Siemens SIMOTICS HV M, Руководство по эксплуатации

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4.16.3 Reducing bearing currents
Reducing bearing currents
Taking the following actions will reduce the bearing currents:
● Grounding: In addition to grounding the machines via the solid protective ground conductor,
supplement the high-frequency grounding using braided flat copper straps or high-
frequency stranded conductors. Ensure that the contacts are made over a large area. Solid
copper cables are not suitable for high-frequency grounding because of the skin effect. Use
equipotential bonding conductors between the motor and the driven machine and motor
and converter.
● Selecting and connecting the cable: As far as possible, use symmetrically arranged,
shielded connection cables with a common outer shield to improve the EMC characteristics.
The cable shielding, made up of as many strands as possible, must have good electrical
conductivity. Braided shields made of copper or aluminum are very suitable.
– The shield must be connected at both ends to the motor and the converter; unshielded
cable ends must be kept as short as possible.
– To ensure good discharging of high-frequency currents, provide contacting over a large
surface area: with 360° contacting at the converter, at the motor for instance with EMC
screw fastenings at the cable entries.
Measures to further reduce bearing currents
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:
● Setting up a properly interconnected grounding system in the system as a whole, with low
impedance for high-frequency currents
● Use iron cores mounted above the motor connecting cable at the converter output. The
iron cores reduce the common-mode components. The sales representative is responsible
for selection and dimensioning.
● Limit the voltage rate of rise by using an output filter to dampen harmonic components in
the output voltage
● The operating instructions for the converter are not part of this documentation. Refer to the
configuration information for the converter.
See also
Insulated bearings when operating the converter (Page 36)
Preparations for use
4.16 Converter operation
SIMOTICS HV M 1RN76308PR900CG0-Z
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Operating Instructions 07/2018