How to check and repair the AC variable frequency power transformer?
As we all know, AC variable frequency power transformers are used in many places in our lives. They are widely used in every corner of our life. It is precisely because transformers are widely used that our lives are brighter and more colorful, but so far, few people can fully understand it.
Today, Xiaobian tells you how to observe and understand AC variable frequency power transformers in daily life.
Careful people will find that after using the variable frequency transformer for a long time, there will be problems, and it is very common to make a "humming sound". At this time, the variable frequency power transformer cannot work normally. For this phenomenon, we can take appropriate measures to find out the error and solve the problem. The error can be caused by the following reasons, which can be checked and fixed:
1. A short circuit occurs in the winding of the power transformer. The sound is mixed with the sound of boiling water, the temperature changes sharply, and the oil level rises. It should be judged that there is a short circuit fault in the transformer winding. In severe cases, there will be a loud roar, and then it may catch fire. At this time, the transformer inspection should be stopped immediately.
2. The terminals or screws of the transformer are loose, and there is obvious noise. It may be that the internal clamp or the screw pressing on the iron core is loose, which causes the silicon steel plate to vibrate more.
3. Overvoltage may occur in the power grid, the transformer is overloaded, the load is too high, and due to the influence of harmonics, there will be a short "wow" or "clack sound" in the transformer and monitoring pointer to drive the system and the instrument to vibrate, the pitch is high and the volume big.
4. Overheating of the lead wire (terminal) and the line card will cause abnormalities. The fixed part of the terminal of the housing is loose or the wire nose slips, etc., and the contact surface is severely oxidized. As a result, if the contact is overheated, the color will become darker and the surface gloss will disappear, and the surface coating is also damaged.
5. The transformer winding of the power transformer is short-circuited. The sound is mixed with the sound of boiling water, the temperature changes sharply, and the oil level rises. It should be judged that there is a short circuit fault in the transformer winding. In severe cases, there will be a loud roar, and then it may catch fire. At this time, the transformer inspection should be stopped immediately. Transformer shell flashover discharge. This noise occurs when high voltage on a transformer winding causes the outgoing wires to flip over and discharge into each other or into the case. At this time, the transformer should be stopped for inspection.
6. Bushing flashover discharge, the flashover discharge of the bushing will cause heating, aging, insulation damage and even explosion.
7. Excessive moisture absorption, damage to the sealing ring, and too much water in the oil chamber will cause the hygroscopic agent to change color.
8. The dirt on the casing will cause abnormality, the dirt on the sleeve will produce corona, the flashover will produce the smell of ozone, and the burning of the fan and oil pump will cause the smell of burning.
9. The explosion-proof membrane of the explosion-proof tube is damaged: the explosion-proof membrane of the explosion-proof tube explodes, causing water and moisture to enter the transformer, emulsifying the insulating oil and insulating oil, and reducing the insulation strength of the transformer.
Facts have proved that under normal circumstances, the oil temperature is more than 10 degrees Celsius higher than usual, or when the temperature continues to rise (under normal operation of the cooling device) and the load remains unchanged, it can be judged that it is an abnormality inside the transformer.
mainly:
1. Abnormal temperature due to abnormal operation of the cooler. The cooler is not working properly or not working properly, for example by shutting down the submersible pump, damaged fan, contaminated cooler pipes, poor cooling, faulty cooler valve, faulty thermometer and many other factors.
2. Due to internal faults, temperature abnormalities, such as short circuits between windings or winding layers, discharge of coils to the housing, heating of internal line connections, multi-point grounding of iron cores, increases in eddy currents and overheating, and loss of magnets, no The balanced zero-sequence current circulates through the iron tank, which creates a thermal factor that causes the temperature of the transformer to be abnormal. In this case, gas protection or differential protection measures will be taken. If the fault is serious, you can fill the explosion-proof pipe or the pressure relief valve with oil. At this time, transformer maintenance should be stopped immediately.
