Everything you need to know about Switchgear systems in energy infrastructure

What is switchgear, how does it work, and why is its maintenance so important?

Switchgear is a broad term that generally refers to a centralised collection of switching devices. Its primary function is to isolate, protect and control electrical hardware in power systems, while power is being distributed to various sections of a facility. The definition also extends to devices that regulate and meter the flow of electricity in a circuit breaker and similar technology within the distribution management system.

The interconnecting components provide shielding, stabilise any unsteady or irregular flow of power, and interrupt any faults without affecting the electrical devices in the circuit. Switchgear systems commonly include switches, fuses, protective relays, isolators, circuit breakers, control panels, and other associated equipment that is connected to the electrical supply.

How does switchgear work?

As circuits are designed to handle a limited amount of electricity, switchgear protects the equipment connected to a power supply from an electrical overload. In the event of a surge, switchgear will trigger and automatically interrupt the flow of power, protecting the internal wiring from overheating, and preventing damage to vital electrical components. It is also used for de-energizing equipment for safe testing, maintenance, and fault clearing.

Low, medium and high voltage switchgear

Switchgear is essential for any facility that requires a centralised source of power for its production, and to safely distribute and supply loads. Switchgear can be classified into three categories, depending on their application and the amount of power required:

Low voltage switchgear (LV)

Ideal for short distance distribution, low voltage switchgear systems generally have capacities of up to 1KV. It uses low voltage, earth leakage and miniature circuit breakers, offload electrical isolators, H.R.C fuses to regulate systems, and offers operational control of both remote and local switching.

Medium voltage switchgear (MV)

Many industrial complexes and factories that require a substantial amount of power often use medium supply voltages. M.V generally refers to switchgear for systems between 1KV to 52KV, and is used for the voltages required for regional power distribution that are a part of the ‘high voltage’ range. It often involves motors, feeder circuits, generators, and transmission and distribution lines. Any factory that uses medium voltage supply to a sub-station requires emergency or backup power supply.

High voltage switchgear (HV)

Power systems that deal with voltages between 52 kV to 230 kV are referred to as high voltage, but regionally these numbers can vary. HV switchgear is used to transmit electrical energy over large distances, and for regional distribution to load centres. Large power plants and industrial users are connected to the HV network for their energy supplies, and depend on HV switchgear for a stable, reliable service.

As switchgear is directly linked to the quality of the electrical supply, an efficiently performing system with high electrical and mechanical endurance is vital for these industrial applications. The circuit breaker is the main component of HV switchgear, and is therefore essential for safe and reliable operation.

The arc caused during the switching operation is high in HV’s, meaning special care needs to be taken for its design and maintenance. The reliability of switchgear depends on the routine, scheduled, and preventative maintenance that is carried out to ensure they are working safely and efficiently.

Maintenance of high voltage switchgear – with Power-as-a-Service

Maintaining HV switchgear is a complex task that requires significant resources, in terms of skills and capital. Technological developments, tougher environmental legislation, and regulations are increasing the challenge for businesses to ensure their electrical installations remain up-to-date and future-proofed.

With Power-as-a-Service model, ownership and management of a site’s switchgear systems is transferred to Vattenfall. We reduce risk and management overhead for businesses, and take full responsibility for the economic, functional and electrical safety of business’s high voltage electrical infrastructure services.

Learn more about Vattenfall’s Power-as-a-Service model.