Converter Operation On A Grounded Network - Siemens 1PH818 Operating Instructions & Installation Instructions

Measures to reduce bearing currents
To specifically reduce and prevent damage caused by bearing currents, consider the system
as a whole, which comprises the motor, converter, and driven machine. The following
precautions help to prevent bearing currents:
● Setting up a properly meshed grounding system in the system as a whole, with low
● No potential difference between the motor, converter, and working machine.
● Limit the voltage rate of rise by using an output filter to dampen harmonic components in
Hazardous voltage at the terminals when the rotor is rotating
There is always a magnetic flux in the machine due to the permanent magnets in the rotor.
An electrical voltage is generated at the terminals each time that the rotor turns. As a result
of this, there is also a voltage at the converter output terminals via the connecting cable. When
working on the drive system, you must prevent the machine shaft from rotating.
6.4.7

Converter operation on a grounded network

NOTICE
Damage resulting from protective conductor currents
When the machine is operated on a converter with current limiter, but without ground-fault
monitoring, protective conductor currents of up to 1.7 times the external conductor current
can arise if there is a ground fault on the output side. Neither the PE conductors of normally
rated multi-core connecting cables nor the PE connecting points of normal terminal boxes
are suitable for this purpose. Material damage can result.
● Use an appropriately sized PE conductor.
● Connect the PE conductor to the grounding terminal on the motor enclosure.
SIMOTICS M-1PH8 1PH818., 1PH822.
Operating Instructions 07/2016
impedance for high-frequency currents
– Use symmetrical, shielded connecting cables.
– Connect the cable shield at both ends over the greatest possible surface area (360°
contact).
– Use equipotential bonding conductors between the motor and the driven machine as
well as between the motor and the converter
the output voltage
WARNING
Electrical connection
6.4 Auxiliary circuits
81