A New Kind of Motor - Lenze MF 120Hz

Inverter Optimised Motor

120Hz, More than Just Increased Hz

For a long time now, three-phase AC motors have remained largely unchanged in their basic construction and operating parameters.

ThereLenze MF 120Hz Motor are good reasons for this, from their robust nature to the ease of making them run with a simple contactor. Times are changing though with greater demands for efficiency coming from the world's governments to the more complex roll they are expected to play in the operation of industrial machinery. In fact, I'm sure you will recognise that more and more of the motors on your machines are controlled by some form of variable speed drive, whether that is a simple low cost inverter or a highly capable servo drive. This is where the Lenze MF motor comes into its own, it has been designed to be operated exclusively with variable speed drives which brings with it many advantages.

The decision to design the Lenze MF Motor with a rated frequency of 120Hz instead of the traditional 50Hz is the major factor in allowing the motor to significantly out perform the standard motors we are used to. As can be seen from the two graphs at the bottom (click to enlarge) the torque range for the 120Hz MF motor is significantly larger than for the 50Hz motor. This gives a new level of performance across a range of speeds not previously possible without the use of true servo motors and their increased costs. The advantage is magnified even more when a ratio, via a gearbox or belt drive, is used. Since the full torque is available to higher speed point a longer ratio can be used. This not only reduces the size of motor required due to the torque magnifying effect of the ratio but makes a significant reduction in the reflected inertia of the system. Since the reflected inertia is reduced by the square of the ratio, a doubling of the ratio will reduce the reflected inertia by 75%. This has particular advantages for positioning applications keeping the motor and drive small, keeping costs down, without running the risk of the system inertia driving the motor and not the motor driving the system.

All these advantages would of course not be advantages if it was difficult to integrate into your machinery, but with the dimensions of the motors standardised in line with IEC 60072-1 and/or DIN EN 50347 they will easily connect to your gearboxes and mountings just like their 50Hz companions, only with significantly more power.

As with all the Lenze application motors they are available with a wide range of options;

  • Foot, Face or Flange Mounting
  • Feedback from low cost 128ppr encoders to high resolution multi-turn absolute encoders
  • Spring applied brakes
  • Separately powered cooling blowers (allows full torque at all speeds)
  • Option to be painted in 100 different colours.

If you would like to discuss the posibilities please contact us.

MF 120Hz Motor Torque Curve
MD 50Hz Standard Motor Torque Curve

Call us on 01782 511161

Cornfield Engineering Solutions Ltd, Unit 5, Brindley Court, Victoria Business Park, Brown Lees, Stoke-on-Trent, ST8 7PP