A direct comparison test has been carried out to see how Bauer Gear Motor’s latest IE4 super premium efficiency Permanent Magnetic Synchronous Motor (PMSM) performed against a standard Asynchronous Motor.

During development it became clear that the PMSM product would offer impressive energy savings over conventional, inverter driven Asynchronous Motors (ASM). There is, however, still reluctance in the market to buy them, as the purchase cost is higher than that of standard motors. If the duty cycle is high, however, then a PM motor can quickly meet its ROI figure and then go on to deliver savings for a long time to come, claims the company.

The test was carried out on a Huber disc thickener at a waste water treatment plant in Germany in partnership with Danfoss. The disc thickener is in continuous operation for seven hours per day, seven days a week.

Prior to the test the existing ASM motor was running on a standard inverter so prior to the PMSM being installed, a Danfoss inverter drive was retro-fitted 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. So 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 1350rpm and operated with 61.5% efficiency using 0.26kW/H.

The PMSM was then installed. This created 3.5Nm at 1500rpm and operated with 87.7% efficiency using only 0.16kW/H. The energy savings from installing the PMSM 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.

Jens Gabel, vice president global sales and R&D for Bauer Gear Motor, said: ?We are very happy with the results of the test as they show that super premium efficiency motors do deliver a real life measurable benefit and in many higher demand applications should certainly be considered both by design engineers and maintenance engineers alike.?