Fundamental Principles and System Description
Engineering Information
SINAMICS Engineering Manual – November 2015
Ó Siemens AG
142/528
Optimized connection for high-frequencies between the converter and motor terminal box [2]
The connection between the converter and motor must be made with a shielded cable. For higher outputs in the
SINAMICS Chassis and cabinet unit power range, a symmetrical 3-wire, three-phase cable should be used to make
the connection whenever possible.
Shielded cables with symmetrically arranged three-phase conductors L1, L2 and L3 and an integrated, 3-wire,
symmetrically arranged PE conductor, such as the PROTOFLEX EMV-FC, type 2XSLCY-J 0.6/1 kV illustrated below
which is supplied by Prysmian, are ideal.
Shielded, symmetrically arranged three-phase cable with 3-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, for example, 3-wire cables of type Protodur NYCWY. In this case, the PE conductor must
be routed separately as close as possible and in parallel to the 3-wire motor cable.
For outputs in the Booksize and Blocksize unit power range, and for lower outputs in the Chassis and cabinet unit
power range, it is also possible to use shielded, asymmetrical, 4-wire cables (L1, L2, L3 plus PE) such as power
cables of type MOTION-CONNECT.
L1
L2 L3
PE PE
PE
L1
L2 L3
PE
PE
L1L2
L3
ideal symmetrical 3-wire cable plus
symmetrically arranged PE conductor
symmetrical 3-wire cable with
separately routed PE conductor
asymmetrical 4-wire cable
including the PE conductor
Shielded three-phase cables with concentric 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.
EMC shield busbar
Cable fixing busbar
PE busbar
Three-phase conductors
L1 - L3
Mounting clamp
EMC shield clip
Shield
Outer sheath
PE potential
Shield bonding to the motor terminal box
using an EMC gland
Shield bonding to the EMC shield busbar in the converter
using an EMC shield clip
Motor terminal box
EMC gland
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