GE F60 Instruction Manual page 474

MONITORING ELEMENTS
5.9.0.7 Incipient fault detector
SETTINGS  CONTROL ELEMENTS  MONITORING ELEMENTS  INCIPIENT FAULT 1(2)
 INCIPIENT FAULT 1

5
There are two incipient cable fault detection elements in the relay.
Before a permanent cable fault occurs, there are usually signs of degrading insulation manifesting itself as a short, mostly
half-cycle spikes asserting at the phase voltage peak. Due to shortness of such spikes, they are not usually detected by the
instantaneous protection of the feeder, which operates on the RMS or fundamental component of the phase current with a
relatively high pickup.
The number of detected incipient faults in each phase is counted and available in the
menus. The counters can be reset with the
INCIPIENT FAULT
command.
COUNTERS
Changes to any of the incipient cable fault detector settings resets of the number of the incipient faults detected to
zero.
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 incipient
fault pattern is confirmed and therefore detected.
The 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.
5-300
INCIPIENT FAULT 1

FUNCTION: Disabled
INCIPNT FLT 1 BLOCK:

Off
INCIPIENT FAULT 1

SOURCE: SRC 1
INCIPIENT FAULT 1

PICKUP: 0.50 pu
INCIPNT FLT 1 MODE:

Number of counts
INCIPIENT FLT 1 TRIP

COUNTS NUMBER: 2
INCIPNT FLT 1 DETECT

WINDOW: 10.00 s
INCIPIENT FAULT 1

RESET DELAY: 0.100 s
INCIPIENT FAULT 1

TARGET: Self-reset
INCIPIENT FAULT 1

EVENTS: Disabled
COMMANDS  CLEAR RECORDS  CLEAR INCIPENT FAULT
Range: Disabled, Enabled
Range: FlexLogic operand
Range: SRC 1, SRC 2, SRC 3, SRC 4
Range: 0.10 to 10.00 pu in steps of 0.01
Range: Number of counts, Counts per window
Range: 1 to 10 in steps of 1
Range: 0.00 to 1000.00 s in steps of 0.01
Range: 0.000 to 65.535 s in steps of 0.001
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
ACTUAL VALUES  STATUS 
F60 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS