GB767558A - A method of and device for ascertaining breaks in multi-wire strands - Google Patents

Abstract

767,558. Continuity testing. VIERLING, O. March 16, 1955 [March 16, 1954], No. 7638/55. Class 37. In an apparatus for testing multi-strand cables with respect to individual broken strands therein, the cable to be tested is inserted in a circuit fed by a voltage free of harmonics and is mechanically moved so that the current pulses due to intermittent contact of the ends of the broken strands are amplified and supplied to a measuring instrument, the deflection of which is an indication of the number of broken strands. In one embodiment, Fig. 1 (not shown), the cable is connected by a switch in series with the primary winding of a transformer and a battery. Any impulses in the secondary circuit are amplified, rectified and fed to a meter. In another arrangement, Fig. 2 (not shown), voltage pulses are developed across a resistor and a differential meter is used. In another arrangement, Fig. 3, the cable is connected in series with the filament heating circuit and also in the grid circuit of an amplifier, the last tube of which has a meter in its anode circuit and is biased by rectified impulses, if any. In Fig. 4 (not shown), the pulses are developed across a relay which switches on the amplifier filaments. In a modification, Fig. 5, when the cable is plugged in to points 17, 18, relay 20 connects battery 19 to transistors PNP, which amplify pulses developed in a transformer 2, and apply them to a meter 6 in such a direction as to reduce the deflection. The meter in this case is short-circuited except when the cable is plugged in. The test set has an additional socket for the connection of a battery-charging plug.