GB596797A - Electric arc welding system - Google Patents

Abstract

596,797. Supply systems for welding arcs. HEWLETT, W. R., and PACKARD, D. [trading as HEWLETT-PACKARD CO.]. Feb. 8, 1945, No. 3226. Convention date, Dec. 17, 1943. [Class 38 (iv)] In a motor generator D.C. arc welding system, the driving motor is switched on or off through a starter switch which is operated manually by ' start ' and ' stop ' switches or automatically by engagement and disengagement of the electrode with the workpiece, the welding electrodes being connected to a transformer which is de-energized during welding. Closure of the main switch A in the A.C. supply to the motor M, energizes transformer C and the coil of relay E, which latter closes its contacts to prepare a circuit through the coil 21 of relay D, the electrode 13 and the workpiece 14. For automatic operation of starter switch B, engagement of the electrode 13 with the workpiece 14 momentarily energizes coil 21 of relay D, which closes its contact 1, 4 and 2, 5, the latter completing the circuit for coil 16 of the starter switch B which then closes its contacts to start the motor generator. Relay F is energized by the generator 11, and opens its contacts 1, 2 to cause relay E to isolate the transformer secondary and closes its contacts 1, 3, to complete the circuit for a totalizer device 36 through contacts 1, 4 of relay D which is now also energized by welding current from the generator. Should welding be interrupted, the coil 16 of the starter switch is de-energized only after a time interval determined by a time-delay relay G, the coil of which is energized through normally, closed contacts .1, 3 of relay D, over which contacts the coil 16 and transformer C are energized by the closure of " starter " button 17, when it is desired to operate switch B manually.