GE L60 Instruction Manual page 277

5 SETTINGS
e) RATE OF CHANGE OF NEGATIVE-SEQUENCE CURRENT FAULT DETECTION

PATH: SETTINGS GROUPED...
 RATE OF CHANGE OF
 NEG SEQ CURRENT
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The element responds to the vector difference of the negative-sequence current phasors taken at the present moment and
one-half a power system cycle earlier. Two current thresholds are provided for the low-set and high-set operation control-
ling keying and tripping. The raw di / dt condition of the element detects the change and resets when reaching a steady
state fault condition. As such, a seal-in timer is provided to maintain the detected fault condition for a user specified period
of time.
• NEG SEQ di/dt FD FUNCTION: This setting enables or disables the rate of change of negative-sequence current fault
detection. Note that all fault detectors operate in parallel toward the 87PC function. If not required, a given fault detec-
tor shall be disabled. To effectively disable the overcurrent fault detectors under the main 87PC menu, set their thresh-
old very high.
• NEG SEQ di/dt FDL PICKUP: This setting controls pickup of the low set stage of the element used to control the key
operation. The nominal current of the phase CT bank of the relay is 1 pu.
• NEG SEQ di/dt FDL SEAL-IN: This setting defines seal-in time of the FDL function. To equalize the response between
all terminals of the line, the timer is started at the rising edge of the raw di / dt condition.
• NEG SEQ di/dt FDH PICKUP: This setting controls pickup of the high set stage of the element used to control the trip
operation. The nominal current of the phase CT bank of the relay is 1 pu.
• NEG SEQ di/dt FDH SEAL-IN: This setting defines seal-in time of the FDH function. To equalize the response
between all terminals of the line, the timer is started at the rising edge of the raw di / dt condition. In this way, the fault
detectors reset approximately at the same time at all line terminals, regardless of responses of individual raw condi-
tions potentially different at different line terminals.
• NEG SEQ FDH SUPV: This setting provides seal-in control of the FDH function for the symmetrical external three-
phase faults starting as non-symmetrical defined by the
tance function should typically be assigned with this setting.
• NEG SEQ di/dt BLK: Note that the fault detector is hard-wired to the 87PC scheme. It can be disabled permanently
using the function setting or blocked temporarily using this block setting. Select a FlexLogic operand that, if asserted,
should block this fault detector.
• NEG SEQ di/dt FD TARGET: This setting controls targets of the function. These targets operate independently from
the 87PC targets.
GE Multilin
 
PHASE COMPARISON... ADVANCED FAULT...
NEG SEQ di/dt FD
FUNCTION: Disabled
NEG SEQ di/dt FDL
PICKUP: 0.10 pu
NEG SEQ di/dt FDL
SEAL-IN: 0.600 s
NEG SEQ di/dt FDH
PICKUP: 0.50 pu
NEG SEQ di/dt FDH
SEAL-IN: 0.200 s
NEG SEQ FDH SUPV:
Off
NEG SEQ di/dt BLK:
Off
NEG SEQ di/dt FD
TARGET: Self-reset
NEG SEQ di/dt FD
EVENTS: Disabled
NEG SEQ DI/DT FDH SEAL-IN
L60 Line Phase Comparison System
5.5 GROUPED ELEMENTS
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RATE OF CHANGE OF NEG SEQ CURRENT
Range: Disabled, Enabled
Range: 0.01 to 5.00 pu in steps of 0.01
Range: 0.000 to 10.000 s in steps of 0.001
Range: 0.01 to 5.00 pu in steps of 0.01
Range: 0.000 to 10.000 s in steps of 0.001
Range: any FlexLogic operand
Range: any FlexLogic operand
Range: Self-Reset, Latched, Disabled
Range: Disabled, Enabled
setting time. The overreaching dis-
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