ALL TYPES OF PROTECTION & THEIR SELECTION

1. Over - current protection

   • Non- directional

   • Directional

2. Distance protection

3. Pilot protection

   • Wire pilot protection

   • Carrier pilot protection

   • Microwave pilot protection


Types of relays used to achieve various type of protections

• For back up protection - Time graded over-current relays.

• For very short lines - Reactance relay.

• For medium lines - Impedance relay.

• For phase fault of longer line - Mho relay.

Pilot protection is used for fault occurring within individual zones of equipments.
Microwave pilot protections are used for long inter-connected lines.