GB2112221A

GB2112221A - Testing apparatus for electrical testing at series terminals

Info

Publication number: GB2112221A
Application number: GB08233661A
Authority: GB
Inventors: Georg Hille; Willi Durkop; Manfred Wilmes; Rainer Schulze
Original assignee: CA Weidmueller GmbH and Co
Current assignee: Weidmueller Interface GmbH and Co KG
Priority date: 1981-11-26
Filing date: 1982-11-25
Publication date: 1983-07-13
Also published as: FR2517128A1; FR2517128B1; GB2112221B; DE8134454U1

Abstract

A testing apparatus for electrical testing at series terminals comprises a spring-loaded contact pin 1 mounted in an insulating casing 3 provided with spring legs 10 for detachably fixing it in a recess of a housing containing the series terminals. The legs have catches 11 at their free end, the other end being moulded onto two opposed sides of a portion of the casing 3 remote from the series terminals when the apparatus is in use. Locking pegs 16 and recesses 17 may be provided to enable a plurality of such casings and pins to be connected side-by-side. <IMAGE>

Description

SPECIFICATION Testing apparatus for electrical testing at series terminals This invention relates to testing apparatus for electrical testing at series terminals, such apparatus comprising a contact pin with one end guided by, and movable within a casing of insulating material against the force of a spring, the casing being provided with a locking means for effecting detachabie fixing in the series terminals.

In a previously proposed testing apparatus of this kind, a plurality of contact pins, corresponding to a predetermined number of electrical terminals or poles, are guided adjacent to one another in a casing, with springs. The casing of insulating material surrounding the contact pins is itself made up of two sections which can move within the casing against the force of an additional spring means. At one end of these sections, there is provided a locking means for fixing them to a housing of, the series terminals. The arrangement of the contact pins is such that, for testing purposes, the contact pins can be put through screwdriver openings onto the series terminal screws associated with the connections at one side of the series terminal, or tension yokes thereof.

Additional bearing members have to be provided on the series terminals in the region of the screwdriver openings, to receive the locking means of the casings of insulating material.

A comparable testing apparatus is described in DE-AS 1 6 15 909, in which a contact pin is spring mounted in a sleeve shaped gripping portion made of insulating material. The sleeve portion has a plug-in heel at the bottom, whereby the apparatus can again be plugged into the screwdriver openings in the series terminals in question, in such a way that the contact pin is again pressed against the terminal screw of the connection at that side of the terminal. The plugin heel is provided with peripheral gripping ribs, which enable the apparatus to be temporarily and detachably fixed in the screwdriver opening in the series terminal in question.

The disadvantage of these previously proposed testing apparatuses is that they are designed to interact with the terminal screws of the series terminal connections. This means that once a particular testing apparatus has been pushed into the terminal screw, the terminal becomes inaccessible, and consequently a change in the circuit, which the apparatus may have shown to be necessary, cannot readily be carried out until the apparatus is removed.

A further problem, is that during a certain phase of the testing, series terminals of this type are frequently not connected up at all at the side of the terminal in question, a fact which is sometimes overlooked. Testing on the terminal screw then gives no result. One must also consider that possibly low voltages must sometimes be found with tests of this type, for example, where the testing of thermocouple elements is concerned. This would presuppose that the terminal screws are made of a highly conductive material, which is frequently not the case. Added to this is the fact that the screws often also carry a corrosion protective layer, and so there is poor conductivity between the pin and the terminal, with the result that sometimes no measurements at all and often inaccurate measurements are obtained.

In the first mentioned type of testing apparatus, the casing is of a complex construction and additional springing is necessary, and there is a predetermined number of poles which cannot be changed.

The second-mentioned construction is simpler, but the sleeve-shaped housings of insulating material, designed as gripping portions, cannot be grouped together to form a testing apparatus having a variable number of poles.

In a testing apparatus as described in DE-GM 77 24 132, a contact pin is guided with springing in a sleeve-shaped casing made of insulating material. The shape and length of the pin and the dimensions of the casing are chosen so that the testing apparatus can, in the central part of the series terminals be put through a recess for internal transverse connections (which is provided here in any case), onto a central part of a current collecting rail of the terminal. This is advantageous for measuring as such, firstly since the rail is always highly conductive (unlike the clamping screw of a series terminal connection) and also since the clamping screws remain accessible during testing, and since even low voltages can be detected satisfactorily here at the current collecting rail, even when one side of the series terminal has not yet been connected at all.

With this testing apparatus there is no opportunity for temporarily fixing it detachably to the series terminal housing. Hence the apparatus must constantly be held by hand. Nor is there any provision for grouping a plurality of testing apparatuses together, to form a testing apparatus having a variable number of poles.

According to the present invention there is provided testing apparatus for electrical testing at series terminals, the apparatus comprising a casing of insulation material, a contact pin with one end guided by and movable within the casing against the force of a spring and locking means for detachably fixing the casing in a recess in a housing for the series terminals, the locking means comprising a pair of spring legs moulded integral with the casing, one or each of two opposite sides thereof, each leg having a free end with a catch thereon to engage the housing of the series terminal and each leg extending from the casing at a position which, in the position of use of the apparatus, is remote from the housing of the series terminals.

A preferred embodiment of this invention, as described hereinbelow provides a testing apparatus which allows for measuring at the central rail portions of the series terminals, and provides a simple way of temporarily fixing the apparatus in the terminal housing.

With this embodiment of this invention, it is relatively easier to make use of the recess already provided in the terminals for internal transverse connections, as a means of temporarily detachably fixing the testing apparatus in such a recess above the central part of the current collecting rail of the terminal. Only minimal constructional changes are necessary in the terminals themselves to adapt them for this use.

In the region of the recess already provided for the internal transverse connection, all that is necessary is to provide a hooking means for the catches at the lower ends of the spring legs, at two opposed sides. The sprung contact pin can be placed on the central part of the current collecting rail. Since the spring legs are moulded onto the upper part of the casing of insulating material, part of them will remain outside the series terminal housing even when the apparatus has been plugged in. In the preferred embodiment, a handle portion may be formed for providing a place where the spring legs can be pressed lightly together so as to release the catches, for the purpose of unlocking and removing the apparatus.

A further advantage of the embodiment is that only two sides of the casing of insulating material is taken up by the spring legs. The sides arranged diametrically thereto are unaffected. The preferred embodiment also has provision for a connecting means for interconnecting and joining up a plurality of casings made of insulating material, so that a testing apparatus having a variable number of poles can very easily be assembled from individual housings.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a part-sectional side elevation of testing apparatus embodying this invention; and Figure 2 is a front elevation of the apparatus of Figure 1.

The Figures illustrate an apparatus comprising a contact pin 1 , with its upper portion (when in the orientation shown in Figure 1) guided by, and movable within a cylindrical interior 2 of a casing 3 made of insulating material. The contact pin 1 has a collar 4 with one end of a spring 5 bearing on it, the other end of the spring being supported against a shoulder 6 of the inside of the casing 3.

An electrical conductor, indicated by a dot-dash line may be electrically connected to a part of the contact pin 1, at least part of which is hollow, inside the casing 3.

At the lower, free end of the contact pin 1 a contact tip 8 is formed offset from the central axis of the contact pin 1 by a bevel 7. The lateral protrusion so formed provides a particularly favourable contact condition in the region of a threaded hole on a current collecting rail of a series terminal.

The casing 3 of insulating material is provided at its upper end (when in the orientation shown in Figure 1) with recesses 9, into which labels may be inserted. The labels can then be used to identify equipment, associated with the apparatus, that is, associated and attached measuring instruments and the like.

Below the recesses 9, but still in the upper portion of the casing 3, two spring legs 10 are moulded onto the casing 3 at two opposed sides thereof. The legs 10 extend downwards from the upper portion substantially parallel with the part of the casing 3 accommodating the contact pin 1.

The lower ends of the legs 10 are free and are provided with catches 11 extending away from the casing 3. All that is required for securing the apparatus in a series terminal, is for two small bearing members or projections to receive the catches 11 to be provided at two sides of the recess of the terminal, which are already arranged in the central part of the series terminal for internal transverse joining, and the apparatus can therefore be detachably fixed in the series terminal, in a reliable manner, by means of the catches 11.

The upper portion of the spring legs 10 comprises a wider portion 1 oa, which is adjoined to a narrower portion 1 Ob below. The dimensions of these portions are chosen so that only the lower, narrower portion 1 orb can be pushed into the open topped recess in the series terminal. The contour of a recess in a series terminal is indicated in dot-dash lines. The upper portion 1 Oa has gripping depressions 12 on its outer edge, to give it an ergonomically favourable shape for being handled. If the spring legs 10 are pressed together at the depressions 12, the catches 11 move inwards and can be freed from the bearing members or projections receiving them in the recesses of the terminal, and the apparatus can be removed therefrom.

Protecting knobs or loops 13 are moulded onto the casing 3 opposite approximately the central part of the spring legs 10, to protect the legs from excessive strain.

Referring to Figure 2, the casing 3 is flat at sides 14 and 15, that is to say the other two sides to the sides at which the spring legs 10 are provided. Projecting locking pegs 16 are moulded onto one flat side surface 1 5, while corresponding locking recesses 17 are provided in a corresponding position on the other side 14. The pegs 16 and the recesses 17 enable a plurality of casings 3 to be assembled together with a strong enough join, so that if required, a plurality of casings 3 may be assembled to form a single new multipolar testing apparatus with a desired number of electrical terminals or poles.

To enable a multipolar testing apparatus of this type to be satisfactorily and simultaneously disengaged at all its spring legs 10, and then removed from a line-up terminal arrangement, some of the spring legs 10 carry locking pegs 1 8 and other spring legs 10 carry locking recesses 1 9 at their corresponding, similarly flat sides.

Claims

1. Testing apparatus for electrical testing at series terminals, the apparatus comprising a casing of insulation material, a contact pin with one end guided by and movable within the casing against the force of a spring and locking means for detachably fixing the casing in a recess in a housing for the series terminals, the locking means comprising a pair of spring legs moulded integral with the casing, one or each of two opposite sides thereof, each leg having a free end with a catch thereon to engage the housing of the series terminal and each leg extending from the casing at a position which, in the position of use of the apparatus, is remote from the housing of the series terminals.

2. Testing apparatus according to claim 1, wherein the spring legs have gripping depressions provided on the outer edge of a portion remote from their free ends.

3. Testing apparatus according to claim 1 or claim 2, wherein recesses for receiving labels are provided on the casing adjacent to the spring legs.

4. Testing apparatus according to any one of claims 1 to 3, wherein the casing includes projecting knobs moulded on a part of the casing which accommodates the contact pin, said part being located approximately opposite a middle part of the spring legs.

5. Testing apparatus according to claim 1 or claim 2, wherein the portion of the spring legs remote from their free ends is wider than the portion adjacent to their free ends.

6. Testing apparatus according to any one of claims 1 to 5, wherein a contact tip, offset from the central axis of the contact pin, is formed at the free end of the contact pin by a bevel.

7. Testing apparatus according to any one of claims 1 to 6, wherein the casing has flat side surfaces at the sides without any spring legs, and locking pegs are provided on one of said flat side surfaces and locking recesses are provided in corresponding positions in the other of said flat side surfaces.

8. Testing apparatus according to claim 7, wherein the spring legs also have locking pegs on one side and locking recesses in the other.

9. Testing apparatus for electrical testing at series terminals substantially as hereinbefore described and illustrated with reference to the accompanying drawings.