Electro-optic high voltage sensor for utility application

Recently, optical sensors for current and voltage measurement in electric transmission grids have attracted increased interest. In comparison to conventional instrument transformers they benefit from being smaller and lighter at reduced cost, easy integration into digital substations, enhanced performance (bandwidth of several 100 kHz; no saturation), and inherent dielectric decoupling of the sensor electronics. State-of-the-art current sensors typically use the Faraday effect in an optical fiber wrapped around the high voltage current conductor in a closed loop [1]. Voltage sensors are often based on the linear electro-optic effect (Pockels effect) in relatively short (<;20 cm) crystals. At voltages of several 100 kV, the resulting high electric field strengths require rather complex and expensive dielectric insulation, e.g. with pressurized SF₆-gas [2].