Welding Industries of Australia Pty. Ltd.

Commonwealth Scientific and Industrial Research Organisation

William K Brougham

Graeme J Ogilvie

David M Leske

Gary L Cheesman

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.

Pulsed arc welding

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. The shunt is formed from a sector of the portion of the laminations cut from the core to define the arcuate section of the opening and the keeper is formed from the remainder of the portion cut from the core and defining the space between the legs of the core. The core and windings are mounted within a casing and means are provided to facilitate the pivotal movement of the movable winding and shunt to any position between the two extremes whereby the welding current may be infinitely varied between the values at the extremes. In a modification two similar cores are connected together by their legs and a movable winding and shunt member is mounted on each. In this arrangement the output current range is increased.

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Novar Gardens, Australia

William K Brougham