Direct current power supply with adjustable inductance control

Claim 1

In a welding system including a welding electrode means and a work member, a direct current arc power supply for establishing and maintaining an arc between the welding electrode means and the work member, the improvement in the direct current arc power supply comprising a transformer means to establish a welding voltage sufficient to establish and maintain an arc between said electrode means and said work member, a rectifier means connected to said transformer means to rectify said welding voltage, a pair of output means connected to said rectifier means and to said electrode means and said work member, said transformer means having a plurality of phase windings, said rectifier means having a plurality of triggered rectifiers connected to said phase windings and having gate means to control the conduction of said rectifiers and forming the sole arc power paths from said phase windings, means connected to the gate means to control the triggered rectifiers and thereby control the current supplied to the electrode means and work member, a saturable inductance control means having a controlled load smoothing winding means in series with said electrode means to insert a smoothing inductance in series with the electrode means and having a saturating control winding means to control the saturation of the inductance control means, said inductance control means being adjustable to include an inductance of the order of 100 to 600 microhenries, a direct current supply connected to said control winding means to supply saturating current to the control winding means, said direct current supply including a full wave transformer rectifier unit having a tapped transformer secondary having a center tap and a pair of triggered control rEctifier means connected across the secondary with the control winding means connected between the center tap and the triggered control rectifier means to supply a full wave pulsating direct current to the control windings, a pulse forming circuit connected to the pair of triggered control rectifier means to selectively fire said triggered control rectifier means and supply a pulsating direct current to the control winding and including a low wattage potentiometer having a movable tap for controlling the phase of the pulse of the pulse forming circuit relative to the output of the secondary winding, and a cable means connecting said low wattage potentiometer in the pulse forming circuit to provide a remote control of the saturable inductance control, said low wattage potentiometer minimizing the generation of heat at the remote control.