There are several basic components of a protection system as listed below:
CT (current transformer)
- Convert the primary current to secondary current and transmit the secondary current to protective relay.
VT (voltage transformer)
- Convert the primary voltage to secondary voltage and transmit the secondary voltage to protective relay.
Protective relay
- Detect and locate the fault and send a trip signal to the circuit breaker.
- When a fault occurred, the relay will operate by closing the relay contact to complete the trip circuit.
Battery / DC system
- To supply the power for the relay and also to the trip circuit.
Trip coil
- As the trip coil of the circuit breaker energized, the CB operating mechanism actuated and will make the CB to open and isolate the fault.
Circuit breaker (CB)
- A mechanical switching device capable of making, carrying and breaking current under normal condition.
- Capable of making, carrying and breaking of current for a specified time during abnormal condition.
- Isolate the faulty part from the rest of network.
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