GB2624419A

GB2624419A - Nulling device for electrical socket testing equipment

Info

Publication number: GB2624419A
Application number: GB2217182.1A
Authority: GB
Inventors: Thomson Duncan; Duncan Malcolm
Original assignee: SUPER ROD Ltd
Current assignee: SUPER ROD Ltd
Priority date: 2022-11-17
Filing date: 2022-11-17
Publication date: 2024-05-22
Also published as: GB202217182D0

Abstract

A nulling device for nulling an electric socket tester or multifunction meter, the nulling device comprising a housing having a plurality of plug pin sockets for receiving and retaining the pins of an electric plug, each plug pin socket comprising an opening or recess 22’ for receiving therein a plug pin and an electrically conductive contact plate 24’ located around an inner wall of said opening or recess, the nulling device further comprising an electrically conductive contact plate 40 that electrically connects together the contact plates of each of said plug pin sockets, said connector plate comprising one or more elongate, rigid or semi-rigid strips 40a of conductive material. A screw hole may be provided at one end of the elongate strip.

Description

NULLING DEVICE FOR ELECTRICAL SOCKET TESTING EQUIPMENT Field of the Invention This invention relates generally to a nulling device for use with electrical testing equipment, such as a socket tester or a multifunction electrical test meter, to enable 5 the equipment to be conveniently and accurately set to zero between uses.

Background of the Invention

It is well known to test that an electrical socket is functioning correctly using either a hand-held socket tester designed specifically for that purpose or by plugging a multifunction test meter into the socket to measure the voltage and resistance. In order to ensure that the reading(s) obtained by the testing equipment are accurate, it is important to ensure that the gauge or meter is accurately set to zero before plugging the equipment into a socket. Otherwise, accumulated charge and/or parasitic resistance in the meter, switches and plug pins may skew the resultant reading.

In order to perform this zeroing or nulling function, users often place a piece of highly conductive metal (in the form of, for example, a coin or a screwdriver shaft) between the plug pins, to effectively create a short circuit between them, and the test equipment gauge or meter can then, if necessary, be reset to zero (whist the plug pins are short-circuited) which ensures that the zero reading is as accurate as possible. After that, the testing equipment can be plugged into the socket to be tested, and the readings that result should be equally accurate.

However, using a screwdriver shaft or coin to perform this nulling function is not always convenient and can, if done incorrectly, result in inaccuracies. In any event, it does not look particularly professional, nor is it particularly efficient. There is, therefore, a need to provide an improved means for nulling these types of electrical socket testing equipment, and it is an object of aspects of the invention to address at least one or more of the above-referenced issues.

Statements of Invention

In accordance with a first aspect of the present invention, there is provided a nulling device for nulling an electric socket tester or multifunction meter, the nulling device comprising a housing having a plurality of plug pin sockets for receiving and retaining the pins of an electric plug, each plug pin socket comprising an opening or recess for receiving therein a plug pin and an electrically conductive contact plate located around an inner wall of said opening or recess, the nulling device further comprising an electrically conductive contact plate that electrically connects together the contact plates of each of said plug pin sockets, said connector plate comprising one or more elongate, rigid or semi-rigid strips of conductive material.

In a preferred embodiment, a screw hole may be provided at least one end of at least one of the one or more elongate strips.

In some embodiments, the conductive contact plate may, beneficially, be substantially rigid and formed of a conductive metal, such as copper or the like.

In an exemplary embodiment, the nulling device may comprise three electric plug pin sockets in the formation of a standard UK electric plug, wherein the conductive contact plate comprises a first elongate strip of rigid or semi-rigid conductive material extending between the conductive contact plates of first and second of the plug pin sockets and a second strip of conductive material electrically coupled to and extending from said first elongate strip to the conductive contact plate of the third plug pin socket.

Beneficially, the second strip of conductive material may extend substantially orthogonally from said first strip to the conductive contact plate of said third plug pin zo socket.

Optionally, the first and second strips are formed integrally with each other, although the electrical coupling between the two could be achieved in an alternative manner, such as by welding or soldering, as will be apparent to a person skilled in the art.

In accordance with another aspect of the invention, there is provided a socket tester holder including a nulling device substantially as described above.

In accordance with yet another aspect of the invention, there is provided a conductive contact plate for a nulling device substantially as described above, comprising a first elongate strip of rigid or semi-rigid conductive material and a second strip of conductive material electrically coupled to and extending substantially orthogonally from said first elongate strip, wherein at least one of the ends of the first elongate strip and the free end of the second strip has a screw hole therein configured to allow the contact plate to be affixed to at least one of the contact plates of a plug pin socket.

In an exemplary embodiment, both ends of the first elongate strip and the free end of the second strip may have screw holes therein.

Beneficially, the second strip may extend from the first elongate strip from a non-central location along its length, such that there is a first portion of the first elongate strip on one side of the second strip and a second portion of the first elongate strip on the other side of the second strip, the first portion being shorter than the second portion.

Optionally, the length of said first portion of the first elongate strip may be substantially the same as the length of the second strip.

These and other aspects will be apparent from the following detailed description. Brief Description of the Drawinas Embodiments of the invention will now be described, by way of examples only, and 15 with reference to the accompanying drawings, in which: Figure 1 is a front view of a socket tester holder according to an exemplary embodiment of the present invention; Figure 2 is an inside view of the front housing section of a socket tester holder according to the prior art; Figure 3A is an inside view of the rear housing section of a nulling device according to an exemplary embodiment of the present invention; and Figure 3B is an inside view of the front housing section of a nulling device according to an exemplary embodiment of the present invention

Detailed Description

Referring to Figure 1 of the drawings, a nulling device comprises an outer casing 10 having a front 12 and rear 14 casing sections. A set of (in this case, three) conventional plug pin sockets 16 are provided in the outward facing face of the front casing section 12, and accessible externally, the plug pin sockets 16 being arranged and configured to receive therein respective pins of an electrical plug or hand-held socket tester (not shown).

The nulling device may be in the form of a (hand-held) socket tester holder that provides a convenient means of storing and carrying a socket tester when it is not in use, as well as providing the nulling function. In this case, the socket tester holder may further comprise a length of cord or rope 18, affixed at one end thereof to the 'top' of the outer casing 12 (when the device is oriented for use as illustrated in Figure 1), and having, at the other end, a carabiner 20 or similar attachment means for enabling the device to be clipped to a user's belt, toolbelt or tool box, for example, for convenient storage and easy access, as required.

Referring now to Figure 2 of the drawings, in a socket tester holder according to the prior art, on the inside face of the front casing section 12, the plug pin sockets 16 are defined by three, substantially rectangular, moulded recesses 22, each slightly larger than the cross-section of a standard plug pin, and formed of an insulative material such as plastic. Within each recess, 22, there is provided a resiliently flexible conductive contact strip 24 that sits around three of the four inner walls of the respective recess, and is affixed, by means of a respective connector plate 26 and screw 28, to the inner wall of the front casing section 12. The two longest side edges of each conductive contact strip 24 is slightly biased inwardly (toward each other) so that when a plug pin is pushed into the recess from the face of the front casing section 12, it pushes the longer side edges of the respective conductive contact strip 24 outwardly (toward and against the inner wall of the respective recess 22), thereby acting to exert a retaining force on the plug pin and keep it securely in the plug pin socket 16.

Referring now to Figure 3B of the drawings, a nulling device according to an exemplary embodiment of the invention is illustrated and embodied, by way of example only, as a socket tester holder of the type illustrated and described with reference to Figure 2 of the drawings. In Figure 3, the front casing section 12' of the device is illustrated, and it will be appreciated that the rear casing section thereof may be substantially the same as that illustrated and described with reference to Figure 2 of the drawings. In the embodiment illustrated in Figure 3 of the drawings, contact strips 24' are once again provided around three of the four inner walls of respective moulded recesses 22' provided on the inner face of the front casing section 12. A conductive strip 25 extends, substantially at right angles, from one of the longer side edges 24a' of each contact strip 24' and extends through an opening 27 in the respective moulded recess 22' to a connector plate 26' located adjacent the outer wall of the respective moulded recess 22'. In some embodiments at least, each contact strip 24, conductive strip 25 and contact plate 26' may be integrally formed of a single piece of highly conductive material, such as copper. However, this is not necessarily essential, provided these three components of each plug pin socket are conductively coupled together in some way.

The nulling device comprises a generally non-symmetrical T-shaped highly conductive plate 40. Accordingly, the conductive plate 40 comprises a first conductive strip 40a that extends, substantially horizontally (when the device is oriented for use as illustrated in Figure 3A, with the two in-line plug pin sockets of a standard UK plug socket configuration being the 'lower' plug pin sockets and the single plug socket between and laterally spaced from the two in-line plug sockets being the 'top' plug socket for the purposes of this description only) between the connector plates 26' of the two 'lower' plug pin sockets 16'. The strip 40a extends over the moulded housing defining the recesses 22', and the ends of the first strip 40a are lightly bent toward the inner face of the front casing section 12 and secured to a respective connector plate 26' by a respective screw 28'.

A second conductive strip 40b extends substantially orthogonally between the first strip 40a and the connector plate 26' of the lop' plug pin socket. Once again, the end of the second strip 40b is bent slightly toward the inner face of the front casing section 12 and secured to the respective connector plate 26' by a screw 28'. The two conductive strips 40a, 40b can be formed integrally and may be of any suitable material such as copper. The T-shaped plate 40 is optionally substantially rigid, which has the benefit of enabling it to be secured in place by just one or two screws, rather than the thee illustrated in Figure 3A, which reduces the resistance of the overall nulling components.

The shape of the T-shaped plate 40 contributes significantly to the effectiveness, consistency and reliability of the nulling function. In effect, there is a single strip 40a that connects the two 'lower' contact strips 24' and then a relatively very short strip 40b extending from immediately adjacent one of the 'lower' contact strips 24' to the connector plate 26' of the lop' contact strip 24'. In the exemplary embodiment illustrated, the second strip 40b extends from the first conductive strip 40a at a non-central location along its length, which means that there is a short section of the first strip on one side of the second strip and a longer portion of the first strip on the other side of the second strip. The length of the second strip is substantially the same as the shorter portion of the first elongate strip. For the avoidance of doubt, the term "strip" is used herein to denote a thin flat piece of conductive material, as opposed to a wire.

Accordingly, the connector plates 26' are arranged to facilitate this configuration, with the connector plate 26' of the 'top' contact plate 24' being located beside and immediately adjacent the 'top' recess 22' and immediately above (longitudinally spaced from) a first of the two 'lower' contact strips, such that the length of the second conductive strips 40b of the T-shaped conductive plate 40 can be made as small as possible by extending orthogonally from immediately adjacent the connector plate of the first 'lower' plug pin socket to the connector plate immediately 'above' it. The two connector plates of the 'lower' in-line plug pin sockets are horizontally in line with each other (when the device is oriented for use as illustrated in Figure 3), thus also minimising the required length of the first conductive strip 40a of the T-shaped conductive plate 40 By using conductive strips 40a, 40b for the T-shaped conductive plate 40 that facilitates the nulling function of the device, the surface area of the T-shaped conductive plate can be made relatively large with the length of the conductive sections extending between the three connector plates 26' being minimised, thus minimising its resistance and optimising the nulling performance of the device. The shape and configuration of the T-shaped conductive plate 40 ensures that it can be manufactured with minimum tolerances, and with no 'additional' or superfluous conductive material being required to facilitate its deployment (beyond what is required to extend between the three connector plates 26). As previously stated, although the device is illustrated in Figure 3 as having three screw 28' holding the T-shaped conductive plate 40 in place, it will be apparent that if it is substantially rigid, it could be held in place by just one or two screws and still work effectively and reliably, thus enabling the overall resistance of the nulling function to be reduced, and minimise potential points of failure.

Referring to Figure 3B of the drawings, an insulative back plate 30 is provided on the inner face of the rear casing section 14, the back plate 30 being shaped and configured to sit over the three recesses 22' (when the two casing sections 12, 14 are secured together), thereby providing an insulative back stop against which each end of the plug pins rests when a plug or socket tester is mounted in the plug pin sockets 16. The two casing sections are secured together to form the outer casing 10 by means of two screws (not shown) that extend through two respective screw holes 33 in the rear casing section 14 into two respective corresponding screw threaded apertures 35 in the front casing section 12.

It will be apparent to a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS1 A nulling device for nulling an electric socket tester or multifunction meter, the nulling device comprising a housing having a plurality of plug pin sockets for receiving and retaining the pins of an electric plug, each plug pin socket comprising an opening or recess for receiving therein a plug pin and an electrically conductive contact plate located around an inner wall of said opening or recess, the nulling device further comprising an electrically conductive contact plate that electrically connects together the contact plates of each of said plug pin sockets, said connector plate comprising one or more elongate, rigid or semi-rigid strips of conductive material.
2 A nulling device according to claim 1, wherein a screw hole is provided at least one end of at least one of the one or more elongate strips.
3 A nulling device according to claim 1 or claim 2, wherein said conductive contact plate is substantially rigid and formed of a conductive metal.is 4 A nulling device according to any of the preceding claims, comprising three electric plug pin sockets in the formation of a standard UK electric plug, wherein the conductive contact plate comprises a first elongate strip of rigid or semi-rigid conductive material extending between the conductive contact plates of first and second of the plug pin sockets and a second strip of conductive material electrically coupled to and extending from said first elongate strip to the conductive contact plate of the third plug pin socket.A nulling device according to claim 4, wherein said second strip of conductive material extends substantially orthogonally from said first strip to the conductive contact plate of said third plug pin socket.6 A nulling device according to claim 5 or claim 6, wherein said first and second strips are formed integrally with each other.7 A socket tester holder including a nulling device according to any of the preceding claims.8 A conductive contact plate for a nulling device according to claim 4, comprising a first elongate strip of rigid or semi-rigid conductive material and a second strip of conductive material electrically coupled to and extending substantially orthogonally from said first elongate strip, wherein at least one of the ends of the first elongate strip and the free end of the second strip has a screw hole therein configured to allow the contact plate to be affixed to at least one of the contact plates of a plug pin socket.9. A conductive contact plate according to claim 8, wherein both ends of the first elongate strip and the free end of the second strip have screw holes therein.10.A conductive plate according to claim 8 or claim 9, wherein the second strip extends from the first elongate strip from a non-central location along its length, such that there is a first portion of the first elongate strip on one side of the second strip and a second portion of the first elongate strip on the other side of the second strip, the first portion being shorter than the second portion.to 11 A conductive plate according to claim 10, wherein the length of said first portion of the first elongate strip is substantially the same as the length of the second strip.