Flashover behavior of different insulating materials under positive switching impulse voltage stress at different climatic conditions

This paper deals with the influence of temperature and humidity on the flashover behavior of different insulating materials under positive switching impulse voltage stress. Five kinds of insulators are used for the flashover tests: a composite insulator; two sorts of porcelain insulators; a semiconducting glazed porcelain insulator; and a pure air gap. The flashover distances of all insulators are about the same, therefore the data is easy to compare. The temperature is varied between 10°C and 40°C, the relative humidity ranges between 10% and 90% in each temperature step. The tests are performed on clean test samples. All tests take place in an environmental chamber. The whole test setup and the test samples are described. A short section deals with the test methods and the statistical analysis of the measured data. The influence of the relative and absolute humidity on the flashover voltage is evaluated. A comparison of the flashover data of the different insulator types is given. For the influence of the absolute humidity on the flashover voltage a temperature correction factor is calculated. By this means the sole influence of humidity on the flashover voltage can be seen