In 10kV to 35kV medium-voltage power distribution projects, air-insulated switchgear (AIS) and gas-insulated switchgear (GIS) are the two mainstream products in this industry. They are also the most commonly compared equipment for domestic and overseas substation & factory power distribution procurement.
Many buyers simply think one type is far better than the other. But after referring to IEC standards, local national specifications and hundreds of finished projects, neither AIS nor GIS has absolute advantages. To make a proper choice, you need to comprehensively evaluate site space, operating environment, project budget and long-term expansion plans. This article sorts out their key differences and shares straightforward, practical selection tips.
Basic Structural Principles of AIS and GIS
AIS Air-Insulated Switchgear
AIS uses normal atmospheric air as internal insulation. Our mainstream models include KYN28 and XGN15 switchgears. Circuit breakers, busbars and all live components are exposed inside the cabinet, and safe spacing inside prevents high-voltage risks.
Its open layout lets workers see every internal part clearly. Daily maintenance and adding new circuits on-site can be finished easily.
GIS Gas Insulated Switchgear
Our standard 12kV gas-insulated compact switchgear (C-GIS) falls under medium-voltage gas-insulated switchgear. All live components are sealed inside airtight metal chambers filled with SF₆ gas, which undertakes insulation and arc extinction work.
All GIS products complete full sealing and leakage tests in our factory. Only simple assembly is required after delivery to the site, and it occupies much less floor space than AIS.
Simplified Core Comparison Table of AIS and GIS
|
Comparison Items |
AIS Air-Insulated Cabinet |
GIS Gas-Insulated Cabinet |
|
Insulating Medium |
Atmospheric Pressure Air |
Sealed SF₆ Gas |
|
Land Occupation |
Large floor area needed |
Only 30%-40% space of AIS |
|
Procurement Cost |
Lower overall price |
Higher initial purchase cost |
|
Environmental Adaptability |
Vulnerable to dust, salt spray and humidity |
Fully sealed design, stable under harsh conditions |
|
Maintenance Difficulty |
Simple internal inspection; ordinary electricians can operate |
Sealed gas chamber; professional tools required for repair |
|
Expansion & Modification |
Easy to add new cabinets later |
Gas chamber modification process is complicated and costly |
Pros, Cons & Applicable Scenarios for Two Types of Switchgear
AIS
AIS stands out for low initial cost and flexible later upgrades. It works great for dry inland factories, rural substations, and industrial plants that plan continuous power expansion.
However, it has obvious drawbacks. It demands a large power distribution room. If deployed at coastal areas or dusty mines, insulators will quickly accumulate dirt and age. Annual cleaning is mandatory, which raises long-term maintenance expenses. Extra dehumidifiers are also necessary for damp locations.
GIS
Compact structure and excellent sealing protection make GIS the top pick for limited and harsh operating sites, such as underground urban power rooms, coastal photovoltaic power stations, rail transit power systems and Middle East overseas projects.
Its fully sealed structure largely cuts down failure rates, enabling long-term maintenance-free operation. The modular design shortens on-site construction time and saves labor costs for overseas projects.
The downside is the high upfront investment. If you need to add new outgoing circuits afterward, technicians have to exhaust gas from the chamber, refill SF₆ and carry out pressure tests again. The whole procedure is time-consuming and complex. GIS suits projects with fixed power loads and no major reconstruction demands.
Simple Four-Dimension Selection Guide
You can judge the suitable cabinet type from four core factors:
1. Site spaceChoose AIS if you own a spacious power room or independent outdoor distribution area. Pick GIS for compact underground or high-rise electrical rooms.
2. Operating environmentAIS fits dry, low-dust inland regions. GIS is the priority choice for coastal salt fog zones and dusty mining sites.
3. Service cycle & budget Go for AIS for short-term use (3–5 years) with limited funds. If your project runs over 20 years with expensive land and civil construction costs, GIS brings better long-term economic benefits.
4. Future expansion demandsSelect AIS for factories and industrial parks that will keep adding power circuits. GIS matches municipal and commercial projects with stable loads and no upgrade plans.
Frequently Asked Questions
Q1: Which switchgear fits 11kV projects in the Middle East? GIS is recommended for coastal Dubai and Qatar due to severe salt wind corrosion. If your project locates in dry inland industrial zones of Saudi Arabia with sufficient space, AIS can control your procurement expenditure.
Q2: Does GIS have a longer service life? In clean and dry environments, their service spans are almost the same. In harsh salt and dust conditions, the sealed GIS structure slows component aging, with a service life about ten years longer than AIS.
Q3: Can both cabinet types be exported globally? AIS and GIS comply with corresponding IEC industrial standards. All our products pass national standards and CE certification, applicable to power distribution projects in most countries worldwide.
Closing Remarks
Simply put, AIS is cost-effective and adjustable for most general projects. GIS is small-sized and sturdy, made for narrow spaces and tough working conditions. Neither single product can satisfy all engineering demands.
If you are designing domestic or overseas power distribution & substation projects and cannot confirm the proper switchgear model, send us your project voltage, power room size, local climate and future expansion plans. LVMA's professional electrical engineers will create a customized selection plan and accurate quotation for you.
About us
Since 2018, Zhejiang Lvma Electric Co., Ltd. has applied 17 years of practical industry experience. ISO 9001:2015 certified, we produce intelligent switchgear systems and premium oil-immersed and dry-type distribution transformers for customers in Europe, the Middle East, South America, Southeast Asia, and Africa.
With more than 40 patents, our R&D capabilities are transforming conventional manufacturing into smart, eco-friendly power systems. Digital operations and live performance monitoring ensure our products consistently meet the highest safety and reliability standards.