Transformer Imbalance Guidance 1

[PLukacovic]

Does anyone have any guidance regarding how “imbalanced” the phases can be with a three-phase, 480 to 240 10kVA tranformer? We’ll have a balanced 3-phase source, but our output (load) will have single-phase components and power supplies turning on and off. We won't be able to keep them balanced. Are there any design rules or guidelines that I need to follow regarding imbalance loads?

 

[jghrist]

Imbalance does not hurt the transformer as long as the most heavily loaded phase is not overloaded. The problem might be voltage unbalance. This should be limited to 5% or less. You will need to calculate this based on the transformer impedance and the load.