Abstract: A pulsed arc welding system includes a current pulse generating circuit and a background current generating circuit. The lowest arc voltage across the arc load is detected during a predetermined time period immediately preceeding the onset of each current pulse. The pulse repetition rate is controlled on the basis of this detected voltage so that the detected arc voltage becomes constant.

Abstract: This specification discloses a leakage reactance transformer for supplying electric arc welding current and comprising a core formed from a stack of laminations having a central `key-hole` shaped opening punched therein and defining an arcuate core portion and two spaced legs. The core has primary and secondary windings mounted thereon and a keeper secured to the legs to close the flux path of the core. One of the windings is mounted on a frame which is pivoted relative to the core so that the winding is movable along the arcuate core section towards and away from the other winding. A magnetic shunt member is also mounted on the frame approximately 180.degree. from the movable winding and in one position bridges the gap between the legs of the core and in another position is remote from this gap. In the bridging position the shunt contributes to the leakage reactance of the transformer and in the remote position contributes substantially no leakage reactance.