Mechanical Spark Electrostatic Property Testing Method

Abstract

Abstract The article describes an attempt to assess the electrostatic properties of mechanical friction-induced sparking. Such sparks are the cause of numerous accidents in hard coal mines. The article summarizes accidents in hard coal mining in Poland in recent years. In most cases, the initials were mechanical sparks. Mechanical sparks contain energy, a part of which is related to their excess electrostatic charge, whereas the other part is of a different origin (kinetic or thermal energy, for example). The article tries to estimate how much of this energy is energy impact generated by electrostatics impact. It is hard to measure the dynamic electrostatic parameters like electric charge. Authors select four measuring methods. This test methods are prepared based on authors knowledge of electrostatic parameters and European standards dedicated to measure the electrostatics parameters. These circuits were prepared for four different spark parameters. Measurement methods of electrostatic field of sparks stream are not able to measure field potential of sparks. The measuring instruments do not have such a fast response time, adequate to the speed of the sparks. Spark generation and parameter measurement experiments were performed. The only method to determine the amount of electrostatic charge on sparks is to measure the entire charge by collecting sparks at the measuring electrode. The measuring system requires that the entire stream of sparks falls on the electrode. Tested transferred electrostatic charge of stream of sparks is about 10 nC. It means that this charge can be an effective ignition source for some explosive atmospheres. Electrostatic charge with Certain methods were rejected as inadequate following result analysis. A claim for one of the methods was submitted to the Patent Office of the Republic of Poland.