Field experience on hot sticks exposed to atmospheric pollution for variable winter periods at two distribution substations

This paper deals with one particular aspect of hot sticks used by electrical utilities, exposure to long-term atmospheric pollution. In order to determine the effect of such exposure, high-voltage laboratory tests were performed to evaluate the maximum leakage-current on the hot stick surface. A test program was set up in which the hot sticks were exposed to atmospheric pollution at two Hydro-Quebec substations and tested at the IREQ HV laboratory. The tests included salt deposit density (SDD) measurements, leakage-current measurements during high-voltage tests, flashover tests, resistivity measurements of collected-water, etc. The results identified several parameters describing the relative pollution level at each substation. A specific high-voltage leakage-current test highlighted two interesting aspects: the maximum RMS alternating current, under a specific set of parameters (e.g. hot stick test length of 1 m, test voltage of 30 kV, salt fog resistivity of 30 Ω.M), combined with the deposit of natural atmospheric pollution on the hot-stick surface; the behavior of hot-stick fiberglass treated with silicone or wax, exposed to salt fog of a given water resistivity level