in the respective insulating members and constructed and arranged so that as the body members are pressed together any air which becomes trapped within the connector is forced into an electrically unstressed cavity between the forward end of the plug pin and the closed end of the co-operating socket member.

The trapping of air in the electrically unstressed cavity obviates the risk of electrical breakdown or arcing within the connector due to electrical discharge across air filled spaces or cavities. This feature may be facilitated by providing the plug pin with axial slots which allow trapped air to pass through the pin into the plug cavity whilst the pin is being moved into the socket cavity as the plug and socket connector parts are pressed together.

By way of example the present invention will now be described with reference to the accompanying single figure drawing which show a diagrammatic longitudinal cross-sectional view of separated plug and socket parts of a high voltage (EHT) electrical connector.

Referring to the drawing the plug and socket parts of the high voltage (EHT) electrical connector are indicated at 1 and 2, respectively. As can be seen from the drawing these plug and sockets parts comprise insulating bodies 3 and 4 which are of generally cylindrical form. More specifically, the insulating member 4 of the socket part 2 comprises a central, axially extending, boss 5 of frustoconical form which is provided by a re-entrant cavity 6 in the member 4. The plug part of the connector comprises a generally cylindrical wall section 7 of tapering form which is constructed to be snugly received by the reentrant cavity 6 of the plug part.As will be appreciated the insulating members 3 and 4 of the plug and socket parts co-operate to define and extended tracking path of zig-zag form shown by the chain line 8 which substantially reduces the risk of electrical breakdown within the connector when the two parts thereof are fully mated. The socket part of the connector has moulded within it a metal (e.g. brass) socket member 9 which is provided with a cylindrical cavity 10 for receiving a plug pin member (e.g. brass) 11 which is of generally cylindrical shape and formed with slots or grooves 1 2 extending axially at points around the periphery thereof so that as the plug and socket parts are pressed together to cause the pin 11 to enter the cavity 10 of the conductive socket member air trapped between the co-operating surfaces of the insulating bodies is forced through the grooves 1 2 of the pin and into the cavity 10 provided in the conductive socket member. In this way when the two parts of the connector are mated any air within the connector will be located between the forward end of the pin 11 and the closed end of the socket cavity 10. In this way the air will be electrically unstressed since there is no potential difference or drop across the cavity and thus the likelihood of electrical breakdown is thereby reduced.

In carrying out the invention the insulating members 3 or 4 of the two connector parts may be moulded from silicon rubber and the socket and plug parts may be enclosed within metallic shells 1 3 and 14, the shell 1 3 being provided with a screw threaded portion 1 5 for receiving the correspondingly threaded portion 1 6 of a threaded cap member 1 7 fitted on the shell 1 4 which serves to bring the two connector parts together and thereby force any air between the two insulating bodies through the plug pin and into the socket cavity which as previously mentioned is electrically unstressed and thereby reduces the risk of electrical breakdown or discharge within the connector body.

1. An electrical connector comprising plug and socket parts having generally cylindrical insulating body members one of which has an axially extending central boss of generally frusto-conical form defined by a re-entrant annular cavity provided in the member for receiving a tapered wall section of the other member whereby the two members engage

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to electrical connectors This invention relates to electrical connectors and is more especially concerned with high voltage (EHT) connectors suitable for use in radar transmitter and x-ray machine cabling. In the case of known constructions of high voltage electrical connectors the tracking path between co-operating surfaces of plug and socket body parts of the connector may be relatively short with the consequential risk of electrical breakdown or tracking along such paths due to the manufacturing surface imperfections and the ingress of dirt and moisture etc. into the connector. Another drawback with known connectors is that air tends to be trapped in high electrical stress areas within the connector as the plug and socket parts of the connector are pressed together. According to the present invention there is provided an electrical connector suitable for high voltage applications comprising plug and socket parts having generally cylindrical insulating body members one of which has an axially extending central boss of generally frusto-conical form defined by a re-entrant annular cavity provided in the member for receiving a tapered wall section of the other member whereby the two members engage one another to provide an extended re-entrant tracking path and the plug and socket parts including conductive pin and socket members embodied in the respective insulating members and constructed and arranged so that as the body members are pressed together any air which becomes trapped within the connector is forced into an electrically unstressed cavity between the forward end of the plug pin and the closed end of the co-operating socket member. The trapping of air in the electrically unstressed cavity obviates the risk of electrical breakdown or arcing within the connector due to electrical discharge across air filled spaces or cavities. This feature may be facilitated by providing the plug pin with axial slots which allow trapped air to pass through the pin into the plug cavity whilst the pin is being moved into the socket cavity as the plug and socket connector parts are pressed together. By way of example the present invention will now be described with reference to the accompanying single figure drawing which show a diagrammatic longitudinal cross-sectional view of separated plug and socket parts of a high voltage (EHT) electrical connector. Referring to the drawing the plug and socket parts of the high voltage (EHT) electrical connector are indicated at 1 and 2, respectively. As can be seen from the drawing these plug and sockets parts comprise insulating bodies 3 and 4 which are of generally cylindrical form. More specifically, the insulating member 4 of the socket part 2 comprises a central, axially extending, boss 5 of frustoconical form which is provided by a re-entrant cavity 6 in the member 4. The plug part of the connector comprises a generally cylindrical wall section 7 of tapering form which is constructed to be snugly received by the reentrant cavity 6 of the plug part.As will be appreciated the insulating members 3 and 4 of the plug and socket parts co-operate to define and extended tracking path of zig-zag form shown by the chain line 8 which substantially reduces the risk of electrical breakdown within the connector when the two parts thereof are fully mated. The socket part of the connector has moulded within it a metal (e.g. brass) socket member 9 which is provided with a cylindrical cavity 10 for receiving a plug pin member (e.g. brass) 11 which is of generally cylindrical shape and formed with slots or grooves 1 2 extending axially at points around the periphery thereof so that as the plug and socket parts are pressed together to cause the pin 11 to enter the cavity 10 of the conductive socket member air trapped between the co-operating surfaces of the insulating bodies is forced through the grooves 1 2 of the pin and into the cavity 10 provided in the conductive socket member. In this way when the two parts of the connector are mated any air within the connector will be located between the forward end of the pin 11 and the closed end of the socket cavity 10. In this way the air will be electrically unstressed since there is no potential difference or drop across the cavity and thus the likelihood of electrical breakdown is thereby reduced. In carrying out the invention the insulating members 3 or 4 of the two connector parts may be moulded from silicon rubber and the socket and plug parts may be enclosed within metallic shells 1 3 and 14, the shell 1 3 being provided with a screw threaded portion 1 5 for receiving the correspondingly threaded portion 1 6 of a threaded cap member 1 7 fitted on the shell 1 4 which serves to bring the two connector parts together and thereby force any air between the two insulating bodies through the plug pin and into the socket cavity which as previously mentioned is electrically unstressed and thereby reduces the risk of electrical breakdown or discharge within the connector body. CLAIMS

1. An electrical connector comprising plug and socket parts having generally cylindrical insulating body members one of which has an axially extending central boss of generally frusto-conical form defined by a re-entrant annular cavity provided in the member for receiving a tapered wall section of the other member whereby the two members engage one another to provide an extended re-entrant tracking path and the plug and socket parts including conductive pin and socket members are constructed and arranged so that as the body members are pressed together any air which becomes trapped within the connector is forced into an electrically unstressed cavity between the forward end of the plug pin and the closed end of the co-operating socket member.

2. An electrical connector as claimed in claim 1, in which the plug pin is provided with axial slots which allow trapped air to pass through the pin into the socket cavity whilst the pin is being moved into the socket cavity as the plug and socket connector parts are pressed together.

3. An electrical connector as claimed in claim 1 or claim 2, in which the insulating body members are moulded from rubber or like material and enclosed within cylindrical metallic shells which are threaded to allow the two connector parts to be drawn together.

4. An electrical connector substantially as hereinbefore described and as illustrated in the accompanying drawing.