Compared to non-selective coordination, selective coordination reduces cascading trips and improves reliability.

Compared to non-selective coordination, selective coordination reduces cascading trips and improves reliability.

• A. True
• B. False
• C. Not sure
• D. Sometimes

Answer: (A)

Selective coordination ensures that only the protective device closest to a fault operates, using appropriate time-current settings. By allowing the downstream device to clear the fault, upstream protections see the fault later or with higher thresholds and remain in service. This minimizes unnecessary trips upstream and prevents a chain reaction known as cascading trips, which can knock out large parts of the system. As a result, service continuity is preserved and overall reliability improves. When protection is designed and tuned correctly, this approach reliably reduces cascading trips compared with non-selective coordination.

Selective coordination ensures that only the protective device closest to a fault operates, using appropriate time-current settings. By allowing the downstream device to clear the fault, upstream protections see the fault later or with higher thresholds and remain in service. This minimizes unnecessary trips upstream and prevents a chain reaction known as cascading trips, which can knock out large parts of the system. As a result, service continuity is preserved and overall reliability improves. When protection is designed and tuned correctly, this approach reliably reduces cascading trips compared with non-selective coordination.