Motors can be supplied with various IC cooling methods (according to IEC 60034-6), with the IP degrees of protection (according to IEC Std. 60034-5). The different versions are indicated by a specific code.

IP IC Description  
23 06 Forced ventilation by fitted fan.
Suction exhaust to the local atmosphere
23 16 Forced ventilation by fitted fan,
with ducted air inlet and outlet vent to local atmosphere
23 17 Ventilation by external system
with ducted air inlet and outlet vent to local atmosphere
44 / 54/ 55 410 Totally enclosed naturally ventilated machine
44 / 54 / 55 36 Force ventilation by integral system
with air inlet and outlet ducts
44 / 54 / 55 37 Ventilation by external system
with air inlet and outlet ducts
44 / 54 / 55 86W Assisted ventilation in closed cycle with air-water heat
exchanger (typically for larger frame sizes 200-800 only)
44 / 54 / 55 666 Assisted ventilation in closed cycle with air-air heat
exchanger (typically for larger frame sizes 200-800 only)