Use Of Emc-Correct Cables - Danfoss VLT Micro Drive FC 51 Design Manual

How to Install

6.9 Use of EMC-Correct Cables

Danfoss recommends braided shielded/armored cables to
optimize EMC immunity of the control cables and the EMC
emission from the motor cables.
The ability of a cable to reduce the ingoing 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
6 6 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.
-
-
-
-
-
-
-
48
). 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
Aluminum-clad with copper wire.
Twisted copper wire or armored steel
wire cable.
Single-layer braided copper wire with
varying percentage shield coverage.
This is the typical Danfoss reference
cable.
Double-layer braided copper wire.
Twin layer of braided copper wire with a
magnetic, shielded/armored
intermediate layer.
Cable that runs in copper tube or steel
tube.
Lead cable with 1.1 mm (0.04 in) wall
thickness.
Danfoss A/S © 01/2016 All rights reserved.
®
VLT Micro Drive FC 51
Transfer impedance, Z
mOhm/m
10
10
10
10
10
1
10
10
10
0,01
Illustration 6.10 Transfer Impedance of Different Wires
t
0,1 1 10 100 MHz
a
b
c
d
e
f
g
MG02K402