Transformer insulation oil breakdown voltage should pay attention to what matters
2018/5/17 Viewers:
The following items should be paid attention to in determining the breakdown voltage of oil products.
(1) the shape and size of the electrode. At present, there are three forms of electrical pull out for breakdown voltage test in the world: spherical, spherical and flat. The first two kinds are the form of the International Electrotechnical Commission, the latter is the form used by the former Soviet Union and our country. From the above three kinds of electrode comparison test, the spherical breakdown voltage is the most quotient. If the breakdown voltage of oil is above 30kV, the spherical surface is about 4~6kV higher than that of the flat plate electrode, 3~4kV higher than that of the ball cap, and the spherical surface is about 2-3kV. higher than that of the flat plate electrode, but when the breakdown voltage of oil is below 30kV, the spherical flat plate electrode test values are basically the same. Plate electrodes are still used in our country at present. But the edge of the electrode must be required to be fillet. Because sharp edges can cause sharp discharge, such as in oil test, oil carbonization will lead to breakdown, affecting the determination results.
(2) the distance of the electrode should be adjusted accurately according to the regulation. For example, the smaller the distance between electrodes is, the easier the formation of conductive bridges is in water and impurities, which is easy to breakdown. The average distance of the electrode is 2.5mm.
(3) the influence of different interval time. Tests show that when testing dry and pure oil, When the interval is short, the breakdown voltage is high because the interval is longer. The oil absorbs moisture and affects the measured value. But when testing oil that is polluted by water and impurities, the length of the interval is higher than the short time pressure, which is longer by the hand time. The impurities in the oil are partially evaporated. 3~ 5min is generally appropriate, and the longest must not exceed 5min.
(4) the boost speed problem is 3kV/s in the original YS-29-1-84 method; while the TEC165 method of the IEC stipulates that the boost speed is 2kV/s. by multiple comparison tests. For the oil with the breakdown voltage value at 40kV and above, the test results of the two different booster speeds are consistent; the breakdown voltage is at 40kV The measured value of 2kV/s boost speed is slightly higher than that of 3kV/s, but most of them are within the allowable range.
(5) the volumetric size of the oil cup will have a certain effect and should be uniformly stipulated as 300~-500m1.
(1) the shape and size of the electrode. At present, there are three forms of electrical pull out for breakdown voltage test in the world: spherical, spherical and flat. The first two kinds are the form of the International Electrotechnical Commission, the latter is the form used by the former Soviet Union and our country. From the above three kinds of electrode comparison test, the spherical breakdown voltage is the most quotient. If the breakdown voltage of oil is above 30kV, the spherical surface is about 4~6kV higher than that of the flat plate electrode, 3~4kV higher than that of the ball cap, and the spherical surface is about 2-3kV. higher than that of the flat plate electrode, but when the breakdown voltage of oil is below 30kV, the spherical flat plate electrode test values are basically the same. Plate electrodes are still used in our country at present. But the edge of the electrode must be required to be fillet. Because sharp edges can cause sharp discharge, such as in oil test, oil carbonization will lead to breakdown, affecting the determination results.
(2) the distance of the electrode should be adjusted accurately according to the regulation. For example, the smaller the distance between electrodes is, the easier the formation of conductive bridges is in water and impurities, which is easy to breakdown. The average distance of the electrode is 2.5mm.
(3) the influence of different interval time. Tests show that when testing dry and pure oil, When the interval is short, the breakdown voltage is high because the interval is longer. The oil absorbs moisture and affects the measured value. But when testing oil that is polluted by water and impurities, the length of the interval is higher than the short time pressure, which is longer by the hand time. The impurities in the oil are partially evaporated. 3~ 5min is generally appropriate, and the longest must not exceed 5min.
(4) the boost speed problem is 3kV/s in the original YS-29-1-84 method; while the TEC165 method of the IEC stipulates that the boost speed is 2kV/s. by multiple comparison tests. For the oil with the breakdown voltage value at 40kV and above, the test results of the two different booster speeds are consistent; the breakdown voltage is at 40kV The measured value of 2kV/s boost speed is slightly higher than that of 3kV/s, but most of them are within the allowable range.
(5) the volumetric size of the oil cup will have a certain effect and should be uniformly stipulated as 300~-500m1.
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