Siemens 1FT Series Safety And Operating Instructions Manual page 17

ENGLISH
If the rotor position encoder and tachogenerator have been removed, they
must be re-adjusted. The rotor position encoder and the tachogenerator
can also be moved out of position by incorrect loadings on the N-end of
the motor.
Incorrect adjustment can be seen by uneven rotation (noticeable variations
in speed) and in extreme cases by activation of the pos. encoder sensor.
The following instructions describe the procedure for checking/
adjusting the rotor position encoder and tachogenerator
NOTE: The rotor position encoder must first be adjusted relative to the
motor stator winding (1) and then the tachogenerator stator (2) must be
adjusted relative to the rotor position encoder.
1 Adjusting the rotor position encoder relative to the motor stator
winding (see Fig. 111.1)
For this operation, the motor must be run as a generator. This can be done,
for example, by briefly turning the motor shaft by hand. While the motor
is being turned, one channel of a two-channel oscilloscope (with memory
if possible) is used to measure a phase-to-phase voltage (e.g. EMF U-V,
EMF = electromotive force) and the second channel used to measure the
corresponding signal (encoder S) from the rotor position encoder. While
the motor is being rotated clockwise (viewed from D-end), the switching
disc (8.02, Fig. 107) is turned until the rotor position encoder signal
switches from low to high when the phase-to-phase voltage passes from
the negative value through the zero point. The rotor position encoder is
then correctly adjusted relative to the motor stator winding.
The assignment of the two other phase-to-phase voltages (e.g. V-W and
W-V) to the rotor position encoder signals (e.g. T and R) should then be
checked as shown in Fig. 111.1!
2 Adjusting the tachogenerator stator relative to the rotor position
encoder (see Fig. 111.2)
For this operation, the motor can either be operated with current control
or as a generator as described in point 1 above. The oscilloscope is then
used to measure the signal (of one tachogenerator phase, e.g. phase T)
and the corresponding position encoder signal (encoder S). The
tachogenerator stator (8.03, Fig. 107) is turned, while the motor is being
rotated clockwise (viewed from D-end), until the rotor position encoder
signal switches from low to high precisely at the point at which the phase
voltage passes from the negative through the zero point. The tachogenerator
stator can be turned by loosening the screws (6.47/1FT506.-6.31) which
are reached through the slots in the rotor position encoder switching disc.
The tachogenerator stator can then be moved with a screwdriver through
the Pg9 cable gland hole in the N-end endshield.
The assignment of the other tachogenerator phases (e.g. R and S) to the
rotor position encoder signals (e.g. T and R) should be checked as shown
in Fig. 111.1!
After completing the adjustments, the assignment of the signals
should be checked once again, and re-adjusted if necessary.
Repeat points 1 and 2 to re-adjust.
3.8.2 Resolver
The resolver mounting arrangement is made to the customer's
requirements.
Details of adjustment can be obtained from the motor manufacturer!
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