Siemens sinamics dcp - Page 40

Electrical connection
5.1 EMC-compliant installation
SINAMICS DCP
38 Operating Instructions, 09/2019, A5E34382853K
7
Crosstalk is generally reduced if the cables are laid close to the control cabinet ground.
Therefore, do n
ot route cables freely around the cabinet, but lay them as close as pos-
sible to the cabinet enclosure / mounting plates. This also applies to spare cables.
8
Signal and power cables must be physically separated (to prevent coupling paths). Min-
imum clearan
ce: 20 cm should be aimed at. If it is not possible to physically separate
the signal cable and electric power cable, the signal cab
le must be decoupled either
using a partition or by routing it in a metal conduit. The partition or metal conduit must
be gr
ounded at several points. If it is not possible to prevent signal and power cables
crossing, make sure that they cross at right angles only.
9
Ground the shields of digital signal cables at both ends (source and destination), ensur-
ing maximum contact area
and good conductivity. In the event of poor equipotential
bonding between the shield connections, run an additional equalizing cond
uctor with a
cross
-section of at least 10 mm² parallel to the shield for the purpose of reducing the
shield current. General
ly speaking, the shields may also be connected to the cabinet
enclosure (ground)
2)
at several points. The shields can be connected several times
even outside the control cabinet. Foil shields should be avoided, as they are are at least
5 times less effective than braided shields.
10
Shields for analog signal cables may be connected to ground at both ends if equipoten-
tial bonding is good (this must be done over a large area with good conductivity). It can
be assumed that equipotential bonding is good if al
l metal parts are well interconnected
and the electronics components are supplied from a single source.
Footnotes
1)
Signal cables are defined as:
Digital signal cables, e.g. cables for incremental encoders
Analog signal cables, e.g. ±10 V setpoint cable
Serial interfaces, e.g. PROFIBUS and PROFINET
2)
Generally speaking, "ground" refers to all metallic conductive parts that can be connect-
ed to a protective conductor, such as the cabinet enclosure, motor enclosure, or founda-
tion ground.
To prevent coupling external interference into the cabinet, the shields of the cables used
must be grounded through the largest possible surface area as close as possible to the point
of entry into the cabinet.
This is achieved by using the appropriate shield bars or comb-type bars.
These bars must be connected to the cabinet housing through largest possible surface area
to establish a good electrical connection.