Improvement on system and components of a rotating electric field mill for atmospheric electric field measurement

Abstract

Lightning, which is also known as the separation of electrical charges in atmosphere, performs energetic discharge. Monitoring of the atmospheric electric field (AEF) helps to provide precaution against the risks of lightning. The rotating electric field mill (REFM) is a sensor used in measuring AEF. For long-term research, REFM should be modified based on several criteria to improve its effectiveness, cost efficiency and functionality. Studies on the applications of several sensor materials on the performance of REFM are limited. The current research’s purpose is to improve REFM as AEF sensor. Furthermore, this research aims to identify the ability of REFM to capture lightning impulses and to track thundercloud development processes and movements. REFM comprises of signal processing circuit (consisting of amplification unit, filtering, conversion and signal conditioning unit) for establishing connection to data acquisition equipment in order to display, collect and analyse data. The calibration and HV impulse experiment have been conducted to this REFM. Moreover, the materials used to develop REFM sensor were mainly made from aluminium or stainless steel. Therefore, an investigation on different materials of REFM rotor and stator was performed to examine their sensitivity and stability towards the high voltage atmosphere. In addition, in order to investigate the characteristics of the signal obtained from a thunderstorm cloud prior to cloud ground lightning discharges, the REFM was installed in an open area. The calibration results showed that the aluminium sensor is more suitable for AEF measurement compared to the stainless steel sensor. The data collected on-site revealed the characteristics of the signals of AEF in the atmosphere as well as the characteristics of the signal from a thunderstorm cloud prior to cloud ground lightning discharges. This research introduced a new design of REFM which offers a reduction of up to one-third of the regular cost of the commercial REFM.