KVA demand is a measure of the actual instantaneous demand for power placed on the electrical delivery system of the plant during the weld cycle. The KVA Demand in turn is used to calculate the KVA rating at 50% duty cycle. Transformers are commonly rated at 50% duty cycle.
Below is an example of a calculation of KVA demand for an application using a 70 KVA AC transformer to determine if it will be adequate?
The instantaneous KVA Demand is 196 KVA
The KVA Demand@ 50% Duty Cycle is 60 KVA
The transform is rated at 70 KVA and is adequate for this job.
Reference: RWMA Manual Section 19-8