A substation in a box.
90% less land, 100% enclosed.
Compact, reliable, and fully enclosed — the ultimate solution for space-constrained HV substations with maximum availability. Circuit breaker, disconnector, earthing switch, CT/VT and busbar in one sealed system.
Same interrupter, sealed enclosure.
Siemens Energy gas-insulated switchgear (GIS) uses the same proven interrupter units, operating mechanisms, and control elements as the standalone 3AP circuit breaker range — housed in a compact, metal-enclosed SF6-insulated system.
GIS integrates circuit breakers, disconnectors, earthing switches, current transformers, voltage transformers, and busbars into a single sealed system — reducing footprint by up to 90% compared to conventional air-insulated substations (AIS).
Available in single-phase (8DA) and three-phase (8DB) encapsulated designs, plus 8DN hybrid variants, covering voltages from 72.5 kV to 550 kV.
Four decades of enclosed reliability.
Space Saving
Up to 90% less land area versus conventional AIS — ideal for urban, offshore, and underground substations where footprint is money.
Maximum Safety
Metal-enclosed design protects against accidental contact, extreme weather, and environmental contamination — safe for public-facing sites.
High Reliability
Sealed SF6 system eliminates external influences — no pollution, no humidity, no altitude limitations. MTBF measured in decades.
Proven Technology
Same interrupter units and drives as 3AP series — field-proven in thousands of substation installations since the 1970s.
Three designs. One platform.
Whether your project is a new-build utility substation, a distribution point in an industrial park, or an extension of an existing AIS bay, one of the three 8D variants fits.
The trade-off, quantified.
A direct side-by-side to help you decide whether GIS is right for the project.
Where 8D bays go to work.
Urban Substations
Downtown 132 kV / 220 kV stations where land value dominates the CAPEX equation.
Industrial Plants
Steel, chemical and refinery sites needing robust switchgear in tight process footprints.
Offshore Platforms
Wind and oil & gas platforms where sealed enclosures are non-negotiable.
Hydro / Pumped Storage
Powerhouse switchgear where damp, confined space rules out AIS.
Renewable Collectors
Solar and wind farm HV collector substations, particularly in coastal or dusty environments.
Underground
Metro traction substations and rock-cavern installations.
Plan your GIS project.
Send us your single-line diagram and bay count. We return a bay-by-bay proposal — with layout drawings, interface schedules and lead-time — within 5 business days.