Plate-type radiators are the core cooling components of oil-immersed transformers. Their functions span the entire thermal management process of the transformer and directly affect the safe operation and service life of the equipment. The following explains their role from the perspectives of working principles, functional details, and practical applications:
1. Core Function: Establishing an Oil Circulation Cooling Path
By connecting to the transformer’s oil circuit, plate-type radiators form a closed-loop cycle of “hot oil rising → heat dissipation → cooled oil returning”. Their core functions include:
Heat-Exchange Medium
During transformer operation, Joule heat generated by the windings and core is transferred to the insulating oil, causing the oil temperature to rise and its density to decrease. The hot oil then flows through the upper oil pipes into the radiator.
Inside the radiator, multiple layers of metal plates (typically made of steel or aluminum) create dense air channels. As the hot oil flows through the radiator pipes, heat is transferred through the metal plates to the surrounding air. After the oil cools, it returns to the transformer through the lower oil pipes, continuously exporting heat from the system.

2. Extended Key Functions
Maintaining the Stability of Insulating Oil Performance
The operating temperature of insulating oil directly affects its electrical properties (such as breakdown voltage and dielectric loss) as well as its chemical stability (such as oxidation resistance).
Plate-type radiators regulate the oil temperature—typically keeping the top-oil temperature within 85–95°C—to prevent rapid oil aging. (For every 8°C rise in oil temperature, the aging rate approximately doubles.)
This significantly extends the oil replacement cycle, with normal service life reaching 15–20 years.

Ensuring the Safety of Solid Insulation Materials
Transformer insulation paper and cardboard, which are cellulose-based materials, are highly sensitive to temperature (long-term allowable temperature usually ≤105°C).
Effective heat dissipation lowers the average winding temperature, preventing thermal degradation of insulation paper (which produces CO, CO₂, and hydrogen). This helps avoid reduced insulation strength and prevents inter-turn short-circuit risks.

Adapting to Load Variations and Environmental Conditions
Load Fluctuation Conditions:
When the transformer is overloaded, the oil temperature rises rapidly. The radiator enhances cooling by increasing the effective heat dissipation area (e.g., multiple radiator groups in parallel) and activating fans in forced-air cooling (ONAF) systems, preventing temperature from exceeding limits.
Environmental Adaptability:
In high-temperature regions or summer seasons, the large surface area design improves natural convection cooling.
In cold regions, hot oil circulation helps maintain oil temperature and prevents oil solidification (insulating oil freezing point typically −45°C to −10°C depending on oil type).

Supporting Fault Prevention and Operational Monitoring
Radiator accessories such as oil circuit valves and oil temperature sensors are useful for:
Oil Flow Observation:
Using an oil flow indicator to determine whether circulation is smooth, helping prevent pipeline blockage or pump failure (for forced-oil circulation systems).
Temperature Monitoring:
By combining top-oil thermometers and winding temperature indicators, operators can evaluate heat dissipation performance in real time and diagnose cooling system issues (such as fan failure or fin blockage by dust).

3. Structural Design and Performance Features
Typical Structural Components
Radiator Panel Fin Body    Made of multiple thin metal plates (1.5–3 mm thick) welded or expanded into tube bundles, forming oil flow channels and air heat-dissipation surfaces.
Header Tank    Connects the radiator to the transformer’s inlet and outlet oil pipes; typically equipped with an air-release valve (to expel trapped air) and a drain valve.
Fan Unit (Optional)    Installed on the exterior side of the radiator; forced air cooling increases heat dissipation efficiency by 30%–50%.
Protective Mesh    Prevents foreign objects (such as insects or debris) from blocking the gaps between fins and affecting airflow.

Performance Advantages Comparison
Comparison Aspect    Plate-Type Radiator    Traditional Tube-Type Radiator
Heat Dissipation Efficiency    High (large heat-dissipation area per unit volume)    Low (limited surface area of smooth tubes)
Size & Weight    Compact (about 30% smaller for the same cooling capacity)    Larger
Vibration Resistance    Strong; welded structure withstands transformer vibration    Tube joints may leak under vibration
Maintenance Cost    Fins easily accumulate dust and require periodic cleaning    Relatively simple maintenance

Installation and Layout Types
Natural Air Cooling (ONAN):Radiators are vertically installed on both sides of the transformer oil tank. Cooling relies on natural air convection and is suitable for small- to medium-capacity transformers (e.g., 10 kV distribution transformers).
Forced Air Cooling (ONAF):Large-capacity transformers (such as 110 kV and above main transformers) use radiators equipped with fans. The fans typically start automatically when the oil temperature exceeds 65°C, significantly enhancing cooling capacity.
Group Control:Multiple radiator groups can be switched on or off through valves, allowing real-time adjustment based on load to balance cooling demand and energy consumption.

4. Common Faults and Maintenance Essentials
Typical Faults and Their Impacts
Fin Blockage:Dust and oil residue accumulate on the radiator panel fins, obstructing airflow and causing oil temperature to rise, which may trigger transformer overload trips.
Weld Leakage:Long-term vibration or corrosion may cause oil leakage at fin welds. Timely repair welding or replacement is necessary to prevent oil level reduction, which could compromise insulation.
Fan Failure:In forced-air cooling systems, fan stoppage can reduce cooling capacity by more than 50%, requiring linkage alarms through temperature control switches.

Maintenance Measures
Regular Cleaning:Clean the surface of the radiator panel fins (recommended 1–2 times per year) using compressed air or high-pressure water to remove accumulated dust.
Valve and Sensor Inspection:Ensure that the oil circuit valves are fully open and oil circulation is unobstructed. Test the oil temperature sensors and fan control system to verify proper operation.
Pressure Testing During Overhaul:Perform pressure testing on the radiator (e.g., 0.05 MPa oil pressure leakage test) to detect hidden leaks and prevent future failures.

Plate-type radiators, through their highly efficient heat exchange design, enable rapid removal of internal heat from oil-immersed transformers, functioning as the “cooling heart” of the equipment. Beyond physical cooling, they help stabilize the insulation system by controlling oil temperature and adapt to varying operating conditions through optimized structural design. In practical applications, proper selection, installation, and maintenance are essential to fully leverage their performance and ensure power grid reliability and transformer longevity.