Danfoss VLT AutomationDrive FC 300 Design Manual page 106

FC 300 Design Guide
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 ). The screen of a cable is normally designed to reduce the transfer of electric noise; how-
T
ever, a screen with a lower transfer impedance (Z
transfer impedance (Z
Transfer impedance (Z
transfer impedance (Z
Transfer impedance (Z
- 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 ca-
ble.
d. Double-layer braided copper wire.
e. Twin layer of braided copper wire with a
magnetic, screened/armoured intermedi-
ate layer.
f. Cable that runs in copper tube or steel
tube.
g. Lead cable with 1.1 mm wall thickness.
106
How to Install
).
T
) is rarely stated by cable manufacturers but it is often possible to estimate
T
) by assessing the physical design of the cable.
T
) can be assessed on the basis of the following factors:
T
MG.33.B8.02 - VLT
) value is more effective than a screen with a higher
T
® is a registered Danfoss trademark