3.8.6.1 Application
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, 27) 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 (27) is used for signallization only through
an output contact or through the event recording function.
3.8.6.2 Setting guidelines
Loss of voltage check (LOVPTUV, 27) 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.
All settings are in primary values or per unit. Set VBase to rated voltage of the system
or the voltage transformer primary rated voltage. Set operating level per phase VPG to
typically 70% of rated VBase level. Set the time delay tTrip=5-20 seconds.
Advanced users settings
For advanced users the following parameters need also to be set. Set the length of the
trip pulse to typical tPulse=0.15 sec. Set the blocking time tBlock to block Loss of
voltage check (LOVPTUV, 27), if some but not all voltage are low, to typical 5.0
seconds and set the time delay for enabling the function after restoration tRestore to 3 -
40 seconds.
3.8.6.3 Setting parameters
Table 137: LOVPTUV (27) Group settings (basic)
Name
Values (Range) Unit Step Default Description
Operation Disabled
Enabled
- - Disabled Operation Enable/Disable
VBase 0.1 - 9999.9 kV 0.1 400.0 Base voltage
VPG 1 - 100 %VB 1 70 Pickup voltage in % of base voltage Vbase
tTrip 0.000 - 60.000 s 0.001 7.000 Operate time delay
1MRK504116-UUS C Section 3
IED application
541
Application manual
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