Question

Why are differential relay more sensitive and faster then overcorrect realys

Answer 1

Differential relays are used to protect transformers and generators from local faults. Overcurrent relays depend on excess current for their operation. ... Differential relays are very sensitive to the faults occurred within the zonee of protection .

Answer 2

Differential relays are very sensitive to the faults that occurs within the zone of protection than compared to overcorrect relays.

Explanation:

• Differential relays are used for protecting generators and transformers from local faults.
• For their operation, overcurrent relays depend on the excess current.
• Whenever there is a specific variant current value between secondary and primary side of transformer, differential relay send a trip signal to circuit breaker.
• Being a type of protective relay, overcurrent relays operates when load current exceeds a pickup value.