Insulation Grade Of Dry-type Transformer

The insulation grade of Dry Type Transformer refers to the heat resistance grade of the insulation material used, which is usually divided into A, E, B, F, and H grades. Different grades correspond to different maximum allowable temperatures and temperature rise limits.

Insulation grade classification:

Grade A: The maximum allowable temperature is 105℃, and the temperature rise limit is 60K.
Grade E: The maximum allowable temperature is 120℃, and the temperature rise limit is 75K.
Grade B: The maximum allowable temperature is 130℃, and the temperature rise limit is 80K.
Grade F: The maximum allowable temperature is 155℃, and the temperature rise limit is 100K.
Grade H: The maximum allowable temperature is 180℃, and the temperature rise limit is 125K.

Application scenarios:

Grade F dry-type transformers are suitable for environments where the indoor or outdoor air temperature does not exceed 40℃.
Grade H dry-type transformers are suitable for environments where the indoor or outdoor air temperature does not exceed 60℃.
Class C dry-type transformers are suitable for environments where the indoor or outdoor air temperature does not exceed 120°C.

Insulation materials:

Common insulation materials for dry-type transformers include epoxy resin and Nomex paper, which correspond to Class F and Class H insulation, respectively.

Temperature rise and performance:

The temperature rise limit and maximum allowable temperature of dry-type transformers are determined by the insulation grade. For example, the temperature rise limit of Class F insulation is 100K and the maximum allowable temperature is 155°C.

In summary, the insulation grade of dry-type transformers directly affects its maximum allowable temperature and applicable environment. Choosing the right insulation grade is crucial to ensure the safe operation of the transformer.