Permanent Magnetic Synchronous Motors deliver big energy savings

The test was carried out on a Hber disc thickener at a waste water treatment plant in Germany in partnership with inverter drive specialist Danfoss. Once installed the motor from Bauer was found to operate with 87.7 per cent efficiency and delivered energy savings of almost 40 per cent.

Bauer Gear Motor is a manufacturer of geared motors, and has always been at the forefront of developing new technologies with a desire to improve energy efficiency and reduce costs for its customers. It is this commitment to efficiency that has led to the introduction of a new range of Permanent Magnetic Synchronous Motors (PMSM) which meet the requirements of the IE4 (Super Premium Efficiency) classification.

Jens Gabel, Vice President Global Sales and R&D for Bauer Gear Motor, comments: "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 series is an environmentally friendly range of motors, employing 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 per cent, total losses by approximately 25 per cent, and increases total efficiency by 10 per cent or more.

For the PMSM user, this improved performance translates into a lower total cost of ownership, a reduction in CO2 emissions, and ongoing savings that buffer against future increases in energy costs.

During the product's development it was clear that the new PMSM would offer consumers energy savings over conventional, inverter-driven Asynchronous Motors (ASM). There has been a large amount of publicity recently about PM motors, but there is still reluctance in the market to buy them, as the purchase cost is higher than that of standard motors. In some light-duty applications where the motor is rarely on, it is still more economical to specify a standard motor, but if the duty cycle is high then a PM motor can quickly meet its ROI figure and then go on to deliver savings for a long time to come.

Test for real-life energy savings

Keen to prove the real-life savings potential of using a PMSM, 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. The disc thickener is in continuous operation for seven hours per day, seven days a week, so provided an excellent 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 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. 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 per cent efficiency.

It was found that with the frequency inverter installed the ASM created 2.62Nm torque at 1350rpm and operated with 61.5 per cent efficiency using 0.26kW/H.

Having completed the measurements on the ASM, the PMSM was installed. The new product from Bauer created 3.5Nm at 1500rpm and operated with 87.7 per cent efficiency using only 0.16kW/H. The energy savings from installing the PMSM yielded a 40 per cent 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.

Mr Gabel continues: "A lot of work has gone into developing our latest series of motors and we had hoped to be able to offer the customer very real savings in terms of energy costs. 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."

For more information about IE4 super premium efficiency Permanent Magnetic Synchronous Motors from Bauer, go to the website at www.bauergears.com/.