Planning the electrical installation
63
A four-conductor system is allowed for input cabling, but shielded symmetrical cable
is recommended. To operate as a protective conductor, the shield conductivity
requirements according to IEC 60439-1 are shown below when the protective
conductor is made of the same metal as the phase conductors:
Compared to a four-conductor system, the use of symmetrical shielded cable
reduces electromagnetic emission of the whole drive system as well as the stress on
motor insulation, bearing currents and wear.
Keep the motor cable and its PE pigtail (twisted shield) as short as possible to
reduce high-frequency electromagnetic emissions.
Typical power cable sizes
The table below gives copper and aluminium cable types for different load currents.
Cable sizing is based on max. 9 cables laid on a cable ladder side by side, three
ladder type trays one on top of the other, ambient temperature 30 °C, PVC
insulation, surface temperature 70 °C (EN 60204-1 and IEC 60364-5-52/2001). For
other conditions, dimension the cables according to local safety regulations,
appropriate input voltage and the load current of the drive.
Cross-sectional area of the phase
conductors
S (mm
2
)
Minimum cross-sectional area of the
corresponding protective conductor
S
p
(mm
2
)
S <
16 S
16 < S < 35 16
35 < S S/2
Copper cables with
concentric copper shield
Aluminium cables with
concentric copper shield
Max. load
current
A
Cable type
mm
2
Max. load
current
A
Cable type
mm
2
274 2 × (3×70) 302 2 × (3×120)
334 2 × (3×95) 348 2 × (3×150)
386 2 × (3×120) 398 2 × (3×185)
446 2 × (3×150) 470 2 × (3×240)
510 2 × (3x185) 522 3 × (3×150)
602 2 × (3×240) 597 3 × (3×185)
579 3 × (3×120) 705 3 × (3×240)
669 3 × (3×150)
765 3 × (3×185)
903 3 × (3×240)
3BFA 01051905 C
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