The maintenance of the dry-type transformer body and the switching of the winding taps can be easily carried out by opening the outer casing of the transformer. It is also very convenient to observe and monitor the operating status of the transformer. During installation, a rubber pad is set between the transformer and the installation foundation to reduce the vibration and noise of the transformer.
(3) Whether the temperature in the house or cabinet where the transformer is located is particularly high, whether its ventilation and ventilation are normal, and whether the air-cooling device of the transformer is operating normally.
(1) Open type. The open type is a commonly used type. Its body is in direct contact with the air. It is suitable for a relatively dry and clean indoor environment (when the ambient temperature is 20 degrees Celsius, the relative humidity does not exceed 80%), generally air-cooled and air-cooled 2 Kind of cooling method.
(2) Closed type. The body of the device is in a closed shell, not in direct contact with the outside air, and can be used in harsh environments. Due to poor sealing and heat dissipation conditions, it is mainly used in mines and other places. The closed type can also be filled with sulfur hexafluoride gas of 0.2-0.3 MPa, and forced to circulate, the insulation and heat dissipation capacity of the transformer is the same as the oil-immersed type, which is suitable for users with high voltage levels.
Since the insulation degree and heat dissipation performance of air are worse than that of oil, the effective material consumption of air-insulated dry-type transformers is higher than that of oil-immersed transformers. Therefore, the fire protection requirements are only higher in underground railways, high-rise buildings, workshops or power stations. Only use dry-type transformers in places where
Dry-type transformers with air insulation are less capable of withstanding impulse voltage than oil-immersed transformers. Dry-type transformer winding insulation adopts A, E, B, F, H, C heat resistance grades, and its temperature limits are respectively 60, 75, 80, 100, 125, and 150 degrees Celsius (all measured by resistance method). The surface of the iron core and the surface of the structural parts shall not exceed the allowable temperature rise of the insulating material (measured by the thermometer method). Because the body is exposed to the air, the winding immersion treatment is very important. In addition to the insulating paint, the winding must be coated with a moisture-proof covering paint.