Brake Functions; Mechanical Holding Brake - Danfoss VLT Midi Drive FC 280 Design Manual

Product Overview
The leakage current also depends on the line distortion.
2 2
Leakage current
Illustration 2.29 Influence of Line Distortion on Leakage
Current
NOTICE
High leakage current may cause the RCDs to switch off.
To avoid this problem, remove the RFI screw when a
filter 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
(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 configu-
ration and environmental considerations.
40
®
VLT Midi Drive FC 280
Leakage current
THDv=0%
THDv=5%
Illustration 2.30 Mains Contributions to Leakage Current
Leakage current [mA]
2
Illustration 2.31 Influence of Cut-off 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.
Danfoss A/S © 03/2016 All rights reserved.
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
MG07B102