The difference between dry-type transformers and oil-immersed transformers

The safe operation and service life of dry-type transformers largely depend on the safety and reliability of the insulation of the transformer windings.

Since the end of the 20th century, dry-type transformers have hardly been imported from abroad, and it is difficult to find traces of foreign dry-type transformers in key projects and major projects in China. China has become the country with the largest production and sales of dry produce in the world so far.

The difference between dry-type transformers and oil immersed transformers:

Dry type transformers rely on air convection for cooling. Small capacity transformer ratio 6000V/400V; The booster station uses oil as the main insulation medium for transformers and relies on oil as the cooling medium (self cooling, air cooling, water cooling). The main transformer of a typical radiator is oil immersed, with a transformation ratio of 20KV/500KV;

The biggest difference between dry-type transformers and oil immersed transformers, apart from the same working principle, is whether there is oil inside the transformer, and there are also many differences.

1. The appearance packaging forms are different. Dry type transformers can directly see the iron core and coil, while oil immersed transformers can only see the outer shell of the transformer;

2. The lead forms are different. Dry type transformers mostly use silicone rubber sleeves, while oil immersed transformers mostly use ceramic sleeves;

3. Due to differences in capacity and voltage, dry-type transformers are generally suitable for distribution, with capacities mostly below 1600KVA and voltages below 10KV. There are also some that achieve a voltage level of 35KV; However, oil immersed transformers can achieve full capacity from small to large, and their voltage levels can also reach all voltages; The ultra-high voltage 1000KV test line currently under construction in our country must use oil immersed transformers.

4. Insulation and heat dissipation are different. Dry type transformers are generally insulated with resin and cooled by natural air, while large capacity transformers are cooled by transformers. Oil immersed transformers are insulated with insulating oil, which circulates inside the transformer to dissipate heat from the heat generated by the coils onto the fan (blade) of the transformer.

5. Dry type transformers are mostly used in places that require fire and explosion protection, and are generally easy to use in large buildings and electrical systems; Oil transformers, due to the possibility of oil spraying or leakage after accidents, can cause fires. They are mostly used outdoors and there are places where "accident oil pools" are excavated.

6. The load-bearing capacity of dry-type transformers varies, and they should operate at their rated capacity, while oil-immersed transformers have better overload capacity.

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