Leakage Current (>3.5 Ma); Grounding Using Shielded Cable; Motor Connection - GE AF-600 FP Series Design And Installation Manual

Installation
•
Do not ground one frequency converter to
another in a "daisy chain" fashion
•
Using high-strand wire to reduce electrical noise
is recommended
•
Follow motor manufacturer wiring requirements
2 2
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Use the clamps provided with on the equipment
for proper ground connections to obtain a low
HF impedance
•
Keep the ground wire connections as short as
possible to reduce the conductor impedance
2.5.2.1 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.
Earth grounding must be reinforced in one of the
following ways:
•
Earth ground wire of at least 10 mm
•
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
18
TM
AF-600 FP Design and Installation Guide

2.5.2.2 Grounding Using Shielded Cable

Earthing (grounding) clamps are provided for motor wiring
(see Illustration 2.7).
Illustration 2.7 Grounding with Shielded Cable

2.5.3 Motor Connection

WARNING
INDUCED VOLTAGE!
Run output motor cables from multiple frequency
2
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.
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NOTE
UNIT SIZE 6X REQUIREMENTS
An equal amount of wires to each inverter module is
required. The cables must be of equal length within 10%
between inverter and first common point in a phase
(recommended at motor terminal)
DET-768b
Comply with local and national electrical codes
for cable sizes
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
Follow motor manufacturer wiring requirements