Danfoss VLT FC 102 Installation Manual page 42

Electrical Installation
5.12.2 Grounding of Shielded Control Cables
Correct shielding
The preferred method usually is to secure control and
serial communication cables with shielding clamps
provided at both ends to ensure best possible high
frequency cable contact. If the ground potential between
the frequency converter and the PLC is different, electric
noise can occur that disturbs the entire system. Solve this
problem by fitting an equalizing cable next to the control
cable. Minimum cable cross-section: 16 mm
5 5
1 Minimum 16 mm
Illustration 5.15 Correct Shielding
50/60 Hz ground loops
With long control cables, ground loops can occur. To
eliminate ground loops, connect 1 end of the shield-to-
ground with a 100 nF capacitor (keeping leads short).
Illustration 5.16 Avoiding Ground Loops
40
VLT
2
PLC FC
PE PE <10 mm
PE PE
1
2
2 2 Equalizing cable
(4 AWG)
PLC FC
PE
PE
100nF <10 mm
Danfoss A/S © 08/2017 All rights reserved.
®
Parallel Drive Modules
Avoid EMC noise on serial communication
This terminal is connected to ground via an internal RC
link. To reduce interference between conductors, use
twisted-pair cables.
(4 AWG).
1 Minimum 16 mm
Illustration 5.17 Recommended Method for Avoiding EMC
Noise
Alternatively, the connection to terminal 61 can be
omitted:
1 Minimum 16 mm
Illustration 5.18 Shielding without Using Terminal 61
FC FC
69 69
68
68
61 61
PE PE
<10 mm
PE PE
1
2
2 Equalizing cable
2
(4 AWG)
FC FC
69 68
68 69
PE PE
<10 mm
PE PE
1
2
2 2 Equalizing cable
(4 AWG)
MG37K302