ABB RELION 670 Series Product Manual page 26

Bay control REC670 2.1 IEC
combined with a directional reactive over-power
function to supervise the system voltage. When
triggered, the function will cause an alarm, switch in
reactors, or switch out capacitor banks.
OV2PTOV has two voltage steps, each of them with
inverse or definite time delayed.
OV2PTOV has a high reset ratio to allow settings close
to system service voltage.
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. Alternatively, it can be used as voltage
differential protection (VDCPTOV) for shunt capacitor
banks.
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.
The operation of LOVPTUV is supervised by the fuse
failure supervision FUFSPVC.
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.
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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
Overfrequency protection SAPTOF
Overfrequency protection function SAPTOF is applicable
in all situations, where reliable detection of high
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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
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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
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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.
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Frequency time accumulation protection FTAQFVR
Frequency time accumulation protection FTAQFVR is
based on measured system frequency and time
counters. FTAQFVR for generator protection provides
the START output for a particular settable frequency
limit, when the system frequency falls in that settable
frequency band limit and positive sequence voltage
within settable voltage band limit. The START signal
1MRK 511 361-BEN D
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GUID-020CE8CF-9BEA-455D-ACBD-13023B93B4D1 v4
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