The significance of transformer insulation level

For dry-type transformers, the allowable temperature during operation is generally related to the heat resistance level of their insulation materials. The H-grade insulation paint has a temperature rise of 125K and a maximum allowable temperature of 180 ℃. The temperature value allowed by the transformer is also within this range. This is a fixed parameter value. If it is a qualified transformer that meets the H-class insulation standard, the maximum temperature is 180 ℃ and the temperature rise is 125K.

The relationship between insulation level and temperature rise:

Of course, most of the wires manufactured by KHZ are H-grade standard insulated enameled wires and insulation paints. There are also some other standard grades of transformers on the market, and the national prescribed values are:

1. Class A, with a maximum operating temperature of 105 ℃ and a maximum temperature rise of less than 60K;

2. Class E, with a maximum operating temperature of 120 ℃ and a maximum temperature rise of less than 75K;

3. Class B, with a maximum operating temperature of 130 ℃ and a maximum temperature rise of less than 80K;

4. Class F, with a maximum operating temperature of 155 ℃ and a maximum temperature rise of less than 100K;

5. Class H, with a maximum operating temperature of 180 ℃ and a maximum temperature rise of less than 125K;

6. Class C, with a maximum operating temperature of 220 ℃ and a maximum temperature rise of less than 150K.

In actual production, because the temperature values throughout the year are constantly changing. So, what we need to pay more attention to is whether the temperature of the transformer during operation exceeds the temperature rise of the insulation level. Temperature rise refers to the difference between the temperature of the component and the temperature of the external cooling medium. A dry-type transformer in direct contact with air can operate normally if its operating temperature is less than the sum of temperature rise and ambient temperature.

Taking H-class transformers as an example, their maximum temperature appreciation is less than 125k. In summer environments (such as 40 ℃), their maximum operating temperature is 165 ℃ (40 ℃+125 ℃), and in winter environments (around 10 ℃), their operating temperature is 135 ℃ (10 ℃+125 ℃). Choosing a transformer with high temperature rating can help ensure its working condition in extreme environments.

Summary:

It can be seen that the higher the level, the stronger its maximum working temperature and heat resistance, and the better its quality, but the corresponding cost will also increase. However, from a long-term economic perspective, selecting transformers with high heat resistance levels is of great significance in improving the lifespan and stability of electrical systems.