Open type: It is a commonly used form. Its body is in direct contact with the atmosphere and is suitable for a relatively dry and clean room. (When the ambient temperature is 20 degrees, the relative humidity should not exceed 85%). Generally, there is air self-cooling and air cooling two cooling methods.
Closed type: the device body is in a closed shell and does not directly contact the atmosphere (due to poor sealing and heat dissipation conditions, it is mainly used for mining and is an explosion-proof type).
Casting type: epoxy resin or other resins are used as the main insulation. It has a simple structure and small size, and is suitable for transformers with small capacity.
Cooling method of dry-type transformer:
Dry-type transformer cooling methods are divided into natural air cooling (AN) and forced air cooling (AF). When naturally air-cooled, the transformer can operate continuously for a long time at the rated capacity. When forced air cooling, the output capacity of the transformer can be increased by 50%. It is suitable for intermittent overload operation or emergency accident overload operation; due to the large increase in load loss and impedance voltage during overload, it is in a non-economic operation state, so it should not be used for long-term continuous overload operation
Types of dry-type transformers:
Impregnated air-insulated dry-type transformer
Epoxy resin casting dry-type transformer
Wrapped insulation dry-type transformer
Composite insulating dry-type transformer
What are the advantages of dry-type transformers compared with oil-immersed transformers?
Dry-type power transformers can avoid the risk of fire and explosion of transformer oil due to failures during operation. Since the insulation materials of dry-type transformers are all flame-retardant materials, even if the transformer fails during operation and causes a fire or an external fire source, the fire disaster will not expand.
Dry-type power transformers will not have oil leakage problems like oil-immersed transformers, and there will be no problems such as transformer oil aging. Usually, dry-type power transformers will greatly reduce the workload of operation, maintenance and inspection, and can even be maintenance-free.
The dry-type power transformer is generally an indoor device, and it can also be made into an outdoor type for places with special requirements. It can be installed in the same room as the switch cabinet to reduce the installation area.
Since the dry-type power transformer has no oil, there are few accessories, no oil conservator, safety airway and a large number of valves, and no sealing problems.
