Impulse-voltage performance of contaminated surfaces

Tests were carried out to analyse the influence of geometrical and physical parameters, and of their uniformity, on the critical impulse flashover voltage of contaminated flat surfaces. As with alternating and direct voltages, the results show that the impulse flashover voltage depends strongly on the surface conductivity and slightly on the geometrical layer parameters. Comparison with results obtained on normal insulators demonstrates the possibility of carrying out research on small specimens, without limiting the effectiveness of resulting information; the only limit concerns the `saturation effect¿, but this is because of the relatively short length of the specimens.