Induction Motor Operation 611A (611D/611U) - Siemens SIMODRIVE 611 Planning Manual

05.01
9.11

Induction motor operation 611A (611D/611U)

9.11.1 Several induction motors 611A operated in parallel
Several motors can be operated in parallel from an induction motor module.
Several design guidelines must be observed when selecting the motor and mo-
dule.
A maximum drive constellation for parallel operation can include up to eight mo-
tors. Motors connected in parallel to an induction motor module must have the
same V/Hz characteristics. Further, it is recommended that motors should have
the same pole number. If more than two motors are operated from a single mo-
dule, then these motors should have, as far as possible, the same output.
For a two–motor constellation, the power differential between the motors may
not exceed a ratio of 1:10.
The following design guidelines should be observed:
S
S
S
When taking into account the above information, load and speed steps applied
to individual motors, are corrected. By applying the selection guidelines, a "sta-
ble", stall–proof operation of the individual motors can be achieved. The speeds
of individual motors are load–
dependent. The actually selected speeds can drift apart by several percent due
to the summed slip control.
2pole ! > 600 RPM
1) Standard motor:
4pole ! > 300 RPM
6pole ! > 200 RPM
8pole ! > 150 RPM
Special motors: n >
min
2) Σ Rated motor currents or, when taking into account the load duty cycle, the total RMS currents of the
motor group.
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SIMODRIVE 611 Planning Guide (PJU) – 05.01 Edition
9.11 Induction motor operation 611A (611D/611U)
Selecting the induction motor module rating
– Steady–state operation of the motors connected in parallel essentially in
the closed–loop controlled range (> n
speed range:
Σ Rated motor currentsv Rated current of the induction motor module
– Operation of motors connected in parallel with dynamic loading and in
the open–loop controlled range require a higher rating:
1,2 (Σ Rated motor currents) v Rated current of the induction motor
module
– The current limit of the induction motor module is increased to 150%
rated current for commissioning.
The motors should not be loaded above rated torque.
For high–speed induction motors (e.g. for woodworking), a series reactor
must be connected between the induction motor module and the motor
group:
Rated reactor current: RMS current of the motor group


40 V n 600 RPM
rated
>
V Pole pair number
rated motor
9 Important Circuit Information
1)
) and preferably in the rated
min
2)
9
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