New developments in ignitron welding control

In this paper the use of resistance-welding timers using igniter-type mercury-cathode tubes is reviewed briefly and a seam-welding control unit containing a new design of inductive timer is described. An “ignition delay” form of control of welding heat or current magnitude is presented in which one set of power tubes controls both current magnitude and time duration. Comparison is made with the tap-changing method; operation of several welding machines from one timer is discussed.