Danfoss VLT Series Design Manual page 106

5. How to Install
5.2.12. Electrical Installation, Control Cables
5
5.16: Terminal 37: Safe Stop input available with Safe Stop Function only!
In rare cases, and depending on the installation, very long control cables and analog signals may
result in 50/60 Hz ground loops due to noise from line supply cables.
If this occurs, you may have to break the shield or insert a 100 nF capacitor between shield and
chassis.
The digital and analog inputs and outputs must be connected separately to the VLT HVAC Drive
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.
106
NOTE
Control cables must be shielded/armored.
MG.11.B4.22 - VLT ® is a registered Danfoss trademark.
VLT ® HVAC Drive Design Guide