Differences Between Dry Transformers and Oil Immersed Transformers

The main differences between dry type transformers and oil immersed transformers are as follows:

Applicable Locations

• Dry Transformers: Commonly used in environments requiring fire and explosion prevention, such as large buildings and high-rise structures.
• Oil Immersed Transformers: Typically used outdoors; some installations feature "accident oil pools" to manage oil spray or leakage in case of a malfunction, reducing fire risk.

Capacities and Voltages

• Dry Transformers: Generally used for power distribution with capacities below 1600 kVA and voltage levels below 15 kV, although some can handle up to 35 kV.
• Oil Immersed Transformers: Capable of handling a wide range of capacities from small to large, with voltage levels reaching up to 1000 kV.

Appearance and Shape

• Dry Type Transformers: The core and coil are visible, as they do not have an outer tank filled with oil.
• Oil Immersed Transformers: Encased within a sealed tank, only the transformer shell is visible.

Lead Wire Form

• Dry Type Transformers: Utilize silicone rubber bushings.
• Oil Immersed Transformers: Use porcelain bushings.

Insulation and Heat Dissipation

• Dry Transformers: Insulated with resin and cooled by natural air. Larger units use fans for additional cooling.
• Oil Immersed Transformers: Insulated with oil. The oil circulates to dissipate heat generated by the coil to the transformer's heat sinks or radiators.

Load Capacity

• Dry Type Transformers: Generally operated at rated capacity.
• Oil Immersed Transformers: Have better overload capacity, allowing them to handle higher loads more effectively.

Costs

• Dry Type Transformers: More expensive to purchase than oil-immersed transformers of the same capacity.

Models of Dry ype Transformers

• Common models include SC (epoxy resin casting), SCR (non-epoxy resin solid insulation), and SG (open type).