This is a continuation of Welding Electrical Fundamentals. Topics include: safety rules, fuses and circuit breakers, CSA code for welding systems, rectifier circuits, transformers, rectifier filters, saturable reactors, SCRs inverter power sources and wire feed control circuits. The aim is not to be able to repair welding equipment but to understand its operation in order to be able to complete preliminary trouble shooting as described in a manual. Knowledge of equipment operation also makes equipment set-up and operation much easier.