Frequency Protection; Two Step Overvoltage Protection Ov2Ptov; Two Step Residual Overvoltage Protection Rov2Ptov; Voltage Differential Protection Vdcptov - ABB REC670 Product Manual

Bay control REC670 2.2
Product version: 2.2.1
prepare for system restoration at power outages or as a long-
time delayed back-up to the primary protection.
UV2PTUV has two voltage steps, each with inverse or definite
time delay.
It has a high reset ratio to allow settings close to the system
service voltage.

Two step overvoltage protection OV2PTOV

Overvoltages may occur in the power system during abnormal
conditions such as sudden power loss, tap changer
regulating failures, and open line ends on long lines.
Two step overvoltage protection (OV2PTOV) function can be
used to detect open line ends, normally then 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.
A 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.
ABB

8. 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
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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.
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.
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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.
Rate-of-change of frequency protection SAPFRC
The rate-of-change of frequency protection function
(SAPFRC ) gives an early indication of a main disturbance in
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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
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operation is based on positive sequence voltage
measurement and requires two phase-phase or three phase-
neutral voltages to be connected.
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
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