2.5.3 Grounding of Shielded Control Cables
Correct shielding
The preferred method in most cases 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 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
2
].
1
2
PE
FC
PE
PLC
130BB922.11
PE
PE
Figure 2.25
1
Min. 0.025 in
2
[16 mm
2
]
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).
100nF
FC
PE
PE
PLC
130BB609.11
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:
PE
FC
PE
FC
130BB923.11
PE
PE
69
68
61
69
68
61
1
2
Figure 2.27
1
Min. 0.025 in
2
[16 mm
2
]
2
Equalizing cable
Table 2.9
Alternatively, the connection to terminal 61 can be
omitted:
PE
FC
PE
FC
130BB924.11
PE
PE
69
69
68
68
1
2
Figure 2.28
1
Min. 0.025 in
2
[16 mm
2
]
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
.
1
4
2
3
130BA012.11
61
68
69
39
42
50
53
54
55
12
13
18
19
27
29
32
33
20
37
Figure 2.29 Control Terminal Locations
Installation
VLT
®
HVAC Drive D-Frame
Instruction Manual
2-22
MG16D222 - VLT
®
is a registered Danfoss trademark
2
2
