In this article, we will teach you How is the dry transformer cooled?, How to cool a transformer?, What are the types of cooling in transformers?
How is the dry transformer cooled?
A dry transformer is cooled primarily by circulating air, either by natural convection or by forced air. During natural convection cooling, heat generated inside the transformer rises and is dissipated across the surface of the transformer into the surrounding air. In forced air cooling, fans are used to improve airflow over the surface of the transformer, thereby improving the heat dissipation rate. Since dry-type transformers use no coolant, efficient air circulation is crucial to maintaining safe operating temperatures.
How to cool a transformer?
To cool a transformer, several methods can be used depending on the design and application of the transformer. Oil-filled transformers are typically cooled by the circulation of transformer oil, which absorbs heat from the windings and core and then transfers it to the external surfaces where it dissipates to the environment. This process can be enhanced by using radiators or fans to increase the cooling surface area. For dry-type transformers, as mentioned, cooling is achieved by circulating air, either by natural convection or by forced air using fans. In larger transformers, additional cooling methods such as water cooling systems or heat exchangers may be used to ensure that the transformer operates within safe temperature limits.
Types of cooling in transformers include several methods suitable for different transformer designs and operating conditions. The main types of cooling are:
Natural Air Cooling (AN or ONAN): Used in dry-type transformers, where air naturally circulates around the transformer to dissipate heat.
What are the types of cooling in transformers?
Forced Air Cooling (AF or ONAF): Fans are used to force air onto the surface of the transformer, thereby improving cooling, commonly used in dry and oil-filled transformers.
Natural Oil Cooling (ON): The oil inside the transformer circulates naturally due to the temperature gradient, transferring heat from the windings to the tank walls.
Forced Oil Cooling (OF): Pumps are used to circulate oil through radiators or heat exchangers, thereby improving cooling efficiency in oil-filled transformers.
Oil and water cooling (OW or ODAF): Oil circulates through the transformer and is cooled by water in a heat exchanger. This method is often used in very large transformers.
Disadvantages of dry-type transformers include their limited power rating and efficiency compared to oil-filled transformers. Due to their reliance on air for cooling, dry-type transformers may not dissipate heat as efficiently as oil-filled units, which can limit their size and application. They also tend to be larger and heavier for the same horsepower, because air is a less efficient coolant than oil. Additionally, dry-type transformers are generally more expensive to manufacture and may have a shorter lifespan in high humidity or dusty environments, as these conditions can affect their insulation properties.
The normal temperature of a dry-type transformer during operation is generally between 80°C and 100°C, depending on the load and environmental conditions. The maximum allowable temperature for a dry-type transformer is generally between 150°C and 180°C, but it is crucial to monitor and manage the temperature to avoid overheating and ensure the longevity of the transformer. Regular monitoring and maintenance is essential to prevent the transformer from exceeding its safe operating temperature limits.
We trust this overview of How is the dry transformer cooled? has been clear.