Transmitter
96 97 9998
91 92 93 95
50
12
L1 L2
L1
PEL3
W PEVU
F1
L2
L3
N
PE
130BA175.12
18
53
37
55
54
M
3
5 kΩ
Illustration 6.63 Electrical Connection Diagram
6.8.2
Use of EMC-Correct Cables
Danfoss recommends braided screened/armoured cables to
optimise EMC immunity of the control cables and the EMC
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
T
). The screen of a cable is normally designed
to reduce the transfer of electric noise; however, a screen
with a lower transfer impedance (Z
T
) value is more
effective than a screen with a higher transfer impedance
(Z
T
).
Transfer impedance (Z
T
) is rarely stated by cable manufac-
turers, but it is often possible to estimate transfer
impedance (Z
T
) by assessing the physical design of the
cable.
Transfer impedance (Z
T
) can be assessed on the basis of
the following factors:
•
The conductibility of the screen material
•
The contact resistance between the individual
screen conductors
•
The screen coverage, i.e. the physical area of the
cable covered by the screen - often stated as a
percentage value
•
Screen type, i.e. braided or twisted pattern
a. Aluminium-clad with copper wire
b. Twisted copper wire or armoured steel wire cable
c. Single-layer braided copper wire with varying
percentage screen coverage
This is the typical Danfoss reference cable
d. Double-layer braided copper wire
e. Twin layer of braided copper wire with a
magnetic, screened/armoured intermediate layer
f. Cable that runs in copper tube or steel tube
g. Lead cable with 1.1 mm wall thickness
175ZA166.13
0,01 0,1 1 10 100 MHz
10
10
10
1
10
10
10
10
10
a
b
c
d
e
f
g
The lower the Z the better the cable screening performance
Transfer impedance, Z
t
mOhm/m
Illustration 6.64 Transfer Impedance
Electrical Installation Design Guide
118 Danfoss A/S © Rev. 06/2014 All rights reserved. MG11BC02
66
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