Siemens SIMOTICS XP 1MD4, Инструкция по эксплуатации и монтажу, Страница: 37 / 128

● If the cable shield is connected as described, then it ensures the specified equipotential
bonding between the motor enclosure and converter. A separate RF equipotential bonding
conductor is then not necessary.
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Concentric copper or aluminum shield Steel armor
● If the cable shield is not connected due to special secondary conditions, or not adequately
connected, then the specified equipotential bonding is not provided. In this particular case,
use a separate RF equipotential bonding conductor:
– Between the motor enclosure and protective ground rail of the converter.
– Between motor enclosure and driven machine
– Use braided flat copper straps or high-frequency cables with finely-stranded conductors
for the separate RF equipotential bonding cable. Solid copper cables are not suitable
for high frequency grounding because of the skin effect.
– Ensure that the contacts are established over a large area.
Overall system design
To specifically reduce and prevent damage caused by bearing currents, you must consider
the system as a whole, which comprises the motor, converter, and driven machine. The
following precautions help to reduce bearing currents:
● In the overall system, set up a properly meshed grounding system with low impedance.
● Use the common-mode filter (damping cores) at the converter output. The Siemens sales
representative is responsible for selection and dimensioning.
● Limit the rise in voltage by using output filters. This dampens the harmonic content in the
output voltage.
Note
Converter documentation
The operating instructions for the converter are not part of this documentation. Refer also to
the configuration information for the converter.
4.10.2 Insulated bearings when operating the converter
Depending on the machine's size and design, an insulated bearing and an insulated
tachometer can be fitted at the non-drive end.
Comply with the plates on the machine relating to bearing insulation and possible bridges.
Preparations for use
4.10 Converter operation
SIMOTICS XP 1MD4/1MD5
Operating Instructions 05/2015
37