Dry-type transformer cooling methods are divided into free air cooling (AN) and forced air cooling (AF).
When free air cooling (AN), the transformer can continuously output 100% of the rated capacity under the normal use conditions specified in the standard.
When forced air cooling (AF), under the normal use conditions specified in the standard, the output capacity of the transformer can be increased by 50%, which is suitable for all kinds of emergency overload or intermittent overload operation, due to the large increase in load loss and impedance voltage, forced air cooling (AF) is not recommended for long-term continuous overload operation.
When the transformer is installed in the basement or other environments with poor ventilation capacity, a heat dissipation ventilation device must be added, and the ventilation volume is selected according to the air volume required (2-4m*/min) per 1kW loss (P0 PK).
Compared with the traditional centralized fan and air duct system, the outstanding advantages of the new curtain fan air cooling system are: uniform cooling and good cooling effect; Low noise; Small size, small space occupation, does not exceed the transformer body dimensions. 
The number of fans, power supply configuration are as follows:

| Transformer Capacity (kVA) | 200-630 | 800-1000 | 1250-2500 | 3150 |

| Number of fans (sets) x power (W) | 2x40 | 6x65 | 6x80 | 6x90 |
| Fan power supply (50HZ) | ~220V | ~220V | ~220V | ~220V

Temperature control, temperature display system
The safe operation and service life of dry-type transformer largely depend on the safety and reliability of the winding insulation of the transformer, and the insulation damage caused by the winding temperature exceeding the insulation withstand temperature is one of the main reasons for the transformer to fail to work normally. The temperature control system measures the temperature signal through the P1100 thermistor embedded in the low-voltage winding, and controls the operation of the cooling fan according to the temperature of the winding, and sends out the signal of over-temperature alarm until over-temperature tripping, so as to achieve the purpose of protecting the transformer to make it operate safely and reliably. Natural air cooling (AN) optional type I temperature control box, its function:
Alarm when winding temperature exceeds 120°C: output trip signal when 150°C. When forced air cooling (AF) is equipped with type II temperature control box, its function (factory setting value): when the winding temperature is greater than 100 °C (adjustable), the system will automatically start the fan cooling; When the temperature drops to 80°C (adjustable), the fan will be automatically stopped; If the temperature continues to rise, when it is greater than 120°C (adjustable), the overtemperature alarm signal will be output; When it is greater than 150°C (adjustable), the over-temperature trip signal is output to the secondary protection system.

The temperature display system can visually display the temperature of each phase winding, and can also be equipped with a computer interface to achieve remote temperature monitoring.

The temperature control box and temperature indicator can be installed within a certain distance from the transformer, and the length of the temperature measurement element lead (1mm2) is as follows:
Thermostat leads: <100 m
Thermostat lead: <10m (2-wire system)
< 100m (three-wire system with compensation)