Emc-Compliant Installation For Optimized Equipotential Bonding In The Drive System - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information

1. EMC-compliant installation for optimized equipotential bonding in the drive system

The purpose of any equipotential bonding measure is to ensure that all drive system components (transformer,
converter, motor, gearbox and driven machine) stay at exactly the same potential, i.e. at ground potential (PE) to
prevent the development of undesirable equalizing currents, e.g. rotor shaft currents.
Effective equipotential bonding is achieved by grounding the drive components by means of a well-designed
grounding system at the site of installation. Where possible, this should be constructed as a meshed network with a
large number of connections to the foundation ground so as to provide optimized equipotential bonding in the low-
frequency range.
Of equal importance, however, is proper installation of the complete drive system including gearbox and driven
machine with respect to the high-frequency point of view, i.e. that there is effective equipotential bonding in the high
frequency range between all drive components in each drive.
The diagram shows a complete drive plus all the major grounding and equipotential bonding measures between the
individual components of the drive.
Drive system with equipotential bonding system for reducing bearing currents
The description below explains how proper installation can reduce the inductance of connections, particularly of those
which are colored orange and red in the diagram. On the one hand, this helps to minimize the voltage drops caused
by high-frequency currents in the drive system. On the other hand, most of the high-frequency currents remain in the
drive system in which they originate and so do not have any significant impact on other drive systems and loads.
Grounding of the components of the drive system [0]
All electrical and mechanical drive components (transformer, converter, motor, gearbox and driven machine) must
first be bonded with the grounding system. These bonding points are shown in black in the diagram and are made
with standard, heavy-power PE cables that are not required to have any special high-frequency properties.
In addition to these connections, the converter (as the source of high-frequency current) and all other components in
each drive system, i.e. motor, gearbox and driven machine, must be interconnected with respect to the high-
frequency point of view. These connections must be made using special cables with good high-frequency properties.
SINAMICS Engineering Manual - May 2008
83/396
© Siemens AG