GB1201679A - Location of short circuits - Google Patents

Abstract

1,201,679. Locating short circuits. BRITISH COMMUNICATIONS CORP. Ltd. March 26, 1969 [April 10, 1968], No.17365/68. Heading G1U. To locate a short circuit in a network, current is caused to flow via the short between two first points in the network between which there is normally a relatively high impedance and the presence or absence of a consequential potential difference between two second points spaced along a network conductor is detected to determine whether the route of the short circuit current includes the portion of the conductor between the second points, these steps being repeated with the position of at least one of the second points adjusted to enable the position of the short circuit to be located. One second point and one first point may be common. The method may be used to locate a faulty module e.g. 3 in an integrated circuit assembly, consisting of a number of modules connected between two lines 1 and 4. Potential is applied between the lines from a supply 6 via a probe 7 also connected to the zero input of a differential amplifier 10. Probes 8 and 9 are located one to each side of the input probe 7 and are connected to the differential inputs of the amplifier. Current flow through the short circuit causes a potential difference between either probe 8 or 9 and probe 7 according to the location of the short circuit, to produce a deflection on the centre zero instrument 11 in a direction corresponding to the direction of flow. The position of the arrangement of probes is adjusted along the line 4 until this direction alters, the location of the fault thereby being established. In an alternative system Fig. 3 (not shown) where only limited access to the system under test is possible, the probe 7 and one of the others e.g. 9 are located at fixed positions at opposite ends of the line 4. The probe 8 is first connected to an access point close to the probe 7 and gradually moved along the line 4. When it reaches a position beyond which no short circuit current is flowing in the part of the line between the probes 8 and 9, no deflection is registered on the meter 11 (which in this arrangement need not be centre zero). Thus the location of the fault is determined.