What Is The Difference between AIS and GIS Substations?

What is the difference between AIS and GIS substations? Many people know the term GIS and AIS, especially this term is related to people who are working in substations. Today we will discuss these two terms of the substation. Let us know about What is the difference between AIS and GIS substations.

What Is The Difference between AIS and GIS Substations

GIS ( Gas Insulated Substation) Substation

This substation is surrounded by a gas insulating chamber. Sulfur hexafluoride gas is used here. A metallic chamber holds the gas and also has a phase, neutral line, circuit breaker, lightning arrester, interrupter chamber.

Why the Sulfur Hexafluoride Gas?

The advantage of using SF6 gas

• It is high dielectric.
• This gas is inflammable and nonpoisonous.
• An unexpected reaction cant happen because of its neutral characteristic.
• It is highly electronegative and SF6 gas can easily prevent arch than other gases.
• And free electrons can move easily. 
• It is highly insulating.

Advantages of GIS Substation

• Metal cover or chamber with the ground ensures security. 
• There is a separate compartment for each device and security for insulation.
• There is less distance between Active and non-active switchgear compared to the AIS system.
• For high assurance of security, there is no need for maintenance.
• No need to top up for almost forty years old sulfur hexafluoride gas and the devices remain secure.

Disadvantages of GIS Substation

• Insulation expense is too much.
• If the substation is in a rural area, collecting gas is difficult and expensive.
• This type of substation needs high maintenance which increases the expense. 
• Faults of this substation are rare. But if something occurs it is very dangerous and the solution is time-consuming.
• If the neutral characteristic of sulfur hexafluoride is not active then it can make metallic fluoride. It can cause breathing problems.

AIS Substation

In this substation, the air is used as a dielectric for phase to phase and phase to ground insulation. This is a very old process of the insulating system. Generally, AIS is used in substations where locality is very less and free of air pollution. That’s why AIS  is used in countryside substations rather than cities. 

Advantages of AIS Substation

• Substation equipment and switchgear installation are less expensive.
• Installation can be done in no time.
• The faults are easy to solve in a short time.

Disadvantages of AIS Substation

• The dielectric power of the air is less than sulfur hexafluoride gas.
• A system fault can occur for chemical presence in the air even can cause accidents.
• A large area is needed for this type of substation.
• Sometimes big faults can occur which is very costly to repair. 

AIS or GIS? Which One is Better?

After considering dielectric power, faults, accident possibility, GIS is better than AIS. Nowadays, GIS is used mostly.

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Hope it was helpful for you to understand the difference between AIS and GIS substations.

You can also read: What is the ground switch? Why it is used?