ABB RELION 670 Series Applications Manual page 386

Section 7
Impedance protection
Protection designed to operate for below types of faults
Faults in the generator, generator terminal connections to the step-up transformer and in the
low voltage (LV) side of the generator step-up transformer are:
1. Phase-to-phase faults in generator
2. Three-phase faults in generator
3. Phase-to-phase faults in the LV winding of the generator transformer or inter-connecting
bus or cables
4. Three-phase faults in the LV winding of the generator transformer or inter-connecting bus
or cables
Faults in the system in the high voltage (HV) side of generator transformer are:
1. Phase-to-earth faults in the HV side of generator transformer and in the power system
2. Phase-to-phase faults in the HV side of generator transformer and in the power system
3. Phase-phase-earth faults in the HV side of generator transformer and in the power system
4. Three-phase faults in the HV side of generator transformer and in the power system
380
1MRK 504 152-UEN B
Application manual