AN OPTICAL CURRENT COMPARATOR

The design and performance of an optical current comparator based upon a triangular shaped bulk glass sensing element are presented. The eff ect of the Faraday rotation produced in the sensing element by an unkn own large current is annulled by a smaller known current of opposite p olarity, thus giving an absolute measurement of the unknown current. T he design requirements of the sensor configuration are analysed theore tically by computer simulation and tested experimentally for both idea l and non-ideal sensors. The sensors have many applications in the pow er distribution industry, as both absolute and differential AC and DC measurements up to very high currents are possible.