Danfoss VLT FC 100 Operating Instructions Manual page 79

4 Electrical Installation
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-
4
nal.
Input polarity of control terminals
PNP (Source)
Digital input wiring
12 13 18 19
NPN (Sink)
Digital input wiring
12 13 18 19
NB!
Control cables must be screened/armoured.
78
27 29 32 33 20 37
27 29 32 33 20 37
MG.11.F3.02 - VLT
VLT HVAC Drive High Power Operating In-
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.
® is a registered Danfoss trademark
structions