A good basic equation to know is: P = 2πfCV2 

where f = applied test frequency, C = capacitance of the test object, and V = applied test voltage.

Already from this equation it can be seen that decreasing the applied test frequency will decrease the power required to apply a voltage, and since P = IV (where I = current), the amount of current required to apply a voltage is also lowered.

From the above relationship, when comparing VLF 0.1 Hz to power frequency (60 Hz), there is a 600x lower power and current requirement when testing a cable at the same test voltage. This has the added benefit that the size of the test instrument can be significantly reduced to allow for a very portable high voltage tester. An example of which is the Frida VLF Tester, which can generate test voltages up to 24 kVRMS or 34 kVpeak and weighs only 22 kg (48 lbs).

Due to the sinusoidal waveform, VLF can also be used for tan delta diagnostics and partial discharge diagnostics.