5-180 L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS55.6.3.5 Rate of change of negative-sequence current fault detectionSETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) PHASE COMPARISON ELEMENTS ADVANCED FAULTDETECTORS RATE OF CHANGE OF NEG SEQ CURRENTThe element responds to the vector difference of the negative-sequence current phasors taken at the present momentand one-half a power system cycle earlier. Two current thresholds are provided for the low-set and high-set operationcontrolling keying and tripping. The raw di / dt condition of the element detects the change and resets when reaching asteady state fault condition. As such, a seal-in timer is provided to maintain the detected fault condition for a userspecified period of time.NEG SEQ di/dt FD FUNCTION — This setting enables or disables the rate of change of negative-sequence current faultdetection. Note that all fault detectors operate in parallel toward the 87PC function. If not required, disable a given faultdetector. To effectively disable the overcurrent fault detectors under the main 87PC menu, set their threshold very high.NEG SEQ di/dt FDL PICKUP — This setting controls pickup of the low set stage of the element used to control the keyoperation. 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 allterminals 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 tripoperation. 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 allterminals of the line, the timer is started at the rising edge of the raw di / dt condition. In this way, the fault detectors resetapproximately at the same time at all line terminals, regardless of responses of individual raw conditions potentiallydifferent at different line terminals.NEG SEQ FDH SUPV — This setting provides seal-in control of the FDH function for the symmetrical external three-phasefaults starting as non-symmetrical defined by the NEG SEQ di/dt FDH SEAL-IN setting time. The overreaching distancefunction typically is 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 usingthe function setting or blocked temporarily using this block setting. Select a FlexLogic operand that, if asserted, blocks thisfault detector.NEG SEQ di/dt FD TARGET — This setting controls targets of the function. These targets operate independently from the 87PCtargets.NEG SEQ di/dt FD EVENTS — This setting controls event recording of the function. These events are logged independentlyfrom the 87PC events. RATE OF CHANGE OF NEG SEQ CURRENT NEG SEQ di/dt FDFUNCTION: DisabledRange: Disabled, Enabled NEG SEQ di/dt FDLPICKUP: 0.10 puRange: 0.01 to 5.00 pu in steps of 0.01 NEG SEQ di/dt FDLSEAL-IN: 0.600 sRange: 0.000 to 10.000 s in steps of 0.001 NEG SEQ di/dt FDHPICKUP: 0.50 puRange: 0.01 to 5.00 pu in steps of 0.01 NEG SEQ di/dt FDHSEAL-IN: 0.200 sRange: 0.000 to 10.000 s in steps of 0.001 NEG SEQ FDH SUPV:OffRange: any FlexLogic operand NEG SEQ di/dt BLK:OffRange: any FlexLogic operand NEG SEQ di/dt FDTARGET: Self-resetRange: Self-Reset, Latched, Disabled NEG SEQ di/dt FDEVENTS: DisabledRange: Disabled, Enabled
