ABB RELION 670 Series Technical Manual page 689

1MRK 502 066-UUS B
FTAQFVR (81A) function will block BFI_3P signal activation and Accumulation of time under two
following conditions even if the system frequency falls within set band limits.
• When the generator is not synchronized as indicated by the CBOPEN signal input: Generator
currents are considered to detect whether the generator is supplying its unit auxiliary supply
transformers or not. FTAQFVR (81A) function will be blocked when the measured current
magnitude drops below the setting
(81A) remains blocked until the generator returns to the operation condition. It can be verified
by using the CBCLOSE signal. Generator's start and stop detection logics for the BFI_3P
output can be ignored by disabling the
• When the positive-sequence voltage of the measured input voltage is outside the band limit.
The BFI_3P output will be blocked if the
positive sequence voltage is not within the voltage band limits.
Voltage band limit check will be ignored for the BFI_3P output if the
disabled. The voltage band limits are set with the settings
The output VOLTOK is activated only if the system positive-sequence voltage falls within the
voltage band limits and the
To avoid oscillations of the BFI_3P output signal, a hysteresis has been added with current input
comparison and voltage input comparison. It is also possible to block FTAQFVR (81A) completely
by activating the binary input BLOCK and its function is to reset all the binary outputs of FTAQFVR
(81A) and freeze the accumulation time.
Time counters
FTAQFVR (81A) 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
BFI_3P output is activated. It holds the registered time value even when the BFI_3P signal is
deactivated and continues from the registered value when the BFI_3P 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
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
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 BFI_3P
signals are activated. A common TRIP signal is generated when either TRIPCONT or TRIPACC is
activated.
Technical manual
PickupCurrentLevel and CBOPEN input is high. FTAQFVR
CBCheck setting.
EnaVoltCheck setting is enabled and the system
EnaVoltCheck setting is enabled.
Frequency protection
EnaVoltCheck setting is
VHighLimit and VLowLimit .
initTimeAcc parameter value by
tCont and tAcclLimit
Section 10
683