Danfoss VLT AQUA Drive Design Manual page 89

VLT ® AQUA Drive Design Guide
No.
No.
5.2.5. Motor Cables
See section
length.
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5.2.6. Electrical Installation of Motor Cables
Shielding of cables
Avoid installation with twisted shield ends (pigtails). They spoil the shielding effect at higher fre-
quencies.
If it is necessary to break the shield to install a motor isolator or motor contactor, the shield must
be continued at the lowest possible HF impedance.
Cable length and cross-section
The adjustable frequency drive has been tested with a given length of cable and a given cross-
section of that cable. If the cross-section is increased, the cable capacitance - and thus the leakage
current - may increase, thereby requiring that the cable length is reduced accordingly.
Switching frequency
When adjustable frequency drives are used together with sine-wave filters to reduce the acoustic
noise from a motor, the switching frequency must be set according to the sine-wave filter in-
structions in par. 14-01.
Aluminum conductors
Aluminum conductors are not recommended. Terminals can accept aluminum conductors, but the
conductor surface has to be clean, oxidation must be removed, and the area must be sealed by
neutral acid-free Vaseline grease before the conductor is connected.
96 97 98
U V W
U1 V1 W1
W2 U2 V2
U1 V1 W1
99
PE
General Specifications
for correct dimensioning of motor cable cross-section and
Use a shielded/armored motor cable to comply with EMC emission specifications.
Keep the motor cable as short as possible to reduce the noise level and leakage currents.
Connect the motor cable shield to both the decoupling plate of the adjustable frequency
drive and to the metal cabinet of the motor.
Make the shield connections with the largest possible surface area (cable clamp). This is
done by using the supplied installation devices in the adjustable frequency drive.
Avoid mounting with twisted shield ends (pigtails), which will spoil high frequency shield-
ing effects.
If it is necessary to split the shield to install a motor isolator or motor relay, the shield
must be continued with the lowest possible HF impedance.
MG.20.N2.22 - VLT ® is a registered Danfoss trademark.
Motor voltage 0-100%
of AC line voltage.
3 wires out of motor
6 wires out of motor, Delta-connected
6 wires out of motor, Star-connected
U2, V2, W2 to be interconnected separately
(optional terminal block)
Ground connection
5. How to Install
5
89