Development of an alternating electrical current meter mobile for low and high voltage: polarimetric analysis, mathematical model, design, and field tests

Abstract. The measurement of current in electric power transmission lines is crucial for the electrical sector, thus demanding optimal control of the system. Such tasks can be carried out by optical sensors. We present a polarimetric study of an electric current sensor using magneto-optical crystal, as well as the complete development of a mobile optical meter for electric current in low- and medium-voltage lines. Based on our polarimetric study of the optical sensor (transducer), we discuss and compare Faraday rotation levels with the developed mathematical model, presenting a peak-to-peak amplitude variation of 1.8534 in the plane of polarization of light. The development of the transducer is described considering the measurement curves, calibration, linearity analysis, design of the mechanical structure, construction of the electronic structure of data acquisition, and the complete structure of the device. In the end, we present a field test. For the measurements carried out in the laboratory, the sensor presented a linear behavior with sensitivity of 2.4  mV  /  A, as well as a high degree of linearity, in comparison to a device with a linearity of 0.001 A. In addition, we show the development of the optical, mechanical, and electronic structures of the device, as well as field measurements in a distribution line of 13.8 kV. The measurements were performed in an energized line, and presented values compatible with those read in the feeder of the distribution company. At the time, the measured current was 220 A. Therefore, this work is presented as a solution for the realization of safe actions in certain high-voltage lines for companies that operate at high-voltage levels, primarily electric power distribution companies.