2.4.2 Earth (Grounding) Requirements
WARNING
GROUNDING HAZARD!
For operator safety, it is important to ground frequency
converter properly in accordance with national and local
electrical codes as well as instructions contained within these
instructions. Ground currents are higher than 3,5mA. Failure
to ground 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 grounding (earthing) of the
equipment in accordance with national and local electrical
codes and standards.
•
Follow all local and national electrical codes to
ground electrical equipment properly
•
Proper protective grounding for equipment with
ground currents higher than 3,5mA must be
established, see Leakage Current (>3,5mA)
•
A dedicatedground wire is required for input
power, motor power and control wiring
•
Use the clamps provided with on the equipment
for proper ground connections
•
Do not ground one frequency converter to another
in a “daisy chain” fashion
•
Keep the ground wire connections as short as
possible
•
Use of high-strand wire to reduce electrical noise is
recommended
•
Follow motor manufacturer wiring requirements
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 3,5mA.
Earth grounding must be reinforced in one of the following
ways:
•
Earth ground wire of at least 10mm
2
•
Two separate earth ground wires both complying
with the dimensioning rules
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:
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
2.4.2.2 Grounding Using Shielded Cable
Earthing (grounding) clamps are provided for motor wiring
(see Illustration 2.8).
Illustration 2.8 Grounding with Shielded Cable
2.4.2.3 Grounding Using Conduit
CAUTION
GROUNDING HAZARD!
Do not use conduit connected to the frequency converter as
a replacement for proper grounding. Ground currents are
higher than 3,5mA. Improper grounding can result in
personal injury or electrical shorts.
Dedicated grounding clamps are provided (See
Illustration 2.9).
Installation
VLT
®
HVAC Drive Operating Instructions
MG.11.AE.02 - VLT
®
is a registered Danfoss trademark 13
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