Moisture in Transformer and Transformer Oil
The transformer is the heart of the power circulation system. To maintain the transformer to its peak performance high purity of insulating oil is a very prime important. Excessive moisture in transformer oil significantly reduces the dielectric strength of the transformer oil.
The term "Moisture" in the transformer is commonly used to indicate water which is absorbed in the paper or dissolved in the oil. Occasionally, the terms "water" or "water content" are used as an alternative way to describe the same substance.
Water in transformers can be found in different parts of the insulation system. It can accumulate in solid insulation, be dissolved in oil, or be found in the form of liquid water at the core or bottom of a transformer.
If it has been determined that a transformer has an excessive moisture content, either through water-in-oil analysis or dew-point-analysis , the transformer should be dehydrated/ dried out . Otherwise, the presence of moisture in the kraft paper will definitely shorten the life due to chemical decomposition through oxidation of the cellulose.
The Danger of Water in Transformer Oil:
Moisture content in transformer oil is a life shortening parameter and has following effect on the insulation system:
→ weaken the dielectric strength ( breakdown capacity) and partial discharge stability;
→ intensive aging of paper insulation;
→ acceleration of oil oxidation;
→ increases formation of carbon with electric arcing;
→ increases corrosion of transformer metal parts caused by the oil;
→ reduces fluidity of the oil at higher temperatures;
→ reduces the overload capability of transformer in emergency conditions;
→ increases the electrical conductivity, tan δ, etc.
Moisture Source into transformer oil
There are two ways for water to get into the oil. The first one is the atmosphere. The second is water from the cellulose insulation and the oil, which appears due to the aging processes. If the transformer is constantly operated with full load, its insulation system will age in approximately 20-30 years. As much as 0.5-0.75% of insulation weight will be released as water during that time.
1) Residual moisture.
2) From the atmosphere i.e. breathing during load cycles (e.g. saturated dehydrating breathers).
3) Via leaks into the power equipment, i.e. bad gasketing, cracked insulation, a loose manhole cover, a ruptured explosion diaphragm etc.
4) During installation and / or repair.
5) Paper degradation produces water.
Oil degradation produces water.
Testing of Moisture Content in Transformer Oil:
Transformer oil testing is performed for both for new transformer oil and unqualified running oil. Moisture content is a part of the testing is both cases.
Knowing the amount of water in the oil is indicative of its quality, and provides information on the causes of oil and solid insulation dielectric strength deterioration.
The highest allowed concentration of water in transformer oil depends on the type of equipment; on average, no more than 10-20 ppm (parts per million) is allowed. Detecting such small amount of water requires the highly precise and sensitive instrument.
Karl Fischer Titrator is one of the most popular and effective method of measuring water content in transformer oil and other type of oils. FUOOTECH’s FTWS-809 trace moisture titrator works more reliably and conveniently by using the most advanced control circuit and 32 bit embedded microcontroller processor as the master control core and utilizing embedded mini operating system. Due to fast analyzing speed, simple operation, high precision and strong automatism, FTWS-809 moisture content tester has been widely used in the industry of petroleum, chemical, power, railway, pesticide, medicine and environmental protection.
Please visit the product link of FTWS-809 to know more.
Transformer Oil Dehydration – The High Effective Method
In the past, the most common transformer oil dehydration processes were centrifugal separation.
Centrifugal force separates the processed liquids from solid particles and water. However, it can remove only emulsified water. This is not enough, so the process is usually only used as a preliminary stage of oil purification.
FUOOTECH produces the high vacuum transformer oil dehydration plant involves high temperature and vacuum. First, the oil is heated upto a certain temperature (60 ~ 65℃); hot oil passes into a vacuum degassing and dehydration chamber. The combined influence of temperature and vacuum causes intensive emission of water and gas from the oil, which is spread as a thin film on the surfaces inside the vacuum degassing and dehydration chamber. The degassing and dehydration chamber is provided for removal of dissolved gases and moisture from the oil. Vacuum pumps are provided for evacuation of degassing and dehydration chamber. This type of oil dehydration equipment is more efficient.
Please visit the product link of ZYD-T Series High Vacuum Transformer Oil Dehydration Machine to know more.
FUOOTECH provides you the one-stop solutions for your transformer manufacturing machines, transformer oil testing, transformer oil dehydration, transformer oil treatment, transformer vacuum pumping system, transformer drying air generator, transformer test equipment, etc. since 2002.
Welcome to contact us for any inquiry and cooperation.
