Onsite mobile AC high voltage test systems are used for withstand voltage testing, partial discharge measurement, tan delta measurement to instrument transformers, GIS, GIL, switchgears and etc after they are installed onsite and for purposes of diagnostics in asset management up to 900kV/10A. .

Onsite mobile AC high voltage test systems can be made by SF6 high voltage test transformer or variable frequency AC resonant test system and complies with requirements according to IEC 60076-3, IEC 60517, IEC62271-203.