Design Guide | VLT® AutomationDrive FC 360
Mains Cable
RCD with low f
Figure 30: Main Contributions to Leakage Current
The amount of leakage current detected by the RCD depends on the cut-off frequency of the RCD.
Figure 31: Influence of the RCD Cut-off Frequency on Leakage Current
7.9 IT Mains
Mains supplies isolated from ground
If the drive is supplied from an isolated mains source (IT mains, floating delta, or grounded delta) or TT/TN-S mains with grounded leg,
the RFI switch is recommended to be turned off via parameter 14-50 RFI Filter on the drive and parameter 14-50 RFI Filter on the filter.
For more detail, see IEC 364-3. In the off position, the 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.
If optimum EMC performance is needed, or parallel motors are connected, or the motor cable length is above 25 m (82 ft), Danfoss
recommends setting parameter 14-50 RFI Filter to [1] ON. Refer also to the Application Note, VLT on IT mains. It is important to use
isolation monitors that are rated for use together with power electronics (IEC 61557-8).
Danfoss A/S © 2024.01 AJ435824192086en-000101 / 130R1295 | 63
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