Results of Pollution Tests on Insulators in the ⩾1100 kV Range and Necessity of Testing in the Future

The necessity of testing at UHV levels depends on the question whether the dielectric strength of polluted insulators is proportional to the insulator length, so that the results at lower voltages can be extrapolated. An analysis of past results of tests on long insulators is presented. The analysis includes evaluation of the corresponding insulation levels in order to show whether the tests have been made in the practical range. The probable voltage drop is computed depending on the available test-circuit ircuit data. The influence of voltage drop on the results is kept in mind while analyzing the results.