Dry Type Transformer Temperature Can Not Exceed How Many Degrees?

Generally speaking, the temperature allowed by the dry type transformer is related to the heat resistance grade of the insulating material used. Usually, when the Dry type transformer uses F and H class insulation materials, the allowable temperature rise of F class is 100K and the maximum allowable temperature is 155 ° C, and the allowable temperature rise of H class is 125K and the maximum allowable temperature is 180 ° C.

The heat resistance grade of the insulation system is the decisive factor of the maximum allowable temperature of the transformer

The insulation materials used in the insulation system of electrical equipment mainly include class A, class E, class B, class F, class H, class C and other levels, and the main heat resistance level is different as follows:

• When class A insulation materials are used, the maximum temperature rise should be less than 60K when the limit operating temperature is 105 ° C;
• When the E class insulation material is used, the maximum temperature rise should be less than 75K when the limit working temperature is 120℃;
• When the B-class insulation material is used, the maximum temperature rise should be less than 80K when the limit working temperature is 130℃;
• When the F-class insulation material is used, the maximum temperature rise should be less than 100K when the limit working temperature is 155 ° C;
• When the H-class insulation material is used, the maximum temperature rise should be less than 125K when the limit working temperature is 180℃;
• When the C-class insulation material is used, the maximum temperature rise should be less than 150K when the limit operating temperature is 220 ° C.

Because the coil insulation of Dry type transformers is usually F and H class insulation materials, the maximum absolute normal temperature is not allowed to exceed 155 ° C and 180 ° C. If the winding temperature of the dry type transformer is too high, it will cause its insulation aging to accelerate, which will affect the service life or short-circuit, fire and other faults, so from the point of view of the hot spot temperature alone, the lower the operating temperature of the transformer, the better, in order to prevent the abnormal operating temperature, the need for strict inspection or monitoring in use.