Use Of Emc Compliant Cables - Danfoss VLT MICRO Manual

Use of EMC compliant cables

In order to comply with requirements for
EMC immunity of the control cables and EMC
emissions from the motor cables screened/
armoured cables must be used.
The ability of a cable to reduce the amount of
ingo-ing and outgoing radiation of electric noise
depends on the transfer impedance (Z
screen of a ca-ble is normally designed to
reduce the transfer of electric noise, and a
screen with a lower Z
screen with a higher Z
). The
T
is more effective than a
T
.
T
14
VLT
Z is rarely stated by cable manufacturers, but
T
it is often possible to estimate Z
and assessing the physical design of the cable.
Z can be assessed on the basis of the
T
following factors:
- 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.
® ® ® ® ®
MICRO
by looking at
T