Selecting Induction Motors; Motor Operates Continuously - Siemens SINAMICS S120 Configuration Manual

Configuring
2.3 Selecting and dimensioning induction motors
For motion control and technology functions (e.g. positioning), as well as for synchronous
functions, the corresponding automation system, e.g. SIMOTION D, is used.
The drives are interfaced to the higher-level automation system via PROFIBUS.
2.3.3

Selecting induction motors

A differentiation must be made between 3 applications when selecting a suitable induction
motor:
Case 1:
Case 2:
Case 3:
The objective is to identify characteristic torque and speed operating points, on the basis of
which the motor can be selected depending on the particular application.
Once the application has been defined and specified, the maximum motor torque is
calculated. Generally, the maximum motor torque is required when accelerating. The load
torque and the torque required to accelerate the motor are added.
The maximum motor torque is then verified with the limiting characteristic curves of the
motors.
The following criteria must be taken into account when selecting the motor:
● The dynamic limits must be adhered to, i.e., all speed-torque points of the relevant load
● The thermal limits must be adhered to, i.e. the rms motor torque at the average motor
● In the field-weakening range, the permissible motor torque is restricted by the voltage
2.3.4

Motor operates continuously

The following motor must be selected: P
An overload is dimensioned for transient overloads (e.g. when accelerating). The peak
torque must lie below the stability limit.
It must then be verified that the selected motor can supply the necessary output over the
desired speed range. If this is not the case, a larger motor or a different winding variant must
be selected.
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The motor essentially operates in continuous duty.
A periodic duty cycle determines how the drive is dimensioned.
A high field weakening range is required.
event must lie below the relevant limiting characteristic curve.
speed resulting from the duty cycle must lie below the S1 characteristic curve (continuous
duty). The rms value of the motor current within a duty cycle must be less than the rated
motor current.
limit characteristic (stability limit). A margin of 30 % should be observed.
≥ P
N, Motor required
Configuration Manual, (APH4S), 08/2008, 6SN1197-0AD64-0BP1
1PH4 Induction Motors