Determination of Characteristic Voltages in Impulse and Switching Surge Testing

The paper deals with the characteristic impulse and switching surge voltages of high-voltage equipment which only temporarily loses its dielectric strength when flashover occurs. A test procedure suitable for determining the highest withstand voltage and the lowest flashover voltage of a test object is described, and a theoretical investigation is carried out in order to show the quality of the test procedure, and also the influence of different factors on the test result. The relation between the specified withstand voltage of a test object, as defined by IEC, and the highest withstand voltage is given some consideration. A simple method for determination of the 50-percent flashover voltage is described.