VLT
®
FCD Series
Installation
NB!:
Do not plug/unplug the electronic part with
mains voltage switched on.
■ Protective earth
The earth connection serves several purposes.
• Safety earth (Protective earth, PE)
The equipment must be properly earthed according
to local regulation. This equipment has a leakage
current > 3.5 mA AC. It must be connected to
an earth connection complying with the local
rules for high leakage current equipment.
Typically, this implies that the PE conductors
must be mechanically enhanced (minimum cross
section 10 mm
2
) or duplicated
• Noise "clamping" (high frequencies)
Stable communication between units call for
screening of the communication cables (1).
Cables must be properly attached to screen
clamps provided for that purpose.
• Equalisation of voltage potential (low frequencies)
To reduce alignment currents in the screen
of the communication cable, always apply a
short earthing cable between units that are
connected to the same communication cable (2)
or connect to an earthed frame (3).
• Potential equalization: All metal parts, where the
motors are fastened, must be potential equalized
PE connections, voltage equalising cables and the
screen of the communication cable should be
connected to the same potential (4).
Keep the conductor as short as possible and use
the greatest possible surface area.
The numbering refers to the figure.
Proper installation earthing
■ EMC-correct electrical installation
General points to be observed to ensure
EMC-correct electrical installation.
- Use only screened/armoured motor cables and
screened/armoured control cables.
- Connect the screen to earth at both ends.
- Avoid installation with twisted screen ends (pigtails),
since this ruins the screening effect at high
frequencies. Use cable clamps instead.
-Don’t remove the cable screen between the
cable clamp and the terminal.
MG.04.B7.02 - VLT is a registered Danfoss trademark
11
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