Permanent magnet motors enter plant mainstream

The cmopany's high efficiency WMagnet motors were designed for usage, where constant torque, low vibration and low noise levels are required – typically on lifts, compressors and conveyors. Because they can operate self-ventilated over a wide speed range, these motors are also ideal for use in applications where gearboxes need to be eliminated to save space. WEG reckons its PM motors reduce size by up to 50% and weight by up to 36%, and deliver higher efficiencies (up to 97.5%) compared to equivalent size induction motors. In fact, they can be at least one frame size or core length smaller and, in some cases, two frame sizes smaller. A major benefits of this is that the cooling system is reduced for the same torque/power ratio. Hence the reduction in noise levels from the fan coupled to the motor shaft. WEG WMagnet motors are manufactured with high energy magnets (NdFeB) in their rotors. These deliver a significant reduction in energy losses, compared to an induction motor, resulting in a lower temperature rise of the motor and increased operating life. Incidentally, in addition to the above advantages, a further benefit of WEG's PM motor is that it can operate on a wide speed range (up to 7,300 rpm) with constant torque. This operation is controlled by a version of WEG's CFWO9 VFD, developed for the Wmagnet range, using vector control technology to drive the motor from zero speed up to the field weakening region.