Electrical Engineering MCQ
Earth fault relay uses the which of the following sequence currents:
- Negative sequence
- Zero sequence
- Positive sequence
- Any of these
Correct answer: 2. Zero sequence
Explanation:
Earth fault relays are used to detect faults to ground in power systems. When a fault occurs, currents flow through the system.
In case of unsymmetrical faults like LG, LLG the fault current pass through ground to the neutral and providing a relay between the neutral and ground, the zero sequence currents are passing through this relay for protection of electrical equipments like generator, transformer etc. This relay is called earth fault relay or ground fault relay.