ABB ACS850-04 series, Руководство по оборудованию

Страница: 56 / 164

Planning the electrical installation
56
Selecting the power cables
General rules
Dimension the input power and motor cables according to local regulations :
• Dimension the cable to carry the drive load current. See chapter Technical data
for the rated currents.
• Select a cable rated for at least 70
°
C (158
°
F) maximum permissible temperature
of conductor in continuous use. For US, see Additional US requirements, page
59 .
• 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.
Use symmetrical shielded motor cable, see page 58 .
Note: When continuous metal conduit is employed, shielded cable is not required.
The conduit must have bonding at both ends as with cable shield.
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.
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