Transformer Cooling System
The cooling system is one of the most important primary components of a power transformer.
- Transformer performance,
- Efficiency,
- Reliability &
- Service life
are directly influenced by its ability to dissipate the heat generated during the operation.
Excessive temperature can accelerate insulation aging, reduces transformer lifespan and increases the risk of failures.
During normal operation heat is generated due to
- Copper losses,
- Core losses,
- Eddy current losses &
- Stray losses.
An effective cooling system removes the heat & maintains the transformer within its designed appropriate temperature limits.
Types of Transformer Cooling Systems
ONAN (Oil Natural Air Natural)
In the ONAN cooling method transformer oil circulates naturally via convection and heat is dissipated to the surrounding air without the use of fans or pumps.
This system is commonly utilized for small and medium sized transformers.
ONAF (Oil Natural Air Forced)
ONAF cooling utilizes natural oil circulation combined with a forced air cooling through radiator mounted fans.
The fans improves heat dissipation & increase the transformers loading capability.
This method is widely utilized in medium & large power transformers.
OFAF (Oil Forced Air Forced)
In OFAF cooling oil circulation is maintained by pumps while the cooling fans provides a forced air circulation.
This arrangement provides higher cooling efficiency & is typically used in large power transformers with a heavy loading requirements.
OFWF (Oil Forced Water Forced)
OFWF cooling use to employs oil pumps & water cooled heat exchangers to attain maximum cooling performance. This method is commonly applied in very large power transformers, generating stations and high capacity substations.
Main Components of Transformer Cooling Systems
- Radiators,
- Cooling Fans,
- Oil Pumps,
- Oil Temperature Indicator (OTI),
- Winding Temperature Indicator (WTI),
- Temperature Sensors and
- Cooling Control Circuits.
Maintenance Requirements
Regular maintenance of the cooling system is essential to ensure a reliable transformer operation.