Non intrusive current and power factor sensor with energy harvesting for maintenance-free operation

In this paper, a current and power factor sensor with non-invasive and energy-harvesting operation is proposed. Our method enables single probe measurement for voltage waveforms on a power supply line without ground connection. The voltage waveforms are measured using a piezoelectric polarized polyvinylidene fluoride film and appropriate capacitance. A current transformer measures the current waveforms and acquires operating power for the sensor circuits. A microcontroller in the sensor calculates the current and power factor. In sequence, the data are transferred to PC using LoRa, a low-power and wide-area wireless communication standard. In the field test, our sensor shows high correlation coefficients of 0.91 and 0.70 for current and power factor, respectively. High linearity between values from the sensor and actual values are also observed. Our sensor can be easily applied to various industrial machines owing to its energy-harvesting, non-invasive, and single-probe features.