Transformer drying process removes traces of moisture in the transformer oil, besides enhancing insulation resistance and flashover voltage of 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, its functionality and heat transfer are affected. Insulation between various phases of the transformer is important attribute because it decides the lifespan of the transformer.
Paper and insulating oils are insulation medium and insulation is affected when such paper absorbs water which in turn conducts electricity. 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 transformer drying oven distinguishes pressure difference between water vapour in the insulation and that around the insulation. The drying time is directly proportional with the operating voltage and transformer size.
The transformer drying oven is kept in supervision and must never be left unattended since it might lead to damage of insulating material. They must also be in the absence of smoke or sparks.
The windings in the transformer play a crucial role in the lifespan and activities of the equipment. The windings remove the moisture which in turn damages the dielectric strength of the transformer and increases ageing of the apparatus.
While employing a drying oven, two parameters namely control over drying temperature and enhancement of vacuum degree of the equipment, are emphasized.
Drying ovens are popular for their simple operations and uniform removal of moisture. The insulation is heated which releases the water content in the inner layers as vapour which is transported to the outer layers.
Conventional methods are tricky in assuring the removal of moisture content and hot air circulation system is preferred owing to use of vacuum which ensures the efficiency of moisture removal.
Drying oven is customized based on their oven size, type of air circulation and applications.
Hot air circulation system plays a vital role in drying out the core coil of the transformer which effectually removes moisture. 112 degree Celsius and 120 degree 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 drying oven in distribution transformer.
The dielectric power loss is measured as loss factor and this loss is decreased as moisture decreases. However, the loss factor is not related to the insulation area or thickness or physical parameters.
The prescribed oven temperature at 120 degree Celsius is based on maintaining safety attributes between conductor and insulation layers.
On a concluding note, transformer drying oven play an important role in the functionality and longevity of transformer and their characteristics should be diligently applied to the atmosphere 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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