40% energy savings shown for permanent magnetic synchronous motor

03 December 2012

The results of a direct product comparison test show how the latest IE4, super premium efficiency permanent magnetic synchronous motor, from Bauer Gear Motor, performed against a standard asynchronous motor.

The test was carried out on a Hüber disc thickener at a waste water treatment plant in Germany in partnership with inverter drive company Danfoss. Once installed the Bauer motor, which meets the requirements of IE4, was found to operate with 87.7% efficiency and delivered energy savings of almost 40%.

Jens Gabel, vice president global sales and R&D for Bauer Gear Motor, said: “In today’s market energy efficiency has to be one of the key determining factors when specifying geared motor solutions. Energy prices are only going to go one way so it is important that a drive’s lifelong running costs are considered; rather than simply the cost of procurement. We have developed the new motor in anticipation of the new IE4 classification and to offer our customers the very best in terms of efficiency.”

Bauer’s PMSM range of motors employs a highly efficient design of rotor that integrates embedded permanent magnets made from rare-earth metals, in place of a squirrel-cage rotor found in most LV induction motors. This design offers a number of key benefits – it reduces heat losses from the rotor by 100%, total losses by approximately 25%, and increases total efficiency by 10% or more. This improved performance translates into a lower total cost of ownership, a reduction in CO2 emissions, and ongoing savings that can help to counter future increases in energy costs.

Bauer was a willing volunteer to take part in the direct product comparison test which was carried out at a live and operational waste water treatment plant in Landsberg am Lech, South West Germany, to show the real-life savings potential of using a PMSM. The disc thickener is in continuous operation for seven hours per day, seven days a week, so provided a good test opportunity.

Prior to the test the existing ASM motor was running on a standard inverter. An inverter drive regulates power consumption based on load and frequency, as required by the application, which inherently makes a motor run more efficiently so, prior to the PMSM being installed, a Danfoss inverter drive was retrofitted to the original system in order to ensure an accurate comparison.

The frequency inverter was programmed to monitor the loads on each motor to ensure that they ran at optimum efficiency. To ensure that any differences in efficiency could be attributed to the motors, each drive used the same Bauer gearbox, which had a reduction ratio of 381:5 at 94% efficiency.

It was found that with the frequency inverter installed the ASM created 2.62Nm torque at 1,350 rpm and operated with 61.5% efficiency using 0.26kW/H.

Having completed the measurements on the ASM, the PMSM was installed. The new motor created 3.5Nm at 1500rpm and operated with 87.7% efficiency using only 0.16kW/hr. The energy savings from installing the motor yielded a 40% saving in energy use over the ASM with the same inverter drive installed.

Over a four year period it was estimated that, with an inverter used in both cases, an ASM would use 2657kW whereas Bauer’s PMSM would use 1635kW; a total saving of 1022kW.

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