Voltage band limit check will be ignored for the
START
output if the
EnaVoltCheck
setting is disabled. The voltage band limits are set with the settings
UHighLimit
and
ULowLimit
.
The output
VOLTOK
is activated only if the system positive-sequence voltage
falls within the voltage band limits and the
EnaVoltCheck
setting is enabled.
To avoid oscillations of the
START
output signal, a hysteresis has been added with
current input comparison and voltage input comparison. It is also possible to block
FTAQFVR completely by activating the binary input
BLOCK
and its function is to
reset all the binary outputs of FTAQFVR and freeze the accumulation time.
Time counters
FTAQFVR uses two time counters.
1. Individual event time: The individual event time counter registers the time
passing if the system frequency falls within the frequency band limits each time.
It resets when the frequency comes out of the frequency band limits and also
when the
BLOCK
binary input is activated and start from zero when a new start is
activated.
2. Accumulation time: The accumulation time counter registers the time passing
whenever the
START
output is activated. It holds the registered time value even
when the
START
signal is deactivated and continues from the registered value
when the
START
signal is reactivated.
The registration of accumulation time is frozen at its present value when the input
HOLDACC
or
BLOCK
is activated. The accumulation time can be set to the
initTimeAcc
parameter value by activating the
LOADINT
input with the LHMI and it
can be reset to zero by activating the
RESETACC
input. The
RESETACC
input can be
activated by a binary input. The accumulated time
ACCTIME
is provided as a service
output.
The last completed individual event time is updated in the
LASTEVTD
output. This
output holds the last completed individual event time until the next event to complete.
Trip logic
The individual event and accumulation timer values are compared to the
tCont
and
tAcclLimit
settings respectively. If these counter values exceed their limit values,
TRIPCONT
and
ACCALARM
outputs will be activated. The
TRIPACC
output is
activated if both the
ACCALARM
and
START
signals are activated. A common
TRIP
signal is generated when either
TRIPCONT
or
TRIPACC
is activated.
1MRK502052-UEN B
Section 10
Frequency protection
561
Technical manual
Summary of Contents for Relion REG670
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