Technology news: June 2012
IE4 PM motors maintain efficiencies at part loads
At the recent Hannover Fair, Bauer Gear Motor demonstrated a range of permanent magnet synchronous motors which meet the requirements of the proposed IE4 Super Premium efficiency classification. The company says the PMSM range can deliver energy savings of up to 40% compared to inverter-driven IE2 squirrel-cage motors.
The motors (shown in a cutaway view, above), which have rare-earth magnets embedded in their rotors, cut total losses by around 25% and raise efficiencies by 10% or more compared to squirrel-cage machines, even under partial load conditions.
The efficiency of some PM motors drops off sharply outside their ideal operating speed and load. Bauer asserts that its PMSM motors will maintain a high efficiency within a wide partial load range, up to a load factor of 1:5.
The PMSM motors also have much higher power densities than standard induction motors. For geared motors, this yields higher system efficiencies with small installation volumes and low weights. The PMSM drives can produce more torque for the same installation volume than conventional induction motors, allowing smaller motors to be used in some applications. The combination of high efficiency, compact size and high torque ratings means that the motors can cut inventories for large plants and third-party stock-holding facilities.
The synchronous design of the PMSM motors means that they can maintain a constant speed, independent of the load. As long as the mains frequency stays constant, the motor speed will not vary, even if the voltage drops or there is an overload.
The PMSM motors are available in ventilated and non-ventilated versions, in ratings from 0.55–15kW. They operate on 380–500V supplies, and are rated for inverter duty, offering an extended speed range with constant torque. They can replace a variety of asynchronous geared motors, reducing inventory, logistic and maintenance costs.
Bauer Gear Motor is a member of the Altra Industrial Motion Group.