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Paraffin based transformer oil is a type of insulating oil derived from refined petroleum, characterized by its high dielectric strength and thermal stability. In power transformers, paraffin based transformer oil is used to insulate and cool the transformer components, preventing overheating and ensuring efficient operation. Its chemical stability also helps to minimize oxidation and prolong the lifespan of the transformer.

The name of transformer oil, as detailed in the PDF, is mineral oil. Mineral oil is commonly used in power transformers due to its excellent insulating properties and thermal conductivity. It serves as both an insulator and a coolant, helping to dissipate heat generated by electrical currents within the transformer. Additionally, mineral oil has a high flash point, enhancing safety in electrical applications.

The SOP for transformer oil filtration in power transformers typically includes several key steps. First, the transformer is isolated and de-energized. Next, the oil is drained and filtered using a vacuum filtration system to remove moisture, particulate matter, and dissolved gases. The filtration process should ensure that the oil meets specified dielectric strength and moisture content standards. Finally, the filtered oil is reintroduced into the transformer, and the system is tested for proper operation.

Major oil filled transformer manufacturers include global OEMs such as Hitachi Energy, Siemens Energy, GE Grid Solutions, Schneider Electric, Eaton, and other regional transformer OEMs that build distribution and power transformers for utilities and industry. The “major” list varies by region and voltage class, and project specs often require approved vendor lists (AVL). When choosing, compare factory test capability, IEC or IEEE compliance, service network, lead times, and reference projects.

A dehydration plant removes moisture and often dissolved gases from transformer oil. Oil is heated to reduce viscosity and release water, then processed under vacuum so water evaporates at lower temperature. Fine filtration removes particles, and degassing strips air and fault gases. The treated oil is returned to the transformer or stored. This restores dielectric strength and improves cooling by reducing water driven aging.

IEC standards commonly referenced include IEC 60296 for requirements of unused mineral insulating oils, IEC 60156 for determination of breakdown voltage, and IEC 60422 for supervision and maintenance guidance for mineral insulating oils in electrical equipment. Additional IEC documents can apply to specific tests such as moisture and dielectric loss depending on the program and oil type. Utilities typically reference a set of IEC test methods and acceptance criteria in procurement and maintenance specifications to ensure consistent quality and comparable results over time.

Common commercial names include mineral oil brands and ester fluid brands supplied by large oil and specialty chemical companies. Examples often seen in the market include Shell Diala series, Nynas Nytro series, and other mineral insulating oils from major refiners, as well as natural ester and synthetic ester fluids used for fire safety and environmental performance. Many regions also have strong local brands. In procurement, utilities typically specify compliance to standards and approve certain vendor lists rather than relying only on brand names, to ensure consistent quality and documentation.

Envirotemp transformer oil is used in urban installations due to its high fire point, low flammability, and biodegradability. These properties significantly reduce fire risk and environmental impact in densely populated areas. It is commonly applied in indoor substations, underground vaults, and locations with strict fire and environmental regulations.