On-line measuring system of temperature for the high voltage apparatus using the thermochromic effect of liquid crystal

Cholesteric liquid crystal optical rotatory dispertion characteristic is affected by temperature. The temperature sense system used for measuring temperature of the high voltage apparatus is presented based on the thermochromic effect of cholesteric liquid crystals. The system consists of the optic source, cholesteric liquid crystals, color sensor, hollow fiber, signal amplification circuits and display module. The cholesteric liquid crystal is packaged in hollow fiber, and its temperature change is represented by the selective reflection wavelength based on the thermochromic effect. The temperature may be real-time measured based on the wavelength demodulating by color sensor, and selective reflection wavelength is related with temperature. The high voltage apparatus mult-point temperature may be measured, error is less than ±0.2°C, and different temperature range may be obtained for the system by selecting different cholesteric liquid crystals mixture. The sense system has the perspective of the intrinsic safety, high precision, high electrical insulation and anti-electromagnetic interference.