GB709737A - Improvements in and relating to test-apparatus for identifying wires - Google Patents

Abstract

709,737. Test apparatus for identifying wires. VUILLE, B. A. Sept. 5, 1952, [June 5, 1951.] No. 13357/51. Class 37. In test apparatus for identifying wires in a group, e.g. each core in a ten-core cable where only the ends are available as at test positions A and B in Fig. 1 there is a different or identifying value of circuit resistance for each core or wire under test. In Fig. 1 at A there is a test unit 19 and wire ends 23 are connected to terminals 10 which are numbered 1-10 and terminal number 10 is earthed and equal value resistors are connected across adjacent terminals. At B there is a test unit 2 i wherein a milliammeter or ohmmeter 30 which is calibrated 1-10 reads full scale when switch 36 is closed to earth. The operator at B connects each wire end 24 in turn to terminal 36 so that instrument 30 reads 10 for the wire on terminal 10 (this wire short circuits switch 36) and indicates approximately for each wire 1-9 with each wire 1-9 connecting in circuit a different total resistance between the corresponding terminal 10 and earth via one or more resistors 18. The test unit 21 is formed with a row of wire holders 26 numbered 1-10 corresponding to terminals 10 and as each wire is identified it is placed in the appropriate wire holder 26. If more than 10 wires have to be identified this may be accomplished in lots of 10. For identifying up to 20 wires at a time Fig. 1 may be modified so that resistors 18 constitute one arm of a bridge network and test unit 21 has two fixed resistor arms and a bridge-balancing potentiometer arm scaled appropriately e.g. 1-20. In another arrangement the test unit 19 is modified so that each of the terminals 10 is connected to earth through a resistor of unique value. Where no earth circuit is available the test unit of Fig. 2 may be utilized and this comprises different value resistors 18 in series with rectifiers 40. In the case of Fig. 2 the operator at B with the aid of a chart identifies the wires by connecting pairs of wire ends to terminals 35 and 34 (unearthed). The milliammeter reading for any pair of wires is unique since all the resistors 18 are of different values. The rectifiers are similarly directional and are included to protect the milliammeter 30.