GIS vs AIS Substations – Which Is Better?
- Akriti Kumari
- Nov 19, 2025
- 2 min read
In the UK power sector, substation reliability, space optimisation, and long-term maintenance cost play a major role in selecting the right technology. Two of the most widely used options are Gas Insulated Substations (GIS) and Air Insulated Substations (AIS). Both have their own benefits, and the best choice depends on project requirements.
🔹 What is an AIS Substation?
AIS (Air Insulated Substation) uses open-air insulation between components. Best for: Large open areas, low-cost projects
Key Advantages:
Lower installation and equipment cost
Easy to maintain & repair
Simple design and flexible layout
Suitable for rural and semi-urban grid expansion
Limitations:
Requires large land area
More exposure to pollution, dust & weather
Higher maintenance in long term
🔹 What is a GIS Substation?
GIS (Gas Insulated Substation) uses SF₆ gas for insulation, allowing very compact designs. Best for: Cities, industries, offshore wind & space-restricted sites
Key Advantages:
70% less space required than AIS
High reliability & safety
Weather-proof and pollution-proof
Minimal maintenance
Ideal for urban & critical infrastructure
Limitations:
Higher upfront cost
Requires skilled technicians for maintenance
SF₆ handling needs environmental safety compliance
🔹 GIS vs AIS: Which One is Better?
There is no “one answer”. The best choice depends on site conditions, budget, reliability needs and future expansion plans.
GIS is better when:
✔ Space is limited✔ High reliability is required✔ Urban, industrial or offshore locations
AIS is better when:
✔ Land is easily available✔ Budget is limited✔ Simple maintenance is preferred
🔹 Conclusion
For modern UK substations, GIS is becoming more popular due to its compact size, safety, and long-term performance. However, AIS remains a cost-effective solution for rural and large-area projects.The right decision depends on matching technical requirements with site constraints. #GISSubstation
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