Use Of Emc-Correct Cables - Danfoss VLT Decentral Drive FCD 302 Design Manual

Product Overview and Functi...
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Illustration 2.40 Connection of Mains Diagram
Electrical safety ground connections
To obtain the electrical safety, always connect the safety
ground on the dedicated connections inside the VLT
Decentral Drive FCD 302 installation box. See
Illustration 2.41.
Illustration 2.41 Electrical Safety Ground Connections
50
VLT
12
37
PE
18
50
53
55
54
99
Transmitter
Danfoss A/S © 05/2018 All rights reserved.
®
Decentral Drive FCD 302
Equalizing cable
As the shield of the communication cable needs to be
connected to ground by each drive/device, there is a risk
of having current in the communication cable. This might
lead to communication problems as the equalizing current
can interfere with the communication. To reduce currents
in the shield of the communication cable, always apply a
short grounding cable between units that are connected
to the same communication cable. Danfoss recommend
using minimum 16 mm
install the equalizing cable parallel with the communi-
cation cable.
5 kΩ
For good equalizing between VLT
in a decentral installation, use the external equalizing
terminal from Danfoss (ordering number 130B5833).

2.9.4.2 Use of EMC-correct Cables

Danfoss recommends braided shielded/armored cables to
optimize EMC immunity of the control cables and emission
from the motor cables.
The ability of a cable to reduce the in- and outgoing
radiation of electric noise depends on the transfer
impedance (Z
to reduce the transfer of electric noise; however, a shield
with a lower transfer impedance (Z
effective than a shield with a higher transfer impedance
®
(Z ).
T
Transfer impedance (Z
turers but it is often possible to estimate transfer
impedance (Z
cable.
Transfer impedance (Z
following factors:
•
The conductibility of the shield material.
•
The contact resistance between the individual
shield conductors.
•
The shield coverage, that is, the physical area of
the cable covered by the shield - often stated as
a percentage value.
•
Shield type, that is, braided or twisted pattern.
2 (6 AWG) equalizing cable and
®
Decentral Drive FCD 302
). The shield of a cable is normally designed
T
) value is more
T
) is rarely stated by cable manufac-
T
) by assessing the physical design of the
T
) can be assessed based on the
T
MG04H302