Siemens Sinamics s120 Commissioning Manual page 270

Commissioning
3.18 Commissioning SIMOTICS T-1FW6 built-in torque motors
Displaying the commutation angle tolerance
For a finely synchronized drive, the difference between EMF phase U and the normalized,
electrical pole position angle may be a maximum of 10°. This means that the zero points of
the falling edge of the sawtooth and EMF phase U may differ by a maximum of 10° electrical.
For motors connected in parallel, this maximum permitted deviation for the EMF, phase U is
valid for each motor connected in parallel.
If the difference is greater, then you must adapt the angular commutation offset. If, when
moving over the zero mark, fault message "F31130 (N, A) encoder 1: Zero mark and position
error from the coarse synchronization" is output, then the deviation of the commutation is
greater than 60° electrical. You must check the commutation angle again using the
techniques described.
Image 3-95
270
Tolerance envelope for the pole position angle
STARTER Commissioning Manual
Commissioning Manual, (IH1), 07/2016, 6SL3097-4AF00-0BP5