ABB RELION REX640 Technical Manual page 1417

1MRS759142 F
excitation faults) to protect the system. The logic for the same has been shown in
Table 1347
Table 1347: Criteria for activation of STOP_ENGINE output
Fault type
Over fueling fault
Under fueling fault (MAX (P1 ... P8) >
Table 1348: Criteria for activation of DE_EXCITE output
Fault type
Over excitation
fault
Under excitation
fault
The activation of STOP_ENGINE or DE_EXCITE outputs, activates the PRE_TRIP
output and initiates the operate delay timer. The timer characteristic is based on DT.
Once the time set by
REX640
Technical Manual
Table 1348
and .
The over/under fueling and over/under excitation logic will be checked
only if the local active and reactive power are above 2% of nominal value
respectively. When the local active and reactive power are less than 2%,
the OPERATE output is issued instantaneously.
Criteria
MIN (P1 ... P8) <
That is, One among the network generators (ex-
cluding the local generator) enter reverse power
OR
Max Freq limit + Max Freq deviation
F >
That is, One among the network generators enter
over power region
OR
Min Freq limit – Max Freq deviation )
F <
AND
P < 0.0
That is, local generator enters reverse power zone.
Criteria
MIN(Q1 ... Q8) <
OR
Max voltage limit + Max Volts deviation
Uavg >
Min voltage limit – Max Volts deviation
(Uavg <
OR
I_MAX > 100% of nominal value
I_MAX = Maximum of the three phase currents ob-
tained from input I3P)
AND
Q < 0.0
That is, local generator enters reverse reactive pow-
er zone.
Operate delay time elapses or when active power (for fueling
Condition monitoring functions
Min active power
Max active power
Min reactive power
Output
STOP_ENGINE
Output
DE_EXCITE
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