Planning the electrical installation
53
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 or copper wire.
The better and tighter the shield, the lower the emission level and bearing currents.
Symmetrical shielded cable: three phase conductors
and a concentric or otherwise symmetrically
constructed PE conductor, and a shield
Recommended
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.
A four-conductor system:
three phase conductors
and a protective
conductor
Shield
PE
PE
PE
Not allowed for motor cables with phase
conductor cross section larger than 10 mm
2
[motors > 30 kW (40 hp)].
Not allowed for motor cables
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