During transportation, storage and use, the transformer may enter from the outside or the oil itself oxidizes to produce water, and the generated water will exist in the following states:
1. Free water. Mostly the water invaded by the outside world, if not stirred, it is not easy to combine with water. Does not affect the breakdown voltage of the oil, but should also be disposed of immediately.
2. The Extremely fine particles are soluble in water. Usually entering the oil from the air, sharply reducing the breakdown voltage of the oil. Increased dielectric loss, vacuum filter oil.
3. Emulsified water. Poor oil refining, or long-term operation caused by oil aging, or oil contamination by emulsion, will reduce the interfacial tension between oil and water, such as oil and water mixed together, it will form an emulsified state. Add emulsifier.
The hazard: First, reduce the breakdown voltage of the oil. The breakdown voltage of 100～200mg/kg is greatly reduced to 1.0kV. The fiber impurities in the oil absorb water easily, and under the action of electric field, a conductive “small bridge” is formed between the electrodes, which is easy to break down. The second is to increase the dielectric loss factor. Suspended emulsified water affects Zui large and uneven. The third is to promote the aging of insulating fibers. The molecules of insulating fibers are glucose (C6H12O6) molecules. When water enters the fiber molecules, the gravitational force is reduced, which promotes hydrolysis into low molecular substances and reduces the mechanical strength and polymerization degree of the fibers. Experiments have shown that at 120 ° C, the mechanical strength of the fiber decreases by 1/2 for each increase in moisture in the insulating fiber. When the temperature rises, the water in the oil increases, the water of the fiber decreases, and the temperature decreases, on the contrary. Therefore, the micro-water in the oil should be monitored to monitor the aging of the insulating fibers. Fourth, water promotes the corrosion resistance of organic acids and accelerates corrosion of metal parts. In summary, the more water content in the oil, the aging of the oil itself, the aging of the equipment and the faster the corrosion rate of the metal parts, it is necessary to monitor the moisture content of the oil, especially the dissolved water content.
JY6611 Oil Breakdown Voltage Tester, transformer oil BDV tester, not affected by the voltage fluctuation of the power grid and the distortion of the waveform. The test results are more deterministic and accurate.