Selection Of The Motor Line; Motor Cable Length And Conducted Interferences At Ac Supply; Figure 26: Symmetrical Motor Line; Table 33: Max. Motor Cable Length - KEB COMBIVERT F6 Series Instructions For Use Manual

cONNecTION OF THe POWer UNIT

4.2.5.3 Selection of the motor line

The correct cabling as well as the motor line itself play an important part in case of low
power in connection with long motor line lengths. Low-capacitance line
(phase/phase < 65 pF / m, phase / screen < 120 pF / m) at the inverter output have the
following effects:
•
•
PE
U
PE
W
Figure 26: Symmetrical motor line

4.2.5.4 Motor cable length and conducted interferences at AC supply

The maximum motor cable length is depending on the capacity of the motor cable as
well as on the EMC emitted interference. External measures must be taken here (e.g.
the use of a line filter). The following information is valid for the operation under rated
conditions and the use of KEB listed filters under chapter „4.3.1 Filters and
Device
Table 33:
allow major motor line lengths
ences at AC supply")
better EMC properties (reduction of the common-mode output currents to earth)
The use of shielded motor lines with symmetrical structure is re-
quired for higher motor power (from 30 kW). In these lines the
protective earth conductor is tripartite and evenly arranged be-
tween the phase lines. A cable without protective earth conductor
can be used if local regulations so permit. Then the protective
V
earth conductor must be laid externally. Certain lines also permit
the shield for the use as protective earth conductor. For this, ob-
serve the details of the line manufacturer!
PE
size
21
22
23
24
Max. motor cable length
The cable length can be increased significant by using motor chokes or motor
filters. KEB recommends the use of motor chokes or filters for a cable length
upto 50 m.
(„4.2.5.4 Motor cable length and conducted interfer-
Max. motor cable length shielded
in accordance with
EN 61800-3
category c2
Motor cable (low capacitance)
100 m
chokes".
67