The IEI Series of Inverter Duty AC Motors range from 0.37kw to 1500kW in frame sizes 90 to 560. These motors are suitable for lower speed (minimum 10% rated) & lower frequency operation by using a separately driven constant RPM cooling fan. They are suitable for both constant torque operation (by maintaining constant V/f ratio) and for constant kW operation (by weakening the flux) and can be used in applications like steel mill stands, extruders, lifts, fans, winder / rewinders etc. IEI Motors have IP55 protection and IC416 cooling.