The effectiveness of high-voltage testing directly depends on the accuracy of modelling the operating conditions of the object under the test. Testing high-capacitance electrical equipment at an industrial frequency requires high power which inevitably leads to an increase in the size of test systems.
The main advantage of resonant test systems is their low power consumption and relatively compact size. The principle of operation of such systems is based on parallel resonance arising in the oscillatory circuit formed by the variable inductance of the test system and the capacitance of the test object (load).
During the testing with high AC voltage, the resonant test system outputs a continuous high sinusoidal voltage, which, unlike the DC voltage, does not damage the healthy insulation. The use of resonant systems is therefore preferable and optimal for testing high-capacitance objects at the industrial frequency: generator stator windings, solid cable insulation, capacitors, SF6-insulated switchgear, electric motors, high-power generators, and power transformers.