tTrip: The time delay for tripping is set by this parameter. Normally, the delay does not need to
be so short in capacitor bank applications as there is no fault requiring urgent tripping.
tReset: The time delay for reset of tripping level element is set by this parameter. Normally, it
can be set to a short delay as faults are permanent when they occur.
For the advanced users following parameters are also available for setting. Default values are
here expected to be acceptable.
U1Low: The setting of the undervoltage level for the first voltage input is decided by this
parameter. The proposed default setting is 70%.
U2Low: The setting of the undervoltage level for the second voltage input is decided by this
parameter. The proposed default setting is 70%.
tBlock: The time delay for blocking of the function at detected undervoltages is set by this
parameter.
UDAlarm: The voltage differential level required for alarm is set with this parameter. For
application on capacitor banks the setting will depend of the capacitor bank voltage and the
number of elements per phase in series and parallel. Normally values required are given by
capacitor bank supplier.
For fuse supervision normally only this alarm level is used and a suitable voltage level is 3-5% if
the ratio correction factor has been properly evaluated during commissioning.
For other applications it has to be decided case by case.
tAlarm: The time delay for alarm is set by this parameter. Normally, few seconds delay can be
used on capacitor banks alarm. For fuse failure supervision (SDDRFUF) the alarm delay can be
set to zero.
9.6
Loss of voltage check LOVPTUV
SEMOD171868-1 v2
9.6.1
Identification
SEMOD171954-2 v2
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Loss of voltage check
LOVPTUV
-
27
9.6.2
Application
SEMOD171876-4 v3
The trip of the circuit breaker at a prolonged loss of voltage at all the three phases is normally
used in automatic restoration systems to facilitate the system restoration after a major
blackout. Loss of voltage check (LOVPTUV) generates a TRIP signal only if the voltage in all the
three phases is low for more than the set time. If the trip to the circuit breaker is not required,
LOVPTUV is used for signallization only through an output contact or through the event
recording function.
9.6.3
Setting guidelines
SEMOD171929-4 v5
Loss of voltage check (LOVPTUV) is in principle independent of the protection functions. It
requires to be set to open the circuit breaker in order to allow a simple system restoration
following a main voltage loss of a big part of the network and only when the voltage is lost
with breakers still closed.
1MRK 505 343-UEN B
Section 9
Voltage protection
485
Application manual
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