Transformerolie

Transformerolie, or transformer oil, is a dielectric insulating oil used in electric power transformers, switchgear, and related equipment to provide electrical insulation and to transfer heat from windings to cooling surfaces. The most common type is mineral-based refined oil, while synthetic esters and silicone oils are used in specialized designs for particular performance goals.

Common types include mineral insulating oil, which is inexpensive and provides reliable dielectric strength; synthetic esters, including natural (vegetable-based) esters and semisynthetic variants, which offer higher flash points and improved fire safety but can have higher viscosity and cost; natural esters are biodegradable and increasingly favored for environmental reasons but can be more hygroscopic; and silicone oils, valued for thermal stability and dielectric performance but used in more limited applications. Polyalphaolefin (PAO) and other synthetic hydrocarbon fluids are also employed in some transformers, typically where specific thermal or chemical properties are required.

The oil serves two primary functions: electrical insulation to prevent arcing between conductors and effective cooling to remove heat generated during operation. Its properties, such as dielectric strength, viscosity, flash point, acidity, and moisture content, influence transformer performance and reliability. Oil quality is monitored through tests like breakdown voltage, acidity (or total acid number), water content, and dissolved gas analysis to detect aging, moisture ingress, or insulation faults.

Maintenance and handling involve purification, dehydration, and, when necessary, reconditioning or replacement of degraded oil. Disposal and recycling follow environmental regulations. Modern practice often seeks oils with favorable fire-safety and environmental profiles, including biodegradable natural esters, while ensuring compatibility with existing windings and seals.