5-232 L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS5There are three neutral overvoltage elements available. The neutral overvoltage element can be used to detectasymmetrical system voltage condition due to a ground fault or to the loss of one or two phases of the source. Theelement responds to the system neutral voltage (3V_0), calculated from the phase voltages. The nominal secondaryvoltage of the phase voltage channels entered under SETTINGS SYSTEM SETUP AC INPUTS VOLTAGE BANK PHASEVT SECONDARY is the p.u. base used when setting the pickup level.The neutral overvoltage element can provide a time-delayed operating characteristic versus the applied voltage (initializedfrom FlexCurves A, B, or C) or be used as a definite time element. The NEUTRAL OV1 PICKUP DELAY setting applies only if theNEUTRAL OV1 CURVE setting is “Definite Time.” The source assigned to this element must be configured for a phase VT.VT errors and normal voltage unbalance must be considered when setting this element. This function requires the VTs tobe wye-connected.Figure 5-119: Neutral overvoltage1 logic5.7.9.5 Negative sequence overvoltage (ANSI 59Q, IEC PTOV)SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) VOLTAGE ELEMENTS NEG SEQ OV1(3)There are three negative-sequence overvoltage elements available.Use the negative-sequence overvoltage element to detect loss of one or two phases of the source, a reversed phasesequence of voltage, or a non-symmetrical system voltage condition. NEG SEQ OV1 NEG SEQ OV1FUNCTION: DisabledRange: Disabled, Enabled NEG SEQ OV1 SIGNALSOURCE: SRC 1Range: SRC 1, SRC 2 NEG SEQ OV1 PICKUP:0.300 puRange: 0.004 to 1.250 pu in steps of 0.001 NEG SEQ OV1 PICKUPDELAY: 0.50 sRange: 0.00 to 600.00 s in steps of 0.01 NEG SEQ OV1 RESETDELAY: 0.50 sRange: 0.00 to 600.00 s in steps of 0.01 NEG SEQ OV1 BLOCK:OffRange: FlexLogic operand NEG SEQ OV1 TARGET:Self-resetRange: Self-reset, Latched, Disabled NEG SEQ OV1 EVENTS:DisabledRange: Disabled, Enabled
