Siemens SINAMICS S120 Configuration Manual page 64

Configuration
5.3 Dimensioning
• It should be noted that the maximum permissible motor torque on synchronous motors at
• When using induction motors, the permissible motor torque in the field-weakening range
Load duty cycles with constant on period
For duty cycles with constant ON period, there are specific requirements for the torque
characteristic curve as a function of the speed:
e.g. M = constant, M ~ n
These drives typically operate at a specific operating point. Drives such as these are
dimensioned for a base load. The base load torque must lie below the S1 characteristic
curve.
In the event of transient overloads (e.g. when accelerating) an overload has to be taken into
consideration. The peak torque must lie below the voltage limiting characteristic curve for
synchronous motors or below the stability limit for induction motors.
In summary, the motor is selected as follows:
Figure 5-5
64
higher speeds is reduced as a result of the voltage limiting characteristic. In addition, a
margin of 10% below the voltage limiting characteristic should be maintained to
safeguard against voltage fluctuations.
is restricted by the voltage limiting characteristic (stability limit). A margin of 30 % should
be observed.
, M ~ n or P = constant.
2
Selection of motors for load duty cycles with constant on period (examples)
Configuration Manual, (PFK7S), Edition 12.2006, 6SN1197-0AD16-0BP1
Synchronous Motors 1FK7