Supplementary Conditions Which Apply When Motor Reactors Are Used - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information
·
n
S max
·
C (A
S max
·
l
S max
2nd step:
Calculation of quantities n
D
·
n
D
·
C (A)
D
·
l
D
3rd step:
Calculation of quantities n
M
·
n
M
·
C (A)
M
4th step:
Calculation of the permissible motor cable length between the subdistributor and each motor using calculation
formula:
×
2 1 . 03
=
l
M
618 nF
=
l
M
13 .
The required cable length of 40 m per motor is within a 10 % tolerance band around the calculated value l
which means that the arrangement can be implemented as planned.
If we compare the maximum cable distance of 600 m which may be connected to the converter for a single-motor
drive (two parallel cables, each 300 m in length and each with a cross-section of 240 mm
1068 m for the multi-motor drive (two parallel cables, each 50 m in length and each with a cross-section of 150 mm
to the subdistributor plus 25 parallel cables to the motors, each 38.7 m in length and with a cross-section of 10 mm
we can see that the reduction in cross-section for the multi-motor drive nearly doubles the maximum permissible
cable distance allowed for single-motor drives, even though the total capacitance is the same.

1.10.1.4 Supplementary conditions which apply when motor reactors are used

With the cabinet units G150 and S150 as well as with the S120 Motor Modules in Cabinet Modules format, it must be
noted that an additional cabinet may be required if two reactors are connected in series.
It must be noted that the motor reactor should be mounted close the converter or inverter output in the case of
SINAMICS G130 and S120 units in Chassis format. The cable length between the converter or inverter output and
the motor reactor should not exceed 5 m.
When motor reactors are installed, the pulse frequency and the output frequency must be limited for thermal reasons:
·
The maximum pulse frequency is limited to twice the factory setting value, i.e. to 4 kHz for units with
factory setting 2 kHz and to 2.5 kHz for units with factory setting 1.25 kHz.
·
The maximum output frequency is limited to 150 Hz.
No limits apply with respect to the permissible pulse patterns of the gating unit, i.e. pulse-edge modulation can be
used without restriction, which means that the attainable output voltage is virtually equal to the input voltage.
The voltage drop across the motor reactor is about 1 %.
As part of the drive commissioning process, the motor reactor should be selected with parameter setting P0230 = 1
and the reactor inductance entered in parameter P0233. This ensures that optimum allowance will be made for the
effect of the reactor in the vector control model.
Motor reactors can be used in both grounded systems (TN/TT) and ungrounded systems (IT).
SINAMICS Engineering Manual – November 2015
152/528
Ó Siemens AG
= 2
2
) = C (240 mm ) = 1.03 nF/m
max S max
= 300 m
, C (A) and l for the cable between the converter and subdistributor:
D D
= 2
2
= C (150 mm ) = 0.86 nF/m
D
= 50 m
, C (A) for the cable between the subdistributor and each motor:
M
= 25
2
= C (10 mm ) = 0.55 nF/m
M
× - ×
nF / m 300 m 2 0
×
25 0 . 55 nF / m
-
86 nF
= »
m 38 . 7 m
75 nF
×
. 86 nF / m 50 m
40 m
=38.7 m
M
2
) and the cable distance of
2
2
),