Choosing a transformer is like choosing a heart, using it correctly can ensure the healthy operation of the power system!
In power engineering, transformers are the heart of energy transmission, but when faced with the two mainstream types of power transformers, dry-type and oil immersed, many people have encountered difficulties - what are the differences between them? Which one is more suitable for my project? Today we will take you to explore the truth!
1、 Insulation and heat dissipation
The insulation medium of dry-type transformers is solid materials such as air or epoxy resin, which dissipate heat through natural wind or fans.
Its advantage is clean and efficient, with no risk of oil leakage, suitable for places with high requirements for fire and explosion prevention, such as shopping malls, hospitals, and subway stations.
But the disadvantage is low heat dissipation efficiency, easy chain breakage in high temperature environments, and the need for forced air cooling to prolong life.
Oil immersed transformers use insulating oil to wrap the windings, which serves as both the insulation layer and the heat sink.
Oil has strong heat storage capacity and can withstand long-term high load operation, so large capacity and high-voltage scenarios (such as ultra-high voltage transmission and power plants) are almost its world.
However, once there is an oil leak or malfunction, it may cause a fire or environmental pollution, and an accident oil tank must be equipped, usually used in outdoor areas.
2、 Safety and Environmental Protection
Dry type transformers have inherent advantages of fire prevention and pollution-free due to their oil-free nature, making them particularly suitable for densely populated areas or places with strict environmental requirements.
For example, a data center once experienced downtime due to oil immersed transformer leakage, but switched to dry-type directly to avoid such risks.
Although oil immersed transformers have oil leakage hazards, their insulation oil can effectively protect the windings and have stronger resistance to short circuits and overloads.
For example, in extreme weather conditions, oil immersed transformers can operate stably even under short-term overload, while dry-type transformers may require emergency capacity reduction.
3、 Applicable scenarios
The three main reasons for choosing dry type:
1. Limited space: Small in size and light in weight, suitable for narrow spaces such as basements and roofs;
2. Safety first: must be selected in hospitals, laboratories, and other prohibited fire areas;
3. Provincial maintenance: No need for oil change testing, low long-term use cost.
Choose three major oil immersed scenarios:
1. Outdoor large capacity: projects with a voltage level of 110kV or above and a capacity exceeding 10MVA, such as substations and industrial parks;
2. High temperature and high load: Strong heat dissipation, suitable for 24-hour high load scenarios such as steel plants and chemical plants;
3. Limited budget: The procurement cost is 30% -50% lower than that of dry type, suitable for users who focus on initial investment.
4、 Maintenance and Cost
Although dry-type transformers have a high purchase price (about 30% -50% more expensive than oil immersed transformers of the same capacity), their advantage lies in their simple maintenance - they only require dust removal for daily use and have a lifespan of up to 20-30 years.
Oil immersed type requires regular inspection of oil quality and replacement of filter elements, resulting in high maintenance costs. But it has a longer service life (20-40 years) and excellent overload capacity, suitable for situations that require pressure resistance.

5、 Performance comparison
How to choose? Remember these 3 golden rules!
1. Look at the environment: choose dry type for indoor narrow or fire-resistant areas, and oil immersed type for outdoor large venues;
2. Check the load: For long-term high loads, choose oil immersed type, and for intermittent loads, choose dry type;
3. Looking at the budget: If you want to save initial costs, choose oil immersed type, and if you want to save long-term worry, choose dry type.
Whether it is dry-type or oil immersed power transformers, there is no absolute quality, only suitability. The specific selection should be based on the actual usage scenario.