Isomatic UK Weblog

I have not discussed Welding Transformers on weblog for some time so an explanation is overdue. The type of welding that requires the most specialised transformers is called resistance welding or spot welding (although seams and mesh use the same technique). A high current (kA) is passed through the metal to be welded via a pair of copper electrodes. The resistance involved causes local heat to melt the metal and weld it together.

A resistance welding transformer converts 400V single phase from across two of the 3 phases in a 3-phase supply to low voltage high current for a short period; just long enough for a successful weld. The thermal shock to the transformer is considerable and it only survives by being water-cooled and being filled with carefully selected epoxy resin. The models that Isomatic manufactures are ISO integrated transgun types, following the modern trend towards lighter, more compact, transformers. We make them for 50Hz input and for 1kHz square wave, fed via an inverter.

Labels: Transformers