Transformer insulating oil in water monitoring of micro-

Abstract The micro-transformer oil described the state of water and hazards, discusses the micro-transformer insulating oil in water testing methods to micro-transformer insulating oil in water monitoring to provide reference.

Keywords transformer; insulating oil; Micro Water Monitoring

Current transformer is a power system not only the most important and most expensive equipment out, but also lead to power system equipment, one of the most accident. Transformer in the event of sudden failure before the insulation deterioration and potential failure in the operating voltage produced under the action of light, electricity, sound, heat, chemical change and a series of effects and information. Thus, not only at home and abroad to preventive test done on a regular basis based on preventive maintenance, and have all the Research based on online monitoring Wei predictive maintenance strategy for real-time or a time-line monitoring and diagnosis of latent failures or defects [1-4]. transformer insulating oil in the micro-water content is the parameter to determine the quality of transformer insulation. transformer line intelligent diagnostic equipment to automatically capture, Analysis of water content in oil based and draw Failure to provide solutions that enable users to promptly solve the hidden dangers that exist in the transformer to prevent accidents.

1 Moisture in transformer oil and damage the state
Transformer in the transport, storage, use of the process may or oil from the outside world into the self-oxidation of water to produce water exists in the following states: First, free water. Mostly outside intrusion of moisture, if not stir easily with water. does not affect the breakdown voltage of oil, but does not allow, that the oil may be dissolved in water immediately. Second, the extremely fine particles in water. usually by air into the oil, drastically reduced oil breakdown voltage. dielectric loss increased, the vacuum filter oil. The third is emulsified in water. oil refining bad, or long run result in the aging oil or contaminated oil is emulsified, it will reduce the interfacial tension between oil and water, such as oil and water mixed together, they the formation of emulsified state. plus broken emulsion. the harm: first, reduce oil breakdown voltage .100 ~ 200 mg / kg significantly reduced the breakdown voltage of 1.0 kV, oil, fiber impurities can easily absorb water, the electric field , in between the electrodes to form a conductive "bridge", which can easily puncture. Second, the dielectric loss factor increased. suspended the greatest impact of emulsion water, uneven. The third is to promote fiber insulation aging, the insulation fibers glucose molecules (C6H12O6) molecules and water molecules into the fibers reduce the gravity to promote the hydrolysis of low molecular weight substances, reduce the fiber mechanical strength and degree of polymerization. Experiments show, 120 ��, insulation fibers in the water increased by 1 fold, fiber Mechanical Strength reduced by 1 / 2, when the temperature rises, the oil in the water increases, the fiber of the water lower the temperature decreased, and vice versa. Therefore, we should monitor the oil in the micro-water, and then monitor the aging of insulation fibers. Fourth, water contributes to organic acid corrosion, accelerated corrosion of metal parts. To sum up, the more water content in oil, oil itself is aging, equipment insulation aging and corrosion of metal parts, the faster the moisture content monitoring of oil , especially the dissolved water content is necessary. reposted elsewhere in the Research Papers Download http://www.hi138.com 2 transformer insulating oil in the micro-water testing methods
Assessment of insulation material in the humidity, the transformer is to ensure the reliability and service life is an important factor. Insulating oil in the humidity is constantly changing, which could adversely affect the quality. In addition, most of the moisture distribution in the insulating paper. Humidity will affect the solid and liquid insulating materials dielectric breakdown strength, and affect the aging rate of cellulose insulation and overload during the bubble formation tendency. ambient temperature, load, aging, leakage and other factors may cause the changing humidity. So , with cyclic changes in temperature, the transformer need continuous monitoring and diagnosis. This is an overload or peak load transformer even more necessary. transformer insulation system from the cellulose in the total moisture and liquid water content in the decision. insulating paper and insulating oil The relationship depends only on the temperature and humidity. When the temperature increases, water solubility in the insulating oil (solution water capacity) increases, the moisture transfer from the insulation paper in insulation oil. When the temperature decreases, this process will vice versa, but the flow of water from the liquid medium to solid insulation material at a fairly slow. Therefore, the insulating oil cooling than heating water during the period. Therefore, to accurately grasp the humidity distribution transformer, must know the equipment in the heat cycle position. to the liquid medium by monitoring the moisture content of insulation paper to understand the true humidity, the transformer must be in a relatively stable temperature conditions.

Insulating oil relative saturation of water need to be standardized, as in the insulating oil is closely related to humidity and temperature changes, and the main box in the transformer there is a certain temperature gradient (usually the box at the top temperature is higher than the bottom). To complete the standardization , expert system analysis should infer the relative saturation percentage at the bottom. can be reported through the use of temperature sensors and their sampling locations to obtain. This analysis assumes that the top temperature of the transformer temperature is higher than the bottom 10 ��. such as the use outside of the top or bottom location for the sampling point, you must specify the temperature deviation. by relative humidity and specific measurement of saturation temperature, the expert system will be a certain percentage of the relative saturation humidity for insulation paper results. must be noted that the calculation is based on only a single measurement results, and may not reflect the true moisture concentration of insulating paper, especially in the transformer just after experiencing dramatic temperature changes. If the expert system determines that the transformer is in equilibrium (neither released nor absorbed insulation paper moisture), the calculated 2 a percentage of the relative saturation of the transformer saturation when in equilibrium relative saturation of the last 30 times the average percentage of measurements. in front of recording changes in temperature and determine the criteria for determining whether there is a balance. There are 4 available alerts. Humidity alarm display the "P" for the first character. The first two characters for the numbers 0 to 3. P0 expressed alarm sensor failure. P1 alarm that did not perform the analysis. P1, P2 and P3 Alerts are dependent on the percentage of the relative saturation . alarm conditions: 1 is the relative humidity of insulating oil saturation percentage> = 50, but <75; 2 is the relative humidity of insulating oil saturation percentage> = 75.

3 References
[1] Zhu Deheng, Tan Kexiong. Electrical insulation diagnostic technology [M]. Beijing: China Electric Power Press, 1999.

[2] Chen Wei roots. To a variety of gas oil in the transformer is characterized by the amount of insulation online monitoring and fault diagnosis technology [D]. Chongqing: Chongqing University, 2003.

[3] Sun Cai-xin, CHEN Wei root. Electrical equipment line dissolved gas monitoring and fault diagnosis [M]. Beijing: Science Press, 2003.

[4] Li Xiaoxiao, SUN Bao-yuan, Dai Heng Chen, et al. Pressboard moisture-line monitoring system [J]. Instrument Technique and Sensor, 2005 (7) :49-50. Reposted elsewhere in the Research Papers Download http:/ / www.hi138.com