ABB Relion 670 Series Product Manual page 18

Busbar protection REB670
Customized
Product version: 1.2
Capacitor bank protection (CBPGAPC)
Shunt Capacitor Banks (SCB) are used in a power system to
provide reactive power compensation and power factor
correction. They are as well used as integral parts of Static
Var Compensators (SVC) or Harmonic Filters installations.
Capacitor bank protection (CBPGAPC) function is specially
designed to provide protection and supervision features for
SCBs.
6. Voltage protection
Two step undervoltage protection UV2PTUV
Undervoltages can occur in the power system during faults or
abnormal conditions. Two step undervoltage protection
(UV2PTUV) function can be used to open circuit breakers to
prepare for system restoration at power outages or as long-
time delayed back-up to primary protection.
UV2PTUV has two voltage steps, each with inverse or definite
time delay.
Two step overvoltage protection OV2PTOV
Overvoltages may occur in the power system during abnormal
conditions such as sudden power loss, tap changer
regulating failures, open line ends on long lines etc.
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 an extremely 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.
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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.
7. 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-
1MRK505273-BEN D
ABB