46
CONNECTION OF THE POWER UNIT
4.2.5 Connection of the motor
4.2.5.1 Selection of the motor cable
The correct cabling as well as the motor cable plays an important part in case of low
power in connection with long motor cable lengths. Ferrite cores and low-capacitance
cables (phase/phase<65 pF/m, phase/screen<120 pF/m) at the output have the follow-
ing effects:
• longer motor line lengths
• less abrasion of the motor gearbox by leakage currents
•
better EMC properties (reduction of the common-mode output currents to earth)
4.2.5.2 Cable-fed disturbances depending on the motor line length at AC supply
The maximum motor line length is depending on the capacity of the motor cable as well
as on the EMC emitted interference. The following data apply for operation under nom-
inal rating conditions.
Size
Max. motor cable length shielded
max. leakage cur-
rent
(at f
N ≤ 100 Hz)
in accordance with EN 61800-3
Category C2
Motor cable (low-capacitance)
12
100 m < 5 mA13
14
Table 23: Maximum motor cable length at AC supply
Thelinelengthcanbeextendsignicantbyusingmotorchokesorlters.KEB
recommendstheuseofmotorchokesorltersforalinelengthupto50m.Motor
chokesorltersareabsolutelynecessaryupto100m.
4.2.5.3 Motor line length at operation with DC voltage
The maximum motor cable length at DC operation is basically dependent on the capaci-
tyofthemotorcable.TheinternallterisnotactiveatDCoperation.Externalmeasures
must be taken here, if necessary. The following data apply for operation under nominal
rating conditions.
Size Motor cable (low-capacitance)
12
50 m13
14
Table 24: Motor cable length at DC operation
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