Siemens MICROMASTER 411 - Manual (Page 39)

Issue 03/01 2 Installation
MICROMASTER 411 & COMBIMASTER 411 Operating Instructions
6SE6400-5CA00-0BP0 39
2.5.5 Avoiding Electro-Magnetic Interference
The inverters are designed to operate in an industrial environment where a high
level of EMI can be expected. Usually, good installation practices will ensure safe
and trouble-free operation. If you encounter problems, follow the guidelines stated
below.
Action to Take
Make sure that any control equipment connected to the inverter (such as a
PLC) is connected to the same ground or star point as the inverter via a short,
thick link.
Flat conductors are preferred as they have lower impedance at higher
frequencies.
Separate the control cables from the power connections as much as
possible, using separate trunking, if necessary at 90
0 right angles.
Ensure that contactors are suppressed, either with R-C suppressors for AC
contactors, or 'flywheel' diodes for DC contactors, fitted to the coils. Varistor
suppressors are also effective. This is important when the contactors are
controlled from the inverter relay.
Screened motor cables should be used when the motor is mounted separately
from the inverter.
Maximum motor cable length is 5 meters (16.40 feet).
WARNING
Safety regulations must not be compromised when installing inverters!