A technique for fiber optic voltage sensor to realize temperature compensation

The technique used is based on thermal optical activity measurement of temp erature combined with electricfield-induced polarization modulation of the input light. Quartz is used as the sensing element. A 1/4 wave plate is pla ced behind the quartz so that a single sensing head can simultaneously outp ut two signals: one includes the Pockels effect for voltage measurement; th e ether optical activity for the temperature measurement. The operating pri nciple of the sensor which detects voltage and temperature is presented the oretically and experimentally. The technique for separating voltage and tem perature from the signals is analyzed theoretically and experimentally. It was found that the sensitivity of the voltage sensor to temperature depends on the magnitudes of voltage applied to it. To realize temperature compens ation over a full range, two key parameters must be obtained: one is the re sponse of the voltage sensor to temperature when the applied voltage is zer o; another is the response of the sensing material to temperature when a ce rtain voltage is applied. In the absence of electrogyration the effect of v oltage on the temperature sensor may be neglected. The technique was demons trated using a fiber-optic voltage sensor with temperature compensation. Th e sensor offered a voltage measurement range of 0-10 kV, and a temperature stability of +/-0.4% within the temperature range of 20-70 degrees C.