6.7 Connecting power cables
All signal lines must be shielded. The cable shield should be braided, because cables shielded
by tape or foil are five times less efficiently protected against interference. Always ground the
cable shields at both ends. Contacting at one end is advantageous in exceptional cases only.
Clamp the shield of incoming analog and binary cables to the shield busbar at the entry point
into the cabinet. Continue running the cable, still shielded, to the terminal strip or board. No
shields are connected to the terminal strips or boards.
Serial connecting cables must be shielded. Place the shield on the metallic connector housing.
Also connect the shield to the shield rail. Do not connect the cable shield to a ground pin of
The connector housing and front plate of the boards do not provide adequate cable shielding.
Connect the cable shields at both ends to the shield rails in the cabinets. Always use shielded
analog signal cables, regardless of whether they are installed inside or outside cabinets. In
order to increase the effectiveness of the shielding, ground spare conductors at both ends.
You should only use the pre-assembled cable sets supplied. These cable sets are marked at
both cable ends with the precise designation of the connection point at which you must connect
or plug in the cable. Please proceed as follows:
1. Connect the signal and power supply cables. For further information, see the connection
2. Seal the cable routing according to the degree of protection required.
Connecting power cables
When connecting the cables, observe all the conditions regarding conductor protection. Do
not exceed the permitted cable lengths between the drive output and motor. The distance
between the motor cable and the signal cable should be at least 20 cm. Do not lay power
cables and motor supply cables in parallel to each other.
The positions of the connections are shown in the layout diagrams. Detailed wiring notes for
the drive are contained in the circuit manual of the drive.
Select the appropriate cable depending on the following conditions:
● Routing conditions
● Accumulation of cables
● Ambient temperature
● Bending radii
● Output voltage
Observe the connection capabilities on the drive and on the motor terminal box.
diagram in the circuit manual.
SINAMICS SM120 6SL38855?B
Operating Instructions 12/2015