Technology Class

The AC withstand voltage test is a destructive test in the insulation test. It can only be carried out after other non-destructive tests (such as insulation resistance and absorption ratio test, DC leakage test, dielectric loss tangent and insulation oil test) are passed. After this test is passed, the transformer can be put into operation.

The DC resistance of a transformer refers to the DC resistance value of each phase winding. The purpose of measuring the DC resistance of a transformer is to check the welding quality of the winding joints and whether there is a short circuit between the winding turns; to check whether the contact of the tap changer is good and whether the actual position of the tap is correct.

Dielectric loss refers to the sum of polarization loss and conductivity loss caused by transformer oil under the action of alternating electric field. Dielectric loss factor can reflect the insulation characteristics of transformer, the aging degree of transformer oil under the action of electric field, oxidation and high temperature, and the degree of pollution of polar impurities transformer and charged colloid in oil.

On the one hand, in addition to the problem of low power factor, a variety of converters and other power electronic devices are increasingly widely used for the introduction of a large number of harmonics into the power grid; on the other hand, a large number of precision instruments are very susceptible to the impact of power harmonics, the power quality of the requirements of more and more high. It is imperative to actively and effectively manage power quality on the user side.

For general enterprises, the smaller the reactive power, the better, because the power bureau needs to assess the power factor. If the power factor of the enterprise is too low, that is, the reactive power cannot be too large: so many enterprises have reactive power compensation devices. Of course, reactive power is more about whether a large or small power factor is better.

According to the regulations, the number of full voltage air load impact tests, the investment of new products should be impacted 5 times continuously; after large repair, it should be impacted 3 times. Each impact interval is not less than 5min, and someone should be sent to the scene to monitor the transformer before the operation. Check the opposite whether there is any abnormality.

Although the DC withstand voltage test and leakage current measurement methods are the same, their functions are different. The former is to test the insulation's dielectric strength, and its test voltage is higher; the latter is used to check the insulation condition, and the test voltage is relatively low.

When an indoor switch using SF6 gas as insulation and arc extinguishing medium leaks during use, the leaked SF6 gas and its decomposition products will accumulate in the indoor low-level space, resulting in localized hypoxia and toxicity, posing a serious danger to the life safety of the staff entering the room.

When cable faults occur, obstacles must be eliminated quickly to restore communications as soon as possible, first of all, the nature of the obstacle should be judged and then select the appropriate instrument to determine the precise location of the obstacle in time to carry out cable line repair work, the determination of the precise location of the obstacle is generally used to determine the precise location of the obstacle to the instrument cable fault tester.