Electrical installation - mains supply
Connect the three mains phases to terminals L
1
, L
2
,
L
3
.
High voltage test
A high voltage test can be carried out by short-circuit-
ing terminals U, V, W, L
1
, L
2
and L
3
and energizing by
max. 2.15 kV DC for one second between this short-
circuit and the chassis.
NOTE
The RFI switch must be closed (position
ON) when high voltage tests are carried
out (see section RFI Switch).
The line power and motor connection
must be interrupted if the leakage currents
are too high when high voltage tests are
carried out on the entire installation.
Safety grounding
NOTE
The adjustable frequency drive has a high
leakage current and must be grounded
appropriately for safety reasons. Use a
ground terminal (see section Electrical in-
stallation, power cables), which enables
reinforced grounding.
Apply national safety regulations.
Motor thermal protection
The electronic thermal relay in UL-approved frequency
converters has received the UL-approval for single
motor protection when parameter 128 has been set for
ETR Trip and parameter 105 has been programmed to
the rated motor current (see motor nameplate).
Extra protection (RCD)
ELCB relays, multiple protective earthing or earthing
can be used as extra protection, provided that local
safety regulations are complied with.
In the case of an earth fault, a DC content may develop
in the faulty current.
If ELCB relays are used, local regulations must be ob-
served. Relays must be suitable for protection of 3-
phase equipment with a bridge rectifier and for a brief
discharge on power-up.
See also the section Special Conditions in the Design
Guide.
RFI switch
Mains supply isolated from earth:
If the frequency converter is supplied from an isolated
mains source (IT mains) or TT/TN-S mains with groun-
ded leg, the RFI switch is recommended to be turned
off (OFF)
1)
. For further reference, see IEC 364-3. In
case optimum EMC performance is needed, parallel
motors are connected or the motor cable length is
above 25 m, it is recommended to set the switch in ON
position.
In OFF position, the internal RFI capacities (filter ca-
pacitors) between the chassis and the intermediate
circuit are cut off to avoid damage to the intermediate
circuit and to reduce the earth capacity currents (ac-
cording to IEC 61800-3).
Please also refer to the application note VLT on IT
mains, MN.90.CX.02. It is important to use isolation
monitors that are capable for use together with power
electronics (IEC 61557-8).
1)
Not possible with 5042-5602, 525-690 V units.
NOTE
The RFI switch is not to be operated with
mains connected to the unit. Check that
the mains supply has been disconnected
before operating the RFI switch.
NOTE
Open RFI switch is only allowed at factory
set switching frequencies.
VLT
®
5000 Series
58 MG.51.C5.22 - VLT
p
is a registered Danfoss trademark.
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