Extension of test range in the IEC test for tracking resistance

The testing methods for measuring the tracking resistance of organic insulators using drops of electrolytic solution such as the IEC recommended test^1,2 and the DIN test^3,4 have some merits; the test device is simple and the test procedure is comparatively easy. However, in the IEC test, test voltages above 500V or 600V cannot be applied because at the higher voltages an arc bridges the electrodes and the C.T.I. (Comparative Tracking Index) is not significant. Consequently the IEC test is not suitable for testing materials having such high tracking resistance because the C.T.I, cannot be measured.