A. impedance
B. Reactance
C. Either of the above
D. None of the above
Answer: D. None of the above
Explanation:
- Reactance relay is suitable for the protection of a short transmission line because its operation is independent of arc resistance.
- Reactance relay is used for the phase faults in a short transmission line.
Important points:
- The relay which is selected for a long transmission line should be less affected due to power swings. Hence Mho relay is preferred.
- Mho relay is used for the phase faults in a long transmission line.
- Impedance relay is used for the phase faults in the medium transmission line.