Earth (Grounding) Requirements; Leakage Current (>3.5 Ma) - Danfoss VLT AutomationDrive FC 300 Operating Instructions Manual

Installation
•
All frequency converters must be provided with
short-circuit and over-current protection. Input
fusing is required to provide this protection, see
Illustration 2.4. If not factory supplied, fuses must
be provided by the installer as part of installation.
See maximum fuse ratings in 10.3.1 Protection.
Fuses
L1
L2
L3
GND
Illustration 2.4 Frequency Converter Fuses
Wire Type and Ratings
•
All wiring must comply with local and national
regulations regarding cross-section and ambient
temperature requirements.
•
Danfoss recommends that all power connections
be made with a minimum 75 °C rated copper
wire.

2.4.2 Earth (Grounding) Requirements

WARNING
EARTHING (GROUNDING) HAZARD!
For operator safety, it is important to earth (ground) the
frequency converter properly in accordance with national
and local electrical codes as well as instructions contained
within this document. Do not use conduit connected to
the frequency converter as a replacement for proper
grounding. Earth (ground) currents are higher than 3.5 mA.
Failure to earth (ground) the frequency converter properly
could result in death or serious injury.
NOTE
It is the responsibility of the user or certified electrical
installer to ensure correct earthing (grounding) of the
equipment in accordance with national and local electrical
codes and standards.
•
Follow all local and national electrical codes to
earth (ground) electrical equipment properly
•
Proper protective earthing (grounding) for
equipment with earth (ground) currents higher
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VLT Automation Drive D-Frame
Operating Instructions
L1 L2 L3
91 92 93
2.4.2.1 Leakage Current (>3.5 mA)
Follow national and local codes regarding protective
earthing of equipment with a leakage current >3.5 mA.
Frequency converter technology implies high frequency
switching at high power. This will generate a leakage
current in the earth connection. A fault current in the
frequency converter at the output power terminals might
contain a DC component, which can charge the filter
capacitors and cause a transient earth current. The earth
leakage current depends on various system configurations
including RFI filtering, screened motor cables, and
frequency converter power.
EN/IEC61800-5-1 (Power Drive System Product Standard)
requires special care if the leakage current exceeds 3.5 mA.
Earthing (grounding) must be reinforced in one of the
following ways:
See EN 60364-5-54 § 543.7 for further information.
Using RCDs
Where residual current devices (RCDs)–also known as earth
leakage circuit breakers (ELCBs)–are used, comply with the
following: residual current devices (RCDs)
®
MG34U202 - VLT is a registered Danfoss trademark
than 3.5 mA must be established, see
2.4.2.1 Leakage Current (>3.5 mA)
•
A dedicated earth wire (ground wire) is required
for input power, motor power and control wiring
•
Use the clamps provided with the equipment for
proper earth connections (ground connections)
•
Do not earth (ground) one frequency converter to
another in a "daisy chain" fashion
•
Keep the earth (ground) wire connections as
short as possible
•
Using high-strand wire to reduce electrical noise
is recommended
•
Follow motor manufacturer wiring requirements
•
Earth (ground) wire of at least 10 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
2 2
2
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