Final answer:
The protection relay that compares currents and protects specific zones of an electrical system is the Differential relay. It works by comparing the current entering and leaving a zone, signaling a circuit breaker to trip when a discrepancy indicating a fault is detected. Differential relays provide critical protection for transformers, buses, and generators.
Step-by-step explanation:
The type of protection relay that compares currents and protects specific zones of an electrical system is the b) Differential relay. A differential relay operates on the principle of comparing the current entering a particular zone of the system to the current leaving that zone. When there is a difference between these currents, indicating a possible fault within the protected zone, the differential relay will act to isolate the affected area by signaling a circuit breaker to trip and disconnect the faulted section. This action helps to prevent damage to equipment, fires, or other safety hazards. Differential relays are essential for the protection of transformers, buses, and large generators.
Circuit breakers, fuses, and ground fault interrupters (GFIs) are some of the protective devices used in electrical systems. Circuit breakers and fuses interrupt excessive currents to prevent thermal hazards, while a GFI prevents shocks by detecting the loss of current to unintended paths. However, the differential relay is particularly used for the protection of electrical power system zones by comparing currents at strategic points within the system.