Illustration 3.78: Compact IP 21 (NEMA 1) and IP 54 (NEMA 12) enclosure E1
3.5.3. Earthing
The following basic issues need to be considered when installing a frequency con-
verter, so as to obtain electromagnetic compatibility (EMC).
•
Safety earthing: Please note that the frequency converter has a high leakage current and
must be earthed appropriately for safety reasons. Apply local safety regulations.
•
High-frequency earthing: Keep the earth wire connections as short as possible.
Connect the different earth systems at the lowest possible conductor impedance. The lowest pos-
sible conductor impedance is obtained by keeping the conductor as short as possible and by using
the greatest possible surface area.
The metal cabinets of the different devices are mounted on the cabinet rear plate using the lowest
possible HF impedance. This avoids having different HF voltages for the individual devices and
avoids the risk of radio interference currents running in connection cables that may be used be-
tween the devices. The radio interference will have been reduced.
In order to obtain a low HF impedance, use the fastening bolts of the devices as HF connection
to the rear plate. It is necessary to remove insulating paint or similar from the fastening points.
3.5.4. Extra Protection (RCD)
ELCB relays, multiple protective earthing or earthing can be used as extra protection, provided
that local safety regulations are complied with.
3. How to Install
VLT
®
Automation Drive FC 300
Operating Instructions High Power
52
MG.33.U1.02 - VLT
®
is a registered Danfoss trademark
3
