ABB REC670 Product Manual page 9

ABB
Bay control REC670
Pre-configured
Product version: 1.1
Two step residual overvoltage protection
ROV2PTOV calculates the residual voltage
from the three-phase voltage input
transformers or from a single-phase voltage
input transformer fed from an open delta or
neutral point voltage transformer.
ROV2PTOV has two voltage steps, each with
inverse or definite time delayed.
Voltage differential protection VDCPTOV
A voltage differential monitoring function is
available. It compares the voltages from two
three phase sets of voltage transformers and
has one sensitive alarm step and one trip
step. It can be used to supervise the voltage
from two fuse groups or two different voltage
transformers fuses as a fuse/MCB supervision
function.
Frequency protection
Underfrequency protection SAPTUF
Underfrequency occurs as a result of lack of
generation in the network.
Underfrequency protection SAPTUF is used
for load shedding systems, remedial action
schemes, gas turbine startup and so on.
SAPTUF is provided with an under voltage
blocking.
The operation may be based on single-phase,
phase-to-phase or positive-sequence voltage
measurement.
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 at sudden load drops
or shunt faults in the power network. Close
to the generating plant, generator governor
problems can also cause over frequency.
SAPTOF is used mainly for generation
shedding and remedial action schemes. It is
also used as a frequency stage initiating load
restoring.
1MRK 511 192-BEN B
SAPTOF is provided with an undervoltage
blocking. The operation is based on single-
phase, phase-to-phase or positive-sequence
voltage measurement.
Rate-of-change frequency protection
SAPFRC
Rate-of-change frequency protection function
(SAPFRC) gives an early indication of a main
disturbance in the system. SAPFRC can be
used for generation shedding, load shedding,
remedial action schemes. SAPFRC can
discriminate between positive or negative
change of frequency.
SAPFRC is provided with an undervoltage
blocking. The operation may be based on
single-phase, phase-to-phase or positive-
sequence voltage measurement.
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.
Secondary system supervision
Current circuit supervision CCSRDIF
Open or short circuited current transformer
cores can cause unwanted operation of many
protection functions such as differential,
earth-fault current and negative-sequence
current functions.
It must be remembered that a blocking of
protection functions at an occurrence of open
Issued: June 2010
9