Enhancing Cooling Performance for Reliable Grid Operation

Oil-immersed transformers remain the backbone of power distribution networks in Brazil and other fast-growing markets. Whether used in substations, renewable energy projects, or industrial facilities, one thing never changes: these transformers must operate safely under continuous electrical load.
To achieve this, every oil-immersed transformer relies on a key component-the radiator.

In this article, we explain why radiators are essential, how they work, and what B2B buyers should look for when selecting reliable radiator suppliers for their transformer projects.

1. Heat Is the No.1 Enemy of Transformer Life

During operation, a transformer generates heat from:

Copper losses (winding resistance losses)

Core losses (magnetic flux)

Load fluctuations

According to IEC standards, every 6–7°C increase in winding temperature will reduce transformer insulation life by half.
This is why controlling temperature is not optional-it determines the transformer's lifespan, stability, and total cost of ownership.

Oil-immersed transformers use mineral oil to absorb heat from the core and windings. But without a way to release that heat, the oil temperature will continue rising, leading to:

Insulation degradation

Accelerated oil oxidation

Higher pressure inside the tank

Risk of tripping or failure

Radiators are the component responsible for removing this heat from the system.

2. How Transformer Radiators Work

Transformer radiators operate on a simple thermal cycle:

Step 1 - Hot oil rises

When the transformer is loaded, hot oil inside the tank becomes less dense and naturally rises into the top pipe of the radiator.

Step 2 - Heat is dissipated through steel fins

The radiator fins increase the cooling surface area.
In natural air cooling (ONAN), the heat is released simply through airflow.
In forced-air cooling (ONAF), fans are added to speed up the process.

Step 3 - Cooled oil returns to the tank

As the oil cools, it becomes denser and sinks back into the transformer tank, completing the circulation cycle.

This continuous process can reduce oil temperature by 15–25°C, depending on radiator size and design.

3. Why Radiators Are Critical for Oil-Immersed Transformers

3.1 Ensures Safe Operating Temperature

Radiators help maintain the transformer within IEC-specified temperature limits:

Top oil temperature rise: ≤ 60–65°C

Winding temperature rise: ≤ 65–70°C

Keeping within these limits prevents thermal aging and extends service life.

3.2 Supports Higher Loading Capability

A transformer with efficient radiators can operate at higher loads without overheating-
a major advantage in emerging markets like Brazil, where grid expansion and industrial demand continue to grow.

3.3 Reduces Operation Costs

3.4 Adapts to Harsh Climate Conditions

Brazil's tropical and humid climate increases thermal stress on transformers.
Radiators designed with anti-corrosion coatings and strong welding quality ensure stable performance in:

Coastal regions

High humidity areas

High ambient temperatures

4. Types of Transformer Radiators and Their Advantages

Choosing the right style can improve cooling efficiency by 10–18%.

Lower temperature = longer insulation life = fewer maintenance interventions.
Radiators provide a low-cost, long-term solution to maximize transformer lifespan.

5. What Buyers Should Look for in a Radiator Supplier

For B2B procurement teams-especially in Brazil's competitive power sector-the quality of radiators directly affects equipment performance and delivery schedules.

Here are the key factors to check:

5.1 Welding Quality

High-strength welds ensure no oil leakage under:

Pressure test (typically 160–180 kPa)

Thermal expansion

Long-term vibration

5.2 Surface Treatment

A durable coating prevents corrosion in tropical climates.
Options include:

Epoxy powder coating

Hot-dip galvanizing

Anti-salt-fog painting

5.3 Dimensional Accuracy

The radiator must be compatible with the customer's transformer tank design:

Center distance

Pipe size

Mounting plate thickness

Number of panels

5.4 Reliable Production Capacity

Large power projects often require large quantities with stable delivery.
A trusted supplier should have:

Automatic welding lines

Pressure test equipment

Large stock of steel plates

Fast shipping for overseas markets

Oil-immersed transformers rely heavily on effective cooling systems to ensure safe operation and long service life. Transformer radiators provide a simple, efficient, and essential solution for releasing heat and protecting internal insulation.

For B2B buyers in Brazil and other emerging markets, choosing a qualified radiator supplier can significantly reduce project risks and improve transformer performance over the long term.

If you need radiator solutions, technical drawings, or a quotation, our engineering team is ready to support your next project.