Grounding; Extra Protection (Rcd); Rfi Switch - Danfoss vlt series Operating Instructions Manual

How to Install

3.4.3 Grounding

To obtain electromagnetic compatibility (EMC), consider
the following basic issues when installing a frequency
converter.
•
Safety grounding: The frequency converter has a
high leakage current (>3.5 mA) and must be
grounded appropriately for safety reasons. Apply
local safety regulations.
•
High frequency grounding: Keep the ground wire
connections as short as possible.
Connect the different ground systems at the lowest
possible conductor impedance. This 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 high
frequency impedance. This avoids having different high-
frequency voltages for the individual devices and avoids
the risk of radio interference currents running in any
connection cables used between the devices. The radio
interference has been reduced.
To obtain a low high-frequency impedance, use the
fastening bolts of the devices as high frequency
connection to the rear plate. Remove any insulating paint
or similar from the fastening points.

3.4.4 Extra Protection (RCD)

EN/IEC61800-5-1 (Power drive system product standard)
requests special care if the leakage current exceeds 3.5 mA.
Reinforce grounding in the following ways:
•
Ground wire of at least 10 mm
•
Install 2 separate ground wires, both complying
with the dimensioning rules. See EN 60364-5-54 §
543.7 for further information.
If local safety regulations are complied with, ELCB relays,
multiple protective earthing, or grounding can be used as
extra protection.
A ground fault may cause a DC component to develop in
the fault current.
If ELCB relays are used, observe local regulations. Relays
must be suitable for the protection of 3-phase equipment
with a bridge rectifier and for a brief discharge on power-
up.
See also Special Conditions in the product relevant design
guide.
MG34Q402
Operating Instructions

3.4.5 RFI Switch

Mains supply isolated from ground
Turn off (OFF)
on the frequency converter and parameter 14-50 RFI Filter
on the filter if:
•
•
1)
Not available for 525–600/690 V frequency converters.
For further reference, see IEC 364-3.
Set parameter 14-50 RFI Filter to [1] ON if:
•
•
•
In OFF, the internal RFI capacities (filter capacitors)
between the chassis and the DC link are cut off to avoid
damage to the DC link and to reduce the ground capacity
currents (according to IEC 61800-3).
Also refer to the application note VLT on IT mains. It is
important to use isolation monitors which are compatible
with power electronics (IEC 61557-8).
2
(7 AWG).
Danfoss A/S © 04/2016 All rights reserved.
1)
the RFI switch via parameter 14-50 RFI Filter
The frequency converter is supplied from an
isolated mains source (IT mains, floating delta,
and grounded delta).
The frequency converter is supplied from TT/TN-S
mains with grounded leg.
Optimum EMC performance is needed.
Parallel motors are connected.
The motor cable length is above 25 m (82 ft).
3 3
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