Danfoss VLT AQUA Drive Design Manual

Also see for vlt aqua: Instructions Design guide Instruction manual Operating instructions Design guide

Contents

5.8.2. Use of EMC-Correct Cablesrecommends 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 normallydesigned to reduce the transfer of electric noise; however, a screen with a lower transfer impedance (ZT ) value is more effective than a screen with ahigher transfer impedance (ZT ).Transfer impedance (ZT ) is rarely stated by cable manufacturers but it is often possible to estimate transfer impedance (Z T ) by assessing the physicaldesign 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 screencoverage.This is the typical 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.VLT® AQUA Drive Design Guide 5. How to InstallMG.20.N4.02 - VLT® is a registered Danfoss trademark 1295