5-126 D30 Line Distance Relay GE Multilin5.5 GROUPED ELEMENTS 5 SETTINGS5d) NEUTRAL DIRECTIONAL OVERCURRENT (ANSI 67N)PATH: SETTINGS ÖØ GROUPED ELEMENTS Ö SETTING GROUP 1(6) Ö NEUTRAL CURRENT ÖØ NEUTRAL DIRECTIONALOC1(2)There are two Neutral Directional Overcurrent protection elements available. The element provides both forward andreverse fault direction indications the NEUTRAL DIR OC1 FWD and NEUTRAL DIR OC1 REV operands, respectively. The out-put operand is asserted if the magnitude of the operating current is above a pickup level (overcurrent unit) and the faultdirection is seen as “forward or “reverse”, respectively (directional unit).The overcurrent unit responds to the magnitude of a fundamental frequency phasor of the either the neutral current calcu-lated from the phase currents or the ground current. There are two separate pickup settings for the forward- and reverse-looking functions, respectively. If set to use the calculated 3I_0, the element applies a “positive-sequence restraint” for bet-ter performance: a small user-programmable portion of the positive–sequence current magnitude is subtracted from thezero-sequence current magnitude when forming the operating quantity.(EQ 5.16)The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious zero-sequence currentsresulting from:• System unbalances under heavy load conditions. NEUTRAL DIRECTIONAL OC1NEUTRAL DIR OC1FUNCTION: DisabledRange: Disabled, EnabledMESSAGE NEUTRAL DIR OC1SOURCE: SRC 1Range: SRC 1, SRC 2MESSAGE NEUTRAL DIR OC1POLARIZING: VoltageRange: Voltage, Current, DualMESSAGE NEUTRAL DIR OC1 POLVOLT: Calculated V0Range: Calculated V0, Measured VXMESSAGE NEUTRAL DIR OC1 OPCURR: Calculated 3I0Range: Calculated 3I0, Measured IGMESSAGE NEUTRAL DIR OC1 POS-SEQ RESTRAINT: 0.063Range: 0.000 to 0.500 in steps of 0.001MESSAGE NEUTRAL DIR OC1OFFSET: 0.00 ΩRange: 0.00 to 250.00 Ω in steps of 0.01MESSAGE NEUTRAL DIR OC1 FWDECA: 75° LagRange: –90 to 90° in steps of 1MESSAGE NEUTRAL DIR OC1 FWDLIMIT ANGLE: 90°Range: 40 to 90° in steps of 1MESSAGE NEUTRAL DIR OC1 FWDPICKUP: 0.050 puRange: 0.002 to 30.000 pu in steps of 0.001MESSAGE NEUTRAL DIR OC1 REVLIMIT ANGLE: 90°Range: 40 to 90° in steps of 1MESSAGE NEUTRAL DIR OC1 REVPICKUP: 0.050 puRange: 0.002 to 30.000 pu in steps of 0.001MESSAGE NEUTRAL DIR OC1 BLK:OffRange: FlexLogic™ operandMESSAGE NEUTRAL DIR OC1TARGET: Self-resetRange: Self-reset, Latched, DisabledMESSAGE NEUTRAL DIR OC1EVENTS: DisabledRange: Disabled, EnabledI op 3 I_0 K I_1×–( )×=
