Development of an optical current transformer for adjustable speed pumped storage systems

The design and testing of a passive optical current transformer utilizing the Faraday effect is described. The optical current transformer (OCT) was developed to measure the rotor excitation current of a 400 MW adjustable speed pumped storage system. Overall dimensions of the bulk optic sensor are 250/spl times/250/spl times/40 mm and the OCT functions as an overcurrent sensor to a maximum current 35000 A/sub p/. This OCT has been practically applied at the Ohkawachi Power Plant of the Kansai Electric Power Co., Inc. since December 1993.