How likely is the low-frequency transformer to fail
The probability of failure varies with the site.
Use multimeter to measure the quality of low-frequency transformer
1.Direct detection with capacitive gear
Some digital multimeters have the function of measuring capacitance, and their measuring ranges are 2000p, 20n, 200n and 2 μ And 20 μ Fifth gear. During measurement, two pins of the discharged capacitor can be directly inserted into the Cx jack on the meter board. After selecting an appropriate range, the display data can be read and the transformer can be judged.
2. Detect with resistance gear
The charging process of the capacitor can also be observed with a digital multimeter, which actually reflects the change of the charging voltage with discrete digital quantities. If the measurement rate of the digital multimeter is n times/second, then during the observation of the charging process of the capacitor, n independent and successively increasing readings can be seen every second. According to this display feature of the digital multimeter, the quality of the capacitor can be detected and the capacitance can be estimated.
Note: The detection principle and method are the same for both high-frequency transformer and low-frequency transformer.
Fault Maintenance of Low Frequency Transformer
Classification and causes of common faults in transformers
(1) Problems existing when the transformer is delivered. Such as loose ends, loose cushion blocks, poor welding, poor core insulation, insufficient short circuit strength, etc.
(2) Line interference. Line interference is the most important factor in all factors causing transformer accidents. It mainly includes: over voltage generated during closing, voltage peak in low load stage, line fault, flash over and other abnormal phenomena. This kind of fault occupies a large proportion in transformer faults. Therefore, the impulse protection test must be carried out on the transformer regularly to detect the strength of the transformer against the inrush current.
(3) The aging speed of transformer insulation caused by improper use is accelerated. The average service life of general transformers is only 17.8 years, which is much lower than the expected service life of 35-40 years.
(4) Over voltage caused by lightning stroke.
(5) Overload. Overload refers to the transformer that is in the working state of exceeding the nameplate power for a long time. Overload often occurs when the power plant continues to slowly increase the load, the cooling device operates abnormally, the internal fault of the transformer, etc., and finally causes the transformer to overload. The resulting excessive temperature will lead to premature aging of the insulation. When the insulating cardboard of the transformer ages, the paper strength will decrease. Therefore, the impact of external faults may lead to insulation damage, which may lead to faults.
(6) Damping: if there is flood, pipeline leakage, head cover leakage, water intrusion into the oil tank along the sleeve or accessories, and there is water in the insulating oil, etc.
(7) Proper maintenance was not carried out.
Post time: Oct-10-2022
