16.8.3 Low active power and power factor protection LAPPGAPC
(37_55)
16.8.3.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Low active power and power factor
protection
LAPPGAPC
- 37_55
16.8.3.2 Application
Low active power and power factor protection (LAPPGAPC, 37_55) is one of the local
criteria to be checked in direct transfer trip (DTT) scheme. In LAPPGAPC (37_55), active
power and power factor are calculated from the voltage and current values at this end. On
detection of low active power or low power factor condition, the trip output will be set. All
the calculation and comparison are done per phase.
If there is a fault and the remote end circuit breaker is tripped, a carrier signal is sent to the
local end and the active power in respective phases will decrease. Hence, detection of low
active power in at least one of the phases would be one of the factors to ascertain the fault
at other end.
The function has two modes, '1 out of 3' and '2 out of 3'. '1 out of 3' mode ensures that there
is low active power in at least one of the three phases, while the '2 out of 3' mode the low
power is ensured in at least two phases simultaneously before sending the trip signal.
Line which is tripped at the remote end will have low active power flowing through it
which also results in low power factor in the respective phase. A low power factor criterion
could also be an added check of the local criterion in DTT. In this function phase wise
power factor is calculated, and a comparison is made for the low power factor condition
to give phase segregated start and trip.
16.8.3.3 Setting guidelines
GlobalBaseSel: Selects the global base value group used by the function to define IBase,
VBase and SBase as applicable.
OperationLAP: Used to set the low power function Enabled or Disabled.
OpModeSel: Can be set 2 out of 3 or 1 out of 3. If 1 out of 3 is set, the function will send
TRIP signal if one or more phases have low power. If 2 out of 3 is set, the function will send
1MRK 506 369-UUS - Section 16
Scheme communication
Line distance protection REL670 2.2 ANSI 777
Application manual
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