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2.7 Undervoltage protection U< (27)
2 Protection functions
Technical description
62
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VM55.EN005
Parameter
Value
Unit
Description
Note
Force
Off
On
Force flag for status forcing for
test purposes. This is a
common flag for all stages and
output relays, too.
Automatically reset by a 5-
minute timeout.
Set
MinU
V
The supervised minimum of
line-to-line voltages in primary
volts
U<, U<<,
U<<<
V
Pick-up value scaled to
primary value
U<, U<<,
U<<<
%Un
Pick-up setting
Set
t<, t<<,
t<<<
S
Definite operation time
Set
LVBlk
%Un
Low limit for self blocking
Set
RlsDly
S
Release delay (U< stage only)
Set
Hyster
Default
3.0 %
%
Dead band setting
Set
For details of setting ranges see chapter 9.3.
Set = An editable parameter (password needed)
C = Can be cleared to zero
F = Editable when force flag is on
Recorded values of the latest eight faults
There are detailed information available of the eight latest
faults for each of the stages: Time stamp, fault voltage, elapsed
delay, voltage before the fault and setting group.
Recorded values of the undervoltage stages (8 latest faults)
U<, U<<, U<<< (27):
Parameter
Value
Unit Description
yyyy-mm-dd
Time stamp of the recording, date
hh:mm:ss.ms
Time stamp, time of day
Flt
%Un Minimum fault voltage
EDly
%
Elapsed time of the operating time
setting. 100% = trip
PreFlt
%Un Supervised value before fault, 1 s
average value.
SetGrp
1
2
Active setting group during fault