ABB REL650 Product Manual page 18

Line distance protection REL650 2.2
Product version: 2.2.1
Normally the own breaker is tripped to correct such a
situation. If the situation persists the surrounding breakers
should be tripped to clear the unsymmetrical load situation.
The Pole discordance protection function (CCPDSC) operates
based on information from auxiliary contacts of the circuit
breaker for the three phases with additional criteria from
unsymmetrical phase currents when required.
Voltage-restrained time overcurrent protection VRPVOC
Voltage-restrained time overcurrent protection (VRPVOC)
function can be used as generator backup protection against
short-circuits.
The overcurrent protection feature has a settable current level
that can be used either with definite time or inverse time
characteristic. Additionally, it can be voltage controlled/
restrained.
One undervoltage step with definite time characteristic is also
available within the function in order to provide functionality
for overcurrent protection with undervoltage seal-in.
5. Voltage protection
Two-step undervoltage protection UV2PTUV
Undervoltages can occur in the power system during faults or
abnormal conditions. The two-step undervoltage protection
function (UV2PTUV) can be used to open circuit breakers to
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.
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GUID-935E1CE8-601F-40E2-8D22-2FF68420FADF v6
M13789-3 v12
M13798-3 v15
M13808-3 v11
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.
6. 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.
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.
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
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.
1MRK 506 384-BEN A
M13349-3 v13
M14953-3 v12
M14965-3 v13
ABB