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

•
n = 2
S max
•
C (A
S max
•
l = 300 m
S max
2nd step:
Calculation of quantities n
D
•
n = 2
D
•
C (A) = C
D
•
l = 50 m
D
3rd step:
Calculation of quantities n
M
•
n = 25
M
•
C (A) = C
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 . 75
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.

Supplementary conditions which apply when motor reactors are used

With the cabinet versions G150 and S150 as well as the S120 Motor Modules in the format Cabinet Modules, it must
be noted that an additional cabinet may be required if two reactors are connected in series.
The pulse frequency and output frequency must be limited for thermal reasons when motor reactors are installed:
•
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.
The voltage drop across the motor reactor is approximately 1 %.
The motor reactor should be sited in the immediate vicinity of the converter or inverter output. The cable length
between the motor reactor and the output of the converter or inverter should not exceed about 5 m.
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 mode.
Fundamental Principles and System Description
2
) = C (240 mm ) = 1.03 nF/m
max S max
, C (A) and l for the cable between the converter and subdistributor:
D D
2
(150 mm ) = 0.86 nF/m
D
, C (A) for the cable between the subdistributor and each motor:
M
2
(10 mm ) = 0.55 nF/m
M
⋅ − ⋅
nF / m 300 m 2 . 0 86 nF
⋅
25 . 0 55 nF / m
−
86 nF
= ≈
m 38 7 . m 40
nF
⋅
/ m 50 m
m
SINAMICS Engineering Manual - May 2008
Engineering Information
= 38.7 m
M
2
) and the cable distance of
93/396
© Siemens AG
2
2
),