Reducing Bearing Currents - Siemens 1FP1/3 Operating Instructions Manual

Preparing for use
4.13 Converter operation
NOTICE
Material damage caused by an excessively high supply voltage
The insulation system will be damaged if the supply voltage is too high for the insulation
system. This can completely destroy the machine.
• Comply with the peak voltages as laid down in the guidelines above.
4.13.3

Reducing bearing currents

To prevent damage due to bearing currents, you must carefully assess the complete system, i.e.
the motor, converter and driven machine.
• In addition to grounding the motors via the solid grounding conductor, use low impedance
grounding in the high frequency range using braided flat copper straps or RF stranded wire
conductors. Connect these conductors through a large contact surface. Solid copper cables
are not suitable for RF grounding because of the skin effect.
• Use symmetrically structured, shielded connecting cables to connect the motor to a
converter. The protective braided shield, comprising many strands, must have a high
electrical conductivity. Braided shields made of copper or aluminum are well suited. Connect
the shielding at both ends on the motor and on the converter. Keep unshielded cable ends
short.
• To ensure that high-frequency currents are appropriately discharged, establish a contact
through the largest possible surface area at both ends. Establish a 360° contact of the cable
shielding on the motor enclosure and on the protective grounding bar of the converter, for
example, as follows:
– Motor side: EMC glands at the cable entries
– Converter side: EMC shield clips
• In the overall system, set up a properly meshed grounding system with low impedance for
high-frequency currents.
• No potential difference between the motor, converter, and working machine.
– Use equipotential bonding cables between the terminal box and the high-frequency
– Use a separate high-frequency equipotential bonding cable between the motor enclosure
– Use a separate high-frequency equipotential bonding cable between the motor enclosure
44
Concentric copper or aluminum shield
grounding point on the motor enclosure.
and the protective grounding bar of the converter.
and the driven machine.
Steel armor
1LE1, 1FP1/3, 1PC1/3 shaft height 63 ... 315
Operating Instructions, 11/2023, A5E38483075A