Important Elements for Power System Protection

Switchgear

It is built of mainly bulk oil circuit breaker, minimum oil circuit breaker, SF6 circuit breaker, air blast circuit breaker and vacuum circuit breaker and other types of circuit breakers. Different operating mechanisms such as solenoid, spring, pneumatic, hydraulic etc. are employed in the circuit breaker. Circuit breaker is the main part of protection system in power system and it automatically isolate the faulty portion of the system by opening its contacts.

Protective Gear

Consists of mainly power system protection relays like current relays, voltage relays, impedance relays, frequency relays, etc. based on operating parameter, definite time relays, inverse time relays, stepped relays etc. as per operating characteristic, logic wise such as differential relays, over fluxing relays etc. During fault the protection relay gives trip signal to the associated circuit breaker for opening its contacts.

Station Battery

All the circuit breakers of electrical power system are DC (Direct Current) operated. Because DC power can be stored in battery and if situation comes when total failure of incoming power occurs, still the circuit breakers can be operated for restoring the situation by the power of storage station battery. Hence, the battery is another essential item of the power system. Some time it is referred as the heart of the electrical substation. An electrical substation battery or simply a station battery containing a number of cells accumulate energy during the period of availability of AC supply and discharge at the time when relays operate so that relevant circuit breaker is tripped at the time failure of incoming AC power.

Source: https://www.electrical4u.com/protection-system-in-power-system/

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