Feb. 18, 2019
The following are common drying methods for transformers such as H Class Dry Type Transformer for your reference:
(1) If the transformer drying chamber such as the Dry Type Cast Resin Transformer is not evacuated, the vent hole should be opened on the tank cover or the moisture should be released by the throttle hole.
(2) When heating with oil, the insulation layer should be installed outside the transformer tank such as the Three Phase Dry Type Transformer. The insulation layer can be insulated with asbestos cloth, glass cloth, etc., and flammable materials should not be used, and corresponding fire prevention measures should be taken.
(3) In order to improve the drying quality of the winding, there are two major factors that must be carefully considered: one is to control the drying temperature; the other is to increase the vacuum of the transformer equipment. For the first point, general drying equipment can meet the process requirements. For the second point, it is affected by many factors, and must be considered and arranged reasonably to achieve good drying effect.
(4) During the vacuuming process during drying, it is not suitable to vacuum or dry under low vacuum in the low temperature stage of drying, otherwise it is not conducive to the rise of core temperature and the elimination of moisture, when the temperature rises to 70~ The vacuum is increased at 80 °C. When drying for 1 to 2 hours, the water vapor in the oil tank is more, the heat radiation capability is improved, the internal temperature tends to be uniform, the moisture is gradually reduced, and the heat radiation capability is lowered.
(5) The method of identifying the insulation after drying and the technical specifications of the transformer for the test. After the transformer has been dried, its insulation performance needs to be fully evaluated to check its drying effect. The identified items, except the casing, are the same as the test items during the overhaul.
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