Testing of HT (High Tension / High Voltage) and LT (Low Tension / Low Voltage) relays is a critical aspect of electrical power system maintenance and commissioning. Relays are the "brains" of the protection system; they detect abnormal conditions (like overcurrent, earth fault, undervoltage) and issue a trip command to the associated circuit breaker to isolate the faulty section.
Reliability: The relay will operate correctly when a fault occurs.
Accuracy: The relay operates at its set pickup values and within its specified time characteristics.
Safety: Proper operation prevents extensive damage to equipment and ensures personnel safety by quickly de-energizing faulty circuits.
Coordination: Ensures that relays operate in the correct sequence (e.g., downstream breaker trips before an upstream breaker for selective fault clearance).