8
05.01
8.11 Series reactor in the motor lead
8-301
©
Siemens AG 2012 All Rights Reserved
SIMODRIVE 611 Configuration Manual (PJU) – 02/2012 Edition
8.11
Series reactor in the motor lead
For special motors with a low leakage inductance (where the controller settings
are not adequate) it may be necessary to provide a series reactor as 3–arm iron
reactor (not a Corovac reactor) and/or increase the inverter clock cycle fre-
quency of the converter. Motors with a low leakage inductance are, from experi-
ence, motors that can achieve high stator frequencies (maximum motor stator
frequency
>
300 Hz) or motors with a high rated current (rated current
>
85 A).
S
The voltage rate–of–rise (gradient) of the drive converter has typical values
such as:
du/dt up to 7 kV/
μ
s
For third–party motors where the insulation is unknown or not designed for
this voltage rate–of–rise, a series reactor should be used, independent of
the selected pulse frequency.
S
In the IM mode, motors can be used with a maximum rated torque of:
M
n
=
650 Nm
2
π
•
n
n
P
n
•
60
The inductance value of a series reactor or the necessary drive converter
pulse frequency can be estimated using the following formula. However, it
must be taken into account that when the inverter clock cycle frequency is
increased, the module current must be reduced; or, a module with a higher
current rating must be selected:
L
s
1
Stator leakage inductance of the motor in H
L
s
2
Rotor leakage inductance of the motor in H
L
series
Inductance of the series reactor in H (=0, if a
series reactor is not used)
1)
V
DC link
Voltage
(=600 V or 625 V for a regulated infeed,
= rectified line supply voltage for a non–regulated infeed
e.g. 570 V at 400 V
rms
line supply voltage)
f
T
Inverter clock cycle frequency of the converter in Hz,
refer to Chapter 5.4.1
n
max
Max. motor speed
n
FS
Speed at the start of field weakening
L
series
[
I
0
Motor no–load current in A
rms
V
nmot
Rated motor voltage in V
rms
n
n
Rated motor speed
V
DC link
1.6
V
nmot
An approximate value can
be calculated with n
FS
[
•
n
n
•
L
s
1
+ L
s
2
U
DC link
•
n
max
30
•
f
T
•
n
FS
•
I
0
–
2
1) For calculated/theoretical inductance values less than 0.1 mH, a series reactor is not required.
For calculated inductance values
u
0.4 mH, 0.4 mH must always be assumed as maximum value.
General
Selection/
calculations
8 Important Circuit Information
02.12
05.08
