New in the frequency converter from Ziehl-Abegg: an autotune function supports the fast start-up of asynchronous motors and also helps lifts with old drives to achieve the desired speed of the car. (Photo: © Ziehl-Abegg)
April 2021
During the start-up of asynchronous motors, fine setting of the lift often takes several hours. This is because the information on old type plates is often inadequate or confusing. Ziehl-Abegg now has a solution for fast, safe start-up.
Frequency converters of the ZAdyn type are not only used for gearless synchronous motors. This is because, as ever, many lifts are fitted with asynchronous motors and drives, especially in the case of modernisations. This involves both new as well as old drives that have been operated for decades with pole-changing motors.
Whether old or new: the information on type plates is often contradictory or confusing. Some type plates of old asynchronous motors only provide the speed of the magnetic field as information. Since in asynchronous motors the mechanical speed is always lower than the magnetic field, this information is not very helpful for start-up. In the case of other type plates by contrast, a nominal current is stated that does not match the power needed of the asynchronous motor in the lift.
But even in the case of new drives, current, power and speed are likewise in part not stated for a defined operating point. These are all cases that make determining the motor data needed for the frequency converter start-up into a challenge. In the worst case, this is very time consuming.
To markedly reduce the effort involved in start-up, frequency converters from Ziehl-Abegg have an autotune function for determining the motor data of asynchronous motors. Only the available motor and lift data have to be entered in the ZAdyn frequency converter. The trick is that it is the values calculated by the ZAdyn that are used as nominal speed and frequency and not the values of the type plate.
How does this work? When the empty car descends, ZAdyn determines the motor data needed for the nominal speed of the lift. Consequently, not only the values are determined with which the drive can somehow be operated. ZAdyn determines the data needed to operate the drive with the best possible efficiency. Only a single trip is needed for this.
Since the parameters determined depend on the temperature in the motor, these are continually adjusted during operation of the lift according to the temperature in the drive.
More information: ziehl-abegg.de
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