Difference Between Dry-Type Transformers and Oil-Immersed Transformers

The biggest difference between oil-immersed transformers and dry-type transformers is whether there is "oil", and because oil is a liquid with fluidity, oil-immersed transformers must have an outer shell, the shell inside is transformer oil, oil soaked transformer coils, from the outside is not visible transformer coils; and dry-type transformers do not have oil, it does not use the shell, you can directly see the transformer coils; another feature is that oil-immersed transformers have oil pillows, the internal storage of transformer oil, but now the new oil-immersed transformers also have transformers without oil pillows production;.

Oil-immersed transformers are designed with a heat sink on the outside, like a heat sink, for the convenience of heat dissipation, i.e. for the flow of insulating oil inside, while dry-type transformers do not have this heat sink, and the heat dissipation depends on the fan under the transformer coil, which is somewhat like the indoor unit of a household air conditioner.

Oil-immersed transformers are generally installed in a separate transformer room or outdoors due to the need for fire protection, while dry-type transformers are definitely installed indoors, usually in the low-voltage distribution room, side by side with the low-voltage distribution cabinet.

In the construction according to the space to choose dry-type transformer and oil transformer, space is larger when you can choose oil transformer, space is more crowded when you choose dry-type transformer.

1、Appearance

Different forms of packaging, dry-type transformers can directly see the core and coil, while oil transformers can only see the transformer shell.

2、Different lead forms

Most dry-type transformers use silicone rubber bushings, while most oil-type transformers use porcelain bushings.

3、Different capacity and voltage

Dry-type transformers are generally used for power distribution, the capacity is mostly below 1600KVA, the voltage is below 10KV, there are also individual to 35KV voltage level; while the oil transformer can be small to large to do all the capacity, voltage level also to do all the voltage; China is building the extra high voltage 1000KV test line, the use of oil transformers.

4、Insulation and heat dissipation is not the same

Dry-type transformers generally use resin insulation, relying on natural air cooling, large capacity by fan cooling, while oil transformers rely on insulation oil for insulation, relying on the circulation of insulating oil in the transformer inside the coil heat generated by the heat to the transformer heat sink (piece) for heat dissipation.

5、Applicable places

Dry-type transformers are mostly used in places that need "fireproof, explosion-proof", generally large buildings, high-rise buildings are easy to use; and oil transformers due to "accident" may have oil spray or leakage, resulting in fire, most of the application in outdoor, and there are sites to dig the "accident oil pool" places.

6、Different ability to bear the load

General dry-type transformers should be operated under the rated capacity, while oil transformers overload capacity is better.