5-232 D30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS55.7.8.2 Neutral time overcurrent (ANSI 51N, IEC PTOC)SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEUTRAL CURRENT NEUTRAL TOC1(2)The neutral time overcurrent element can provide a desired time-delay operating characteristic versus the applied currentor be used as a simple definite time element. The neutral current input value is a quantity calculated as 3Io from the phasecurrents and can be programmed as fundamental phasor magnitude or total waveform RMS magnitude as required by theapplication.Two methods of resetting operation are available: “Timed” and “Instantaneous” (see the Inverse TOC Curve Characteristicssection for details on curve setup, trip times, and reset operation). When the element is blocked, the time accumulatorresets according to the reset characteristic. For example, if the element reset characteristic is set to “Instantaneous” andthe element is blocked, the time accumulator clears immediately.NEUTRAL TOC1 FUNCTION — This setting enables and disables the neutral time overcurrent protection element.NEUTRAL TOC1 SIGNAL SOURCE — This setting selects the signal source for the neutral time overcurrent protection element.NEUTRAL TOC1 INPUT — This setting selects how neutral current input quantities are interpreted by the D30. Inputs can beselected as fundamental phasor magnitudes or total waveform RMS magnitudes as required by the application.NEUTRAL TOC1 PICKUP — This setting specifies the neutral time overcurrent pickup level in per-unit values.NEUTRAL TOC1 CURVE — This setting selects the inverse time overcurrent curve style.NEUTRAL TOC1 TD MULTIPLIER — This setting specifies a multiple of the base curve shape specified by the CURVE setting.Programming this value to zero results in an instantaneous response to all current levels above pickup.NEUTRAL TOC1 RESET — The “Instantaneous” reset method is intended for applications with other relays, such as most staticrelays, which set the energy capacity directly to zero when the current falls below the reset threshold. The “Timed” resetmethod can be used where the relay must coordinate with electromechanical relays.NEUTRAL TOC1 BLOCK — Assertion of the operand assigned to this setting blocks operation of the neutral time overcurrentelement. NEUTRAL DIRECTIONAL OC1See page 5-234 NEUTRAL DIRECTIONAL OC2 NEUTRAL TOC1 NEUTRAL TOC1FUNCTION: DisabledRange: Disabled, Enabled NEUTRAL TOC1 SIGNALSOURCE: SRC 1Range: SRC 1, SRC 2 NEUTRAL TOC1INPUT: PhasorRange: Phasor, RMS NEUTRAL TOC1PICKUP: 1.000 puRange: 0.020 to 30.000 pu in steps of 0.001 NEUTRAL TOC1CURVE: IEEE Mod InvRange: see Overcurrent Curve Types table NEUTRAL TOC1TD MULTIPLIER: 1.00Range: 0.00 to 600.00 in steps of 0.01 NEUTRAL TOC1RESET: InstantaneousRange: Instantaneous, Timed NEUTRAL TOC1 BLOCK:OffRange: FlexLogic operand NEUTRAL TOC1TARGET: Self-resetRange: Self-reset, Latched, Disabled NEUTRAL TOC1EVENTS: DisabledRange: Disabled, Enabled
