Danfoss VLT 5000 FLUX Instruções de Operação descarregar pdf (Página 40)

VLT

5000 FLUX

Installation

■ Use o f emc-correct cables

Braided screened/armoured cables are recommended

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;

however, a screen with a lower transfer impedance

) value is more effective than a screen with a

higher transfer impedance (Z

Transfer impedance (Z

) is rarely stated by

cable manufacturers, but it is often possible to

estimate transfer impedance (Z

) by assessing

the physical design of the cable.

Transfer impedance (Z

) 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.

Aluminium-clad with copper wire.

Twisted copper wire or armoured steel wire cable.

Single-layer braided copper wire with varying percentage screen

coverage.

This is the typical Danfoss reference cable.

Double-layer braided copper wire.

Twin layer of braided copper wire with a magnetic,

screened/armoured intermediate layer.

Cable that runs in copper tube or steel tube.

Lead cable with 1.1 mm wall thickness.

MG.55.A7.02 - VLT is a registered Danfoss trademark

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Danfoss VLT 5000 FLUX Instruções de Operação Página 40