Stator earth-fault protection
The common practice to earth the generator neutral through a resistor limits the earth current to 5 - 10 A. The COMBIFLEX stator earth-fault protections are based on detection of the fundamental and third harmonic voltages in the neutral (or broken delta).
The RAGEK 95 % stator earth-fault protection is set at 5 % of maximum neutral voltage at solid earth faults. At this setting 95 % of the stator winding and also the generator bus and ancillaries up to the next step-up transformer are protected.
The RAGEK 100 % stator earth-fault protection covers 100 % of the stator winding and consists of a 95 % measuring relay and an additional relay covering as a minimum 95 - 100 % of the winding.
Main Features:
- Flexibility in mounting and wiring
- Delivered pre-wired and tested or as individual relays
- Easy modification and extension
- Calculations can be based on machine specifications and equipment capacitance or on field measurements