Danfoss VLT Design Manual page 71

How to Install
5.2.12 Electrical Installation, Control Cables
5 5
Illustration 5.23 Diagram Showing all Electrical Terminals.
Very long control cables and analog signals may in rare
cases and depending on installation result in 50/60 Hz
earth loops due to noise from mains supply cables.
If this occurs, you may have to break the screen or insert a
100 nF capacitor between screen and chassis.
The digital and analog in- and outputs must be connected
separately to the frequency converter common inputs
(terminal 20, 55, 39) to avoid ground currents from both
groups to affect other groups. For example, switching on
the digital input may disturb the analog input signal.
70
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VLT Refrigeration Drive Design Guide
NOTE
Control cables must be screened/armoured.
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MG16G102 - VLT is a registered Danfoss trademark