Preparing for use 
  4.14 Converter operation 
1LA5/6/7/9, 1LG4/6, 1MA6/7, 1MB..1/2/3/4/5 - SH 63 ... 355 
Operating Instructions, 06/2018, A5E44455710A 
49 
Measures to reduce bearing currents  
To specifically reduce bearing currents, you must consider the system as a whole, which 
comprises the motor, converter, and driven machine. The following measures support you 
when reducing bearing currents and help to avoid damage: 
●  In the overall system, set up a properly meshed grounding system with low impedance.  
●  Use the common-mode filter (damping cores) at the converter output. The Siemens sales 
representative is responsible for selection and dimensioning.  
●  Limit the rise in voltage by using output filters. Output filters dampen the harmonic content 
in the output voltage. 
●  The operating instructions for the converter are not part of this documentation. Refer to 
the configuration information for the converter. 
 
Insulated bearings when operated with a converter 
If the machine is operated from a low-voltage converter, insulated bearings are fitted at the 
NDE and an insulated encoder with insulated bearings (option).  
Comply with the plates on the machine relating to bearing insulation and possible bridges.  
 
Insulated tachometer fitting 
Figure 4-2  Schematic representation of a single drive 
 
The bearing insulation must not be bridged. Bearing currents can damage bearings. 
•  Also for subsequent installation work, such as the installation of an automatic lubrication 
system or a non-insulated vibration sensor, make sure that the bearing insulation cannot 
be bridged. 
•  Please contact the service center if necessary.