1. There is no commercial insurance on both sides of the distribution transformer at high or low voltage. Some of them have been installed with drop-out fuses and claw commercial insurance, but most of their fuses are replaced by aluminum or copper wires. When the bottom voltage short-circuit fault or load is caused, the fuses cannot be melted normally and burn the transformer. The high and low fuses of the distribution transformer are poorly equipped. The fuse on the transformer is generally over-equipped, which leads to the transformer being burned when the distribution transformer is heavily loaded.

Second, because of the large number of rural lighting fixtures, most of them also use single-phase electric power supply systems. In addition, the blindness of the construction site leakage and the untimely management method lead to the partial operation of the distribution transformer load. Long-term application leads to embrittlement of the insulating layer of a certain electromagnetic coil and burns the transformer.

3. Tap power switch.

1. Adjust the tap power switch without authorization. Because the difference in electricity load between the four seasons of the year is large, the height of the operating voltage changes greatly. Therefore, the electric welders of some villages and companies did not adjust the tap power switch without the experimental adjustment of the power engineering repair unit, resulting in the distribution transformer tap power switch not being timely, loose and burned.

2. The tap power switch has poor quality, unscientific structure, insufficient working pressure, and unreliable touch. The external word wheel part is not completely consistent with the internal specific part, causing the star-shaped circuit breaker part to not touch and shift. 3. The static contact reduces the distance between the insulating layers of the two taps, and under the effect of the potential difference between the two taps, a short-circuit fault or charging and discharging to the ground will occur. The short-circuit capacity will quickly burn the tap turns, and even cause all the windings to be destroyed.

4. Oil leakage is a more common surface anomaly in transformers. Because the transformer body is filled with oil, there are often rubber beads and leather pads at each connection position to avoid oil leakage. After a long period of operation, some rubber beads and leather pads in the transformer will become brittle and cracked to cause oil leakage, which may cause the characteristics of the insulation layer to deteriorate after moisture regain, short-circuit charge and discharge failure, and burn the transformer.

5. Most of the high and low voltage routes of the distribution transformer are imported from the transmission line, because the zinc oxide surge arrester is not used immediately or the 10kV zinc oxide surge arrester is not installed, causing the transformer to be burned when it is struck by lightning.

6. Some distribution transformers are not equipped with first-level maintenance, or are equipped with first-level maintenance, but their mobility and credibility are relatively low.