Why Is A Power Transformer Vacuum Dried And What Does Vacuum Drying Entail

Water content inside an insulation material affects good insulation. Thus, the need to develop insulation with the minimum water content. It will help accomplish better insulation properties. Removing water from an insulating material is referred to as drying. It is possible to an extent by heating an insulating material and evaporating water from the insulation. The sad fact is that heating an insulation material is not advised. The reason is that there are chances of damage to the chemical and physical properties of insulation material. Let us assume the case of power transformers. It’s not possible to elevate temperature for evaporating water from this insulation. The transformer’s physical properties are destroyed. Moreover, it could be hazardous.

Below, we are going to discuss the vacuum drying of transformers.

How To Achieve Drying Without Heating The Insulation Material In Transformers

Insulation materials can be dried at low temperature and pressure. The pressure and temperature for drying differ for separate materials. What happens under vacuum? The water vapor evaporation rate accelerates when adequate heat is given to insulation material. Thus, an insulating material appropriately heated and exposed to vacuum dries well.

Vacuum Drying Of Power Transformers Requires Some Components

Some components are needed for a Transformer Vacuum Drying Process. They are a closed chamber with low pressure, a vacuum system, a heating system, and a controlling mechanism. Next, we discuss these components.

This closed chamber with low pressure s mostly rectangular and has a size for placing a transformer or several transformers. This chamber has a rigid construction to endure heat and vacuum. A trolley maneuvers a transformer into the chamber and out.

This Vacuum System features condensers, vacuum pumps, and booster pumps. The vacuum and booster pumps vacate the chamber and remove moisture or gas from inside. Condensers are deployed in a sequence of vacuum pumps. They condense the water vapor removed from the insulation of a transformer.

What is the function of the Heating system in a power transformer vacuum drying process? Tubes are present on the inside walls of the oven. A searing fluid flows in the tubes and transfers heat to the item within the oven.  A gas-powered boiler or electrical heaters are deployed outside to heat the fluid. A fan within the oven distributes the temperature uniformly. Thus, the insulation of the transformer warms faster.

Now, the Controlling Mechanism. PLC and SCADA are results of advanced technology. They monitor and control the complete process of drying to preferred levels. The monitoring and control of vacuum levels are possible. The control of the temperature within the vacuum drying oven is possible. So, what can be monitored and controlled in the vacuum dying of a power transformer? The drying time, the drying amount, and the ending of the drying process.

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