Load calc question for welder

[dhalleron]

I don't do this often enough to be proficient at it. I am running a calculation for a friend of mine who really knows nothing about the calculations. Since I'm the brains of the outfit and I am not sure what I am doing I ask you guys. I always get good answers here.

The local poco wants things listed in KVA. We plan to have a 225 amp stick welder that the specs says draws 47 amps at 240 volts with 20% duty cycle. Something like this welder: http://manuals.harborfreight.com/manuals/69000-69999/69029.pdf

At first I thought it might be 11.3 KVA but am I looking at it wrong? 47A x 240V = 11,280 Watts

Thanks guys,

 

[Smart $]

For an arc welder, Table 220.3 sends you to 630.11. It's a bit confusing because 630.11 is a requirement for conductor ampacity... but you simple multiply the required ampacity by the supply voltage to get the VA. With the given rated current at 47A, multiply by Table 630.11(A) 20% duty cycle factor (0.45 for non-motor generator), then multiply by 240V... gives you 5,076VA.

I should note that Table 630.11(A) method is only used if I_leff is not specified on name plate.

 

[dhalleron]

Thank you. That was very helpful.