Differentiating fiber optic Mach-Zehnder interferometer for alternating current measurements

摘要

A multiplexed Mach-Zehnder interferometer is proposed for measuring time varying signals. The system was implemented to measure electrical currents. These measurements are facilitated by a current transformer terminated with a resistive load, which derives a piezoelectric phase modulator. Frequency domain demultiplexing allows interrogation of the sensors in each of the conductors of a three-phase electrical system. Different phase modulating carriers are applied to each arm with additional piezoelectric phase modulators. Synchronous phase detection followed by integration yield the current signals. Results of current measurements between 9 A and 200 A on a single- phase system and on two 50 Hz phases of a three-phase system are discussed.