Grounding Of Shielded Control Cables; Control Terminal Types - Danfoss VLT FC 100 Instruction Manual

Installation

2.5.3 Grounding of Shielded Control Cables

Correct shielding
The preferred method in most cases is to secure control
2 2
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 adjustable frequency drive and the PLC is different,
electric noise may occur that will disturb the entire system.
Solve this problem by fitting an equalizing cable next to
the control cable. Minimum cable cross-section: 0.025 in
2
[16 mm ].
Figure 2.25
1
Min. 0.025 in
2 Equalizing cable
Table 2.8
50/60 Hz ground loops
With very long control cables, ground loops may occur. To
eliminate ground loops, connect one end of the shield-to-
ground with a 100 nF capacitor (keeping leads short).
Figure 2.26
Avoid EMC noise on serial communication
This terminal is connected to ground via an internal RC
link. Use twisted-pair cables to reduce interference
between conductors. The recommended method is shown
below:
Figure 2.27
2-22
VLT
Instruction Manual
PLC FC
PE PE
PE PE
1
2
2 [16 mm 2 ]
PLC FC
PE
PE
100nF
FC FC
69
69
68
68
61 61
PE PE
PE PE
1
2
MG16D222 - VLT
®
HVAC Drive D-Frame
1
Min. 0.025 in
2 Equalizing cable
Table 2.9
Alternatively, the connection to terminal 61 can be
omitted:
2
Figure 2.28
1
Min. 0.025 in
2 Equalizing cable
Table 2.10

2.5.4 Control Terminal Types

Terminal functions and default settings are summarized in
2.5.6 Control Terminal Functions.
Figure 2.29 Control Terminal Locations
®
is a registered Danfoss trademark
2 [16 mm 2 ]
FC FC
69 68
68 69
PE PE
PE PE
1
2
2 2
[16 mm ]
4
2
1
3