Accurate optical measurement of high voltage waveform using novel optical liquid crystal based sensor

Abstract

We have developed a novel method for measuring electric field strength, and by inference, voltage for high power applications. This is achieved in a contact-less manner using a passive, liquid-crystal based optical device which guarantees galvanic isolation. We illustrate the method through a series of experiments in which we show that the device can measure electric field strength in a hysteresis-free and linear manner. The experimental setup restricted measurements to electric field strengths with an upper limit of 380kV/m, but measurements of up to 2MV/m should be possible. Applied voltage on a phase conductor can be measured to better than 1% accuracy for applied voltages above 10kV and yet the device is sensitive enough to measure signals as low as 0.1kV with no discernible drift. These results taken together demonstrate that our approach shows great promise for applications in which accurate high field strength or voltage measurements are required.