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EVI-12 Eco-friendly Air Insulated Metal-enclosed Switchgear


The newly developed EVI Air Insulated Switchgear is designed upon newly introduced technologies and computer-aided simulation. The modular design gives the flexibility. It fulfills technical reqiurements of both network nodes and terminal users, and the needs about flexibility concerning all secondary substations.


EVI-12 Eco-friendly metal-enclosed dry air switchgear.pdf


All live parts and mechanisms are sealed in a stainless steel enclosure filled with dry air, thus makes it not easily being affected by external conditions,  the operation reliability and safety can be ensured. The dielectric material is eco-friendly, and has a good environmental adaptability. Common-cased structure is used. Complete primary programs can fully meet a variety of wiring requirements.


Product Model

Development Background 

  • Greenhouse Effect and Gas Emission Cost 

SF6 gas as one of the six greenhouse gasses is 23,000 times stronger than CO2. The emissions of SF6 are unavoidable during the whole handling processes of MV switchgears from production till the final disposal. It has caused public attention to environment due to the increased use of SF6 gas in MV switchgears. Users from industries and utility companies may also face increased cost as some policies launched to include SF6 into greenhouse gas emissions category. China National Development and Reform Commission has already published the calculation formula for emissions of SF6 together with CO2 consumption for power grid companies. The formula is E=ESF6+E lost. Price will be charged for emitted volumes during repairing and switchgear disposal.

  • Demand for SF6 Free Switchgear

There is an urgent demand for SF6 free switchgear which comes without environmental issue and no increased cost on emissions. 

Product Design Features

  • Purely Dry Air Switchgear 

We use dried Air for insulation. There is no chemical processing, no substance or byproduct to environment.

  • Optimized Electrical and Magnetic Field for better and reliable Performance    

We used computing assisted design for improving electrical and magnetic distribution which enables us to optimize the designs for electrical components. We have improved the design of several internal parts such as contacts, driving rods, embedded conductive parts. This will provide better and more reliable performance for longer term application. 

  • Compact and Modular Design

The complete switchgear is modulated into compartments including mechanism, switching, disconnector switch and earthing switch. Cubicles made of organic polymer materials not only separates different compartments but also increases insulation ability besides dry air. Arc quenching through vacuum interrupters. All those features contribute to compact size and better suitability for outdoor sever applications. 

  • Maintenance-free Product Design

Traditional air insulated switchgears have all components exposed to free air circulation which demands for larger space for insulation, installation and frequent maintenance to dust, corrosion and pollution removal. 

While, we have all live parts welded into stainless-steel enclosure which is filled with micro-positive pressured dry air which prevents free air circulation ensures a healthy internal environment against dusty, humidity and corrosion. 

Providing its advantage for maintenance-free application.  

Technical Features

  • Down Streaming Fault Making Earthing Switch

Because air is considerably much weaker than SF6 by insulation. SOJO developed a new type of earthing switch. This SOJO Patented New Earthing Switch has unique design of dynamic and static contacts which largely reduces the repulsive forces and suppresses the voltage and energy of arching during fault making process. This improves the making capacity meanwhile prevent the contacts being melted after fault making. Earthing Switch is located below main switch enables direct and quick earthing operation. 

  • Increased Insulation Ability 

Switch and Fuse function has spring and encapsulated/piston type earthing contacts. This increases insulation between phases and insulation from phase to earth. The closing and opening operation forces while not increased. 

  • Flexible Connection and Extension

Standard unit can be connected through bushings both left and right sides. 

Optional top located busbar also available under special requests. 

  • No pressure Container and Reliable Composite Insulation

The total insulation is depending on Air and Recyclable Polymer materials. Stainless steel tank and micro-pressed pressure are intended to keep a healthier internal environment. If there were any leakages of the tank, the insulation ability will not be weakened. The switchgear is still safe to operate without causing potential hazard to operator. 

Rated Voltage 12kV
Rated Current 630A 
Rated Short-time Withstand Current 20kA, 4s
Rated Peak Withstand Current  50kA
1min Power Frequency Withstand Voltage   42kV
Lightning Impulse Withstand Voltage  75kV
Mechanical Endurance  10000 times 
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