(1) Transformer itself problems such as loose ends, loose blocks, poor welding, poor core insulation, and insufficient short-circuit strength.
(2) Line interference. Line interference is among the most important of all the factors that cause a transformer accident. It mainly includes: overvoltage generated during closing, voltage peak appearing during low load phase, and so on.
(3) Overloading. Overloading means that the transformer is working under the rated power for a long time. If the transformer is overloaded, it will generate excessive temperature, which will lead to premature aging of the insulation.
(4) Improper use. The speed of insulation degradation of small transformers due to improper use is accelerated.
(5) No proper maintenance has been performed.