Table of Contents
Advertisement
56 Guidelines for planning the electrical installation
Selecting the power cables
General rules
Select the input power and motor cables according to local regulations:
•
Select a cable capable of carrying the drive nominal current. See section
(page 137) for the rated currents.
Select a cable rated for at least 70 °C (158 ℉)maximum permissible temperature of
•
conductor in continuous use.
•
The inductance and impedance of the PE conductor/cable (grounding wire) must be
rated according to permissible touch voltage appearing under fault conditions (so that
the fault point voltage will not rise excessively when a ground fault occurs).
•
600 V AC cable is accepted for up to 500 V AC. For 690 V AC rated equipment, the
rated voltage between the conductors of the cable should be at least 1 kV.
Use symmetrical shielded motor cable (see page 58). Ground motor cable shields 360° at
both ends. Keep the motor cable and its PE pigtail (twisted shield) as short as possible to
reduce high-frequency electromagnetic emissions.
Note: When continuous metal conduit is employed, shielded cable is not required. The
conduit must have bonding at both ends.
A four-conductor system is allowed for input cabling, but shielded symmetrical cable is
recommended.
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.
The protective conductor must always have an adequate conductivity. The table below
shows the minimum cross-sectional area related to the phase conductor size according to
IEC 61439-1 when the phase conductor and the protective conductor are made of the
same metal.
Cross-sectional area of the phase conductors
S (mm
16 < S < 35
35 < S < 400
400 < S < 800
2
)
S < 16
Minimum cross-sectional area of the
corresponding protective conductor
2
S
(mm
p
S
16
S/2
200
Ratings
)
Advertisement
Table of Contents
