What Is The Prevalent Field Practice For Drying Transformer Insulation

The life of a transformer depends on the insulation system. What happens when a minute part of the insulation present in a critical location has an electrical or mechanical failure? The transformer’s possibly doomed. The average life-span of a transformer is 20.5 years when three conditions are imposed. What are they? The entire rated load nonstop, insulation temperature is 110°C, Moisture content present in insulation is structured to around 0.5% over life. Usually, constant operating conditions aren’t this severe. However, there is a break down in the glucose molecule chain of the paper insulation with time. However, the fact is that aging can be slowed.

The Three Leading Causes Of Insulation Aging

Oxygen, moisture, and heat are the three main components that cause insulation aging. The transformer owner must regulate them to get the most life from the transformer.

A constant cooling system and regulation of the load can control the temperature. A continual oil preservation system can control the oxygen.

Why Does The Insulation Moisture Level Of The Transformer Increase?

As we have stated above, the transformer's maximum insulation moisture level is 0.5% at the time of installation. What makes this level go up with use? There are three explanations. Insulation aging results in water, leaking gaskets, and water that the transformer absorbs during open time.

A common practice among owners is regasketing the unit at an interval of approximately 12 to 15 years.

The Prevalent Field Practice For Effective Moisture Removal From A Transformer Insulation

Boiling the water straight from the paper insulation is a common field practice for moisture removal from transformer insulation. This process is called Vacuum Transformer Drying. How is this done? With a rise in temperature and a decrease in the pressure within the unit. What this does is convert the moisture into a gaseous state. Subsequently, the moisture goes out of the transformer via the vacuum pump. Transformer owners can also physically measure the moisture removed by integrating a cold trap within the vacuum stream.

The solid insulating material can be heated in several ways. Some of them are hot oil bath, the use of electrical current, and hot air circulation. Most transformer owners use an equipment in the field. It draws on the transformer oil for heating the solid insulation. They circulate this oil between the equipment and the transformer till the active part reaches the maximum achievable temperature. Throughout the circulation, the oil is warmed and moved through quite a few filters to eliminate particulate matter. A couple of transfer pumps are often used in sequence to supply a greater vacuum and flow rate. Moreover, the oil goes through a vacuum chamber. Here, moisture and gas are removed. Now, the last part of "Vacuum Transformer Drying."

The oil is removed while keeping a "vacuum" on the transformer tank. The result is that the solid insulation surface is exposed to deep vacuum. The process can last between 12 and 48 hours. The blend of vacuum and temperature makes the moisture present in the insulation boil. Next, the vacuum pump system is deployed to extract water vapor.

Ricky is a graduate of computer science engineering, a writer and marketing consultant. he continues to study on Nano technology and its resulting benefits to achieving almost there.