Planning the electrical installation
72
Selecting the power cables
General rules
Dimension the supply (input power) and motor cables according to local
regulations:
• The cable must be able to carry the drive load current. See chapter Technical
data for the rated currents.
• The cable must be rated for at least 70
°C maximum permissible temperature of
conductor in continuous use. For US, see Additional US requirements on
page 74.
• 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 minimum 1 kV.
We recommend shielded symmetrical multicore cables for input cabling. Single-core
cables are also allowed, but unshielded single-core cables are not on IT
(ungrounded) networks.
WARNING! Do not use unshielded single-core supply cables in IT (ungrounded)
networks. A dangerous voltage can become present on the non-conductive outer
sheath of the cable. This can cause injury or death.
Symmetrical shielded cable must be used for motor cabling; see section Alternative
power cable types on page 73.
Note: When continuous conduit is employed, shielded cable is not required.
To operate as a protective conductor, the shield conductivity must be as follows
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 motor
bearing currents and wear.
Note: The cabinet configuration of the drive may require multiple supply and/or
motor cabling. Refer to the connection diagrams in Electrical installation.
The motor cable and its PE pigtail (twisted screen) should be kept as short as
possible in order to reduce electromagnetic emission as well as capacitive current.
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
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