Product category:
Industrial Drives/Controls
News Release from: Lenze | Subject: Lenze SDS motor
Edited by the Engineeringtalk Editorial
Team on 06 November 2000
Inverter optimised motor improves size
and cost
Inverter optimised motors like the new Lenze SDS can open up a new range of options for the designer, particularly in applications where DC drives have previously been used
In the area of Low Power variable speed drives, inverter optimised motors can open up a new range of options for the designer Particularly in applications where dc drives have previously been used, such motors offers advantages of performance, size and cost
This article was originally published on Engineeringtalk on 21 Feb 2000 at 8.00am (UK)
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The new Lenze SDS is one such inverter optimised motor.
It is smooth bodied and self-cooled without a fan leading to IP54 enclosure and an ambient range of -20C to +40C.
The SDS is available at 240W, 400W and 600W powers with particularly compact dimensions, for example the 240W model has a body diameter of just 85mm.
Inverter optimised means detail differences to the internal structure of the motor.
Large cross section areas reduce losses.
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Windings are optimised with less space between the stator slots.
High specification insulation is used between phases, also between the conductors and earth.
These features, plus the fact that there are no cooling fan windage losses, result in a high efficiency of about 80%.
This is both energy saving and contributes to the compact frame sizes.
SDS is a 4-pole motor but rated at 100Hz and 230/390V supply.
Thus it runs at a rated speed of 2800rpm with a capacity to run up to 5000rpm maximum.
Using 100Hz as the rated speed instead of the conventional 50Hz reflects the fact that these motors are nearly always driven by inverters which have high frequency outputs available.
The result is better torque delivery at low speeds and a wider operating range.
When combined with an inverter such as the Lenze vector series, a 10:1 speed range with constant torque is possible without feedback.
Many dc applications can be replaced in this way, with smaller physical size, equal or greater peak torques and lower cost.
Compared to a conventional ac asynchronous motor, the inverter optimised model delivers similar torque - speed characteristics.
Although cost is higher, the inverter optimised motor has advantages of smaller size, higher efficiency, and needs no blower to achieve a 10:1 speed range.
Adding feedback in the form of an incremental encoder extends the speed range to approximately 100:1 dependent on the inverter.
Physically, mounting the encoder is a simple task as there is no fan in the way, so costs are low.
The table shows that such a closed loop drive system sits mid-way between standard induction motors and servo packages.
SDS motors are finding increasing applications in conjunction with servo motor controllers such as the Lenze 9300 Global drives.
The speed range extends to a nominal 1000:1, but in fact the advantage is full torque availability down to a standstill.
Performance approaches that of a full servo system yet with significant cost savings.
The practicality of these motors is enhanced by a wide range of options.
It is possible to fit a spring applied brake, even with an encoder.
Motors have IEC56/63 standard connection dimensions and standard packages are available with planetary gear heads or right-angle worm gears.
For a panel-free installation, a terminal box inverter can be fitted suiting remote control by fieldbus.
The SDS inverter optimised motor is often chosen to replace dc systems because it is more compact, maintenance free and can deliver comparable torques and speeds.
Some successful applications are for adhesive pumps on a varnishing machine in the automobile industry, small machine tools, motions on complex packaging machinery and automatic positioning systems when combined with servo drives.
The absence of a fan keeps noise levels low suiting drives in hospitals and theatres.
In the food industry, the smooth body of the motor minimises dirt traps and an epoxy paint finish is possible.
Such inverter optimised motors will take business away from dc systems, often because they deliver the required performance at lower cost.
At the same time they open up new applications which were previously in the domain of servo systems, led by advantages in size and cost.
Their market niche will remain in the lower powers although further developments will soon result in similar motors at 1kW or more. Request a free brochure from Lenze ...
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