Siemens Simodrive 611 - Page 290

9
05.01
9.11 Induction motor operation 611A (611D/611U)
9-290
 Siemens AG 2001 All rights reserved
SIMODRIVE 611 Planning Guide (PJU) – 05.01 Edition
Load surges and overload conditions in the field–weakening range can result in
oscillations and should be avoided.
An induction motor module cannot identify if an individual motor is overloaded.
Individual thermal monitoring devices should be provided for overload protection
of the individual motors. We recommend that the motor is monitored using a
PTC thermistor evaluation circuit.
3–ph. 400 V AC
50/60 Hz
SIMODRIVE 611 SIMODRIVE 611
PTC
Motor 1
1)
M8
3 
M3
3
M2
3
M1
3
PTC PTC PTC
Motor 2 Motor 3 Motor 8
I/R IM
Fig. 9-29 Parallel motor configuration with a SIMODRIVE 611 induction motor module
Notice
For parallel operation, all of the motors must always be simultaneously opera-
ted. When a motor is shutdown (e. g. due to a fault), the motor data set must be
adapted (e. g. by using a motor changeover function).
When connecting motors in parallel, the cable protection for the motor cables
must be implemented outside the drive converter.
1) Σ Rated motor currents or, when taking into account the load duty cycle, the total RMS currents of the
motor group
9 Important Circuit Information