A transformer insulation drying standards
(1) transformer insulating oil does not contain water. Oil breakdown voltage of not less than 75% of the factory data.
(2) The insulation resistance of not less than 70% of the factory data.
(3) dielectric loss tangent is not more than 130 percent of the factory data.
Two, transformers meet the following conditions should be dried
(1) maintenance, replacement of the winding or insulation.
(2) in the repair or installation of the body of inspection, the body of exposure in the air longer than the specified time.
(3) The insulation resistance and transformer winding moisture absorption ratio measurement proved.
, Dry transformers deal with the common method
(1) induction heating method, the body of the original tank, the tank outside the winding pass into the coil current, the use of eddy current heating of the tank skin to dry. Tank wall pad asbestos board more than one wire around the asbestos bar board. Induction heating power, determined in accordance with the type of transformer and dry conditions.
(2) hot air drying method: transformer placed in the drying chamber, which leads to a hot air drying. The drying chamber wall ride together in accordance with the variator body size, paved with asbestos board siding or other fire protection solution impregnated canvas or asbestos linen. The drying room should be as small as possible, the spacing between the panel and the transformer should not exceed 200mm. Available furnace, steam serpentine tube to heat. Hot air at the inlet filter should be installed or the installation of metal grid to eliminate Mars, dust. The hot air should not blow directly to the body of blowing evenly as possible from the body of the following ministries, so that moisture released through the ventilation holes in the box.
(3) oven drying method: If the repair place oven equipment, small capacity transformers using this method is better. Dry the body of the crane into the oven, control the internal temperature is 95 ° C per h test for insulation resistance. Oven upper part should vent to release the evaporated moisture. In addition, during the drying process should be manned, paying particular attention to safety.
, Transformer drying process should be consistent with the requirements
(1) Regardless of which method to heat and dry transformer, oil transformer device body temperature must not exceed 95 ℃, dried with oil when the oil temperature shall not exceed 80 ° C, in order to avoid the aging of the oil. If drying can not improve the insulation resistance should be used when the oil-free dry with oil.
(2) with oil drying method 4h measuring a breakdown voltage of insulation resistance and oil. Steady state when the oil breakdown voltage, insulation resistance values ??are also continuous 6h remain stable, you can stop dry.
(3) drying chamber, such as vacuuming, should open the vent in the lid on or use of the throttle holes so moisture release.
(4) is heated with oil, should be installed outside the tank insulation layer, the insulating layer can be used asbestos cloth, glass cloth insulation material shall not use combustible materials, and shall take ap propriate fire prevention measures.
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