Dew Point of Transformer Air Drying

When the transformer body needs to be exposed during the installation of transformer accessories, the relative humidity of the environment must be less than 80%, and an appropriate amount of dry air should be supplemented (dew point should be lower than -40°). What does "dew point" mean here?

We know that there is a certain relationship between the saturated water vapor pressure and the saturation temperature in humid air. When the temperature decreases, the saturated water vapor pressure P decreases with the decrease, and the saturated moisture content d decreases with the same. In the process of decreasing the air temperature, as long as the water vapor in the air is not precipitated, the moisture content d of the air remains unchanged. As the temperature of the air decreases, the saturated moisture content d also decreases accordingly. At this time, although the moisture content d changes, the relative humidity of the air increases. When the relative humidity increases to 100% (that is, the humid air reaches a saturated state), if the temperature continues to decrease, water vapor will condense out. Therefore, the humidity corresponding to cooling the humid air to the relative humidity φ=100% under the condition of constant moisture content becomes the dew point temperature of the air.

When air reaches saturation, its dew point temperature, wet bulb temperature, and dry bulb temperature are all equal.

During the installation or maintenance of the transformer, it is necessary to supplement dry air. The dry air generator developed and manufactured by PureTech can continuously supply the transformer with high-purity dry air with a dew point of -50℃~-80℃.

PureTech's DAG series dry air generators also called as transformer air drying systems, which are designed to provide dry air during installation and maintenance of large transformers, reactors and other power equipment of 220KV and above. It can replace the traditional drying methods such as hot oil circulation, nitrogen supplementation, and vacuuming, and is more efficient, economical, safe and environmentally friendly. When using PureTech's DAG series dry air generator for installation and maintenance of electrical equipment, it is completely unaffected by changes in external climate conditions (even in cloudy and rainy days, it can be filled with dry air while working). If it is an overnight operation, you only need to seal the flanges everywhere and fill with dry air to reach 0.02~0.03MPa. There is no need for oil injection, nitrogen supplementation or vacuuming, etc., and the power equipment such as transformers and reactors will not be affected by moisture. It reduces the workload, shortens the operation time, and improves the quality of installation and maintenance.

PureTech's DAG series dry air generators can also be used for air drying and circulating drying in warehouse, packaging, electronics, pharmaceutical and other industries, as well as nitrogen, generator hydrogen and SF6 equipment drying.

DAG dry air generator can replace the traditional drying method, which is efficient, economical, safe and environmentally friendly. It integrates air compression, cold drying and adsorption, and can be moved freely.

More information about transformer dry air generators, please consult us PureTech.