The insulating oil treated by the transformer oil filter affects the breakdown voltage
2018/5/17 Viewers:
The main factors affecting the breakdown voltage of oil are: (1) moisture. Water is the most common and the most sensitive spoils of breakdown voltage. Because water is a kind of polar molecule, under the action of electric field force, it is easy to be elongated and arranged along the direction of electric field, thus forming a conductive "small bridge" between the two poles. That is even a small amount of water. This kind of conductive bridge will be produced immediately, connecting the poles to make the electrical pressure drop dramatically, such as the water in the general new oil is 0.01%. In the range of ~0.02%, the saturation state can be reached, but a small amount of water can reduce the breakdown voltage of the oil very low. Besides water, the oil often contains other stolen goods. Therefore, the relation between water content and breakdown voltage can not be expressed by formula. In addition, the size of the breakdown voltage depends not only on the water content, but also on the state of the water in the oil, like the water content of the sample, but it can reduce the voltage in varying degrees. Generally, the emulsified water has the greatest impact on breakdown voltage and the number of dissolved water is the second. (2) oil contains the smallest bubbles and the breakdown voltage will decrease obviously. Because bubbles exist in oil, bubbles can be dissociated at lower voltages, and a small "conductivity" can be formed between electrodes under the action of electric field. The oil is broken through and the breakdown voltage of the oil is reduced. (3) the influence of temperature on the breakdown voltage is whether the impurities and moisture in the oil are different, without impurities, and the oil which is dry and free of moisture has little effect on the breakdown voltage in general temperature. This is because at a certain field strength and temperature, the oil molecule itself is not easy to break down, that is, it is not easy to ionize (but when the temperature rises to a certain extent, the oil molecule itself is ionized by the cracking surface, and with the increase of temperature, the viscosity of the oil decreases significantly, the ionizing electricity and the ions are produced, and the speed is smaller and the velocity is faster. " The degree of acceleration has led to breakdown of oil and breakdown voltage. If the oil contains water and impurities, the breakdown voltage of the oil is lower than that of the oil without impurities or moisture at the same temperature. When the temperature is low, the water in the oil is mostly suspended in the emulsion, and the breakdown voltage is smaller. With the increase of temperature, the emulsion gradually turns to dissolve, and the breakdown voltage of the oil also rises. However, if the oil temperature rises to a certain extent, the moisture in the oil evaporates, the number of bubbles in the oil will increase, and the resistance is reduced because of the high viscosity and low temperature. The water, impurities and the generated bubbles are easily formed in the oil. The result makes the breakdown voltage of oil decrease quickly. Especially when impurities and moisture exist in the oil, the "bridging" effect makes the conductive bridge easier to form, and the breakdown voltage decreases more obviously. (4) when the oil contains free carbon and water, the breakdown voltage of oil decreases with the increase of carbon particles. (5) the product of acid value, which is generated after oil aging, is the unfavorable factor to keep the water in the emulsification state, and thus the breakdown voltage of the oil will decrease, and the drying oil without moisture, the acid value and other aging products have no obvious effect on the breakdown voltage.
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