What is switchgear ?
Switchgear is an electrical apparatus used for Switching, Controlling and protecting the electrical circuits and equipments .
In an electric power system, switchgear is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment.
It is mainly associated with power system protection.
What it includes
It includes circuit breaker, current transformer,voltage transformer, protection relay,measuring instrument,electrical switch,electrical fuse,miniature circuit break,lighting, arrestor,Electrical Isolator etc.
1.One of the basic functions of switchgear is protection, which is interruption of short-circuit and overload fault currents while maintaining service to unaffected circuits.
2. It also provides isolation of circuits from power supplies.
3. It is also used to enhance system availability by allowing more than one source to feed a load.
4.It performs the function of carrying,making and breaking the normal load current like a switch .
5.It has to perform the functions of clearing the fault in addition to that it also has provision of metering and regulating the various parameters of electrical power system.
Circuit breaker can be operated manually as when required and it is also operated during over current and short circuit or any other faults in the system by sensing the abnormality of system.
Circuit breaker senses the faulty condition of system through protection relay and this relay is again actuated by the faulty signal normally comes from C.T or V.T.
It is Classified into following on basis of voltage class :-
1.Low Voltage Switchgear
2.Medium Voltage ” ”
2.Absolute Certain discrimination