Siemens Simodrive 611 Configuration Manual page 305

8 Important Circuit Information
8.12 Induction motor operation
3–ph. 400 V AC
50/60 Hz
PTC
M1
3 
Motor 1
Notes:
1) Σ Rated motor currents, or when taking into account the load duty cycles, the total rms current of the
motor group
Fig. 8-27 Motors connected in parallel to SIMODRIVE 611
8-304
Load surges and overload conditions in the field–weakening range can result in
oscillation and should be avoided.
The drive module cannot detect if an individual motor is overloaded.
Individual thermal monitoring functions must be provided to ensure that each
individual motor has overload protection. We recommend that the motor is moni-
tored using a PTC thermistor evaluation circuit.
Infeed module
I/R
PTC PTC
M2
3 
Motor 2
Notice
For parallel operation, all of the motors must always be operated
simultaneously. The motor data set must be adapted, e.g. by using a motor
changeover function, when a motor is shutdown, e.g. when a fault condition
develops.
When motors are connected in parallel, motor cable protection must be imple-
mented outside the drive converter.
Drive module
M3
3 
Motor 3
© Siemens AG 2012 All Rights Reserved
SIMODRIVE 611 Configuration Manual (PJU) – 02/2012 Edition
10.04
05.01
1)
PTC
M8
3 
Motor 8