What is the Significance of Measuring the Interfacial Tension of Transformer Oil

The interfacial tension between oil and water reacts to the affinity between oil and water. If the tension is large, oil and water are not easily miscible (emulsified), and oil is easy to dehydrate during refining (an important indicator of insulating oil is that trace water PPM cannot exceed the standard). It is not easy to absorb water during operation, so the standard of transformer oil should stipulate that its interfacial tension should be greater than a certain value.

If the transformer oil is polluted or oxidized and aged during operation to generate some trace new substances, there is no doubt that the tension of the oil-water interface will decrease. The decrease in tension objectively reflects the amount of foreign matter in the oil in some aspects. These extremely small amounts of foreign matter may be difficult to qualitatively and quantitatively detect, but they tend to have obvious reactions to the dielectric loss of oil. Although the interfacial tension between oil and water and the dielectric loss of oil are not simple linear relationships, the insulation The interfacial tension between oil and water will definitely affect the ease of mixing oil and water. If the interfacial tension between oil and water is small, the degassing (dehydration) refining process of oil is more difficult, and the time required is longer. It is easier to absorb "moisture", and it is well known that the presence of trace water in insulating oil will have a greater impact on many properties of the oil. Therefore, it can be considered that the decrease of the interfacial tension between oil and water can objectively reflect the existence of unknown trace impurities in the oil and the mutual affinity between oil and water.

The measurement of the interfacial tension of insulating oil and transformer oil is based on ASTM D971. The ring method measures the surface tension of various liquids (liquid-gas interface) and the interfacial tension between mineral oil and water under non-equilibrium conditions ( liquid-liquid interface). The instrument adopts microprocessor technology, which has a high degree of automation, simple operation and reliable work. After the sample to be tested is injected into the sample cup, as long as the start button is pressed, the instrument can automatically complete the measurement of the sample, and can automatically measure the sample according to the input value. The specific parameters calculate the tension value of the tested sample.

The instrument adopts single chip technology, large-screen liquid crystal display, beautiful appearance, high degree of automation, simple operation, high accuracy and good repeatability. Input data parameters are saved when power off; with temperature correction function. The instrument is widely used in the determination of interfacial tension in the production process and products of electric power, petroleum, chemical, railway and other industries.

Technical parameter:

Display system: large-screen LCD display interface tension

Measurement methods: Ring method (ASTM D971);

Test sample: Liquid to liquid, liquid to gas

Pt ring diameter: R9.55, Pt wire r0.3

Measuring range: 2～200mN/m

Resolution: 0.1mN/m

Self-checking: Fault auto analysis

Temperature compensation: Automatic temperature compensation

Applicable temperature: 10--30℃

Adapt to temperature: ≤80%

Power supply: AC 220V±5%, 50H2