Very long control cables and analogue signals may in rare cases and
depending on installation result in 50/60Hz earth loops due to noise
from mains supply cables.
If this occurs, it may be necessary to break the screen or insert a
100nF capacitor between screen and chassis.
The digital and analog inputs and outputs must be connected separate-
ly to the frequency converter common inputs (terminal 20, 55, 39) to
avoid earth currents from both groups to affect other groups. For ex-
ample, switching on the digital input may disturb the analog input sig-
nal.
Input polarity of control terminals
12
13
18
19
27
29
32
33
20
37
+24
VDC
0
VDC
130B
T106.10
PNP (Source)
Digital input wiring
NPN (Sink)
Digital input wiring
12
13
18
19
27
29
32
33
20
37
+24
VDC
0
VDC
130B
T107.11
NB!
Control cables must be screened/armoured.
130B
T340.10
Connect the wires as described in the Operating Instruction for the
frequency converter. Remember to connect the shields in a proper way
to ensure optimum electrical immunity.
4 Electrical Installation
VLT HVAC Drive High Power Operating In-
structions
78
MG.11.F3.02 - VLT
®
is a registered Danfoss trademark
4