GE F60 Instruction Manual page 386

5.7 CONTROL ELEMENTS
The number of detected incipient faults in each phase is counted and available in the
menus. The counters can be reset with the
ENT FAULT
command.
TERS
Changes to any of the incipient cable fault detector settings resets of the number of the incipient faults detected to
zero.
NOTE
To provide a clear timing indication when the incipient fault occurred, the incipient fault event is time-stamped with
the time the fault actually occurred. However, the FlexLogic™ operand is asserted four cycles later, when the incip-
ient fault pattern is confirmed and therefore detected.
NOTE
The following figure illustrates a recorded field case of an incipient phase B fault. The top portion of the figure shows the
raw A, B and C currents. The bottom portion shows the neutral current (blue) and reveals the fault period from under the
load and the superimposed phase B current (red). The superimposed current shows two fault current blips as the data
slides through the two-cycle memory window. During the actual fault, the neutral current and the superimposed phase B
currents closely correspond, confirming the incipient fault hypothesis and identifying the affected phase.
2.0
1.0
0
5
–0.5
0.62
2.0
1.0
0
–1.0
–2.0
0.62
Figure 5–126: ILLUSTRATION OF THE INCIPIENT FAULT DETECTOR ALGORITHM
The following settings are available for each incipient cable fault detector.
• INCIPIENT FAULT 1 FUNCTION: This setting enable and disables operation of the incipient fault detection element.
• INCIPNT FLT 1 BLOCK: This setting is used to block operation of the incipient cable fault detector element. Assertion
of the FlexLogic™ operand assigned to this setting block operation.
• INCIPIENT FAULT 1 SOURCE: This setting selects a current source for the incipient cable fault detector element. This
source must be assigned a valid CT bank.
• INCIPIENT FAULT 1 PICKUP: This setting specifies pickup level of the overcurrent detector in per-unit values of the
CT nominal current.
• INCIPNT FLT 1 MODE: There are two modes of operation available for the incipient cable fault detector element. In
the "Number of counts" mode, a trip will be initiated only after the selected number of faults is detected. In the "Counts
per window" mode, a trip will be initiated only after the selected number of faults is detected within the time specified by
the
INCIPNT FLT 1 DETECT WINDOW
• INCIPIENT FLT 1 TRIP COUNTS NUMBER: This setting selects the number of faults required to initiate a trip.
• INCIPNT FLT 1 DETECT WINDOW: This setting specifies a time window for "Counts per window" mode of operation.
5-254
COMMANDS
Incipient phase B fault
0.64 0.66 0.68
I
(neutral current)
N
0.64 0.66 0.68
setting.
F60 Feeder Protection System
ACTUAL VALUES
 
CLEAR RECORDS
PHASE CURRENTS
0.70 0.72
CALCULATED NEUTRAL AND
SUPERIMPOSED PHASE B CURRENT
I
FB
0.7 0.72
5 SETTINGS
 
STATUS INCIPI-
CLEAR INCIPENT FAULT COUN-
Phase C
Phase A
Phase B
0.74
0.74
832774A1.CDR
GE Multilin