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Technical description
2 Protection functions
2.15 Undervoltage protection U< (27)
VM259.EN007
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107
Setting groups
There are two settings groups available for all stages.
Switching between setting groups can be controlled by digital
inputs, virtual inputs (mimic display, communication, logic)
and manually.
Parameters of the under voltage stages U<, U<<, U<<< (27)
Parameter
Value
Unit
Description
Note
Status
-
Blocked
Start
Trip
Current status of the stage
F
F
SCntr
Cumulative start counter
C
TCntr
Cumulative trip counter
C
SetGrp
1 or 2
Active setting group
Set
SGrpDI
-
DIx
VIx
LEDx
VOx
Digital signal to select the
active setting group
None
Digital input
Virtual input
LED indicator signal
Virtual output
Set
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.