Protection relays protect electrical systems from faults and abnormal conditions.
A relay continuously monitors electrical parameters such as current, voltage, frequency, and impedance.
When a parameter exceeds a predefined threshold the relay sends a trip signal to a circuit breaker.
The breaker opens and isolates the faulty section of the network.
Types of Protection Relays
Overcurrent Relay
Detects excessive current caused by short circuits or overloads.
Distance Relay
Used in transmission lines. It measures impedance between the relay and the fault location.
Differential Relay
Compares current entering and leaving equipment such as transformers or generators.
If the currents differ the relay detects an internal fault.
Modern Protection Relays
Modern relays are digital. They analyze signals using microprocessors. They also record fault data and support communication with SCADA systems.
Protection relays improve system reliability and prevent equipment damage.