Danfoss VLT FC 360 Design Manual page 38

Product Overview
Leakage current [mA]
2 2
Illustration 2.19 Leakage Current Influenced by the Cable Length
and Power Size
The leakage current also depends on the line distortion.
Leakage current [mA]
Illustration 2.20 Leakage Current Influenced by Line Distortion
NOTE
When a filter is used, remove the RFI screw (enclosure size
J1 to J5) or turn off 14-50 RFI Filter (enclosure size J6 to J7)
when charging the filter, to avoid that a high leakage
current makes the RCD switch.
EN/IEC61800-5-1 (Power Drive System Product Standard)
requires special care if the leakage current exceeds 3.5mA.
Earth grounding must be reinforced in one of the
following ways:
36
®
VLT AutomationDrive FC 360 Design Guide
a
See EN/IEC61800-5-1 and EN50178 for further information.
Using RCDs
Where residual current devices (RCDs), also known as earth
leakage circuit breakers (ELCBs), are used, comply with the
following:
b
Cable length [m]
L
leakage
THVD=0%
THVD=5%
Illustration 2.21 Main Contributions to Leakage Current
®
MG06B202 - VLT is a registered Danfoss trademark
•
Earth ground wire (terminal 95) of at least 10
2
mm
•
Two separate earth ground wires both complying
with the dimensioning rules
•
Use RCDs of type B only which are capable of
detecting AC and DC currents
•
Use RCDs with an inrush delay to prevent faults
due to transient earth currents
•
Dimension RCDs according to the system configu-
ration and environmental considerations
RCD with low f
[mA]
RCD with high f
50 Hz 150 Hz
Mains 3rd harmonics
f
s
cut-o
cut-o
f
f [Hz]
sw
Cable