Supply control for cable butt welding - is continuously variable and includes cooling power supply to cable jaw circuits

摘要

Control circuit for equipment butt-jointing electrical cables in cable works and mines. Current is supplied via heavy, normally braided, conductors to, usually cooled jaws close to the proposed junction and either side of a carbon block which is used to contain the jointing process. The control circuit allows continuous alteration of current level to accommodate cables having cross-sectional areas between several square millimeters and 2000 square millimeters. Power is also supplied to the jaw cooling circuits. Failure of this supply results in the welding power being cut-off. The circuit is based on a shunted (35) multi-tap transformer (32) with a pair of head to tail connected thyristors (50,52) in the primary supply (30) in parallel with a varistor (62) and a relay operated switch (44). Both thyristors are fired from a regulation control circuit (58).