Transformer drying process removes traces of moisture in thetransformer oil, besides enhancing insulation resistance and flashover voltageof transformers. The drying process is almost a part of production and is done regularly. Moisture management is an important aspect of transformer maintenance because moisture is connected to ageing and deterioration of the equipment.
When the insulation gets damp and accumulates moisture, itsfunctionality and heat transfer are affected. Insulation between various phasesof the transformer is important attribute because it decides the lifespan of the transformer.
Paper and insulating oils are insulation medium andinsulation is affected when such paper absorbs water which in turn conductselectricity. If insulation of the transformer is not in prescribed levels, it results in surge of electricity which the transformer might not withstand and ultimately breakdown or collapse in failure.
The transformerdrying oven distinguishes pressure difference between water vapour in theinsulation and that around the insulation. The drying time is directlyproportional with the operating voltage and transformer size.
The transformerdrying oven is kept in supervision and must never be left unattended sinceit might lead to damage of insulating material. They must also be in theabsence of smoke or sparks.
The windings in the transformer play a crucial role in thelifespan and activities of the equipment. The windings remove the moisturewhich in turn damages the dielectric strength of the transformer and increases ageing of the apparatus.
While employing a dryingoven, two parameters namely control over drying temperature and enhancementof vacuum degree of the equipment, are emphasized.
Dryingovens are popular for their simple operations and uniform removal ofmoisture. The insulation is heated which releases the water content in theinner layers as vapour which is transported to the outer layers.
Conventional methods are tricky in assuring the removal ofmoisture content and hot aircirculation system is preferred owing to use of vacuum which ensures theefficiency of moisture removal.
Dryingoven is customized based on their oven size, type of air circulation andapplications.
Hot aircirculation system plays a vital role in drying out the core coil of thetransformer which effectually removes moisture. 112 degree Celsius and 120degree Celsius is set as temperature range in the core coil and definite temperature inside the oven is 125 degree Celsius, which is apt setting for dryingoven in distribution transformer.
The dielectric power loss is measured as loss factor andthis loss is decreased as moisture decreases. However, the loss factor is notrelated to the insulation area or thickness or physical parameters.
The prescribed oven temperature at 120 degree Celsius isbased on maintaining safety attributes between conductor and insulation layers.
On a concluding note, transformerdrying oven play an important role in the functionality and longevity oftransformer and their characteristics should be diligently applied to theatmosphere in which they function. With increase in production of transformers, the drying ovens are evolving accordingly so that their drying parameters meet with the requirements that the transformers might demand.
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