GB2355601A

GB2355601A - Fused electric plug with pins equidistant from a central axis

Info

Publication number: GB2355601A
Application number: GB9921004A
Authority: GB
Inventors: David Malcolm Goodwin
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-07
Filing date: 1999-09-07
Publication date: 2001-04-25
Anticipated expiration: 2019-09-07
Also published as: GB2355601B; GB9921004D0

Abstract

A plug comprises a body part 1 with apertures 3 for receiving conductive pins 4. The pins 4 are positioned equidistantly from a common axis, which may be the central axis of the plug. To polarise the plug and prevent it from being inserted in the socket in the wrong orientation one pin 4a may be larger that the others 4; alternatively, a rib and groove may be provided on the body of the plug. A fuse 14 is mounted centrally in the body 1 and can be linked into anyone of the pins 4 via a connecting link conductor 6 being placed in alternative positions within the plug. The connector allows a fused connection to be made to a selected phase in a socket in which different phases are available in different pin positions.

Description

2355601 Fused Electric Plugs This invention relates to fused electrical

connecting plugs for portable power supply, primarily for use in -industrial" rather than domestic contexts.

It is a commonplace requirement to take off a single phase supply (for example to supply a luminaire or a small power tool) from a 3-phase A C supply, and is desirable in many cases to do so without cutting and jointing the conductors of the main cable. Current techniques for doing this using individually applied and hand-routed flexible insulated conductors to make the required connections is labour intensive, expensive, and liable to mistakes, and I have, in another patent application filed simultaneously with this one, described a technique in which the use of such flexible conductors is avoided. In this and other applications, it may be desirable so to arrange a socket that power can be taken from different phases by the insertion of appropriate plugs, and even if this facility is not needed, it may be difficult to arrange connections from different phase conductors of the supply cable to the same terminal of the socket.

There is therefore a need for plugs that can be quickly and easily arranged to make a connection to any selected phase terminal of a mating socket, and to provide fusing for that connection. The need is supplied by the present invention.

The plug in accordance with the invention comprises a plurality of pins arranged equidistantly from an axis (preferably a central axis of the plug); a cartridge fuse holder set longitudinally on the said axis; means for connecting a phase conductor of a cable to one end of the fuse holder and at least one other conductor of the cable to a pin of the plug; and a connecting link shaped and dimensioned to allow assembly in alternative positions in the plug in each of which it connects the other end of the fuse 2 holder to a dif f erent one of the said plurality of pins.

Usually there will be only three (phase) pins to which such connections will be required and other pins (neutral and earth/ground pins) could if desired be arranged (a) different distance(s) from the axis; but maximum flexiblity is achieved if all the pins are symmetrically arranged on a common pitch circle around the axis.

Preferably the link connects to the selected pin by a 112-part" connector, for example by an auxiliary plug forming part of the link entering a mating socket on the pin. This may be an auxiliary socket provided for the purpose, or could be a socket into which a cable end would otherwise be secured (by crimping, swaging, soldering or the like).

Preferably the plug is "polarised" by having one pin different in size from the others, preferably following the usual practice that the protective earth (ground) pin is larger than the others. Alternatively or in addition, there may be polarising formations (such as a rib and a mating groove) on insulating members of the plug.

The invention will be further described, by way of example, with reference to the accompanying drawing in which:

Figure 1 is a diagrammatic view showing the components of one form of plug in accordance with the invention ready for assembly on the end of a flexible cable (for clarity not shown); Figure 2 shows two of the parts assembled; and Figure 3 clarifies the layout of the pins of the plug.

The plug comprises a base moulding 1 with a central threaded aperture 2 (which defines the central axis of the plug) and six other apertures 3 at equal distances from it and uniformly spaced, some or all of which accomodate plug pins 4. One of these (4a) is larger in length and diameter to serve as an earth pin and polariser, and this may require a larger aperture 3 than the others, which are all alike. In any event, this earth pin provides a reference for 3 identifying the individual pins. In the main use of the plug, three of the other pins will be potential phase pins (only one of which is to be used); the others may be, for example neutral and/or pilot circuit pins.

Those pins (or at least one pin) to which connections are to be made, except the phase pin, are (or is) f irst secured to the ends of the appropriate cable conductor(s) ("tails") and a fuse terminal 5 secured to the phase conductor of the cable. The phase pin is inserted in the aperture 3 corresponding to the required phase and a link 6 plugged into it so as to locate an apertured lug 7 over the central aperture 2 of the base moulding. The pins previously fixed to the tail(s) are now inserted in their respective apertures, and any unconnected pins preferably also inserted - if desired unused pins could be replaced by insulating dummy pins or blanking plugs. The fuse terminal 5 is inserted in the centre of an insulating moulding 8 which has slots 9, 10 to clear the link 6 and the cable conductors, allowing it to be assembled inside the base moulding to trap the pins.

A top moulding 11 with a cable outlet 12 and optional locking skirt 13 secures to the base moulding to complete the plug. The cable outlet can be arranged in any required direction around the axis of the plug, subject to the length and flexibility of the cable tails (and if the direction is to be changed repeatedly, to their work hardening characteristics) The base and top mouldings may snap together, if required irreversibly, or they can be fixed with screws or the like.

A cartridge fuse 14 can now be inserted through the central aperture 2 and secured with the usual assembly of a threaded insulating cap 15, spring 16 and terminal socket 17, the last two accomodated within the cap 15 and the socket 17 being biassed by the spring 16 into contact with the lug 7 to complete the phase connection.

4

Claims

I A fused electric plug comprising a plurality of pins arranged equidistantly from an axis; a cartridge fuse holder set longitudinally on the said axis; means for connecting a phase conductor of a cable to one end of the fuse holder and at least one other conductor of the cable to a pin of the plug; and a connecting link shaped and dimensioned to allow assembly in alternative positions in the plug in each of which it connects the other end of the fuse holder to a different one of the said plurality of pins.
2 A fused electric plug as claimed in claim 1 in which the said axis is a central axis of the plug.
3 A fused electric plug as claimed in claim I or claim 2 in which all the pins are symmetrically arranged on a common pitch circle around the said axis.
4 A fused electric plug as claimed in any one of claims 1-3 in which the link connects to the selected pin by a "2-part" connector.

A fused electric plug substantially as described with reference to the drawings.