ABB Relion 670 Series Product Manual page 31

Line differential protection RED670 2.0
Product version: 2.0
Radial feeder protection PAPGAPC
The PAPGAPC function is used to provide protection of radial
feeders having passive loads or weak end in-feed sources. It is
possible to achieve fast tripping using communication system
with remote end or delayed tripping not requiring
communication or upon communication system failure. For fast
tripping, scheme communication is required. Delayed tripping
does not require scheme communication.
The PAPGAPC function performs phase selection using
measured voltages. Each phase voltage is compared to the
opposite phase-phase voltage. A phase is deemed to have a
fault if its phase voltage drops below a settable percentage of
the opposite phase-phase voltage. The phase - phase voltages
include memory. This memory function has a settable time
constant.
The voltage-based phase selection is used for both fast and
delayed tripping. To achieve fast tripping, scheme
communication is required. Delayed tripping does not require
scheme communication. It is possible to permit delayed
tripping only upon failure of the communications channel by
blocking the delayed tripping logic with a communications
channel healthy input signal.
On receipt of the communications signal, phase selective
outputs for fast tripping are set based on the phase(s) in which
the phase selection function has operated.
For delayed tripping, single pole and three pole delays are
separately and independently settable. Furthermore, it is
possible to enable or disable single pole and three pole delayed
tripping. For single phase faults, it is possible to include a
residual current check in the tripping logic. Three pole tripping
is always selected for phase selection on more than one phase.
Three pole tripping will also occur if the residual current
exceeds the set level during fuse failure for a time longer than
the three pole trip delay time.
7. Frequency protection
Underfrequency protection SAPTUF
Underfrequency occurs as a result of a lack of generation in the
network.
Underfrequency protection SAPTUF measures frequency with
high accuracy, and is used for load shedding systems, remedial
action schemes, gas turbine startup and so on. Separate
definite time delays are provided for operate and restore.
SAPTUF is provided with undervoltage blocking.
The operation is based on positive sequence voltage
measurement and requires two phase-phase or three phase-
neutral voltages to be connected. For information about how to
connect analog inputs, refer to Application manual/IED
application/Analog inputs/Setting guidelines
ABB
Overfrequency protection SAPTOF
Overfrequency protection function SAPTOF is applicable in all
situations, where reliable detection of high fundamental power
system frequency is needed.
Overfrequency occurs because of sudden load drops or shunt
faults in the power network. Close to the generating plant,
generator governor problems can also cause over frequency.
SAPTOF measures frequency with high accuracy, and is used
mainly for generation shedding and remedial action schemes. It
is also used as a frequency stage initiating load restoring. A
definite time delay is provided for operate.
SAPTOF is provided with an undervoltage blocking.
The operation is based on positive sequence voltage
measurement and requires two phase-phase or three phase-
neutral voltages to be connected. For information about how to
connect analog inputs, refer to Application manual/IED
application/Analog inputs/Setting guidelines
Rate-of-change frequency protection SAPFRC
The rate-of-change frequency protection function SAPFRC
gives an early indication of a main disturbance in the system.
SAPFRC measures frequency with high accuracy, and can be
used for generation shedding, load shedding and remedial
action schemes. SAPFRC can discriminate between a positive
or negative change of frequency. A definite time delay is
provided for operate.
SAPFRC is provided with an undervoltage blocking. The
operation is based on positive sequence voltage measurement
and requires two phase-phase or three phase-neutral voltages
to be connected. For information about how to connect analog
inputs, refer to Application manual/IED application/Analog
inputs/Setting guidelines.
8. Multipurpose protection
General current and voltage protection CVGAPC
The General current and voltage protection (CVGAPC) can be
utilized as a negative sequence current protection detecting
unsymmetrical conditions such as open phase or
unsymmetrical faults.
CVGAPC can also be used to improve phase selection for high
resistive earth faults, outside the distance protection reach, for
the transmission line. Three functions are used, which
measures the neutral current and each of the three phase
voltages. This will give an independence from load currents and
this phase selection will be used in conjunction with the
detection of the earth fault from the directional earth fault
protection function.
1MRK505310-BEN C
31