Abstract: Adjusted voltage measurements of monitored AC electrical energy supplied during a welding operation are evaluated by integration with respect to time during half cycles to develop a variable criterion each half cycle that is compared with adjusted limits to electronically make weld quality judgements. The generation of a fail signal during two consecutive half cycles as a result of such judgements, is operative through logic gating to produce a reject signal to control the marking of defective welds, interrupt the supply of energy to the welding electrodes and effect timely operation of an ejector removing articles with defective welds from a production line.