Abstract: In an electrical resistance welder, whenever a material to be welded approaches the welding electrodes, a start signal is produced, so that welding current is supplied to the welding transformer in one direction for a certain period of time set by a time limit circuit, with the polarity changing in response to the start signal, whereby, even if materials are repeatedly fed for welding at high speed, they can be positively welded in a uniform manner.

Abstract: An apparatus for electrolytically processing aluminium material comprising rectifier means for supplying a pulse power to the electrodes, at least one of which is the aluminium material to be processed, and controller means for supplying a control signal to the rectifier means to enable the same to produce from a multi-phase AC power a pulse power balanced between the phases. The electrodes are connected with each other by a by-pass circuit which is controlled such that the electrodes are short-circuited by the by-pass circuit during the quiescent time of the pulse power to enable the electric charge stored in the electrolytic bath to be discharged rapidly to prevent the trailed natural discharge through the electrolytic path from interfering with the rise of the next pulse, thus preventing the deformation of the pulse waveform supplied to the electrodes.