Cooling types of electric motors

Cooling of an electric motor is the transmission of the losses that occur in the motor and turn into heat to the external environment. The aim is to keep the temperature of insulating materials below the limit values.

Most of the standard Fabrika and Siemens electric motors are cooled through self-ventilation (IC 411 in acc. with DIN EN 60034-6) and are fitted with a synthetic
two-way axial fan mounted on the non-drive end of the shaft.

The most important cooling types of our motors are as follows:

With fan:

  • IC 411: Self-ventilated surface-cooled motor (TEFC)
  • IC 416: Separately-ventilated, surface-cooled (TEFC) motor with separately mounted, driven fan

 

Without fan:

  • IC 418: Without fan and fan cover, e.g. fan in the air flow driven by the motor

 

According to DIN IEC 60034, two systems for coding cooling types exist; both start with the letters IC (= International
Cooling).

For the “full coding”, the letters IC are following by two blocks each comprising one letter and two
digits: e.g. IC W37 A71. In the German draft standard – for air-cooled motors – users are recommended to
use the “simplified coding”; this only has two digits after the letters IC. The first digit defines the type of
coolant circulation, the second digit, the type of drive to move or pump the coolant, as shown in table 1:

Cooling types of electric motors

Table 1: Cooling types of electric motors according to DIN IEC 60034, Part 6

Minimum distance when mounting motors

Motors must be mounted paying attention to a minimum distance between the fan cover and the closest object, so that the air circulation is not compromised. As a rule of thumb, this minimum distance should be half the axle height. For easier access for servicing, it is recommended to keep a minimum distance matching the size of the fan cover.

Starting with frame size 63, motors can be supplied with an independently driven external ventilator if required. This is also referred to as “forced ventilation” and defined as cooling method IC416. In this case, cooling is provided by an axial ventilator mounted in place of the standard fan cover. This design should be used in cases where the motor is operated using a frequency converter with a very low frequency. A motor with forced ventilation can be operated at constant torque at low rotation velocity, or when there is a broad range of rotation velocity. This option is not available for motors with second shaft end.