Low-Power, Cost-Effective Differential Electric Field Mill Sensor

The electric field mill is the prevalent electrostatic field sensing device in applications ranging from weather and thunderstorm forecasting to the assessment of the electric environment under high-voltage direct current (HVdc) transmission lines. In this article, the study, fabrication, and experimental evaluation of a compact differential low-cost and low-power electric field mill is conducted, suitable for electric field measurements under foul and extreme weather conditions. The main focus is the evaluation of a low-cost and low-power motor, combined with circular stationary sensing electrodes and a sector-shaped rotor. The formulas of the induced currents are derived. An improved analog readout front end is presented, along with a microcontroller unit for signal control and increased system adaptability. Both single-ended and differential-ended outputs are examined. The field mill is initially calibrated indoors in accordance with IEEE Standard specifications. It is then operated outdoors under various weather conditions and compared to the commercial field mill sensor Boltek EFM-100. The results indicate similar behavior to the commercial sensor, fast response, at a significantly lower power consumption, leading to the possibility of autonomous operation, in cases where it needs to be installed in hostile or inaccessible environments for extended periods, supported by energy harvesting modules.