There are many reasons for faults that cause transformer core overheating, such as winding short circuit, overload operation, poor grounding and abnormal grounding of the core itself, short circuit between iron chips or partial iron core short circuit, iron choke screw grounding, iron core magnetic leakage, iron core local Short circuit, high power supply voltage, blockage of core cooling oil passage, etc. In addition to the above, poor oil circulation, low oil volume in the tank, oil deterioration, large burrs around the iron core stack, and uneven gaps when stacking iron chips may cause core overheating failure.
The local overheating failure parts of the iron core are basically on the iron core and clamps. If the transformer core is overheated in operation, especially if a local overheating fault occurs, characteristic gases H2, CH4, C2H2, C2H6 will be produced. Chromatographic analysis found that the content of dissolved gas components in the oil exceeds the standard.