The difference between dry type transformer and oil immersed type transformer

Oil-immersed transformers use oil as the main insulation means of the transformer, relying on oil as the cooling medium (self-cooling, air-cooling, water-cooling).

The main transformer of the general booster station is oil-immersed, with a ratio of 20KV/500KV. Dry transformers rely on air convection to cool.

The small-capacity transformer has a ratio of 6000V/400V. Compared with the oil-type transformer, the dry transformer and the oil-type transformer have the same difference. The biggest difference is whether there is oil inside the transformer, and there are many differences.

1. From the appearance point of view, the package form is different, the dry type transformer can directly see the iron core and the coil, and the oil type transformer can only see the outer casing of the transformer;

2, the lead form is different, dry type transformer mostly uses silicone rubber casing, and oil type transformer mostly uses porcelain casing;

3, different capacity and voltage, dry-type transformers are generally suitable for power distribution, the capacity is mostly below 1600KVA, the voltage is below 10KV, and some can achieve 35KV voltage level; while the oil-type transformer can do all the capacity from small to large The voltage level has also achieved all voltages; the UHV 1000KV test line under construction in China must be an oil-type transformer.

4. Insulation and heat dissipation are different. Dry-type transformers are generally insulated with resin, relying on natural air cooling, large-capacity cooling by fan, and oil-type transformers are insulated by insulating oil. The circulation of insulating oil inside the transformer will produce a tropical coil. Dissipate heat on the heat sink (piece) of the transformer.

5. From the application site, dry-type transformers are mostly used in places where “fireproof and explosion-proof” are required. Generally, large-scale buildings and high-rise buildings are easy to adopt; while oil-type transformers may have oil squirting or leaking after “fault”. Most of the fires are caused by outdoor use, and there are places where the site "excavation oil pool" is dug.

6. The bearing capacity is different. Generally, the dry type transformer should be operated under the rated capacity, while the oil type transformer has better overload capacity.

7, the cost is not the same, for the same capacity transformer, the purchase price of dry-type transformer is higher than the price of oil-type transformer.