In high voltage (HV) systems, the three main types of switchgear used are:
- Air-insulated switchgear (AIS):
- This is the most common type of switchgear used in high voltage systems. It uses air as the insulating medium. The components such as circuit breakers, disconnectors, and switches are exposed to air, and their operation is based on the principle of arc quenching in the air when a fault occurs. It’s reliable and cost-effective, but can be bulky and requires more space.
- Gas-insulated switchgear (GIS):
- GIS uses a gas, typically sulfur hexafluoride (SF6), as an insulating medium. The switchgear components are enclosed in a metal tank filled with SF6 gas, which is highly effective at insulating and quenching electrical arcs. GIS is more compact than AIS and is often used in urban areas or places where space is limited. However, it can be more expensive and requires maintenance to ensure gas integrity.
- Oil-insulated switchgear:
- This type uses oil as an insulating and arc-quenching medium. The oil is used in circuit breakers, where it helps in extinguishing the arc when the switchgear operates. Oil-insulated switchgear has become less common in recent years due to environmental concerns and maintenance issues, but it is still used in certain high-voltage applications.
Each type has its advantages and disadvantages depending on the specific application and the environment in which it’s used.
