Siemens SINAMICS G130 Engineering Manual page 132

EMC Installation Guideline
Engineering Information
Transformer
Z
Line
Interference current route when a shielded motor cable is used in combination with an EMC filter in the converter
To achieve the intended reduction in interference, it is essential to install the entire drive system correctly. The
installation must be such that the interference current I
interruptions or weak points from the shield of the motor cable to the PE or EMC shield busbar and the line filter back
to the inverter.
For this reason, the cable used to connect the converter to the motor must be shielded. A symmetrical, three-wire,
three-phase cable should be used here.
Shielded cables with symmetrically arranged three-phase conductors L1, L2 and L3 and an integrated, three-wire,
symmetrically arranged PE conductor, such as the PROTOFLEX EMV cable, type 2YSLCY-J supplied by Prysmian,
are ideal.
Shielded, symmetrical, three-phase cable with three-wire PE conductor
Alternatively, it is also possible to use a shielded cable containing only three-phase conductors L1, L2 and L3 in a
symmetrical arrangement. In this case, the PE conductor must be installed separately.
Symmetrical 3-wire, three-phase cables with concentric copper or aluminum shield
Effective shield bonding is achieved if EMC cable glands are used to create a solid 360° contact between the shield
and motor terminal box and, at the other side in the converter cabinet, a solid 360° contact with the EMC shield
busbar using EMC shield clips. An alternative shield connection to the PE busbar in the converter using only long,
braided "pigtails" is less suitable, particularly if the pigtails are very long, as this type of shield bond represents a
relatively high impedance for high-frequency currents.
Further additional shield bonds between the converter and motor, e.g. in intermediate terminal boxes, must never be
created as the shield will then become far less effective in preventing interference currents from spreading beyond
the drive system.
SINAMICS Engineering Manual – May 2008
132/396
© Siemens AG
Converter cabinet unit
Chassis unit
Line filter
category C3
PE busbar or EMC shield busbar in the converter cabinet unit
IGBT inverter
I
Leak
Z
Ground
can find a continuous, low-inductance path without
I
Motor cable Motor
C C
P P