~YDSG series SF6 gas insulated AC test transformers are especially designed for factory and field test of metal-clad switchgear (GIS), and substation equipments on-site testing. These transformers can be flanged directly to GIS, they make testing of such installations possible without feeding them through an air-SF6 bushing. They can also be used for AC voltage test of other HV apparatus when equipped with output bushing.

In the factory, these transformers allow to test sub-assemblies and components directly in the manufacturing line, thus avoiding transportation to a central test facility, and extra handling. Particularly they are suited for on-site tests of GIS after assembly.

Compared to conventional oil insulated AC test systems, they are lighter and smaller, only about 1/6 height and 1/7 weight, also the merits of encapsulation remain effective during tests which is essential for PD testing.