•
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 2.7).
Illustration 2.7 Grounding with Shielded Cable
2.4.3 Motor Connection
WARNING
INDUCED VOLTAGE!
Run output motor cables from multiple frequency converters
separately. Induced voltage from output motor cables run
together can charge equipment capacitors even with the
equipment turned off and locked out. Failure to run output
motor cables separately could result in death or serious
injury.
•
For maximum wire sizes see 10.1 Power-dependent
Specifications
•
Comply with local and national electrical codes for
cable sizes
•
Motor wiring knockouts or access panels are
provided at the base of IP21 and higher
(NEMA1/12) units
•
Do not install power factor correction capacitors
between the frequency converter and the motor
•
Do not wire a starting or pole-changing device
between the frequency converter and the motor
•
Connect the 3-phase motor wiring to terminals 96
(U), 97 (V), and 98 (W)
•
Ground the cable in accordance with grounding
instructions provided
•
Torque terminals in accordance with the
information provided in 10.4.1 Connection
Tightening Torques
Installation
VLT
®
AutomationDrive Operating
Instructions
MG.33.AJ.02 - VLT
®
is a registered Danfoss trademark 13
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