Numerical Electromagnetic Field Analysis of Unit Step Response Characteristics of Impulse Voltage Measuring Systems

Unit step response characteristics of impulse voltage measuring systems are studied with the help of numerical electromagnetics code (NEC-2). Prior to this analysis, the accuracy of a transient analysis by this method is investigated for a simple structure. An impulse voltage measuring system, under application of step voltage, behaves like an antenna until a traveling wave makes several roundtrips in its lead wire. NEC-2 code can analyze such dynamic electromagnetic field around a three-dimensional (3-D) conductor system. In the present paper, the role of a shield ring of a divider for lightning impulse voltage is intensively investigated and discussed.