Transformer oil plays a crucial role in the operation of power transformers. It not only helps in cooling but also provides necessary insulation.
Ⅰ. What is PCB in Transformer Oil?
Polychlorinated Biphenyls (PCBs) are a class of synthetic organic compounds. Due to their non-flammability and excellent insulating properties, PCBs were widely used as coolants and lubricants in transformers, capacitors, and other electrical equipment. However, in 1977, the United States stopped the production of PCBs because evidence showed that PCBs accumulate in the environment and pose harmful health effects. Additionally, PCBs are difficult to degrade, making them prone to long-term environmental accumulation and pollution. To date, many countries and regions have banned or restricted the use of transformer oil containing PCBs.
Ⅱ. How to Identify the Type of Transformer Oil?
1、Labels and Documentation
The simplest way to distinguish different types of transformer oil is by checking the labels or manufacturer-provided specification sheets and technical documentation. Most transformer oils have clear labels on the packaging indicating the type of oil and the manufacturer. Specification sheets or technical documentation provided by the manufacturer typically contain detailed information about the oil used in the transformer.
2、Physical Observation
– Color and Odor: Mineral oils are usually light yellow, while synthetic oils may come in different colors. Vegetable oils typically have a specific plant smell. Observing the color and smelling the odor can give an initial indication of the oil type.
– Appearance and Transparency: Different types of oils may vary in transparency and appearance. Mineral oils are usually transparent, while vegetable oils may appear slightly cloudy.
3、Chemical Analysis
– Gas Chromatography (GC): By using gas chromatography, the chemical components of transformer oil can be separated and identified. For example, synthetic oil may have multiple, sharper peaks in the GC spectrum, while mineral oil may show broader, more symmetrical peaks.
– Infrared Spectroscopy (IR): Infrared spectroscopy can identify the chemical structure of transformer oil by detecting characteristic absorption peaks, thus determining the oil type. For instance, mineral oil typically shows broader, irregular absorption peaks in the IR spectrum.
4、Laboratory Testing
Laboratory testing is the most accurate method for distinguishing types of transformer oil. By testing various parameters such as dielectric strength, viscosity, and flash point, the type and quality of the oil can be determined. For example, the dielectric strength of mineral oil usually ranges between 30-50 kV/2.5mm, while vegetable oils (such as rapeseed oil, soybean oil, etc.) usually have a dielectric strength between 50-60 kV/2.5mm.
5、Professional Testing Institutions If the oil type cannot be accurately identified using the above methods, oil samples can be sent to professional testing institutions for comprehensive analysis. Professional institutions have advanced testing equipment and technology to provide accurate results.
Fourier Transform Infrared Spectroscopy (FTIR) Analysis of Mineral Oil
Ⅲ. Why We Cannot Use Oil-Type Transformers in Basements?
Using oil-filled transformers in basements presents several safety and operational issues that limit their application. Here are the main reasons:
1、Safety Hazards
Oil-filled transformers use mineral oil or other insulating oils that are flammable. In the confined space of a basement, a fire or explosion would be difficult to control, making rescue efforts challenging and potentially leading to significant casualties and property damage.
2、Cooling Issues
Oil-filled transformers generate a lot of heat during operation. Basements usually have poor ventilation, making it difficult to effectively dissipate this heat. This can lead to transformer overheating, affecting its performance and lifespan, and possibly causing a fire.
3、Installation and Maintenance Challenges
Basement spaces are often limited, posing difficulties in installing large oil-filled transformers and related equipment (such as radiators, oil tanks, etc.). Additionally, the confined nature of a basement makes it challenging to inspect and maintain the transformer if a fault occurs, and poor ventilation complicates heat dissipation during such incidents.
4、Environmental Pollution Risk
Oil leakage is a potential risk with oil-filled transformers. If leakage occurs, mineral oil can pollute groundwater and soil, leading to environmental issues. In basements, such pollution is harder to clean and manage, causing long-term environmental impact.
5、Regulations and Standards Restrictions
Many countries and regions have strict electrical and safety regulations that restrict the use of oil-filled transformers in confined spaces like basements. These regulations aim to ensure public safety and environmental protection, encouraging the use of safer and more environmentally friendly transformer types.
Therefore, dry-type transformers are typically used in basements. Dry-type transformers do not contain oil and are safe, environmentally friendly, and easy to maintain, making them more suitable for enclosed spaces like basements. If you need to install a transformer in a basement, consult a professional electrical engineer or supplier for the best equipment selection and installation advice.
For more professional guidance and services regarding transformers, please contact SUNPOLE. SUNPOLE specializes in producing 10kV and 20kV oil-immersed transformers as well as 35kV dry-type transformers. In addition to standard products, we also offer customization services to meet your specific transformer requirements. Our expert team is dedicated to providing you with the best solutions to ensure the safety and stability of your electrical system. Whether you need high-quality transformers for industrial applications or specially designed configurations for unique electrical setups, SUNPOLE is your trusted partner.
