we have a ac reliance drive of 15kw which gives unbalance output in one phase (R 170, Y 300, B 300). when motor is isolated from the circuit, then also it give unbalance voltage. what may be the reason for that unbalance voltage.?

 

Self… the values you cited indicate very severe unbalance!

Based on both NEMA and IEC Standards, the VUF (Voltage Unbalance Factor) is about 32%.

Since the values are the same whether or not the motor is connected then the Reliance drive is suspect!

Regards, Phil Corso ([email protected])