5-196 T60 Transformer Protection System GE Multilin5.6 GROUPED ELEMENTS 5 SETTINGS5d) NEUTRAL DIRECTIONAL OVERCURRENT (ANSI 67N)PATH: SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEUTRAL CURRENT NEUTRAL DIRECTIONAL OC1The neutral directional overcurrent element provides both forward and reverse fault direction indications the NEUTRAL DIROC1 FWD and NEUTRAL DIR OC1 REV operands, respectively. The output operand is asserted if the magnitude of the oper-ating current is above a pickup level (overcurrent unit) and the fault direction 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 separate pickup settings for the forward-looking andreverse-looking functions. If set to use the calculated 3I_0, the element applies a positive-sequence restraint for better per-formance: a small user-programmable portion of the positive-sequence current magnitude is subtracted from the zero-sequence current magnitude when forming the operating quantity.(EQ 5.38)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 2, SRC 3, SRC 4, SRC 5, SRC 6MESSAGE 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 250.00Ω 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: 0.006 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: 0.006 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×–( )×=
