The Main Factors Affecting Transformer Insulation Faults

The main factors affecting the insulation performance of the transformer are: temperature, humidity, oil protection method, and overvoltage effect.

1. The effect of temperature.

The power transformer is oil and paper insulation, and the water content in the oil and paper at different temperatures has a different balanced relationship curve. Under normal circumstances, the temperature is rising, and the water in the paper should be precipitated in the wand; on the contrary, the paper must absorb the water in the oil. Therefore, when the temperature is high, the micro -water content of the insulation oil in the transformer is large; otherwise, the micro -water content is small.

The temperature is not at the same time, which makes the cellulose resolve ring and disconnect with the degree of gases. At a certain temperature, the generated speed of CO and CO? Is constant, that is, the gas content of CO and CO? The gas content in the oil is linear relationship over time. When the temperature continues to rise, the generation rate of CO and CO? Often increases the index of index. Therefore, the content of CO and CO? In oil has a direct relationship with the aging of insulating paper, and can use the content changes as one of the abnormal judgments in the paper layer in the seal transformer.

The life of the transformer depends on the aging of insulation, and the aging of insulation depends on the operating temperature. If the oil immersion transformer is under the rated load, the average winding temperature rises to 65 ° C, the hottest temperature rising to 78 ° C, if the average ambient temperature is 20C, the hottest temperature is 98 ° C; at this temperature, the transformer can run 20 — In 30 years, if the transformer runs overloaded and the temperature rises, it will shorten life.

The International Electricity Commission (1EC) believes that the transformer of A -class insulation is within the temperature range of 80 to 140C. Each temperature increases at 6 ° C, and the speed of the transformer insulation is doubled. It is stricter than the 8 ° C law recognized in the past.

2. Effect of humidity.

The existence of water degrades accelerated paper cellulose. Therefore, the production of CO and CO? It is also related to the water content of cellulose material. When the humidity is certain, the higher the water content, the more CO? Conversely, the lower the moisture content, the more COs decomposed.

The trace water in the insulation oil is one of the important factors that affect the insulation characteristics. The existence of trace water in the insulation oil is greatly harmful to the electrical performance and physical and chemical performance of the insulating medium. The water discharge voltage of the insulating oil can be reduced. Essence The moisture of the equipment not only leads to the reduction of the reliability and life of power equipment, but also may cause equipment damage or even endangering personal safety.

3. The effect of oil protection method.

The effect of oxygen in the transformer oil will accelerate the insulation and decomposition reaction, and the oxygen content is related to the oil protection method. In addition, the pool protection method is different, so that CO and CO? Different from solving and diffusion in oils. For example, the dissolving of CO can easily spread to the oil surface space. Therefore, the volume score of the CO of the open transformer in general is not more than 300x10-6. The seal transformer, because the oil surface and the air are insulated, make CO and CO? It is not easy to volatilize, so its content is high.

4. The effect of overvoltage.

① The impact of temporary excessive voltage.

The phase and inter -voltage of the normal operation of the three -phase transformer are 58%of the phase voltage, but the voltage of the main insulation to the neutral point grounding system when the single -phase failure occurs. %, Thus damaging insulation.

② The influence of lightning over voltage.

Due to the steep wave head, the thunderbolt voltage causes the voltage distribution of vertical insulation (turning, inter -insulation), and the voltage distribution is very uneven. It may leave a trace of discharge on the insulation, which will damage the solid insulation.

③ The effect of operating overvoltage.

Because the wave head that operates the voltage is quite gentle, the voltage distribution is close to linear, and when the operating overvoltage wave is transferred from one winding to another winding, it is about the number of turns between the two winding. The deterioration and damage of the permanent insulation.

5. The influence of short -circuit electrical power.

The electric power at the short circuit of export may deform and shift the transformer winding and lead, thereby changing the original insulation distance, which causes insulation to heat, accelerate aging or damage causes discharge, arc and short circuit failure.

In summary, mastering the insulation performance of the power transformer and reasonable operation and maintenance directly affect the safe operation, service life and power supply reliability of the transformer. The power transformer is an important and key main device in the power system. Personnel and managers must understand and master the insulation structure, material performance, process quality, maintenance methods and scientific diagnostic technologies of the electric transformer, and optimize and reasonably operate management in order to ensure the efficiency, life and power supply reliability of the power transformer.

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