Electrical engineering & Electromechanics (Jun 2017)
INFLUENCE OF CORONARY DISCHARGE PARAMETERS ON THE EFFICIENCY OF LIGHTNING PROTECTION SYSTEM ELEMENTS
Abstract
Purpose. Investigation of the formation of space charge in the region of the apex of lighting rod, under the action of the electric field of a thunderstorm cloud, to evaluate the efficiency of elements of lighting protection systems. Methodology. We have applied the mathematical simulation of electromagnetic field distribution on the top of metal rod by different forms. As a mathematical apparatus, we use the finite element method. We considered two forms of the rod section: round and square. The round (cylindrical) rod has a sharp apex. The square rod has a flat top. The experimental study investigates the features of corona discharge formation. A high-voltage test equipment is created an electric field. Experiments carried out using a configuration consisting a potential plate and vertical rod electrode on grounded plate. The electric field strength varied from 1 kVm-1 to 100 kVm-1. This range corresponds to the thunderstorm condition. Results. We have obtained a correlation between the corona current and the strength of the electric field for various shapes of the rod top. The results of experimental studies confirmed the correctness of the conclusions of theoretical estimates. We show that the time parameters of streamer current pulses vary by no more than 30%, but a streamer charge increase to three time with increasing electric field strength. We proposed and applied a method for measuring the velocity of motion of a streamer in the discharge gap. As a result, it is established that the streamer speed is nonlinear in time. For a discharge gap of 1.2 m, the speed varies from 1.8∙104 m/s to 1.1∙106 m/s. Originality. For the first time, we have carried out a complex of studies of corona discharge parameters from lightning protector rod to apply for the certification procedure of ESE terminals. Practical value. Based on the set of obtained results, it is obviously that the standard NF C 17-102:2011 will not be introduced as a national standard of Ukraine before full introduction of scientifically justified data will be include into the requirements of the standard.
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