Siemens SINAMICS G130 Engineering Manual page 85

Fundamental Principles and System Description
Engineering Information
Optimized connections for high-frequencies between the motor terminal box and motor housing [3]
Since the electrical connection between the motor terminal box to which the motor cable shield is bonded and the
motor housing is not generally designed to offer optimum high-frequency properties, it is recommended to install an
additional equipotential bonding connection with good high-frequency properties between the terminal box and the
motor housing. This connection should be made with short ground conductors with a large cross-section
2
( ≥ 95 mm
). These must be designed to have a low impedance over a wide frequency range, e.g. made of finely
stranded, braided round copper wires or finely stranded, braided flat copper strips. Examples of suitable conductors
are shown below.
Finely stranded, braided round copper wires Finely stranded, braided flat copper strips
Optimized connection for high-frequencies between motor housing, gearbox and driven machine [4], [5]
The final measure in this equipotential bonding system is to link the motor housing to the gearbox and the driven
machine in a conductive connection with good high-frequency properties. A lead made of finely stranded, braided
2
copper cable with a large cross-section ( ≥ 95 mm
) should also be used for this purpose.
Overview of grounding and equipotential bonding measures
The following diagram illustrates all grounding and high-frequency equipotential bonding measures using the
example of a typical installation comprising several SINAMICS S120 Cabinet Modules.
Grounding and high-frequency equipotential bonding measures for reducing bearing currents
SINAMICS Engineering Manual - May 2008
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