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 (>3,5mA)
Follow national and local codes regarding protective
earthing of equipment with a leakage current > 3,5mA.
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 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:
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).
130BA266.10
+DC
BR-
B
MAINS
L1 L2 L3
91 92 93
RELAY 1 RELAY 2
99
- LC -
UVW
MOTOR
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
14 MG.11.AG.02 - VLT
®
is a registered Danfoss trademark
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