This answer has been given in the reverse mode in another published article:
HOW MANY PRIMARY AMPS WILL A 64 KVA RESISTANCE WELDING TRANSFORMER PULL?
If you look at this referenced article, several important data points are necessary in order to calculate the output of the 10 KVA transformer. The turns ratio being the first. The turns ratio shows that power in the primary equals power in the secondary. Secondary voltage is a second necessary data point.
The actual current will be influenced by the secondary circuit.
If you know your turns ration and primary amps at least an estimate can be made. If you measure the input versus the output voltage you have an estimate of the turns ratio for that set up. If there is a tap switch on the transformer one can change the secondary voltage. Then all of the calculations change. Do study the above document so that duty cycle and all factors are considered.
For additional assistance contact a local equipment manufacturer or distributor.
References: RWMA - Resistance Welding Manual 4th Edition