effect of temperature on high pressure test
The change of temperature will fully affect the insulation resistance, so when the external temperature continues to rise, the movement of molecules and ions in the insulation material will continue to accelerate the speed of movement with the increase of temperature, which will lead to the polarity of insulation resistance can be improved, and the insulation resistance is reduced. At the same time, in the process of increasing temperature, the movement speed of water molecules in the insulation resistance will continue to accelerate, so that the impurities on the surface of insulation resistance can be quickly dissolved, so that the resistance can be rapidly reduced. In addition, the decrease of insulation resistance is directly related to the dirt on the surface. At the same time, the analysis of some research data shows that the change of temperature will also lead to the change of insulation absorption ratio of transformer. In this case, it can be divided into two cases. For dry variable pressure Lu, the absorption ratio will increase with the increase of temperature. However, once the temperature rises to more than 40 ℃, the absorption ratio will decrease. In other cases, with the increase of temperature, the absorption ratio will decrease.
the influence of pressure rise speed
In the high-voltage test, the speed of boosting will affect the current leakage, so in the test, it is necessary to grasp flexibly according to the capacity of the transformer to control the occurrence of error as much as possible, so as to ensure the accuracy of the high-voltage test results.
power transformer test example
Taking the DC resistance test of winding and bushing as an example, the matters needing attention in the test are briefly explained. Because the transformer winding has large inductance and mutual inductance, but has a small resistance, according to the time constant is L / R, it will be found that the time constant is very large. In this case, if the current is to be stable, the charging time will be very long. Therefore, for some large transformers, the test time should be shortened as far as possible. If it is to measure the resistance in the low-voltage winding of a large-scale transformer, since there are few exciting turns at the low-voltage end, the method of series winding magnetization can be adopted and the correct connection mode should be selected.
Post time: Jul-15-2020