Danfoss VLT AutomationDrive FC 361 Series Design Manual page 50

Electrical Installation Con...
Leakage current
7 7
Illustration 7.12 Line Distortion Influences Leakage Current
If the leakage current exceeds 3.5 mA, compliance with
EN/IEC61800-5-1 (power drive system product standard)
requires special care.
Reinforce grounding with the following protective ground
connection requirements:
•
Ground wire (terminal 95) of at least 10 mm
(8 AWG) cross-section.
•
2 separate ground wires both complying with the
dimensioning rules.
See EN/IEC61800-5-1 and EN 50178 for further information.
Using RCDs
Where residual current devices (RCDs), also known as
ground leakage circuit breakers, are used, comply with the
following:
•
Use RCDs of type B only as they can detect AC
and DC currents.
•
Use RCDs with a delay to prevent faults due to
transient ground currents.
•
Dimension RCDs according to the system configu-
ration and environmental considerations.
The leakage current includes several frequencies
originating from both the mains frequency and the
switching frequency. Whether the switching frequency is
detected depends on the type of RCD used.
48
VLT® AutomationDrive FC 361
Leakage current
THDv=0%
THDv=5%
Illustration 7.13 Main Contributions to Leakage Current
The amount of leakage current detected by the RCD
depends on the cut-off frequency of the RCD.
Leakage current [mA]
2
Illustration 7.14 Influence of the RCD Cut-off Frequency on
Leakage Current
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RCD with low f
cut-
RCD with high f
50 Hz 150 Hz
Mains 3rd harmonics
cut-
f Frequency
sw
Cable
100 Hz
2 kHz
100 kHz
MG06K102