Electric field analysis for a static induction type of voltage sensor in three-phase power distribution systems

The real-time observation of a power factor is going to be indispensable for the maintenance, control and stable voltage regulation of general three-phase power distribution systems in Japan. The voltage in the transmission lines is so high that its waveform must be measured with a static induction type of noncontact voltage sensor, which can be attached simply and at a reasonable price compared with other voltage sensors such as a photovoltage sensor. Since the sensor is constructed from a pair of electrodes, there is likely to be a problem in the discrepancy between the actual voltage waveform and the measured waveform in three-phase power distribution systems. The authors have investigated the cause of the problem in the phase shift between the actual voltage waveform and the measured waveform for the static induction type of voltage sensor. This paper presents the results of the electric field analysis concerning another influence of the overhead ground wire, i.e. that on the phase shift in three-phase power distribution systems.