Variable Frequency Resonant Test Systems are generally used where a lightweight, transportable unit is a requirement. Primary application is GIS / GIL testing. Other test objects which are capacitive in nature such as cables, generators, and motors may also be tested. Non-mobile systems for factory or laboratory use are also available.
A Variable Frequency Resonant Test System takes advantage of resonance theory. To achieve resonance, the capacitive reactance (test object) has to equal the inductive reactance (high voltage reactor). In a Variable Frequency Resonance System, the reactor is non-variable; therefore, the frequency of the circuit is adjusted until resonance is achieved. This adjustment of the resonant circuit is commonly referred to as “tuning”. Once resonance has been achieved only the resistive (real) losses in the circuit have to be supplied. The output voltage and the incoming power drawn from the mains is a function of the “Q” or quality factor of the circuit. The higher the system Q, the lower the incoming power requirement.
