Motor Drive Current Imbalance 1

[rdrago]

A 20 HP, 3 phase, 480 volt motor is connected to a motor drive. The measured current (Fluke 43B) at the input to the drive is as follows:
Phase 1- 2.3A
Phase 2- 5.4A
Phase 3- 5.3A

Does anyone have any idea why the Phase 1 current at the input to the drive is so low? The motor and drive seem to be functioning ok. Because the load is not balanced, my Fluke 43B power measurements may be invalid. Can someone help?

rdrago

 

[electromike]

What other loads are connected on the problem phase?

 

[jbartos]

Suggestion: The three phase AC - DC full wave rectifier will charge the capacitors at DC bus according to three-phase voltage magnitudes up to the voltage values that become different in magnitude. The highest voltage magnitude will be the last one charging the DC bus and will cover any losses, stray currents, etc. if within the highest voltage magnitude difference with respect to the second lower voltage magnitude.

 

[buzzp]

Again, ask your manufacturer about the PF. You will likely find this is also normal.