ABB 615 Series ANSI, Техническое руководство

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Section 6
1MAC050144-MB C
Supervision functions
472 615 series ANSI
Technical Manual
Figure 252: Functional module diagram.
SCFD analysis
The SCFD (Self Clearing Fault Detection) Analysis module detects the self clearing fault
in each phase by comparing the corresponding phase current magnitude with the set value
PhPu .
If the phase current I_A magnitude goes above 2 times the set value PhPu , the module
calculates the time duration for which the current I_A is continuously stays above 2 times
the set value
PhPu. If the calculated time duration is greater than ¼ cycles, and less than
the number of cycles set by CyMulit , it regards that the self clearing fault is observed in
phase A and DetectfaultPhA in monitored data is set to TRUE. If the time duration
criterion fails, the PickUpNoTripA in monitored data is set to TRUE. Once the self
clearing fault is detected in phase A, function increments the count SCA in monitored data,
which keeps record of the number of times the fault has been detected.
Self clearing faults in phase B and phase C are detected similarly as explained for phase A
in above paragraph, by comparing I_B and I_C magnitudes with the set value
PhPu and
by checking the time duration. If the fault is detected in phase B or phase C the
DetectfaultPhB or respectively DetectfaultPhC in monitored data are set to TRUE. If the
time duration criterion fails for phase B or phase C, the corresponding PickUpNoTripB or
PickUpNoTripC in monitored data is set to TRUE. Once the fault is detected in phase B
or phase C, the corresponding fault counts SCB or SCC is incremented.
If the setting AdapPhPu is set to TRUE, the threshold setting value PhPu is adaptively
calculated for each phase separately. The adaptive threshold value set equal to the average
of the phase current over the 2
nd
and 3
rd
cycle after the setting AdapPhPu is set to TRUE.
Until the 3
rd
cycle the set value PhPu is used for detecting the self clearing fault. After the
3
rd
cycle adaptively calculated threshold value for each phase is used for detecting the self
clearing fault.
This adaptive threshold implementation for each phase is considered only if the average of
the phase current over the 2
nd
and 3
rd
cycle is greater than setting AbsMinLoad. Otherwise
the set value PhPu is considered for corresponding phase fault detection.
I_A
BLOCK
SCFD
analysis
TRIP
PICKUP
SCFD
decision
I_B
I_C