GB2262161A - Testing multicore cables - Google Patents

Apparatus (10) (Figure 1) for testing a cable (1) (Figure 3) comprising a plurality of conductors (2a-2h) comprises sockets (12, 14) into which the ends of the cable (1) can be inserted and light emitting diodes (3a-3g) for connecting the conductors into a serpentine configuration, the diodes emitting light when current flows in the circuit. <IMAGE>

CABLE TESTER This invention relates to an apparatus for testing the integrity of an electrical cable comprising a plurality of conductors.

When, after manufacture, a cable is incorporated into a product, for example, a mobile radio telephone, defects in the cable can be difficult to repair or replace. If a defect is not discovered until the product is in use and away from the factory these difficulties are increased and may give rise to customer dissatisfaction.

According to the present invention, there is provided an apparatus for determining the integrity of a cable comprising a plurality of conductors, the apparatus including means for electrically intercoupling the respective conductors in a generally serpentine configuration, means for coupling the serpentine configuration of conductors to an electrical power supply, and means responsive to current flow through said intercoupling means for indicating the integrity of said cable.

The apparatus in accordance with the present invention has the advantage of enabling a multi-core cable to be tested quickly and simply with the indicating means indicating whether the cable has a defect or not. It is therefore a simple matter for the integrity of the cable to be checked by an unskilled worker before the cable is incorporated in a product, with any defective cables being discarded.

In a preferred embodiment, the indicating means may include a respective indicator for each pair of intercoupled conductors. The indicating means may form part of the intercoupling means and may provide a visual indication e.g. using light emitting devices. Thus, not only is it simple to check whether a cable is defective or not, but also depending upon whether only some or none of the light emitting devices are activated, an indication of what type of defect is present is given.

In a preferred embodiment, the apparatus may further comprise a housing which includes means for receiving both ends of the cable to provide the intercoupling between the conductors, with the indicating means provided on an external part of the housing.

The invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a testing apparatus in accordance with the invention; Figure 2 is a front view of the apparatus of Figure 1 without a housing; and Figure 3 is a schematic circuit diagram of the apparatus of Figures 1 and 2.

A cable testing apparatus 10 shown in Figures 1 and 2 comprises a housing 11 having two sockets 12, 14 comprising rectangularly shaped open-ended boxes each having eight substantially L-shaped contacts 16a-16h;32 18a-18h therein. These sockets 12,14 may be of the type used in United Kingdom telephone systems for receiving plugs attached to the leads of disconnectable telephones.

Between each one of a pair of adjacent contacts 16a-16h in one socket 12 is connected a respective LED 3a-3d.

For example, LED 3a will be connected between contacts 16a and 16b. In the other socket 14, the outer contacts 18a and 18h are connected to first and second conductive leads 20 and 22 respectively, contact 18a directly to first lead 20, and contact 18h via a resistor R. The inner contacts 18b-18g are connected to LED's 3e-3g as in the other socket 12. For example, contacts 18d and 18e will be connected via LED 3g.

The first and second leads 20, 22 are provided with connectors (not shown) for connection to a 12V power supply (not shown).

A printed circuit board 24 is provided to assist connection of the LED's 3a-3g, leads 20,22, resistor R and contracts 16a-16h. The LED's 3a-3g protrude through the roof 26 of the housing 12 so that they can be seen.

For testing a cable 1 each end of the cable is provided with a suitable plug (not shown) of the type described above, one of which is inserted into one socket 12, and the other into the other socket 14. The first lead 20 is connected to ground and the second lead 22 to the positive terminal of the power supply. Insertion of the plugs into the two sockets 12,14 enables the conductors 2a-2h of the cable 1 to be connected via the contacts 16a-16h; 18a-18h to the LED's 3a-3g, as discussed below in relation to Figure 3. The LED's 3a-3g will all be activated if the cable 1 is not defective. If the cable 1 is defective in some way then none, or only some, of the LED's will be activated, as discussed in more detail below.

The operation of the apparatus 10 will now be described with reference to figure 3.

Figure 3 shows schematically a cable 1 - in this example, an eight core cable - comprising eight conductors 2a-2h, each surrounded by an insulating sheath (not shown).

To test the cable 1, connections are made between one end of a first conductor 2a and one end of a second conductor 2b, while the other end of this second conductor 2b is connected to one end of the third conductor 2c and so on until all the conductors 2a-2h are connected in series in a generally serpentine configuration. These connections are made via respective LED's 3a-3g as is shown in Figure 3.

A voltage V of, for example 12V, is applied through a resistor R of, for example, 100 Q to the two remaining free ends of the conductors 2a-2h, so as to forward bias the LED's 3a-3g. If none of the conductors 2a-2h are defective, then current will flow through the conductors 2a-2h and the forward biased LED's 3a-3g, which will all be activated.

If any of the conductors 2a-2h has a break in them, ie if there is an open circuit in any of the conductors 2a-2h, then current will not flow through the intercoupled conductors 2a-2h and none of the LED's 3a-3g will be activated, thus giving an indication that one or more of the conductors 2a-2h are broken.

Should there be a short circuit between any two conductors, for example between conductors 2b and 2c, then current will still flow, but one or more of the LED's 3a-3g will be bypassed and will not be activated.

In the example given above, LED 3b would fail to activate. Thus, an indication that there is a short circuit between two or more conductors is given when only some of the LED's are activated.

Should any of the conductors 2a-2h in the cable 1 be crossed in some way, then, either some or none of the LED's 3a-3g will be inactivated depending upon whether it is adjacent conductors which are crossed, or non-adjacent conductors that are crossed. For example if conductor 2e is crossed with conductor 2c so that conductor 2e is connected to LED's 3f and 3b, instead of 3f and 3c, while conductor 2c is connected to LED's 3e and 3c rather than 3e and 3b, then LED's 3b and 3g will be bypassed and will not be activated. However, if, for example, conductors 2e and 2f are crossed, then current will not flow and none of the LED's 3a-3g will light.

It can be seen, therefore, at a glance whether or not the cable is defective depending on whether all the LED's 3a-3g are activated or not. Additionally, if none of the LED's 3a-3g are activated, it indicates that one of the conductors 2a-2h has a break in it, or that adjacent conductors are crossed whereas if some but not all of the LED's 3a-3g are activated, this indicates a short-circuit or a cross-over of non-adjacent conductors 2a-2h.

It will be appreciated to a person skilled in the art that the apparatus could be used with cables with more or less than eight cores, with the sockets and the configuration of the LED's being adapted to suit the particular cable type.

It will also be appreciated, that other indicators could be used instead of LED's, for example, lamps or audible indicators.