Discharge measurements in cables using a solid state 30 kV bipolar low frequency generator

A design of a 30 kV, 10 mA VLF power supply has been tested which uses solid state components to produce a device which is low noise, portable and suitable for partial discharge testing of high voltage cables up to 33 kV. The device is designed for use in testing installed high voltage cables. The power supply is sufficiently quiet that wide-band partial discharge measurements on polymeric cables may be performed with sensitivities of a few picoCoulombs. No account has been taken of any external noise. The high voltage current stacks can be controlled to operate at any frequency which the HV rails can supply current. In practice this means DC-10 Hz is the useful operating range for the power supply, depending on cable capacitance. Typical frequencies for 1000 m of installed cable would be in the range 0.1-0.5 Hz