kmh1
Electrical
- Sep 12, 2003
- 47
We have a 256 kW, 600 V induction generator coupled to a hydro turbine. We also have a 120 kVAR capacitor bank which switches in step after the generator in online. The unit is connected to a relatively small residential utility distribution system via a 600/4160 volt step up transformer (HV grounded wye - LV ungrounded delta).
Recently, after the unit was briefly shutdown for some mechanical work, the generator began tripping on negative sequence timed overcurrent (pick up set to 40 amps)at higher loads. LV system ph-ph voltages range from 601 to 608 when the unit is online. We are seeing a 12% current imbalance from the generator to the grid (capacitor currents only have a 4% unbalance).
Can any one give me a typical unbalance trip setting for an induction machine such as this? Could this possibly be a problem with the windings in the generator?
Recently, after the unit was briefly shutdown for some mechanical work, the generator began tripping on negative sequence timed overcurrent (pick up set to 40 amps)at higher loads. LV system ph-ph voltages range from 601 to 608 when the unit is online. We are seeing a 12% current imbalance from the generator to the grid (capacitor currents only have a 4% unbalance).
Can any one give me a typical unbalance trip setting for an induction machine such as this? Could this possibly be a problem with the windings in the generator?