On the Characteristics of Noise Induced in a Measuring Circuit of Lightning Impulse Voltages

Abstract

The interference test is prescribed in the international standard, IEC60060-2 High-voltage test techniques, to convince that the induced noise in the low-voltage arm of an impulse measuring system is sufficiently small. However, the high-voltage arm of a measuring system also suffers some electro-magnetic noise, especially when a sphere gap is connected near the voltage divider, which is frequently used for the tests prescribed in the IEC.
This paper experimentally discusses the characteristics of the noise induced in the high-voltage arm of an impulse measuring system with a sphere gap, after the noise in the low voltage arm has been convinced to be small enough by the interference test.
Many voltage waves, which are obtained in our experiments and thought to be noise induced in the high voltage arm, may be understood without contradiction, if the main part of the noise is assumed to be induced through the capacitance connecting between the sphere and the high voltage arm of the divider.