Comparison of Measuring Systems for Puncture Test According to IEC 61211

In this paper, we summarise the experience gained during comparisons between four measuring systems designed specifically for performing the test according to IEC 61211. Two of the systems are based on dividers using low-ohmic wire-wound resistors. The other two are identical and they are based on dividers using ceramic resistors both in high-voltage and low-voltage arms. Two comparisons were performed by measuring the flashover voltage on a glass insulator simultaneously with two or three systems. A 120 kV insulator was tested in both cases, and the test voltage was approximately 270 kV. Both the recorded waveforms and measured peak values were compared, even though only the peak value measurement is required by the present standard. The first comparison was performed between one ceramic and one wire-wound divider. The second comparison performed in a different laboratory was between two ceramic and the other wire-wound dividers. Even with the compact test circuits used, and with wideband measuring systems specifically built for this test, large differences in the waveforms measured with different systems were observed. In most cases the agreement in measured peak values was within 3 %. Higher differences occurred only in one measuring circuit setup on negative polarity with one divider in an abnormal measurement position.