Further Developments of Metrological and Simulation-Based Characterization of the Non-contact Measurement of Electrostatic Charge by Means of Electric Field Meters

Abstract

Electrostatic charges and discharges on surfaces can result in safety-relevant problems under certain conditions in different areas of application, from electrical energy technology to explosion protection. In the field of electrical energy technology, electrostatic charging is important for high-voltage direct current transmission (HVDC). In this case, the stress of insulation systems results in effects such as volume conductivity and surface charges. Furthermore, electrostatic discharges in potentially explosive atmospheres can lead to ignition of an explosive mixture and thus to explosion. Many electric and mechanical devices have enclosures made of chargeable insulating materials and must be evaluated for use in potentially explosive atmospheres. The measurement of the electric field strength by means of electrical field meters can be carried out without contact or disturbing the object under investigation - the charge of the material - and without causing a discharge. In order to establish the electrical field meter as a measuring instrument, precise knowledge of the measurement method, the characterization of the influencing parameters on the measurement and the traceability of the measured values to national standards are required. For the metrological characterization of the non-contact measurement of electrostatic charge, a test setup was developed which represents the parameters to be investigated (e.g. real surface geometries, distance dependence). Furthermore, theoretical approaches for a simulation-based characterization were considered. Preliminary results of the characterization for idealized conditions (homogeneous electric field configurations) showed that the measurement accuracy with regard to distance dependence and object size could be determined. In addition, a cone detection method of the electric field meter measuring head has been verified by simulation. As a next step, to the simulation-based determination of the measuring angle a metrological method for the determination is developed. Thereby, the measurement setup is refined which is here considered together with the analytical evaluation. Furthermore, it is necessary to quantify the simulation-based characterization for different types of electrical field meter measuring devices. The influence of the diameter of the electric field meter measuring head on the measuring angle and the resulting detection cone is investigated.