GE Multilin G60 Generator Protection System 5-2035 SETTINGS 5.6 GROUPED ELEMENTS55.6.9 NEGATIVE SEQUENCE CURRENTa) NEGATIVE SEQUENCE DIRECTIONAL OVERCURRENT (ANSI 67Q, IEC PDEF/PTOC)PATH: SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEGATIVE SEQUENCE CURRENT NEG SEQ DIR OC1(2)There are two negative-sequence directional overcurrent protection elements available. The element provides both forwardand reverse fault direction indications through its output operands NEG SEQ DIR OC1 FWD and NEG SEQ DIR OC1 REV,respectively. The output operand is asserted if the magnitude of the operating current is above a pickup level (overcurrentunit) and the fault direction is seen as forward or reverse, respectively (directional unit).The overcurrent unit of the element essentially responds to the magnitude of a fundamental frequency phasor of either thenegative-sequence or neutral current as per user selection.A positive-sequence restraint is applied for better performance: a small user-programmable portion of the positive-sequence current magnitude is subtracted from the negative or zero-sequence current magnitude, respectively, when form-ing the element operating quantity.(EQ 5.23)The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious negative-sequence andzero-sequence currents resulting from:• System unbalances under heavy load conditions.• Transformation errors of current transformers (CTs).• Fault inception and switch-off transients. NEG SEQ DIR OC1NEG SEQ DIR OC1FUNCTION: DisabledRange: Disabled, EnabledMESSAGE NEG SEQ DIR OC1SOURCE: SRC 1Range: SRC 1, SRC 2, SRC 3, SRC 4MESSAGE NEG SEQ DIR OC1OFFSET: 0.00 ΩRange: 0.00 to 250.00 ohms in steps of 0.01MESSAGE NEG SEQ DIR OC1TYPE: Neg SequenceRange: Neg Sequence, Zero SequenceMESSAGE NEG SEQ DIR OC1 POS-SEQ RESTRAINT: 0.063Range: 0.000 to 0.500 in steps of 0.001MESSAGE NEG SEQ DIR OC1 FWDECA: 75° LagRange: 0 to 90° Lag in steps of 1MESSAGE NEG SEQ DIR OC1 FWDLIMIT ANGLE: 90°Range: 40 to 90° in steps of 1MESSAGE NEG SEQ DIR OC1 FWDPICKUP: 0.050 puRange: 0.015 to 30.000 pu in steps of 0.001MESSAGE NEG SEQ DIR OC1 REVLIMIT ANGLE: 90°Range: 40 to 90° in steps of 1MESSAGE NEG SEQ DIR OC1 REVPICKUP: 0.050 puRange: 0.015 to 30.000 pu in steps of 0.001MESSAGE NEG SEQ DIR OC1 BLK:OffRange: FlexLogic operandMESSAGE NEG SEQ DIR OC1TARGET: Self-resetRange: Self-reset, Latched, DisabledMESSAGE NEG SEQ DIR OC1EVENTS: DisabledRange: Disabled, EnabledI op I_2 K I_1×–= or I op 3 I_0 K I_1×–( )×=
