1PM6/1PM4 Hollow-Shaft Motors for Main Spindle Drives
Configuration Manual, PPMS, 04/2008, 6SN1197-0AD23-0BP0
55
Technical data and characteristics
4
Torque and power characteristics
Constant-torque operation is possible from standstill up to the rated operating point. The field
and therefore the motor torque remain constant in this base speed range. This is the reason
that the power increases linearly with the speed.
The constant-power range, characterized by field weakening, begins from the rated
operating point. In the constant power range, the maximum available torque M
max
at a
specific speed n is approximated according to the following formula:
0>1P@
PD[
3>N:@෬
PD[
Q>USP@
3>N:@ ෬3
PD[
1
Induction motors have a high overload capacity in the constant power range. For some
induction motors, the overload capacity is reduced in the highest speed range.
The field-weakening range is limited by the voltage limit. In order that safe, reliable operation
is guaranteed even when the line supply voltage fluctuates and the motor parameters vary, a
safety margin of 30% should always be maintained to the voltage limit at every operating
point.
Note
For main spindle applications, the constant power range used to machine a workpiece with
constant cutting power is extremely important. The required drive system power can be
reduced by optimally utilizing the constant power range.
