I have a question I am not sure there is a perfect answer for so I guess I am just looking for opinions. At a welding shop there are 4 custom made welding machines. They are an automated process and draw current in huge short spikes. I am tying to get an acceptable load for plan check purposes. They are currently fed from a 480V 1200A service and there hasn't been any issues with the main fuses blowing. I put a power monitor on them and took readings at one second intervals for one hour. The short story of the report is that the current ranges from a couple of amps to 961A on one machine and a couple amps to 562A on the other type of machine. The average VA for all phases are 80,811 (97A) and 128.2 (154A) respectively. The machine with to lower maximum current has a higher average VA because there is a shorter period between weld cycles. The phases are not anywhere near balanced these are just the maximum and average values. Would it be be acceptable to use the average VA for the loads in the load cacls for plan check? As far as sizing the feeders do you think the average amps as calced from the average VA would be acceptable?
Welder Load Calc
- Thread starter Nick
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