All RWMA resistance welding equipment is designed on a maximum 50% duty cycle. All power calculations are based upon this premise.
An article has been written which builds upon this premise and determines the power usage of a 150 kva welder.
Power calculations can be found in the article:
HOW MUCH POWER IS USED RESISTANCE WELDING ON A 150 KVA WELDER?
The calculations for duty cycles can be found in another article for AC & DC:
Reference: RWMA – Resistance Welding Manual Section 19.3