There are many common faults that occur with conventional oil-immersed transformers, but sometimes the probability of oil-immersed transformers being burned out is quite high.
Therefore, when an oil-immersed transformer is burned out, it is necessary to find the cause of the burnout. What are the common causes of burnout for conventional oil-immersed transformers? Let's take a look together!
There is no circuit breaker on the high and low voltage sides of the oil-immersed transformer
Even though some oil-immersed transformers have already installed drop-out circuit breakers and horn-type commercial insurance, their fuse parts are mostly replaced by aluminum or copper wire. Therefore, when there is a short circuit fault or load, their fuse parts cannot melt properly and end up damaging the oil-immersed transformers.
The high and low voltage fuse parts of the oil-immersed transformer are inadequately equipped
The fuse parts on the oil-immersed transformer are generally oversized. When there is a serious load, it damages the oil-immersed transformers.
Power switching of the oil-immersed transformer
Unauthorized adjustment of the power switching causes poor contact of the distribution transformer power switching, resulting in damage.
Poor quality of the power switching causes incomplete contact with the star-shaped circuit breaker, resulting in short circuit faults or ground charging and discharging.
Oil leakage is a common surface abnormality of oil-immersed transformers.
Because the oil-immersed transformer is filled with oil, all connection positions have gaskets and rubber pads to prevent oil leakage. After a long period of operation, some gaskets and rubber pads in the oil-immersed transformers become brittle and crack, causing oil leakage, resulting in a decrease in insulation characteristics after moisture returns, charging and discharging short circuit faults, and damage to oil-immersed transformers.
Most of the high and low voltage lines of the oil-immersed transformer are introduced from the power transmission line. When the lightning arrester is not put into use immediately or the 10kV lightning arrester is not installed, the oil-immersed transformer is damaged when struck by lightning.
When the low voltage side of the oil-immersed transformer has a grounding device or a two-color short circuit fault, it will cause a short circuit capacity that is 20 to 30 times higher than the rated voltage.
Such a large current effect on the high-voltage winding will cause very large mechanical stress inside the electromagnetic coil, which will cause the electromagnetic coil to shrink.
After the common fault is eliminated, the mechanical stress will also disappear, but if the electromagnetic coil is repeatedly subjected to the mechanical stress effect, the oil-immersed transformer's insulation gaskets, rubber pads, etc. will become loose and fall off; the foot bolts of the iron core straightening clamp will also loosen, and the high-voltage coil will deform or fracture. In addition, it will cause high temperature, and eventually cause the oil-immersed transformer to be damaged in a very short time.
Human factors that damage the oil-immersed transformer.
The grounding wire of the oil-immersed transformer is a copper extruder screw, while suspended cables generally use aluminum core rubber-insulated wires. The copper-aluminum interface is very susceptible to thermal and electrochemical erosion.
Short-circuit faults and charging and discharging caused by waterproof sleeves are also common abnormal situations in oil-immersed transformers. The cause of the burnout of the oil-immersed transformer must be found to ensure that it operates normally.
