Danfoss VLT FC 103 Operating Instructions Manual

Also see for VLT FC 103: Service guide Installation guide Installation guide Operating guide Installation guide

Contents

Danfoss VLT FC 103 Operating Instructions Manual Manual pdf 51 page image

3.4.8 Shielding against Electrical NoiseTo ensure best EMC performance, mount the EMC metalcover before mounting the mains power cable.NOTICEThe EMC metal cover is only included in units with anRFI filter.175ZT975.10Illustration 3.53 Mounting of EMC Shield.3.5 Control Wiring Connection• Isolate control wiring from high powercomponents in the frequency converter.• If the frequency converter is connected to athermistor for PELV isolation, optional thermistorcontrol wiring must be reinforced/doubleinsulated. A 24 V DC supply voltage isrecommended.3.5.1 AccessAll terminals to the control cables are located underneaththe LCP on the inside of the frequency converter. Toaccess, open the door (IP21/54) or remove the front panel(IP20).3.5.2 Using Screened Control CablesDanfoss recommends braided screened/armoured cables tooptimise EMC immunity of the control cables and the EMCemission from the motor cables.The ability of a cable to reduce the incoming andoutgoing radiation of electric noise depends on thetransfer impedance (ZT). The screen of a cable is normallydesigned to reduce the transfer of electric noise; however,a screen with a lower transfer impedance (ZT) value ismore effective than a screen with a higher transferimpedance (ZT).Transfer impedance (ZT) is rarely stated by cable manufac-turers, but it is often possible to estimate transferimpedance (ZT) by assessing the physical design of thecable.Transfer impedance (ZT) can be assessed on the basis ofthe following factors:• The conductibility of the screen material.• The contact resistance between the individualscreen conductors.• The screen coverage, i.e. the physical area of thecable covered by the screen - often stated as apercentage value.• Screen type, i.e. braided or twisted pattern.Installation Operating InstructionsMG16J202 Danfoss A/S © Rev. 05/2014 All rights reserved. 493 3