Planning the electrical installation
74
Sine filters
Sine filters protect the motor insulation system. Therefore, a du/dt filter can be replaced with a sine
filter. The peak phase-to-phase voltage with a sine filter is approximately 1.5 × U
N
.
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 maximum permissible temperature of
conductor in continuous use. For US, see Additional US requirements, page 79.
• 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.
Use symmetrical shielded motor cable, see page 76. Ground the shield(s) of motor
cable(s) 360° at both ends.
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.
Û
LL
/U
N
Without du/dt Filter
Cable length (m)
du/dt
U
N
-------------(1/μs)
1.0
2.0
5.0
4.0
3.0
1.5
2.5
3.5
4.5
100 200 300
100 200 300
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Cable length (m)
With du/dt Filter
du/dt
U
N
-------------(1/μs)
Û
LL
/U
N
5.5
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