2.3.2 TEST PROCEDURE
2.3.2.1 WETTING
After the polluted insulators dried naturally, they were
suspended vertically on the electric hoist at the center of
the artificial climate chamber. The pollution layer on the
specimen surfaces was wetted by steam fog generated by
the steam boiler with an input rate of 0.05±0.01 kg/h·m3.
The hydrophobicity of the composite insulators would
gain a certain recovery to WC3 or WC4 after 22-26 h of
natural drying, which would be different from the tests
that the hydrophobicity was still WC4 or WC5 after only
1 h of drying [12, 13]. As the artificial climate chamber is
airtight and has good heat-insulation, the wetting time of
the insulators in the chamber is shorter than in most fog
rooms. However, the wetting time is related to the type of
insulator and the pollution level [26]. Generally, the
higher the pollution level has, the shorter the wetting time
is [6]. Moreover, the wetting time for composite
insulators is longer than that for porcelain or glass
insulators. The pollutant layer on the insulator surfaces
could be wetted completely around 12 min. In the wholewetting process, the temperature in the chamber was
controlled lower than 35 °C.