ABB Relion 670 series REC670, Руководство по эксплуатации продукта

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Two step residual overvoltage protection ROV2PTOV
Residual voltages may occur in the power system during
earth faults.
Two step residual overvoltage protection ROV2PTOV function
calculates the residual voltage from the three-phase voltage
input transformers or measures it from a single voltage input
transformer fed from an open delta or neutral point voltage
transformer.
ROV2PTOV has two voltage steps, each with inverse or
definite time delay.
Reset delay ensures operation for intermittent earth faults.
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.
Loss of voltage check LOVPTUV
Loss of voltage check (LOVPTUV) is suitable for use in
networks with an automatic system restoration function.
LOVPTUV issues a three-pole trip command to the circuit
breaker, if all three phase voltages fall below the set value for
a time longer than the set time and the circuit breaker
remains closed.
6. Frequency protection
Underfrequency protection SAPTUF
Underfrequency occurs as a result of a 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 also 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
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 is used mainly for generation shedding and remedial
action schemes. It is also used as a frequency stage initiating
load restoring.
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
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
and remedial action schemes. SAPFRC can discriminate
between positive or negative change of frequency.
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.
7. 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.
8. 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 CT circuit will mean that
the situation will remain and extremely high voltages will
stress the secondary circuit.
Current circuit supervision (CCSRDIF) compares the residual
current from a three phase set of current transformer cores
Bay control REC670 1MRK511232-BEN E
Pre-configured
Product version: 1.2
12 ABB