A transformer is an important part of a power distribution system. It makes it possible for power coming from a power station to be used by appliances and devices that need it. Electricity coming from a power station has a high voltage and cannot be used directly in houses, factories, and offices. So, a transformer “transforms” this voltage.

Transformers are of two types, namely dry-type and oil-filled transformers. Oil-filled transformers are also known as liquid-filled transformers. These two types of transformers do the same thing, but there are a few differences between them. These differences often define what type of transformer is suitable for a specific purpose.

Cooling medium

Without a cooling medium, it will not be possible to control the temperature of a transformer. Hence, there is a huge risk of fire and overheating. Normally, when a transformer works for a period, it is expected to get hot. However, this must be checked because the continuous rise in temperature may be hazardous. The cooling medium of a dry-type transformer is air while the cooling medium of an oil-filled transformer is oil.

There is a school of thought that oil-based transformers are a fire risk because of the flammability of the oil being used. Hence, public places like malls, banks, and offices prefer to use dry-type transformers. Hence, oil-filled transformers are used for outdoor purposes.


Dry-type transformers require less maintenance than oil-filled transformers. It is also important to check the oil for contamination. The oil-filled transformer is highly prone to chemical contaminants.


Dry-type transformers are usually more expensive than oil-filled transformers.


Oil-filled transformers are usually quieter than dry-type transformers. This is in spite of the fact that transformers are known to be noisy in operation.


Dry-type transformers are less efficient than oil-filled transformers. This is not unconnected with the fact that dry-type transformers have size limitations and voltage restrictions. Hence, they get heated more easily in an overload situation. During overload, dry-type transformers do not perform very well.

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