The state of micro-water in the transformer oil, the transformer may be in the process of transportation, storage and use, or the oil itself may oxidize to produce water, and the generated water will exist in the following state: First, free water. Second, extremely fine particles are soluble in water. 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. At present, power transformers are not only among the most important and expensive equipment in power systems, but also one of the most troublesome equipment in power systems. Before the sudden failure of the transformer, the deterioration of the insulation and the latent fault will produce a series of effects and information such as light, electricity, sound, heat and chemical changes under the action of the operating voltage. Therefore, not only preventive maintenance based on preventive testing should be done regularly at home and abroad, but also predictive maintenance strategies based on online monitoring are being studied in order to monitor and diagnose latent faults or defects online or in real time [1] -4]. The content of micro water in the transformer insulating oil is also a parameter for determining the insulation quality of the transformer. Transformer online intelligent diagnostic equipment can automatically collect and analyze the content of micro-water in oil and get the cause of the fault, and provide solutions to enable users to solve the hidden dangers in the transformer in time to prevent accidents. 1. The state and harm of micro water in transformer oil 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: One is 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 it is also not allowed, indicating that there may be dissolved water in the oil, and it is disposed of immediately. Second, 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. The third is 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. The suspended emulsified water has the greatest influence and is 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. 2. Test method for micro water in transformer insulating oil Assessing the humidity in the insulation is an important factor in ensuring the reliability and service life of the transformer. The humidity in the insulating oil is constantly changing and may adversely affect the quality. In addition, most of the humidity is distributed in the insulating paper. Humidity affects the dielectric breakdown strength of solid and liquid insulating materials and affects the rate of aging of the cellulosic insulating material and the tendency of bubbles to form during overload. Ambient temperature, load, aging, leakage, and other factors can cause constant changes in humidity. Therefore, as the temperature of the transformer changes cyclically, continuous monitoring and diagnosis are required. This is more necessary for overload or peak load transformers. The total humidity in the transformer insulation system is determined by the moisture content of the cellulose and liquid. The humidity relationship between insulating paper and insulating oil depends only on the temperature. As the temperature increases, the solubility of water in the insulating oil (the water content of the solution) increases, and moisture is transferred from the insulating paper to the insulating oil. When the temperature is lowered, the process proceeds in the opposite direction, but the rate at which moisture flows from the liquid medium to the solid insulation material is rather slow. Therefore, the water content during the cooling of the insulating oil is higher than during the heating. Therefore, to accurately grasp the humidity distribution in the transformer, you must know where the equipment is in its thermal cycle. To monitor the true moisture content of the insulation paper by monitoring the moisture content in the liquid medium, the transformer must be in a relatively stable temperature state. The relative saturation of moisture in the insulating oil needs to be standardized, because the humidity in the insulating oil is closely related to the temperature change, and there is a certain temperature gradient in the main tank of the transformer (usually the top temperature of the tank is higher than the bottom). To complete the standardization, the expert system analysis needs to infer the relative saturation percentage at the bottom. It can be obtained by using the temperature reported by the sensor and its sampling position. This analysis assumes that the transformer top temperature is 10 °C higher than the bottom temperature. If you use a position other than the top or bottom as the sampling point, you must specify the temperature deviation. Through the relative saturation of the humidity and the specific measured temperature, the expert system will use the relative saturation percentage as the calculation result of the insulation paper humidity. It must be noted that this calculation is based solely on the results of a single measurement and may not reflect the true moisture concentration of the insulating paper, especially after the transformer has just experienced severe temperature changes. If the expert system determines that the transformer is in equilibrium (the insulation paper neither releases nor absorbs humidity), calculate the second relative saturation percentage, which is the result of the last 30 relative saturation percentage measurements when the transformer is in equilibrium. average value. The previously recorded temperature and changes determine whether there is a balance of judgment criteria. There are 4 available alerts. The humidity alarm is displayed with “P†as the first character. The second character is a number from 0 to 3. A P0 alarm indicates a sensor failure. A P1 alert indicates that the analysis was not performed. The P1, P2, and P3 alarms all depend on the relative saturation percentage. The conditions of the alarm: 1 is the relative saturation percentage of the insulating oil humidity ≥ 50, but <75; 2 is the relative saturation percentage of the insulating oil humidity ≥ 75 As the name implies, it refers to some warehouse equipment used to transport and transfer goods in some small and medium-sized warehouses, ports, docks and other places of production enterprises with large space and high transferability. Material Handling Equipment,Forklifts And Equipment,Self Lifting Stacker,Hoist Cable Machine Jiangsu Minnuo Group Co.,Ltd , https://www.js-minnuomachinery.com