•
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/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
).
130BA266.10
+DC
BR-
B
M
A
I
N
S
L1 L2 L3
91 92 93
RELA
Y 1 RELA
Y 2
99
- LC -
U V
W
MO
TOR
Illustration 2.7 Grounding with Shielded Cable
Installation
VLT
®
AQUA Drive
Operating Instructions
MG.20.M8.02 - VLT
®
is a registered Danfoss trademark
13
2
2
