8
05.01
8.12 Induction motor operation
8-305
© Siemens AG 2008 All Rights Reserved
SIMODRIVE 611 Configuration Manual (PJU) – 05/2008 Edition
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.
3–ph. 400 V AC
50/60 Hz
Infeed module
PTC
Motor 1
1)
M8
3
M3
3
M2
3
M1
3
PTC PTC PTC
Motor 2 Motor 3 Motor 8
I/R
Drive module
Notes:
1) Σ Rated motor currents, or when taking into account the load duty cycles, the total rms current of the
motor group
Fig. 8-29 Motors connected in parallel to SIMODRIVE 611
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.
8 Im
ortant Circuit Information10.04
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