Most High Voltage equipment from 3KV and above can be tested, of types such as GIS, Vacuum or oil breakers, motor, transformer and tap changers etc.Depending on the design of the electrical equipment and the strength of the electric field,even low voltage equipment can generate Partial Discharges such as LV busbars,LV motors etc.Also, the higher the voltage the higher is the likelihood of occurrence of Partial Discharge.