Gas-insulated switchgear
Gas-insulated switchgear (GIS) integrates circuit-breaking, disconnecting, earthing, measurement, and surge protection in compact metal-enclosed bays. This catalog covers the proven SF6-insulated 8D series — 8DN8 (145–170 kV), 8DN9 (up to 245 kV onshore, 300 kV offshore), and 8DQ1 (245–550 kV, up to 80 kA) — alongside the SF6-free 8VN1 Blue GIS, which pairs clean-air insulation with a sealed-for-life vacuum interrupter at up to 145 kV.
Gas-insulated switchgear (GIS) is high-voltage switchgear in which all live parts — circuit-breaker, disconnectors, earthing switches, busbars, and instrument transformers — are sealed inside earthed, gas-tight metal enclosures filled with an insulating gas, traditionally SF6 and increasingly clean air in SF6-free designs. Because the pressurised gas insulates far better than open air, a GIS bay occupies only a fraction of the space of the equivalent air-insulated (AIS) arrangement, and the enclosure shields the live parts from accidental contact and environmental pollution. GIS is specified per bay — one complete switching branch of a substation — and is typically chosen for urban, indoor, and offshore substations where space, safety, or ambient conditions rule out AIS. Glossary →
System-voltage coverage per family (√ scale) — bars link to the product pages. Families without a published kV rating are not drawn.
11 of 11 products
Why it matters
Every substation in a transmission grid needs equipment that can switch, disconnect, earth, and measure — and where that equipment lives determines the substation's footprint, safety profile, and maintenance burden. GIS puts all of these functions inside sealed metal enclosures, which reduces space requirements to a fraction of an equivalent air-insulated (AIS) substation and fully protects live parts against contact and pollution — critical for urban, indoor, and offshore installations. The insulation medium is now a planning decision in its own right: SF6, the dominant insulating gas of recent decades, has a global warming potential 24,300 times that of CO2 and persists in the atmosphere for up to 1,000 years — a problem the new EU F-gas regulation now addresses directly. Clean-air designs such as the 8VN1 Blue GIS eliminate F-gases entirely, removing gas-handling training, density monitoring, and gas reporting from the operating routine. Because GIS bays routinely stay in service for more than 50 years, the designation chosen today defines a grid operator's spares, service, and compliance obligations for decades.
Compact, enclosed substations
Metal-enclosed gas compartments need minimal space compared with an AIS substation and completely shield live parts from accidental contact and from environmental pollution — enabling indoor, urban, and offshore siting.
Proven platform since 1968
The 8D series (8DN8, 8DN9, 8DQ1) has more than 24,000 bays installed worldwide with well over 285,000 recorded bay-years of operation, and a type-tested gas leakage rate below 0.1% per year per gas compartment.
Low lifecycle cost
First major inspection falls beyond 25 years and expected lifetime exceeds 50 years across the 8D series. Blue GIS runs a 12-year visual-inspection schedule with maintenance-free, sealed-for-life vacuum interrupters.
An SF6-free path to compliance
The 8VN1 Blue GIS insulates with clean air (80% nitrogen, 20% oxygen) and carries 0 kg of fluorinated gases — zero GWP, and no gas-handling training, density checks, gas reporting, or end-of-life gas disposal obligations.
Frequently asked questions
What is gas-insulated switchgear (GIS)?
GIS is high-voltage switchgear in which the switching, disconnecting, earthing, measurement, and surge-protection functions are housed in sealed, metal-enclosed compartments filled with an insulating gas. Because the insulating medium performs far better than open air, a GIS bay is much more compact than the equivalent air-insulated (AIS) arrangement, and the enclosure protects live parts from contact and environmental pollution.
What is in a GIS bay?
A circuit-breaker bay combines the interrupter unit with disconnecting and earthing switches, instrument transformers for measurement and protection, and the associated control, interlocking, and monitoring equipment. In this catalog, each product page breaks the bay down in its spec tables — Main, Electrical, Mechanical/environment, and Standards & certifications.
What is the alternative to SF6 in switchgear?
SF6 has been the dominant GIS insulating gas for decades, but it is also the most potent greenhouse gas in use, with a global warming potential 24,300 times that of CO2. Alternatives include fluoronitrile mixtures, CO2, and clean air. The 8VN1 Blue GIS in this catalog takes the clean-air route: an 80/20 nitrogen-oxygen mixture with zero global warming potential and zero toxicity, combined with a vacuum interrupter for switching.
How do I choose between the 8DN8, 8DN9, 8DQ1, and 8VN1?
Start from rated voltage and short-circuit breaking current: 8DN8 covers 145–170 kV up to 63 kA, 8DN9 covers up to 245 kV (300 kV offshore) at 50 kA, and 8DQ1 covers 245–550 kV up to 80 kA. If your project requires SF6-free equipment — for example under the EU F-gas regulation — the 8VN1 Blue GIS covers up to 145 kV at 50 kA with clean-air insulation. Compare the Electrical and Mechanical/environment spec tables on each product page, including bay width, weight, ambient temperature range, and indoor/outdoor suitability.
What information do I need to request a quote for GIS?
Reference the type designation (8DN8, 8DN9, 8DQ1, or 8VN1) together with the ratings from the product spec tables: rated voltage, short-circuit breaking current, normal/busbar current, number and configuration of bays, indoor or outdoor installation, and site ambient conditions. The designation and spec rows on each product page map directly to an orderable configuration, so quoting from them avoids a clarification round-trip.
Where do I find technical datasheets for these switchgear families?
Each product page carries a downloads section: the 8DN8, 8DN9, and 8DQ1 pages include the official technical data sheets and the 72.5–550 kV portfolio overview, and the 8VN1 page includes the Blue GIS product flyer and the technical product presentation covering modules and LPIT options. These are the same reference documents used for tender specifications.
What does GIS maintenance look like over the equipment's lifetime?
The 8D series is type-tested to a gas leakage rate below 0.1% per year per compartment, with the first major inspection due after more than 25 years and an expected lifetime beyond 50 years. Blue GIS runs on a 12-year visual-inspection cycle, and its vacuum interrupters are sealed for life and maintenance-free. To keep spares, inspections, and service support matched to your exact bays over that horizon, register your installed equipment with us — our service team can then plan interventions against your specific serial numbers and configurations.