Application of optical fibre sensor for partial discharge detection in high-voltage power equipment

The insulation system of HV power equipment deteriorates due to partial discharges. It is thus desirable to monitor the insulation of power apparatus whilst in service. Ultrasonic signals generated by the partial discharges in high-voltage power equipment can be detected with suitable pressure transducers and related to the PD (Partial Discharge) source. Acoustooptic sensors have shown high sensitivity and good accuracy of measurement of physical parameters. Optical fibres are chemically inert and do not affect the integrity of the insulation system, hence they provide a suitable means of monitoring of the condition of the HV equipment. An optical signal is launched periodically into an all-fibre sensor system. The induced stress on the fibre core caused by the pressure wave perturbation changes the phase of the optical signal traversing the fibre. The phase shift is detected by using a reflectrometric pulsed interferometer technique with a phase modulated type sensor. The extracted PD signals show a high sensitivity.