What is Gas Insulated Switchgear?

Gas insulated switchgear, commonly referred to as GIS, is a solid metal-enclosed device that contains a variety of high-voltage components, including disconnecting switches and circuit breakers.

These gadgets can be used in a very safe manner in limited areas, such as tight spaces.

The main function of a GIS substation is to switch, separate, transform, measure and distribute electrical energy in the power system.
The main feature of GIS equipment is the use of SF6, an inert gas with excellent insulating properties and chemical and thermal stability.

In contrast, GIS units require only centimeters for effective insulation, whereas air-insulated switchgear requires instrumentation to perform the same function. All of these features make GIS a more reliable device than AIS, with fewer space and maintenance requirements.

 

How GIS Works

Switchgear using​ SF6 protects the power supply and distribution by interrupting the current in the circuit when necessary. Under normal conditions, the circuit breaker contacts are closed, but in the event of a fault in the electrical system, these contacts separate and arc between them . The displacement of the moving contacts is synchronized with the displacement of a valve that allows high voltage SF6 to enter the chamber where the arc is generated. The properties of SF6 allow the absorption of free electrons in the path of the arc, forming ions that do not carry an electrical charge - because they become too heavy. The dielectric strength of the gas increases dramatically, so the arc is extinguished. Because of its ability to compound quickly, the pressure of SF6 decreases as the arc is extinguished, so it is stored in low-pressure tanks and then in high-pressure tanks for reuse.

Because of these properties, SF6 insulation is more effective than air insulation-about three times more effective-that makes these substations ideal for medium- and high-voltage power systems.

 

Applications

Due to their small size, compactness and armored construction, GIS substations are the preferred choice for such installations in areas with limited space and/or exposure to high levels of contamination (dust, chemicals, salt layers, etc.) that can produce flashover in other types of substations.
Industrial townships
Hydroelectric power stations
Underground substations
Highly contaminated areas
Urban building extensions
Offshore platforms
Rooftops
Railroads
Power Transmission
As renewable energy generators to the power system
Large towns with little space
Valley
Mountainous areas
Industrial parks
High voltage transmission systems

 

Advantages of Gas-insulated Switchgear

These devices are ideal for urban or industrial areas where space is small and pollution levels are high.
Thanks to their compact construction, these devices can be more easily integrated into their environment without affecting the aesthetics of the place.
High reliability, as these devices are not subject to environmental damage - they are also less sensitive to earthquakes.
No risk of electrical failures due to flying animals.
This switchgear has different configurations for different types of busbars (switching, double, ring, etc.).
There is no risk of oil leakage or explosion due to fire.
They are easy to maintain devices, since most of the maintenance consists in checking that they are working properly.
Installation is simpler.
The units run quietly.
Lower operating costs.
Some models use their metal covers to counteract external electromagnetic interference.