When the weather is cold, the transformer oil level gauge is on the high side, and the oil temperature is 40 degrees. What is the reason?

When it is found that the transformer oil temperature is too high, the load of the transformer should be checked first, and the temperature at the same moment should be compared with the temperature under the same load in the past, then the thermometer itself should be checked for faults, and finally the air-cooled equipment should be checked for normal operation. If the above inspection is normal, but the oil temperature is higher than before and the temperature rise continues to increase, it may be an internal fault of the transformer.

The internal faults of general oil-immersed transformers are as follows: 1. Poor contact of on-load tap changer. During the operation of on-load tap changer, due to insufficient contact pressure or unclean contact, the contact resistance increases, resulting in the contact temperature rising and heating. After the transformer voltage regulation is overloaded, it is easy to cause poor contact of tap changer and heat, resulting in high oil temperature of transformer. 2. The inter-turn short circuit of the coil or the insulation between switches is reduced. When the insulation between several adjacent coil turns is damaged, a short-circuit current will be generated between them. This short-circuit current will make the oil temperature rise rapidly. There are many reasons for coil insulation damage, including external force, high temperature and manufacturing technology. The main causes of turn-to-turn short circuit are overcurrent and overvoltage. 3. Reduce the short circuit between iron core silicon steel sheets or the insulation of silicon steel sheets. Due to external force damage or insulation aging, the short circuit between sheets leads to the increase of eddy current loss of iron core and local overheating. In addition, the insulation damage of the piercing screw is also the cause of eddy current.

The above main reasons about oil immersion or high transformer oil temperature are for reference only, but which part is the main reason needs to be analyzed in combination with transformer oil temperature and sound. If necessary, high voltage test can be conducted for transformer power failure to determine the specific reasons!