In extremely dry areas, would the big variation in day/night temperatures cause a moisture increase in the oil?
It is somewhat difficult to define the term “dry areas”. The desert, for example, we would normally think of as being dry. In most cases this is not true as we find that the humidity of the air is fairly high and for that reason, the air that enters the transformer is still moist. The big change in temperature between the day and night conditions affects the air above the oil, especially in a conservator tank, due to the expansion and contraction of this air mass. The oil in the transformer also expands and contracts and in doing so, assists the process of the air movement in and out of the transformer. This means that the oil in the transformer is well mixed with oxygen and enhances the process of moisture forming inside the transformer due to oxidation of the oil and paper. It is also true that moisture will be carried into the transformer when the flow rate of air through the silica gel breather is too fast to allow the silica gel to absorb all the moisture entering the breather. It
