Experimental evaluation of the transient behavior of a 3-rod grounded system under current impulse

摘要

This work aims to evaluate experimentally the grounding system transient behavior subjected to current impulse. The grounding system studied has three rods vertically grounded and interconnected. For this purpose, a mobile current impulse generator is used. The mobile generator is charged with voltage levels of 15, 20 and 25 kV and at the instant of pulse application, the voltage and current signals at the pulse injection terminal are captured by means of two oscilloscopes. From the acquisition of the voltage and current curves, the parameters are calculated: the impulsive impedance, the impulse coefficient, the transient impedance and the times of the front and half volts, the voltage and the current. Also analyzed are the characteristic curves of the relationship between voltage and current measured in the field. The results show that the grounding system has a predominantly inductive characteristic, however, it is influenced by capacitive effects, when the intensity of the current impulse increases. Finally, it was also identified that the transient analysis of a grounding system, submitted to current impulse, should be evaluated by more than one parameter, since the evaluation by only one parameter, can lead to erroneous interpretations.