Motors and Drives
Fig. 4. SEW-Eurodrive has created the IE4-rated DRU motor as part of its modular DR family that can be configured with a choice of integral brakes and encoders.
WQuattro motors employ the same frame size as standard induction motors with the same output. WQuattro motors are available in four- and six-pole versions, with frame sizes from 80 to 132S and outputs of 0.37kW to 7.5kW. The motors feature class F insulation and are suitable for operation on 230/400, 400/690 or 525V supplies. Configured for maximum efficiency, ABB’s new motor
and drive packages are claimed to have energy losses that are 40 per cent lower than for conventional motors. Åke Andersson, the technical manager of ABB Low Voltage Motors, states: “Variable-speed drives save customers a lot of money since they reduce the energy used by the motor.
Running a pump or a fan at 80 per cent speed can reduce the energy consumption to one half compared to running at full speed. The low bearing operating temperature extends bearing lifetime while reducing greasing intervals. This brings down maintenance costs and improves reliability.” SEW-Eurodrive has created the IE4-rated DRU motor as
part of its modular DR family that can be configured with a choice of integral brakes and encoders. DRU motors will initially be offered only as four-pole units in frame sizes from 71 to 100 and power ratings of 0.18 to 2.2kW, with operation from 50Hz supplies. Line-start versions feature permanent magnets installed within the cage. Siemens displayed a motor concept for the future at
the 2011 Hanover Fair. Michael Müller of Siemens motor development, states: “Our version of the IE4 asynchronous motor is a further refinement of the IE3 motor. We improved the manufacturing technology for the motor by using more energy-efficient and low-loss materials. This corresponds to an efficiency rate of 94 per cent.” According to Geoff Spear of Lenze UK, the jump from
IE1 to IE2 was not big; running currents fell a little, starting currents tended to rise and a small number of customers had to review their contactors and fusing. In most cases frame sizes remained unchanged, though motor lengths sometimes increased slightly. He comments: “The step up to IE3, however, will not be so easy, as we anticipate problems with increasing dimensions. We see the take up of IE3 motors as being slow, with little demand at this time - only a few big cases like airports. Yes there will be a minority of customers who want the highest levels of efficiency but also need variable speed.” IE4 motors will, like many other energy-saving measures,
require a higher initial investment. Whether or not the extra cost is worthwhile will depend on the predicted service life and usage pattern. Given that IE3 motors are larger than similarly-rated IE1
and IE2 motors, while some IE4 motors may be no larger than IE2 motors, some designers may find it preferable to opt for IE4 rather than IE3 motors. It is too soon to tell how the market will react to IE4 motors, but those manufacturers that are already offering compliant products have perhaps made a wise decision. l
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