An OVT Based on Conoscopic Interference and Position Sensitive Detector

The measurement mode of the existing optical voltage transducer (OVT) is mostly based on light intensity detection. In such a way, the OVT has some big issues, such as a light intensity dependency, a temperature drift, an additional birefringence in the crystal and a half-wave voltage limitation to its measurement range. A new OVT based on conoscopic interference and bi-dimensional position sensitive detector (PSD) is proposed in the paper, which can convert the electro-optical phase delay of the crystal to a rotation angle of spot pattern, and therefore, a high voltage can be measured by the PSD. Compared with the existing OVT, the measurement mode of the new one is independent of light intensity, capable of measuring the electro-optical phase delay from 0° to 180° linearly and directly, and has a wide measurement range with no restriction of the half-wave voltage. The rotation angle of the spot pattern is positioned by a bi-dimensional PSD and the new OVT has a good linearity better than 0.5%.

I. Introduction

OVT is based on optical sensing technology and has advantages of excellent insulating properties, strong anti-disturbance ability, small size, light weight, and wide frequency band. These can’t be matched by a conventional electromagnetic voltage transformer [1]–[4]. But the OVT based on light intensity detection has some issues and limitations which are discussed in details as follow.