Cooling motor in energy conversion, there is always a small part of the loss is converted into heat, it must be through the motor shell and the surrounding medium will continue to heat is emitted out, the heat dissipation process, we'll call for cooling. Cooling medium: a gas or liquid medium that transfers heat. A gas or liquid medium in which the temperature is lower than a part of a motor, which is in contact with the part of the motor and is taken away by the heat. Secondary cooling medium: the temperature is lower than the primary coolant gas or liquid medium, the outer surface of the motor or cooler will be released by the primary cooling medium heat away. The final cooling medium: heat transfer to the final cooling medium. Ambient cooling medium: gas or liquid media in the surrounding environment of the motor. Remote medium: a medium away from the motor, through the inlet, outlet pipe or channel intake of motor heat and discharge cooling medium to the distance. A device for transferring heat from a cooling medium to another, and keeping two separate types of cooling media.