Siemens SINAMICS S120 Equipment Manual page 168

Cabinet Design and EMC
7.3 EMC-compliant drive installation
Connect comb bars to
cabinet enclosure on
both sides ensuring
good conductivity and
Fig. 7-6
All cables inside the cabinet must be connected as closely as possible to parts connected
(grounded) to the cabinet ground, such as a mounting plate or cabinet wall. This also applies
to reserve cables.
With good equipotential bonding (all metallic parts in the cabinet are connected to each other
with the greatest possible surface area and with good conductance), the shields for analog
signal cables must be connected to ground at both ends. If low-frequency interference
occurs on analog cables, the shield only needs to applied at one end on the converter. The
other end of the shield should be grounded via a capacitor (e.g. 10 nF/100 V, type MKT).
With digital signal cables, the shields must be applied with a good conductive connection
and the greatest possible surface area at both ends (transmitter and receiver). The shields
can be applied more than once inside and outside the cabinet. An equalizing conductor of at
least 10 mm² must be routed in parallel with the shield if the equipotential bonding is not
sufficient.
Whenever possible, only feed cables into the cabinet from side.
Encoder, resolver, or tachometer cables must have a shield. The shield must be applied with
the greatest possible surface area on the tachometer, resolver, or encoder, as well as on the
Power Module or Motor Module, and must not contain any gaps. Prefabricated cables with
multiple shielding must be used for the encoder and resolver (see catalog D21.1).
When unshielded cables are used, avoid laying them close to noise sources (e.g.
transformers). Signal cables (shielded and unshielded) must be kept at a good distance from
strong external magnetic fields (e.g. transformers, reactors). In both cases, a minimum
distance of 30 cm must be maintained.
Unshielded cables in the same circuit (outgoing/incoming conductors) must be twisted to
prevent unnecessary frame antenna.
To reduce coupling capacitance and inductance, cables must not be unnecessarily long.
Shielding effects can also be achieved by grounding reserve cores at both ends.
If the SINAMICS S120 chassis components are supplied externally with 230 V AC and 24 V
DC, these supplies must not be used for multiple consumers that are physically separated
from each other in different cabinets.
Caution
Connected power and signal cables must not cover any ventilation openings.
Signal cables must not be routed parallel to power cables.
7-10
Comb bar
maximum contact
area!
Shield connection for the signal cables in the cabinet
SINAMICS S120 Equipment Manual, Edition 12/2007, 6SL3097-2AM00-0BP4
Cable tie
Intermediate terminal
Chassis Power Units Liquid Cooled