Definition
Transformer oil refers to an insulating oil product used in oil-filled electrical equipment such as transformers, reactors, instrument transformers, and bushings, serving the purposes of insulation and cooling.
Function
First, transformer oil offers superior insulation compared to air. Immersing the core in oil enhances insulation across key components - between leads, windings, and the windings and tank - and protects the winding insulation from moisture
Second, it also handles cooling through a simple cycle. The oil heats up and rises into the radiators. There, it cools down and flows back into the tank. This continuous flow carries the heat from inside the transformer out to the surrounding air.
Finally, there's another critical role: arc suppression. When a high-energy arc occurs inside the equipment, the surrounding insulating oil is subjected to extreme heat. This causes it to decompose, generating a surge of gas and a rapid pressure increase. The expanding gas effectively displaces and cools the arc channel, thereby raising the dielectric strength and ensuring the arc is swiftly interrupted.
Basic Requirements
High dielectric strength is essential for transformer oil. To achieve this, the oil must be free of impurities such as acids, alkalis, sulfur, moisture, dust, and fibers, which in turn allows it to withstand the transformer's operating voltage, isolate components at different potentials, and prevent short circuits.
The oil's viscosity is also critical.
| Property / Aspect | Requirement / Ideal State | Consequence of Deviation / Degradation |
| Viscosity | Must be moderate (balanced) - • Low enough to ensure good fluidity for convective heat transfer. • High enough to maintain a safe flash point. |
• Increases with oil degradation. • Slows down oil circulation. • Impairs heat dissipation. • Leads to higher winding temperatures. • Ultimately shortens equipment service life. |
| Purity | Must be free from solid impurities such as fibers and metal particles. | • Can clog oil passages (impeding flow). • May form conductive paths (compromising insulation). |
Sourcing
VKE places great importance on the quality of the transformer oil. We follow industry guidelines closely and source oil from reputable brands that meet both national and international standards. Basic checks are carried out before oil is filled, to make sure key properties meet design specifications.
Before delivery, every transformer undergoes simple oil testing. We provide the test records along with the product. We also offer practical advice on how to monitor and maintain the oil during operation-helping our clients spot potential issues early and keep their transformers running safely and smoothly.