Use Of Emc Compliant Cables - Danfoss VLT 2800 Design Manual

Installation

3.3.8 Use of EMC Compliant Cables

To comply with requirements for EMC immunity of the control cables and EMC emissions for the motor cables, use
screened/armoured cables.
The ability of a cable to reduce the amount of ingoing and outgoing radiation of electric noise depends on the transfer
3 3 impedance (Z
lower Z is more effective than a screen with a higher Z
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Z is rarely stated by cable manufacturers, but it is often possible to estimate Z
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design of the cable.
Z can be assessed on the basis of the following factors:
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•
The contact resistance between the individual screen conductors.
•
Screen coverage, i.e. the physical area of the cable covered by the screen. Is often stated as a percentage and
should be no less than 85%.
•
The screen type, i.e. braided or twisted pattern. A braided pattern or closed pipe is recommended.
Illustration 3.18 Cable Comparison
42
). The screen of a cable is normally designed to reduce the transfer of electric noise, and a screen with a
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Danfoss A/S © Rev. May/2014 All rights reserved.
Design Guide
.
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by looking at and assessing the physical
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MG27E402