How is the interfacial tension test of transformer oil conducted?

The interfacial tension test of transformer oil is conducted using standard methods defined by ASTM D971 or similar specifications. The procedure involves taking a sample of transformer oil and placing it in a clean, dry test vessel. An aqueous solution, typically distilled water, is added to the oil sample. The mixture is allowed to settle, enabling the formation of distinct oil and water layers. A tensiometer is then employed to measure the interfacial tension between the two liquids, which is crucial for assessing the oil’s ability to separate from contamination and for evaluating its overall quality. This test is important in monitoring the condition of transformer oil, ensuring optimal performance and longevity of transformer equipment.