Danfoss VLT AutomationDrive FC 302 Programming Manual page 11

Introduction
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, it may be necessary to break the screen or
insert a 100 nF capacitor between screen and chassis.
The digital and analog inputs and outputs must be
connected separately to the common inputs (terminal 20,
55, 39) of the frequency converter to avoid ground
currents from both groups to affect other groups. For
example, switching on the digital input may disturb the
analog input signal.
Input polarity of control terminals
PNP (Source)
Digital input wiring
12 13 18 19 27 29
Illustration 1.3 PNP (Source)
NPN (Sink)
Digital input wiring
12 13 18 19 27 29
Illustration 1.4 NPN (Sink)
NOTICE
Control cables must be screened/armoured.
MG33MJ02
Programming Guide
32 33 20 37
32 33 20 37
Danfoss A/S © Rev. 10/2014 All rights reserved.
See section Grounding of Screened Control Cables in the
Design Guide for the correct termination of control cables.
Illustration 1.5 Grounding of Screened/Armoured Control
Cables
1.5.1 Start/Stop
Terminal 18=5-10 Terminal 18 Digital Input [8] Start
Terminal 27=5-12 Terminal 27 Digital Input [0] No operation
(Default coast inverse)
Terminal 37=Safe Torque Off (where available)
12 13 18 19
Start/Stop
Speed
Start/Stop
[18]
Illustration 1.6 Start/Stop
27 29 32 33 20 37
Safe Stop
9
1 1