The variation in the resistivity of dust deposit with temperature, for the dust emanating
from different sources can be seen in Fig. 1. The plot shows a peak at certain
temperature. In the ESP, at temperatures below 100C, the dust layer is covered with
a thin layer of moisture. This moisture also contains soluble alkalies. Most electricity that the dust conducts, passes over its surface and these two constituents, namely water
and alkalies, assist conduction. As the temperature increases, moisture gets evaporated.
As it rises above 100C, the alkali content also gets depleted. Thus, we see a gradual
rise of dust resistivity with temperature. At temperature above 150C, the surface becomes
completely dry and conduction through the core of particles becomes important.
At higher temperatures, core conductivity increases and resistivity decreases, as evident in