Planning the electrical installation
78
Alternative power cable types
Power cable types that can be used with the drive are represented below.
Motor cable shield
To effectively suppress radiated and conducted radio-frequency emissions, the
shield conductivity must be at least 1/10 of the phase conductor conductivity. The
requirements are easily met with a copper or aluminium shield. The minimum
requirement of the motor cable shield of the drive is shown below. It consists of a
concentric layer of copper wires with an open helix of copper tape. The better and
tighter the shield, the lower the emission level and the bearing currents.
Recommended: Symmetrical shielded cable: three
phase conductors and a concentric or otherwise
symmetrically constructed PE conductor, and a shield
PE conductor
and shield
Shield
Shield
A separate PE conductor is required if
the conductivity of the cable shield is <
50 % of the conductivity of the phase
conductor.
Shield
PE
PE
PE
Not allowed for motor cabling: A four-conductor
system: three phase conductors and a protective
conductor.
Not allowed: Symmetrical cable with individual shields
for each phase conductor
Shield
PE
Insulation jacket
Copper wire screen
Helix of copper tape
Cable core
Inner insulation
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