GIS switchgear is gas-insulated, sealed, and almost always configured as a ring main unit for secondary distribution. It mounts outdoors on a pad. Metal clad vs metal enclosed covers indoor panel types — metal clad is withdrawable with full segregation, metal enclosed is fixed with simpler construction. The two product groups serve different network positions. GIS RMU handles ring switching at transformer tap points. Metal clad and metal enclosed handle main incoming protection and distribution indoors. A complete substation often uses metal clad panels indoors and GIS RMUs outdoors at each transformer.
Gas insulated switchgear RMUs seal live parts in SF6 inside a stainless steel tank — compact, outdoor-ready, zero internal maintenance for 30 years. Air insulated switchgear uses solid barriers and vacuum interrupters with no SF6 at all. Pick gas insulated if you need the smallest outdoor footprint and do not face SF6 restrictions. Pick air insulated if your market regulates greenhouse gases — the EU, Australia, and sustainability-certified projects increasingly mandate SF6-free equipment. Performance is comparable for secondary distribution up to 24kV.
Metal clad switchgear uses withdrawable circuit breakers in compartmentalized panels with busbar, breaker, and cable sections fully segregated per IEC 62271-200 Form 3 or Form 4. You roll a VCB out on guide rails for inspection. Metal enclosed switchgear bolts the breaker into the panel — fixed type, no trolley. Construction is simpler and costs 20 to 30 percent less. Both meet the same short-circuit and arc standards. Your maintenance team preference and budget decide which one fits.
A ring main unit is a compact switchgear assembly for 11kV secondary distribution networks. It manages ring network topology — a cable loop with transformers tapped at intervals, fed from two directions so a fault on one side does not knock out the whole area. The RMU has three-position load break switches (closed, open, earthed) and a fuse or circuit breaker for transformer protection. You install it outdoors on a pad. No building required. That is the core answer to what is ring main unit topology. Every 11kV switchgear project in urban distribution uses RMUs at each transformer tap point.
Yes, where specified. RCCB with 30mA trip sensitivity on circuits feeding socket outlets, wet areas, and outdoor equipment. Earth leakage protection is not optional — it saves lives. We ship the RCCB trip test result with every panel that includes one.
Yes. Your logo on the enclosure. Your color scheme. Multi-language circuit schedules and labels. Region-specific compliance — CE, CCC, SASO, SNI, GOST. Dedicated project manager from design review to pre-shipment inspection. NDA available if required.
Standard SMDBs ship in 4 to 6 weeks from our 20,000 m² factory. Custom circuit counts, non-standard voltages, or special enclosure dimensions add 2 to 3 weeks. We keep buffer stock of Schneider and ABB breakers for common ratings'
IP41 standard for indoor electrical rooms. IP54 for dusty basements or plant rooms. IP65 for outdoor mounting or coastal environments. Powder-coated steel with full-perimeter neoprene door gasket on IP65 versions. Key lock on every door.
