Required Cable Cross-Sections For Line And Motor Connections - Siemens SINAMICS G130 Engineering Manual

SINAMICS S120 Cabinet Modules
Engineering Information
Order DC busbar
code
Rated current I
DC
M80 1170
M81 1500
M82 1840
M83 2150
M84 2730
M85 3320
M86 3720
M87 4480
DC busbar options
In a typical application such as a gearing test station, for example, one Motor Module might supply an asynchronous
motor that simulates a combustion engine, while other Motor Modules are driving asynchronous motors that simulate
the load. While the asynchronous motor simulating the combustion engine operates as a motor, the two load-
simulating motors are feeding all their energy back into the DC link. As regards the total energy balance, this means
that only a small proportion of energy is drawn from the feeding (power loss of the complete drive line plus energy
required for acceleration). In this application, energy is exchanged primarily between the Motor Modules. The
significance of this in relation to DC busbar dimensioning is that a smaller size of busbar can be installed between the
Line Module / Infeed and the first Motor Module.
The Modules must be arranged according to the relevant load conditions and demand factor so that the DC busbars
can be dimensioned as efficiently as possible.
The DC busbars between the Cabinet Modules are interconnected by means of special busbar links. These form part
of the busbar system and are attached to the right-hand face of the bar for a module / transport unit when it is
delivered. When the Cabinet Modules have been lined up, the links can be unfastened, taken into the adjacent
cabinet and fastened tight again.
If Cabinet Modules are ordered with option Y11, i.e. as factory-assembled transport units, the busbars must be
uniform throughout the transport unit.

Required cable cross-sections for line and motor connections

It is always advisable to use symmetrical, 3-wire, three-phase cables or to connect several cables of this type in
parallel. This is especially important for two reasons:
•
This is the only way in which the high IP55 degree of protection or better can be achieved for the motor terminal
box without any problems because the cables are introduced into the terminal box via screwed glands and the
number of possible glands is limited by the geometry of the terminal box. Therefore single cables are less
suitable.
•
With three-phase cables, the summed ampere-turns over the cable outer diameter are equal to zero. They can
easily be routed in (conductive, metal) cable ducts or racks without any significant currents (ground current or
leakage current) being induced in these conductive, metal connections.
The danger of induced leakage currents and thus of increased cable sheath losses is greater for single cables.
The required cable cross-section depends on the amperage which flows through the cable. The permissible current
loading of cables is defined e.g. in DIN VDE 0298 Part 2/DIN VDE 0276-1000. It depends on ambient conditions such
as the temperature, but also on the type of routing.
Cross-section of Single routing
3-wire cables
2
[mm ] [A]
50 138
70 176
95 212
120 245
150 282
185 323
240 380
300 418
Current carrying capacity of cables acc. to DIN VDE 0298 part 2 at 40°C
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© Siemens AG
Number Dimensions
[mm]
[A]
1 60 x 10
1 80 x 10
1 100 x 10
2 60 x 10
2 80 x 10
2 100 x 10
3 80 x 10
3 100 x 10
Several cables on a
common cable rack
[A]
95
121
146
169
194
222
261
289
Compat ble with
M83
M84 and M86
M85 and M87
M80
M81 and M86
M82 and M87
M81 and M84
M82 and M85
Routing cables singly ensures relatively good
cooling. It must be noted that cables can heat
one another and are therefore far less well
ventilated if several cables are routed together.
Reference should be made to the corresponding
reduction factors for such conditions as specified
in DIN VDE 0298 Part 2 / DIN VDE 0276-1000.
With an ambient temperature of 40 °C, the cross-
sections of copper cables can be based on the
following table.