GE Multilin D30 Line Distance Protection System 5-1735 SETTINGS 5.6 GROUPED ELEMENTS5c) NEGATIVE SEQUENCE INSTANTANEOUS OVERCURRENT (ANSI 50Q, IEC PIOC)PATH: SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEGATIVE SEQUENCE CURRENT NEG SEQ OC1(2)The negative-sequence instantaneous overcurrent element may be used as an instantaneous function with no intentionaldelay or as a definite time function. The element responds to the negative-sequence current fundamental frequency phasormagnitude (calculated from the phase currents) and applies a positive-sequence restraint for better performance: a smallportion (12.5%) of the positive-sequence current magnitude is subtracted from the negative-sequence current magnitudewhen forming the operating quantity:(EQ 5.17)The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious negative-sequence cur-rents resulting from:• system unbalances under heavy load conditions• transformation errors of current transformers (CTs) during three-phase faults• fault inception and switch-off transients during three-phase faultsThe positive-sequence restraint must be considered when testing for pickup accuracy and response time (multiple ofpickup). The operating quantity depends on the way the test currents are injected into the relay (single-phase injection:; three-phase injection, opposite rotation: ).Figure 5–88: NEGATIVE SEQUENCE IOC1 SCHEME LOGIC NEG SEQ IOC1NEG SEQ IOC1FUNCTION: DisabledRange: Disabled, EnabledMESSAGE NEG SEQ IOC1 SIGNALSOURCE: SRC 1Range: SRC 1, SRC 2MESSAGE NEG SEQ IOC1PICKUP: 1.000 puRange: 0.000 to 30.000 pu in steps of 0.001MESSAGE NEG SEQ IOC1 PICKUPDELAY: 0.00 sRange: 0.00 to 600.00 s in steps of 0.01MESSAGE NEG SEQ IOC1 RESETDELAY: 0.00 sRange: 0.00 to 600.00 s in steps of 0.01MESSAGE NEG SEQ IOC1 BLOCK:OffRange: FlexLogic operandMESSAGE NEG SEQ IOC1TARGET: Self-resetRange: Self-reset, Latched, DisabledMESSAGE NEG SEQ IOC1EVENTS: DisabledRange: Disabled, EnabledI op I_2 K I_1 where K⋅– 1 8⁄= =I op 0.2917 I injected⋅= I op I injected=FLEXLOGIC OPERANDSNEG SEQ IOC1 FUNCTION:NEG SEQ IOC1 PICKUP:NEG SEQ IOC1 SOURCE:NEG SEQ IOC1 BLOCK:NEG SEQ IOC1 DPONEG SEQ IOC1 OPNEG SEQ IOC1 PKPRUNAND827058A5.CDRSETTINGSETTINGEnabled=1Disabled=0SETTINGSETTINGI_2Off=0SETTINGNEG SEQ IOC1RESET DELAY:NEG SEQ IOC1PICKUP DELAY:tPKPt RSTI I_2 - K _1 PICKUP
