7 Causes for High-frequency Transformer Heating You Must Be Aware of !

 

High-frequency transformers will produce copper loss and iron loss during operation. These two losses are finally converted into heat energy, which makes the iron core and winding of the high-frequency transformer heat up and the temperature rises. In addition, the windings also generate heat through current. When the heat of the high-frequency transformer is dissipated to the environment to reach thermal equilibrium, the temperature of each part of the high-frequency transformer should be a stable value.

If the temperature of each part of the high-frequency transformer exceeds its allowable range for a long time, especially when the oil temperature of the high-frequency transformer is higher than normal by more than 10℃ or the temperature is still rising, the insulation of the high-frequency transformer is easy to be damaged, and it is easy to be damaged. High voltage breakdown causes malfunction or accident. Therefore, during normal operation of the transformer, it is not allowed to exceed the allowable temperature of the insulation.

Reasons for the Temperature Rise of High-frequency Transformers

(1) Internal reasons

1. There is internal loss

When the high frequency transformer is in operation, due to the hysteresis loss of the iron core, the eddy current loss and the copper loss of the coil are all converted into heat, which increases the temperature, and the heat diffuses to the surroundings by means of radiation and conduction. When heat generation and heat dissipation reach a balanced state, the temperature of each part tends to be stable. The iron loss (hysteresis loss and eddy current loss) is basically the same loss, which is related to the structure of the high-frequency transformer, so it cannot be reduced or eliminated during operation, and the copper loss (line loss) changes with the load.

2. Poor contact of tap changer

In the operation of high-frequency transformers, the tap changer has insufficient spring pressure, small contact contact, oil film, contamination, etc., which cause the contact resistance of the contact to increase. Overheating of the contact is the most common, and the temperature continues to rise. Especially when the tap changer or the high-frequency transformer is overloaded, the contacts of the tap changer are likely to make poor contact and overheat.

3. Short circuit between winding turns

Due to insulation damage or aging of the adjacent turns of the high-frequency transformer winding, a closed short-circuit circulating current will appear, which reduces the number of winding turns. The short-circuit circulating current generates high heat and raises the temperature of the transformer, which will burn the high-frequency transformer in severe cases.

4. Local core overheating

 

The iron core is superimposed by insulating silicon steel sheets. In the operation of high-frequency transformers, the insulation between the silicon steel sheets is damaged due to external force damage or insulation aging, and core screw insulation aging damage, and the eddy current increases, causing local heating.

5. The high-frequency transformer is short of oil or blocked in the radiating pipe

High-frequency transformer oil is the main insulation inside the transformer, which plays the role of insulation, cooling, and isolation. If there is a shortage of oil or the inside of the radiating pipe is blocked, the circulating cooling rate of the oil will decrease, leading to an increase in temperature during high-frequency transformer operation.

(2) External reasons

1. Failure of high-frequency transformer cooling circulation system

In addition to the use of heat pipes for cooling and heat dissipation, power high frequency transformers also have forced oil circulation air cooling, water circulation and other heat dissipation methods. Once the cooling and heat dissipation system fails or the heat dissipation conditions are poor, the temperature of the high frequency transformer during operation will rise (especially in the hot summer season ).

2. The air inlet and outlet of the high-frequency transformer room are blocked or dusty

The air inlet and outlet of the high-frequency transformer room is the passage of air convection during the operation of the transformer. Once blocked or severely accumulated, the heating condition of the high-frequency transformer has not changed and the heat dissipation condition has deteriorated, and the surrounding air cannot be dissipated in time, resulting in the operation of the high-frequency transformer The temperature rises.

In this episode, we have shared 7 reasons that cause high-frequency transformer heating. Next time, we will bring you effective heat dissipation methods! You are welcome to continue to follow JRPanel Blog!