Nidec DFS 1, Power Installation Manual

Page: 35 / 61

DFS1/DFS2 Power Installation Guide
35
Issue Number: 2
Saf
e
ty
inf
or
m
atio
n
Pr
oduct
in
fo
rmat
ion
Mecha
n
ical
inst
a
llati
o
n
El
ect
ri
cal
inst
a
lla
tion
Te
chnical dat
a
Table 4-1 AC supply specification
4.4 Operation on IT (ungrounded) supplies
Parameter Rating
Voltage 380 V to 480 V ±10 % 500 V to 690 V ±10 %
No of phases 3
Supply frequency 45 to 66 Hz
Supply type TN-S, TN-C-S, TT, IT
Overvoltage category
OVC III (according to IEC 60664-1)
1
1. For installations where the equipment is installed at the origin of the supply, additional over-voltage
suppression (transient voltage surge suppression) must be provided to reduce the overvoltage category
from OVC IV to OVC III.
Impulse voltage rating 4 kV for 400 V, 6 kV for 690 V drives
Maximum supply imbalance
2 % negative phase sequence (equivalent to 3 % voltage imbalance between
phases).
Auxiliary transformer tap setting
Before powering up the drive, it is important to check that the auxiliary transformer tapping
has been set correctly. Wrong selection could result in damage to transformer and the roof
fans.
Operation on IT (ungrounded) supplies
Unusual hazards can occur on IT (ungrounded supplies).
A ground (earth) fault in the incoming supply has no effect. The drive will continue to run.
However, the phase to phase voltage will appear between two of the supply terminals and
ground (Earth). On a 690 V supply, this will stress the insulation.
A ground (earth) fault in the motor circuit may not cause the drive to trip. If the motor
is required to continue to run with a ground fault in its circuit, then an input isolating
transformer must be provided. If an EMC filter is required, it must be located on the
primary side of the isolating transformer.
The following measures must be taken:
Additional, independent motor ground fault protection must be provided.
EMC filters must not be used
The internal EMC filter inside the drive module must be disconnected
1
.
1. Disconnection of the internal EMC filter on frame size 11E is only possible at the factory. This must be
specified when ordering.
WARNING
WARNING