Switchgear
Definition:
The apparatus (device, machine) used for controlling, regulating and switching on or off the electrical circuit in the electrical power system is known as #switchgear (it is used to control, protect and isolate electrical equipment)
Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream.
Components
In an electric power system, switchgear is composed of electrical disconnect switches, fuses, circuit breaker, isolator, relays, current and potential transformer, indicating instrument, lightning arresters and control panels.
A switchgear assembly has two types of components:
۱٫ Power conducting components, such as switches, circuit breakers, fuses, and lightning arrestors, that conduct or interrupt the flow of electrical power.
۲٫ Control systems such as control panels, current transformers, potential transformers, protective relays, and associated circuitry, that monitor, control, and protect the power conducting components.
Functions
۱٫ Protection
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.
۲٫ isolation
Switchgear also provides isolation of circuits from power supplies.
۳٫ Enhance availability (reliability)
Switchgear is also used to enhance system availability by allowing more than one source to feed a load.
It is used for de-energizing the equipment for testing and maintenance and for clearing the fault. When the fault occurs in the power system, heavy current flow through equipment due to which the equipment get damaged, and the service also get interrupted. So to protect the lines, generators, transformers and other electrical equipment from damage automatic protective devices or switchgear devices are required.
When the fault occurs in any section of the system, the relay of that section comes into operation and close the trip circuit of the breaker which disconnects the faulty section. The healthy section continues supplying loads as usual, and thus there is no damage to equipment and no complete interruption of supply.
