The leakage current also depends on the line distortion.
Illustration 2.29 Inuence of Line Distortion on Leakage
Current
NOTICE
High leakage current may cause the RCDs to switch o.
To avoid this problem, remove the RFI screw when a
lter is being charged.
EN/IEC61800-5-1 (Power Drive System Product Standard)
requires special care if the leakage current exceeds 3.5 mA.
Grounding must be reinforced in 1 of the following ways:
•
Ground wire (terminal 95) of at least 10 mm
2
(8 AWG).
•
2 separate ground wires that comply with the
dimensioning rules.
See EN/IEC61800-5-1 for further information.
Using RCDs
Where residual current devices (RCDs), also known as earth
leakage circuit breakers (ELCBs), are used, comply with the
following:
•
Use RCDs of type B only, which are capable of
detecting AC and DC currents.
•
Use RCDs with an inrush delay to prevent faults
caused by transient ground currents.
•
Dimension RCDs according to the system
congu-
ration and environmental considerations.
130BB958.12
f
sw
Cable
150 Hz
3rd harmonics
50 Hz
Mains
RCD with low f
cut-
RCD with high f
cut-
Leakage current
Frequency
Illustration 2.30 Mains Contributions to Leakage Current
130BB957.11
Leakage current [mA]
100 Hz
2 kHz
100 kHz
Illustration 2.31 Inuence of Cut-o Frequency of the RCD on
what is Responded to/Measured
For more details, refer to the RCD Application Note.
2.9
Brake Functions
2.9.1 Mechanical Holding Brake
A mechanical holding brake mounted directly on the
motor shaft normally performs static braking.
NOTICE
When the holding brake is included in a safety chain, a
frequency converter cannot provide a safe control of a
mechanical brake. Include a redundancy circuitry for the
brake control in the total installation.
Product Overview
VLT
®
Midi Drive FC 280
40 Danfoss A/S © 03/2016 All rights reserved. MG07B102
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