ABB Relion 670 Series Applications Manual page 235

1MRK 511 401-UUS F
9.5.2 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.
9.5.3 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 operate level per phase to typically 70% of the
global parameter
9.5.3.1 Advanced users settings
For advanced users the following parameters need also to be set. Set the length of the trip pulse
to typical
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
Bay control REC670
Application manual
VBase level. Set the time delay tTrip =5-20 seconds.
tPulse =0.15 sec. Set the blocking time tBlock to block Loss of voltage check (LOVPTUV,
tRestore to 3 - 40 seconds.
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Section 9
Voltage protection
SEMOD171876-4 v3
SEMOD171929-4 v5
SEMOD171929-8 v4
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