What Is Transformer Oil Testing and Properties?

Transformer oil, also known as insulating oil or mineral oil, serves as a dielectric and a coolant in transformers, oil type vacuum circuit breaker, cable, etc. Transformer oil’s primary functions are to insulate and cool a transformer. It must therefore have high dielectric strength, thermal conductivity, and chemical stability, and must keep these properties when held at high temperatures for extended periods. Its quality needs to be regularly assessed to ensure proper transformer operation and prevent failures. Lucyelec Test Equipment Co., Ltd is engaged in transformer oil testing equipments since 2015. We offer a range of transformer oil testing devices and service to make sure your quick and accurate testing of transformer oil. In this article, we’ll take a closer look at transformer oil testing and its properties.

 

Basic Tests of Transformer Oil: Breakdown Voltage/Dielectric Strength, power factor, water in oil/moisture content, flash point, neutralization number, interfacial tension, dissolved gas analysis, Furan analysis, PCB analysis…

1. Breakdown voltage (BDV) indicates the ability to withstand voltage without failure. Acidity, measured as total acid number (TAN), indicates the presence of acidic compounds that can degrade the oil and affect transformer performance. Moisture content, measured as parts per million (ppm), is critical as moisture can reduce the dielectric strength of the oil. Flash point, measured in degrees Celsius, is the temperature at which the oil gives off vapors that can ignite, and it indicates the oil’s fire resistance. Interfacial tension, measured in dynes/cm, is an indicator of the oil’s ability to prevent the formation of emulsions.

2. Dissolved gas analysis (DGA): DGA is a crucial test that helps detect the presence of gases dissolved in transformer oil, which can indicate the type and severity of faults in the transformer. Common fault gases such as hydrogen, methane, ethane, ethylene, acetylene, and carbon monoxide are monitored, as their presence can indicate various issues such as overheating, partial discharges, and arcing. DGA can provide early warning signs of developing faults and help prevent catastrophic transformer failures.

3. Furans analysis: Furans are organic compounds that are formed during the degradation of cellulose, which is used as insulation in transformers. Analysis of furans in transformer oil can provide insights into the condition of the transformer’s solid insulation and detect any abnormal degradation or aging.

4. PCB analysis: Polychlorinated biphenyls (PCBs) are toxic and persistent environmental pollutants that were used as insulating fluids in older transformers. PCBs have been banned in many countries due to their harmful effects, and transformer oil is tested for PCB content to ensure compliance with environmental regulations.

5. Standards and guidelines: Transformer oil testing is typically performed in accordance with industry standards and guidelines, such as ASTM D3612, IEC 60422, IEEE C57.104, and CIGRE. These standards provide recommended practices and procedures for sampling, testing, and interpreting the results of transformer oil tests.

 

In summary, transformer oil testing is a critical part of transformer maintenance, involving various tests such as basic oil tests, DGA, furans analysis, and PCB analysis. Trend analysis and adherence to industry standards and guidelines are important aspects of transformer oil testing. Regular testing and proactive maintenance based on test results can help ensure the optimal performance and longevity of power transformers.

 

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