Dry Type vs Oil Immersed Transformer: Which One Should You Choose?

Are you trying to decide between a dry-type and an oil-immersed transformer? Choosing the right transformer can be crucial for your power needs, whether it's for industrial, commercial, or residential areas. While both types serve the purpose of transforming voltage levels, they each have unique characteristics that make them suitable for different settings and performance demands.

In this guide, we’ll dive into the key differences between dry-type and oil-immersed transformers, examining their strengths and limitations to help you make a well-informed choice. So, read on to discover which transformer type is best for you!

1) Dry-type transformer: The Eco-friendly Powerhouse

The dry-type transformers contain winding and a core that has solid insulating materials such as epoxy or polyester resin which provide electrical insulation. These types of transformers may also be referred to as cast resin or epoxy resin transformers.

These types of insulating materials are solid, have high dielectric strength and thermal stability, and are also non-combustible and self-extinguishing, hence making them more fire-safe.

These transformers are mostly found in medium-voltage applications where oil-filled transformers would not be suitable. Some common applications include indoor substations, commercial complexes, and underground substations.

➔  Advantages

• Controlled Mechanical Force: They can handle high mechanical forces without any risks of fire or explosion.

• Maintenance-Friendly & Non-hazardous: The absence of oil ensures that there are no outflows and they do not require complex maintenance.

• Self-extinguishing Reliable Safeguards: The reinforcements made with resin substantiate better safety and due reliability.

• Reliable Power Supply: These types of transformers provide reliable power supply to various applications, which rely on them.

➔  Disadvantages

• Power Limitations: Dry-type transformers have a far lower capacity to operate and have a lower transformer rating than oil-filled transformers.

• Higher Operational Cost: Dry-type transformers are relatively expensive as compared to other types of transformers.

• Cooling Efficiency: Cooling purposes and mechanisms are insufficient for dry types as it is impossible to use them for high-capacity applications.

• Temperature Sensitivity: The mechanical properties and operational capabilities of dry transformers will vary with temperature.

• Application Constraints: Not all electrical systems will be suitable for dry transformers because they cannot handle the insulation or even cooling requirements needed.

2) Oil-immersed transformer: Efficient Cooling

In oil-immersed transformers, the core and windings are suspended in a steel tank filled with oil. This oil serves for better insulation and cooling purposes. During these transformers’ operation, the heat energy from the core & windings is absorbed by oil which moves this heat towards the surrounding atmosphere and cools down.

Because of their effective cooling characteristics and insulation properties, oil-filled transformers are commonly used in generation, distribution, and transmission systems, and outdoor substations.

➔  Advantages

• Long Lifespan: The operating life of oil-immersed transformers is long provisioned with proper maintenance.

• Stable Performance: Its construction achieves a design that reduces overheating leading to consistent running.

• Wide Acceptance: These transformers are quite popular and widely installed owing to their reliability.

• More Power Rating: These transformers are recommended for high-power use due to competent insulation.

• Wide Range of Applications: They apply to a wide range of uses and can handle high voltage ratings.

➔  Disadvantages

• Safety Risks & Environmental Impact: Risk to the earth remains through oil leakage.

• Design Complexity: High power and high voltage arrangements can limit design simplicity.

• Cost Factors: Initial costs are quite high because of the oil management.

• Limited Compatibility: These transformers cannot be used for all purposes.

3) Dry-type vs. Oil-immersed transformer: Key Differences

Dry-type vs. Oil-Immeresed Transformers is found to be the most common debate in the market today. So, we’ve given the distinct features of both transformers to help you choose a better one. Let’s break them down together!

• Cooling Method: The windings and core of dry-type transformers are exposed to the surrounding air, and heat is dissipated naturally or with the help of fans.

In oil-immersed, the oil absorbs the heat generated during operation, and it circulates through the transformer to transfer heat to the surface for cooling. The oil also provides insulation to prevent electrical discharges.

• Size and Capacity: The dry-type are smaller and more compact due to the absence of oil and associated cooling systems and are used for lower power ratings, usually up to 2000 kVA.

While oil-immersed can be much larger and have a higher power capacity (up to several hundred MVA).

• Installation Location: The dry-type is more suitable for indoor installation and commonly used in residential, commercial, or industrial buildings where space is limited.

Whereas, oil-immersed are widely used in electrical distribution networks, substations, and large-scale industrial applications where higher power ratings are required.

• Role of Recycling: In terms of sustainability, a dry-type transformer contains materials that can be recycled in a limited way but oil-immersed furnishes the possibility to fetch back the core and coil elements with ease.

Further, oil-immersed transformers are claimed to have longer working life and are simple to maintain with the outcome of less waste generation, fewer replacements, and fewer labor requirements.

• Operational Cost: The dry-type may have higher operational costs due to lower efficiency and the potential need for more frequent maintenance as they operate at higher temperatures.

Oil-immersed transformers tend to be more efficient in the long term due to better cooling, resulting in lower energy costs over time.

• Efficiency: The oil-immersed transformers are more efficient as compared to dry-type in terms of cooling and heat dissipation, which allows for higher power ratings and prolonged operation under load.

• Maintenance: Oil immersed requires regular maintenance to monitor the oil level, condition, and quality. The oil may need to be replaced periodically, and the transformer must be checked for leaks or oil contamination. Dry-type doesn’t require much maintenance.

• Safety and Environmental Concerns: The former one is environmentally more favorable as they don’t require oil, which can be hazardous.

There is a potential risk of fire or environmental pollution in case of oil leaks or spills. So, the latter transformers require more safety measures to manage the oil and prevent accidents.

• Noise Levels: The dry-type transformer produces more noise as compared to oil immersed transformer.

Here’s a table given below highlighting the key differences between dry-type and oil-immersed transformers for your quick understanding.

	Dry-type Transformers	Oil-immersed Transformers
Alternate name	Cast resin or epoxy resin transformers	Oil-filled transformers
Insulating material	Epoxy or polyester resin	Dielectric oil
Cooling medium	Air	Oil
Size and capacity	Smaller with low power capacity	Larger with high power capacity
Installation location	Being environmentally safer they are used in indoor applications	Installed outdoors due to the risk of oil spill
Recyclability	Restricted	Enhanced oil recycling property
Initial cost	Involve low initial cost as it requires less maintenance	Require high initial cost due to the need for oil and associated measures
Operational cost	Imply high operational costs as they require more energy	Utilize conventional energy efficiently, hence demanding lower operational cost
Efficiency	Less efficient	More efficient
Maintainance	Require less maintenance	Require regular maintenance
Safety & Environmental Impact	Less waste is produced	Risk of oil leakage
Noise level	high	low

4) Final Thought: Which one should you choose

When it comes to large energy requirements, oil-immersed and dry-type transformers have their own merits. Oil-immersed transformers are perfect for external and industrial applications since they are well-cooled and rugged in construction.

In case you would need a transformer for the interiors, dry-type would be suitable; they come with air-cooling and are low in maintenance and therefore safe for commercial and small-scale operations.

We at Delixi are a reputable manufacturer of high-quality transformers. We offer a range of oil-immersed transformers that are effective and reliable to work as per the intended application. Make the right decision for your power needs - contact us.