Eight-module GIS E-House assembled on site at the Huadian Yancheng solar project

The GIS building for the step-up substation at the Huadian Yancheng Honggang solar project now stands assembled on site in Yancheng, Jiangsu. ETENZ manufactured the E-House enclosure for Sieyuan Electric. Its eight modules were fabricated separately in the factory and joined on arrival into a single continuous building of roughly 22 × 11 × 4.5 m, which houses Sieyuan Electric's 220 kV gas-insulated switchgear.

Why one GIS building is split into eight modules

A full line-up of 220 kV GIS bays needs a long, wide equipment building. Built in one piece, it would exceed normal transport and lifting limits in both size and weight. Split into eight modules, the building ships section by section, each to suit its own dimensions, and at site eight standard lifts take the place of one heavy lift of the entire building. Once joined, the modules open into one continuous hall: the GIS bays run in a single line-up across the module boundaries, and busbar and gas-compartment lengths are set by the switchgear rather than by the module divisions.

Three steps of E-House assembly

Assembly accuracy is settled in the factory. Every module frame is built to one common datum and checked for dimensions and structure before dispatch, so once the modules reach site, assembling the enclosure comes down to three operations: lifting each module into position, bolting the joints, and sealing them with capping strips. Neighbouring modules meet face to face along the joint line, where splice plates bridge the seam and are fastened with paired bolts. Externally, an aluminium capping strip closes off the joint and seals it; internally, the lining panels trim the seam.

Penetrations and ventilation openings fixed at the manufacturing stage

Bus ducts leave the building in groups through the long wall, each penetration framed and closed with a cover plate. Penetration openings, cable entries and terminal box positions were all set out in one pass during manufacture. Because SF6 is heavier than air, the exhaust openings sit low in the outer wall near floor level, with air intakes placed high; each module also has an air-conditioner opening in its outer wall, sheltered by a rain hood above the unit. The bus ducts now pass out through the long wall and connect to the substation's outdoor bushings.

On this project, ETENZ handled the structural detailing and fabrication of all eight modules, along with prefabricating the mounting bases, operating and maintenance aisles, bus duct and cable entry openings, and installation openings for the building's equipment. The enclosure was delivered to Sieyuan Electric on an OEM basis. GIS buildings for other voltage levels, and larger-span equipment buildings too big to travel in one piece, can be custom-built the same way: in factory-made sections, assembled on site.