Selecting The Power Cables - ABB ACS800-04 Hardware Manual

54 Planning the electrical installation

Selecting the power cables

Dimension the mains (input power) and motor cables according to the local
regulations:
•
The cable must be able to carry the drive load current. See
(page 99) for the rated currents.
•
The cable must be rated for at least 70
temperature of conductor in continuous use. For US, see
requirements
(page 56).
•
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 if a ground
fault occurs).
•
600 V AC cable is accepted for up to 500 V AC. 750 V AC cable is accepted for up
to 600 V AC. For 690 V AC rated equipment, the rated voltage between the
conductors of the cable should be at least 1 kV.
For drive frame size R5 and larger, or motors larger than 30 kW (40 hp), symmetrical
shielded motor cable must be used. A four-conductor system can be used up to
frame size R4 with up to 30 kW (40 hp) motors, but shielded symmetrical motor
cable is always recommended. The shield(s) of motor cable(s) must have 360°
bonding at both ends.
Note: When a continuous metal conduit is used, 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 must
be as follows when the protective conductor is made of the same metal as the phase
conductors:
Cross-sectional area of 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.
The motor cable and its PE pigtail (twisted shield) should be kept as short as
possible in order to reduce high-frequency electromagnetic emission, as well as
stray currents outside the cable and capacitive current (relevant in power range
below 20 kW).
Longer cables cause a motor voltage decrease which limits the available motor
power. The decrease depends on the motor cable length and characteristics.
Contact ABB for more information. Note that a sine filter (optional) at the drive
output also causes a voltage decrease.
2
S (mm )
S < 16
16 < S < 35
35 < S
° °
C (158 F) maximum permissible
Additional US
Minimum cross-sectional area of the
corresponding protective conductor
2
S (mm
p
S
16
S/2
Technical data
)