Switching frequency
When frequency converters 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 instruction in par. 14-01 Switching
Frequency
.
Precautions while using Aluminium conductors
Aluminium conductors are not recommended for cable cross sections below 35 mm². Terminals can accept aluminium conductors but the conductor
surface has to be clean and the oxidation must be removed and sealed by neutral acid free Vaseline grease before the conductor is connected.
Furthermore, the terminal screw must be retightened after two days due to the softness of the aluminium. It is crucial to ensure the connection makes
a gas tight joint, otherwise the aluminium surface will oxidize again.
All types of three-phase asynchronous standard motors can be connected
to the frequency converter. Normally, small motors are star-connected
(230/400 V, D/Y). Large motors are delta-connected (400/690 V, D/Y).
Refer to the motor name plate for correct connection mode and voltage.
Illustration 5.19: Terminals for motor connection
NB!
In motors without phase insulation paper or other insulation reinforcement suitable for operation with voltage supply (such as a fre-
quency converter), fit a sine-wave filter on the output of the frequency converter. (Motors that comply with IEC 60034-17 do not require
an Sine-wave filter).
No.
96
97
98
Motor voltage 0-100% of mains voltage.
U
V
W
3 cables out of motor
U1
V1
W1
6 cables out of motor, Delta-connected
W2
U2
V2
U1
V1
W1
6 cables out of motor, Star-connected
U2, V2, W2 to be interconnected separately
(optional terminal block)
No.
99
Earth connection
PE
Table 5.6: 3 and 6 cable motor connection.
VLT
®
AQUA Drive
Operating Instructions
5. Electrical installation
MG.20.M5.02 - VLT
®
is a registered Danfoss trademark
29
5
