Siemens SIMOTICS T-1FW68, Configuration Manual

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Configuring
5.1 Configuring workflow
1FW68 radial segment motors
Configuration Manual, 08/2021, A5E51132930B AA
85
Frictional torque
The frictional torque M
r
acts in the opposite direction to the direction of rotation of the
moved part of the motor. It can be approximately calculated from a constant "stiction
component"M
RH
and a "sliding friction component" M
RG
. Both components also depend
on the bearing used and its load.
Depending on the mechanical design, loads here generally include axial forces and
tension forces between the bearing components.
Next steps
The moment of inertia of a suitable motor type can be used here initially.
If it transpires that the discrepancy between the assumed and actual moment of inertia
is too great when further calculations are made, you then have to carry out a further
iterative step when selecting the motor. To calculate the frictional torque, the bearing
manufacturer's data must be used.
5.1.3 Specification of the duty cycle
Uninterrupted duty S1
With uninterrupted duty S1, the motor runs permanently with a constant load. The load
period is sufficient to achieve thermal equilibrium.
The rated data is of relevance when dimensioning the motor for uninterrupted duty.
NOTICE
Motor overload
An excessively high load can lead to shutdown, or if the temperature sensors are not
correctly evaluated, then the motor could be destroyed.
• Ensure that the load does not exceed the value I
N
specified in the data sheets!
• Ensure that the temperature sensors are correctly connected and evaluated.