How likely is the low frequency transformer to be broken

　　 The probability of failure varies from plant to plant.

　　Use a multimeter to measure the quality of low-frequency transformers separately

　　 1. Direct detection with capacitance file

Some digital multimeters have the function of measuring capacitance, and their ranges are divided into five ranges: 2000p, 20n, 200n, 2μ and 20μ. During measurement, the two pins of the discharged capacitor can be directly inserted into the Cx jack on the meter board, and the display data can be read and the quality of the transformer can be judged after selecting the appropriate range.

　　 2. Detect with resistance file

　　Using a digital multimeter, the charging process of the capacitor can also be observed. This is actually a discrete digital quantity that reflects the change of the charging voltage. Assuming that the measurement rate of the digital multimeter is n times per second, in the process of observing the charging 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 size of the capacitance can be estimated.

　　Note: Whether it is a high-frequency transformer or a low-frequency transformer, the detection principle and method are the same.

　　Fault maintenance of low frequency transformer

　　Classification and causes of common faults in transformers

(1) The transformer itself has problems when it leaves the factory. Such as loose ends, loose pads, poor welding, poor core insulation, insufficient short-circuit strength, etc.

　　 (2) Line interference. Line interference is the most important of all factors that cause transformer accidents. Mainly include: overvoltage generated during closing, voltage peaks during low-load phases, line failures, flashovers and other abnormal phenomena. This type of fault occupies a large proportion of transformer faults. Therefore, the impact protection test must be performed on the transformer regularly to detect the strength of the transformer against the inrush current.

　　 (3) The speed of transformer insulation aging caused by improper use is accelerated. The average life span of a general transformer is only 17.8 years, which is much lower than the expected life span of 35-40 years.

　　 (4) Overvoltage caused by lightning strike.

(5) Overload. Overload refers to a transformer whose power exceeds the nameplate power for a long time. Overload often occurs when the power plant continues to slowly increase the load, the cooling device does not operate normally, the internal fault of the transformer, etc., eventually cause the overload operation of the transformer. The resulting excessively high temperature will lead to premature aging of the insulation. When the insulation board of the transformer is aging, the paper strength will decrease. Therefore, the impact force of an external fault may cause insulation damage and further failure.

(6) Moisture: If there is flooding, pipeline leakage, top cover leakage, water intrusion into the tank along the casing or fittings, and moisture in the insulating oil, etc.

　　 (7) Correct maintenance is not performed.