Monitored Data - ABB RES670 Technical Manual

1MRK 511 408-UUS A
10.4.6
10.4.7
Phasor measurement unit RES670 2.2 ANSI
Technical manual

Monitored data

Table 181: FTAQFVR (81A) Monitored data
Name Type
FREQ REAL
ACCTIME REAL
Operation principle
Frequency time accumulation protection function FTAQFVR (81A) is used to protect
the turbine against an abnormal frequency operation. During the startup and shutdown
of the turbine-generator set, FTAQFVR (81A) is blocked to avoid unnecessary
accumulation of time or tripping of generator. FTAQFVR (81A) is also blocked when
the system positive-sequence voltage magnitude deviates from the given voltage band
limit, which can be enabled with the EnaVoltCheck setting. The overall logic of
FTAQFVR (81A) is explained in Figure112.
The frequency of the measured input voltage is monitored continuously and compared
to the set frequency band limits FreqHighLimit and FreqLowLimit. When the measured
system frequency is above the FreqLowLimit setting and below the FreqHighLimit
setting, the FREQOK and PICKUP signals are activated. The BFI_3P signal is
controlled by the measured current and voltage input magnitude and the status of the
circuit breaker position.
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
PickupCurrentLevel and CBOPEN input is high. FTAQFVR (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 CBCheck setting.
• When the positive-sequence voltage of the measured input voltage is outside the
band limit.
The BFI_3P output will be blocked if the EnaVoltCheck setting is enabled and the
system positive sequence voltage is not within the voltage band limits.
Values (Range) Unit
- Hz
- s
Section 10
Frequency protection
PID-6515-MONITOREDDATA v4
Description
Measured frequency value
Accumulated time for
frequency band limits
GUID-DB8A3411-2FA6-47B1-BC75-9892BD224DC0 v4
321