Introduction to Gas Insulated Switchgear

Gas Insulated Switchgear (GIS) has revolutionized medium and high voltage power distribution. By using SF6 gas as insulation, GIS panels achieve 1/10th the footprint of conventional air-insulated switchgear. But selecting the right GIS for your project requires careful consideration of technical, environmental, and economic factors. Here are the top 10 GIS switchgear selection tips to guide your purchase.

What is GIS Switchgear?

GIS encapsulates all live parts—circuit breakers, disconnectors, earthing switches, busbars, and transformers—within a hermetically sealed SF6 gas tank. This design makes GIS ideal for space-constrained urban substations, underground installations, and harsh environments.

Top 10 GIS Selection Tips

1. Choose the Right Voltage Class

GIS is available from 12 kV up to 800 kV. For distribution networks, 12 kV and 24 kV are most common. Transmission substations typically use 145 kV, 245 kV, or 420 kV GIS.

2. Evaluate the Busbar Configuration

Single busbar, double busbar, and one-and-a-half breaker configurations each offer different reliability levels. Critical hospitals and data centers should use double busbar design.

3. Check SF6 Gas Handling Capability

SF6 is a potent greenhouse gas. Modern GIS uses minimum interruption devices (MIDs) and sealed pressure systems. Ask suppliers about gas leakage rates—good GIS should leak less than 0.1% per year.

4. Consider Climate and Environment

Outdoor GIS requires weatherproof enclosures. Coastal installations need corrosion-resistant coating. Desert applications require derating for high ambient temperatures.

5. Verify Protection Relay Integration

Ensure the GIS can integrate with your existing protection relay system. IEC 61850 compatibility is essential for modern digital substations.

6. Evaluate Maintenance Requirements

GIS is maintenance-free for the first 20 years, unlike AIS which requires annual inspections. But you still need gas density monitoring and SF6 handling equipment.

7. Check Type Test Certificates

Always demand full type test reports from accredited laboratories (KEMA, CESI, CGGC). Key tests include: short circuit, temperature rise, dielectric, and IP rating tests.

8. Plan for Future Expansion

GIS is modular. Specify spare bay positions in the original order. Adding bays later is much cheaper than replacing the entire installation.

9. Compare Total Cost of Ownership

GIS costs 2-3 times more upfront than AIS, but saves space, maintenance, and infrastructure costs. Over a 30-year lifespan, GIS is often the better financial choice.

10. Choose an Experienced Manufacturer

GIS is high-voltage equipment with serious safety implications. Choose a manufacturer with at least 10 years of GIS experience and global references. Electric-GS has supplied GIS panels to over 30 countries.

Frequently Asked Questions

What is the difference between GIS and AIS?

GIS uses SF6 gas insulation in sealed tanks; AIS uses open air insulation. GIS is 1/10th the size, safer, and requires less maintenance, but costs more upfront.

What voltage range is available for GIS?

GIS is available from 12 kV up to 800 kV. For most distribution applications, 12-36 kV GIS is sufficient.

How often does GIS need maintenance?

Sealed GIS requires no routine maintenance for the first 20 years. After that, gas handling and minor inspections are needed.

Is SF6 gas bad for the environment?

SF6 has high global warming potential, but modern GIS systems are sealed and leak at less than 0.1% per year. Alternative gases (dry air, vacuum) are gaining popularity.

About Electric-GS

Electric-GS manufactures medium voltage gas insulated switchgear, RMU, and VCB for global markets. Our GIS panels are type-tested to IEC 62271 standards and shipped to 30+ countries.

Request a free quote: info@electric-gs.com | WhatsApp: +86 135 8897 8050 | Browse products on our sister site.