My customer, from Northern Cailifornia, has an open delta or some people call it high leg delta utility. I am not sure what the correct name is for it.
As I understand it, it is regular delta with one winding of the transformer center-tapped to connect the neutral. So if A-B, B-C and C-A are all 240 volts, then A-N and C-N will both be 120 volts, but B-N will be 208 volts.
He also says they struggle with load imbalance on the motor phases. The current on each leg is not equal, up to 10% imbalance.
Anyway, we were checking into adding a vfd to an existing pump installation. What all should we be thinking about installing a vfd? Line reactor? Derate the drive?
Look forward to your thoughts. Thanks!
As I understand it, it is regular delta with one winding of the transformer center-tapped to connect the neutral. So if A-B, B-C and C-A are all 240 volts, then A-N and C-N will both be 120 volts, but B-N will be 208 volts.
He also says they struggle with load imbalance on the motor phases. The current on each leg is not equal, up to 10% imbalance.
Anyway, we were checking into adding a vfd to an existing pump installation. What all should we be thinking about installing a vfd? Line reactor? Derate the drive?
Look forward to your thoughts. Thanks!