What is a Switchgear?


What is a Switchgear?

Switchgear is a combination of electrical disconnect switches, fuses or circuit breakers used to control protect and isolate electrical equipment. Electrical devices used for metering, protection and control of an electrical system are defined as a switch. The safe operation of the system requires the switching to open lines automatically in case of a fault, or manually when the operation requires it.
The devices which are used for switching, protecting and controlling in an electrical circuit is known as switchgear.
The electrical devices used to measure, protect and control an electrical system are defined as switches. The safe operation of the system requires the switch to automatically open lines in case of failure, or manually when the operation requires it.

One of the basic functions of switchgear is protection, which is an interruption of short-circuiting and overload fault currents while maintaining service to unaffected circuits. Switchgear also provides isolation of circuits from power supplies. Switchgear is also used to enhance system availability by allowing more than one source to feed a load.

Types of Switch gears:

• LT switchgear
• H.T switchgear

The basic function of L.T and H.T switchgear are:

• Electrical protection
• Isolation
• Overvoltage protection
• Under voltage protection
• Overcurrent protection

L.T switchgear

L.T stands for low tension. These panels work on 415v.
The low voltage switchgear

Low voltage gear consist of following panels:

• L.T switchboard
• Distribution board
• Relay panel
• Control panel
• PFI(Power factor improvement) pane


Tests that are performed on Switchgear are:

• Short circuit test
• Power frequency test (In main circuit 36KV for 1 minute)
• Test on auxiliary(to test the electrical device installed)
• Dielectric test (Control winding 2KV for 1 minute)
• Measurement resistance test of the main circuit
• Rack in rack out Interlocking