Lightning impulse waveshapes: Defining the true origin and its impact on parameter evaluation.

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Description/Abstract

High-voltage testing of equipment is conducted in accordance with IEC 60060-1 which defines the parameters of full lighning impulse wave-shapes and methods for generating and recording the test wave-shape. In the next revision of the standard it is proposed that the signal be digitally recorded and after suitable signal processing the parameter evaluation be implemented by a standardized algorithm. This paper examines two methods for parameter evaluation; firstly using a linear rising edge approximation and secondly a 3 standard deviations method. Obtained parameters are benchmarked against the IEC 61083-2 Test Data Generator and experimental results generated at the Tony Davies High Voltage Laboratory, University of Southampton. The sensitivity of the results to the method of implementation whilst using a double exponential function for the curve fitting is highlighted. The use of a separated double exponential function for curve fitting is proposed and shown to overcome htis sensitivity.