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3. ELECTRICAL INSTALLATION 21
Motor Selection
Usually optimum performance will be obtained when the current rating of the motor is
between 1 and 1.5 times the drive rating. Drives can be de-rated to accommodate motors
with lower current ratings (using variable MC within the MOTOR command), however the
high speed torque will be reduced.
Do not use a drive setting which gives an output current greater than the motor rating.
With 4 lead motors the bipolar rating is quoted and this should match the criteria stated
above.
With 8 lead motors the bipolar rating of the motor, which is normally quoted, refers to a
parallel winding connection. With the windings connected in series the current rating of the
motor connection will be 50% that of the bipolar rating, and the motor will give improved low-
speed torque, but reduced high-speed torque.
The ViX250IM/ViX500IM will drive motors having an inductance as low as 0.5mH and as
high as 20mH, but the recommended motor inductance range is between 0.8mH and 10mH.
Performance of the ViX250/ViX500IM is optimised for the following motor types, listed in
Table 3-5.
Motor Type Motor Rated
Current in
Amps*
Motor
Inductance
in mH per
phase*
ViX500IM ViX250IM
SY561 4.2 1.0
✔
SY562 4.2 2.6
✔✔
SY563 6.5 1.2
✔
SY871 4.2 1.6
✔✔
SY872 6.5 1.5
✔
SY873 8.4 1.7
✔
SY1072 8.0 2.4
✔
*(parallel connection)
Table 3-5. SY Optimum Motor Types
Motor Voltage Ratings
Motors with a withstand voltage rating from phase to earth of 1000V AC should be used. An
insulation withstand rating of 500V AC is acceptable if an isolating transformer with earthed
screen is used to power the system, and 0V input is earthed, as specified.