How does pilot protection operate?

How does pilot protection operate?

• A. Uses no communication; local trip
• B. Dedicated mechanical signaling
• C. Uses a communication link to compare relay signals or line-channel signaling; coordinates tripping; may use permissive signals
• D. Only for single-ended faults

Answer: (C)

Pilot protection uses a dedicated communication link between protection relays at the ends of a line to exchange fault information and coordinate the trip. Each end monitors local conditions, and when a fault is detected, a signal is sent over the pilot channel. The relays compare the local indication with the remote indication; if both ends agree that the fault lies in the protected line and the conditions are right, the line is tripped. Some schemes may require a permissive signal from the remote end, meaning both ends must authorize the trip for faster, secure clearing. This approach gives fast, selective protection and avoids unnecessary trips that a purely local, non-communicating scheme could cause, and it isn’t limited to one-ended faults.

Pilot protection uses a dedicated communication link between protection relays at the ends of a line to exchange fault information and coordinate the trip. Each end monitors local conditions, and when a fault is detected, a signal is sent over the pilot channel. The relays compare the local indication with the remote indication; if both ends agree that the fault lies in the protected line and the conditions are right, the line is tripped. Some schemes may require a permissive signal from the remote end, meaning both ends must authorize the trip for faster, secure clearing. This approach gives fast, selective protection and avoids unnecessary trips that a purely local, non-communicating scheme could cause, and it isn’t limited to one-ended faults.