(1) For oil-immersed air-cooled transformers, when the temperature of the upper layer oil does not exceed 65°C, it is allowed to operate with the rated load without the cooling device.

 (2) Forced oil circulation air-cooled transformers can operate with rated load for a long time when the cooling device is operating normally.

 (3) Forced oil circulation air-cooled transformers are not allowed to operate without a cooler under any circumstances.

 (4) The transformer forced oil circulation air cooling system must have dual power supplies that can be automatically switched, and regular testing of its switching function. When the oil temperature or load of the upper layer of the transformer reaches the specified value, the auxiliary cooler should be able to be automatically turned on; when the working or auxiliary cooler fails, the standby cooler can also be automatically turned on.

 (5) The site shall determine the number of groups put into the cooler under various loads according to the load and ambient temperature of the forced oil circulation air-cooled transformer and in accordance with the manufacturer's regulations.

 (6) When the forced oil circulation air-cooled transformer is in operation, when the cooler is completely stopped, it is allowed to run at rated load for 20 minutes. If the upper oil temperature does not exceed 75°C, it is allowed to rise to 75°C, but the maximum operating time shall not exceed 1h under any circumstances.