1, dry transformer cooling mode

Dry transformer cooling is divided into natural air cooling and forced air cooling. With natural air cooling, the transformer can operate continuously at rated capacity for a long time. When forced air cooling, the output capacity of the transformer can be increased by 50%. Suitable for intermittent over-load operation, or emergency over-load operation; Because of the large increase of load loss and impedance voltage during overload, it is in non-economic operation state, so it should not be in continuous overload operation for a long time.

2, dry transformer overload capacity

The overload capacity of the dry transformer is related to the ambient temperature, the load before the overload (initial load), the insulation and heat dissipation of the transformer and the heating time constant. If necessary, the overload curve of the dry transformer can be obtained from the production factory.

3, how to use the overload capacity of dry transformer

(1) It can reduce the reserve capacity or number of transformers: in some places, the reserve coefficient of transformers is required to be high, so that the transformer selected in the project has a large capacity and a large number of transformers. With the dry transformer overload capacity, it can be compressed when considering its spare capacity. In determining the number of standby units can also be reduced. When the transformer is in overload operation, it is necessary to pay attention to monitoring its operating temperature: if the temperature rises up to 155° C (alarm is issued), load reduction measures should be taken (minus some minor loads) to ensure the safety of power supply to the main load.

(2) When selecting the transformer capacity, it can be reduced appropriately: give full consideration to the possibility of short-term impact overload of some steel rolling and welding equipment -- try to reduce the transformer capacity by using the strong overload capacity of dry transformer; For some places with uneven load, such as residential areas mainly for night lighting, cultural and recreational facilities, as well as shopping malls mainly for air conditioning and daytime lighting, the overload capacity can be fully utilized and the transformer capacity can be appropriately reduced to make the main operation time at full load or short overload.