Medium Voltage Motors, HVM - HVC Series The MEDIUM VOLTAGE motors with frame height 400/500 "HVM-HVC" series are made of steel, of the closed type with IC 411 or IC 416 ventilation and welded copper cage rotor (die-cast for size 355) in order to optimise operation with inverter power supply. Water-Cooled Motors and Generators, WM Series The WM series three-phase motors, closed, water-cooled, manufactured in compliance with the main international standards and in particular with IEC 34 and 72, are available in the same shaft heights, polarities and power ratings as the EMA and EM series, using the same active components.