SU1365265A1 - Method of drying solid insulation of electric machines and apparatus in sealed tank - Google Patents

Abstract

The invention relates to the field of electrical engineering, in particular to drying in a sealed tank of solid insulation of transformers. The purpose of the invention is to expand the field of application by allowing for effective drying at a high residual pressure in the tank. When drying in the tank, circulation and spraying of hot oil is created, which irrigates the transformer insulation. Air circulation in the tank is also ensured with its drying. Drying is carried out before reaching. given moisture content. 1 ill., 1 tab. c (o

Description

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The invention relates to electrical engineering, in particular, to methods of drying in a sealed tank of solid insulation of electrical machines and apparatus, mainly transformers, during their operation.

The purpose of the invention is to expand the field of application by allowing for effective drying at a high residual pressure in the tank.

The drawing shows a diagram of an apparatus for carrying out the proposed method.

An oil pump 3, an oil heater 4 with a temperature control device 5 are installed in the oil pipeline 1 of the circulation of oil in the tank 2 of the transformer. Inside the tank there are mounted sprinklers 6, to which the oil pipes are connected. The sprinklers are installed so as to ensure that the insulation 7 is almost completely washed with heated oil. On the transformer tank 2, a device 8 for controlling the residual pressure / geni is installed, if during drying a negative pressure is created by the tank design. A vapor trap 10, a compressor 11 (an electric fan or a vacuum pump) and a filter 12 can be installed in the vapor-vapor circulation pipe 9 in the tank and the filter 12 to clean the oil from the vacuum pump or compressor.

The method is carried out as follows.

The transformer tank 2 is sealed carefully. Using a compressor or vacuum pump 11, a vacuum is created in the transformer, for which the tank is designed (if necessary). To do this, it is necessary to open valve 13 and shut off valve 14. Fill the ba with transformer oil 15 to the level of isolation 7. They turn on the oil pump 3 and the oil heater 4 and ensure hot oil circulation and spraying. The valve 14 is opened, the valve 13 is closed and the vapor-air medium in the tank 2 is circulated. After the insulation temperature reaches 75-85 ° C, the oil heater and the oil pump are turned off and the air circulation and the removal of moisture from it by means of sorbents and freezing are continued. After cooling the insulation to 45-50 ° C, the operations of heating and drying are repeated at

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Klyuchenny oil heater. Control over the process and termination of drying is carried out by the amount of moisture released in the water vapor trap, by the value of the dew point of the air circulating in the tank and by the values of the insulation resistance.

Example. The solid insulation of the transformer TDTG-40500/110 / 38,5 / 6,6 is dried. For drying the transformer, ten cycles of removing moisture from the insulation are performed. The duration of each cycle is 24 hours (12 hours of heating and 12 hours of circulation and drying of the drying medium). After the sixth cycle in the tank, a vacuum of 350 mm Hg is created and maintained until the end of drying. The insulation is heated to 80-88 ° C with an oil of 9Q ° C. After the heating and spraying is turned off, the medium is circulated in the tank by means of a vacuum pump. The dehydration of the vapor-air medium is carried out in a trap by freezing water vapor (the temperature of the cooling surface of the trap is minus).

The drying process is monitored by changing the amount of moisture in the trap and changing the moisture content of solid insulation samples taken from transformer insulation (sample No. 1) and a specially prepared layout (sample No. 2). The results are shown in the table.

The proposed method of solid insulation of transformers, in comparison with known methods, makes it possible to efficiently dry solid insulation in containers that are not designed for vacuum and does not require the use of vacuum equipment.

Claims (1)

Invention Formula The method of drying in a sealed tank of solid insulation of electrical machines and apparatus, mainly transformers, based on the repetition of cycles, including irrigation of the insulation with heated oil when splashing until the specified insulation temperature is reached, reducing the temperature of the insulation after the completion of irrigation, characterized in that in order to expand the field of application by obtaining the possibility of effective drying with a large balance of 1365265 exact pressure in the tank, in addition, the vapor-air medium in the tank is forced to circulate just the same by simultaneously draining it, mainly by freezing, until a given moisture content is reached.