Advantages and Disadvantages of Oil-immersed Transformers

Oil-immersed transformers have consistently held a central position in global power transmission and distribution systems. Whether in power plants, substations, industrial parks, or large-scale infrastructure projects, these transformers serve as the “anchor of stability” for electrical engineering due to their exceptional stability, superior load capacity, and extremely high reliability.

As a specialized manufacturer of oil-immersed transformers, CLHT Power understand that what customers truly seek is not merely a list of specifications, but safety, stability, longevity, and a solid return on investment. Below, we comprehensively analyze the advantages and limitations of oil-immersed transformers from a practical engineering perspective, helping you make a more informed choice.

Advantages of Oil-Immersed Transformers

Exceptional Heat Dissipation Capability, Particularly Suited for High-Capacity Operation

Oil-immersed transformers utilize transformer oil as both a cooling and insulating medium. Compared to air, oil possesses superior thermal conductivity, enabling rapid removal of heat generated by windings and cores. Through natural or forced circulation, it achieves highly efficient heat dissipation.

This translates to:

• Ability to withstand higher loads

• Permits greater overload capacity

• Stable operation in high-temperature environments

Consequently, oil-immersed designs dominate large-capacity transformers at 10kV, 35kV, 110kV, and even higher voltage levels. This makes them indispensable for factories, mines, power plants, data centers, and large-scale projects.

Superior Insulation Properties and Enhanced Electrical Safety

Transformer oil not only facilitates heat dissipation but, more critically, provides robust electrical insulation. It fully encapsulates windings and cores, ensuring uniform electric field distribution and significantly reducing partial discharge risks.

Compared to dry-type transformers, oil-immersed units:

• Offer higher breakdown voltages

• Demonstrate greater resistance to electrical shocks

• Greater safety in high-voltage environments

This is why oil-immersed transformers remain the preferred solution in high-voltage substations, outdoor power systems, and critical power hubs.

Extended Lifespan and High ROI

Under proper maintenance, oil-immersed transformers typically achieve a service life of 25–40 years—far exceeding most dry-type transformers.

Reasons include:

• Oil isolates air and moisture, delaying insulation aging

• Windings maintain stable temperature conditions

• Lower mechanical and electrical stress

From a total lifecycle cost perspective, oil-immersed transformers offer lower cost per unit capacity, longer maintenance intervals, and greater long-term operational economy, making them ideal for sustained power projects.

Technologically mature, globally compatible, and easy to maintain

With over a century of development, oil-immersed transformers feature mature manufacturing processes and highly standardized components, enabling maintenance and replacement worldwide.

This is particularly crucial for overseas projects, EPC contracts, and long-term operation clients—

You're not just purchasing equipment, but a globally accessible, reliable technological ecosystem.

Disadvantages of Oil-Immersed Transformers

Every product has its operational boundaries, and oil-immersed transformers are no exception.

Risk of Oil Leakage and Fire

Due to the use of insulating oil, the following scenarios may occur:

• Enclosure damage

• Seal degradation

• Severe malfunctions

may cause oil leakage, posing a combustion risk in extreme cases. Therefore, in densely populated areas, indoor structures, or high-fire-risk zones, additional safeguards or switching to dry-type transformers are typically required.

However, modern designs significantly mitigate these risks through:

• Fully sealed oil tanks

• Explosion-proof valves

• Oil temperature and pressure protection systems

significantly reduced these risks, making oil-immersed transformers highly safe and reliable for outdoor and industrial environments.

Slightly Higher Environmental Requirements

Oil-immersed transformers are better suited for:

• Outdoor settings

• Standalone substations

• Industrial zones

• Power plants and energy projects

For shopping malls, office buildings, or high-density residential areas, dry-type transformers are typically preferred.

Why Oil-immersed Transformers Remain the Global Mainstream

From a global power grid perspective, over 90% of medium- and high-voltage transformers are still oil-immersed. The reason is straightforward:

Oil-immersed transformers have virtually no rivals in four core metrics: capacity, reliability, lifespan, and cost.

For power companies, industrial users, and energy investors, what truly matters is:

• Can it deliver long-term stable power supply

• Can it withstand high loads

• Minimized downtime and maintenance

• Maximized return on investment

Across these critical metrics, oil-immersed transformers remain the optimal solution.

Selecting a Professional Manufacturer Unlocks the True Value of Oil-Immersed Transformers

The performance of oil-immersed transformers depends not only on design but also on manufacturing processes, oil treatment technology, winding structure, and sealing systems.

As a specialized oil-immersed transformer manufacturer, CLHT Power strictly adhere to international standards (IEC/IEEE/ANSI) in:

• Insulation system design

• Low-loss cores

• High-purity transformer oil processing

• Vacuum drying and integral sealing processes

We strictly adhere to international standards (IEC/IEEE/ANSI) to ensure every unit delivers high reliability, extended lifespan, and superior electrical performance upon delivery.

Conclusion

If your project demands:

High capacity, exceptional stability, long-term reliable operation, and lower total cost of ownership,

then oil-immersed transformers remain the most dependable choice.

Selecting the right technology is crucial—but choosing the right manufacturer is equally vital.

A high-quality oil-immersed transformer is not merely equipment; it is decades of stable power assurance.

For all these reasons, submerged transformers have become the majority reference within the electrical network. Are you interested in delving into the technical advantages of this type of insulation? Contact us so that we can assist you with your project.