The on-site drying treatment system is mainly composed of a hot oil circulation system, a vacuum drying system and a main transformer winding insulation test system.
(1) The function of the hot oil circulation system is to heat the main transformer circulating oil. The heated oil transfers heat to the transformer windings, the core and the insulating material, so that the whole body is heated, so that the water in the insulating material evaporates.
(2) The function of the vacuum drying system is to evaporate the moisture in the transformer insulation material and extract it from the transformer tank. Because moisture easily evaporates in high temperature vacuum.
(3) The function of the insulation test system is: the insulation resistance test and the dielectric loss test are generally carried out in the insulation test. The dielectric loss test voltage under the oil-free state in the transformer body is controlled at about 2 kV. The measured data in the test can be For the purpose of determining the degree of dryness.
On-site drying preparation
Drying equipment such as oil tank, vacuum oil filter and vacuum pump, fire-fighting equipment in place; close the upper and lower butterfly valves of the cooler, connect the pipeline between the drying equipment, and install the temperature measuring device (installation position should be easy to monitor and record) ), connect the power supply; surround the transformer with canvas, so as not to lose heat when the transformer body is heated. Strengthen duty and pay attention to fire prevention.
Drying process and analysis of test results
80% of the transformer oil is stored in the transformer and heated to 90 °C ± 5 °C. Then the oil is introduced into the winding through the strong oil passage, and the two oil filters dehydrate the transformer oil to make the water content of the transformer oil. Always stay at a low level. In this case, the insulating member, especially the water molecules in the low-voltage winding, will continuously diffuse into the oil, and the insulation performance will also increase.