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What Is the Function of a Switchgear?

Switchgear refers to a combination of one or more switching devices and associated equipment that controls the distribution of electricity within a particular premises. Switchgear protects other equipment in the event of overload, short-circuit and other abnormal conditions, so it is typically a feature of any premises with a high-voltage electricity supply.

Switches
- A switch is a control device that can be manually opened and closed to connect or disconnect an electrical circuit. A switch has two stable positions, open and closed, and doesn̵7;t require electrical energy to stay in either position. However, for safety reasons, switches should always be used in conjunction with an overload and short-circuit protection device of some kind.
Fuses and Circuit Breakers
- In some switchgear installations, overload and short-circuit protection is provided by fuses,wherein a metal conductor melts under the heat produced by excess current, thereby opening the circuit. However, the amount of current that fuses can interrupt -- otherwise known as their breaking capacity -- is limited, and replacing fuses disturbs the normal operation of the circuits they protect. Consequently, circuit breakers -- switches that activate, or trip, to switch off the electricity supply if the current exceeds a certain level -- are used to protect circuits carrying higher levels of current. Unlike fuses, circuit breakers can be reset and reused.
Isolation
- Switchgear also allows some or all of the circuits that form an electrical installation to be isolated from power supplies so that they can be maintained, serviced or modified. If isolation takes place during the normal operation of an installation or, in other words, when no overcurrent condition exists, it is known as ̶0;functional̶1; isolation. If, on the other hand, isolation is essential, because of a potentially hazardous overcurrent condition or other abnormal condition, it is known as ̶0;emergency stop̶1; isolation.
Other Types of Switchgear
- Electricity obviously has a wide variety of applications, so switchgear comes in a range of shapes and sizes and performs a range of functions. Trips and relays typically consist of an electromagnet and a current-carrying winding, called an armature. They react to changes in current or voltage in one circuit by making or breaking a connection in another circuit, and are used to control devices in the same or another circuit. Regulators, on the other hand, maintain the current or voltage at a certain level, or vary it according to a predetermined plan.

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