CHAPTER 5: SETTINGS GROUPED ELEMENTSC70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL 5-21755.7.5.2 Ground time overcurrent (ANSI 51G, IEC PTOC)SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) GROUND CURRENT GROUND TOC1(6)This element can provide a required time-delay operating characteristic versus the applied current or be used as a simpledefinite time element. The ground current input value is the quantity measured by the ground input CT and is thefundamental phasor or RMS magnitude. Two methods of resetting operation are available: “Timed” and “Instantaneous”(see the Inverse TOC Curve Characteristics section for details). When the element is blocked, the time accumulator resetsaccording to the reset characteristic. For example, if the element reset characteristic is set to “Instantaneous” and theelement is blocked, the time accumulator clears immediately.GROUND TOC1 FUNCTION — This setting enables and disables the ground time overcurrent protection element.GROUND TOC1 SIGNAL SOURCE — This setting selects the signal source for the ground time overcurrent protection element.GROUND TOC1 INPUT — This setting selects how ground current input quantities are interpreted by the C70. Inputs can beselected as fundamental phasor magnitudes or total waveform RMS magnitudes as required by the application.GROUND TOC1 PICKUP — This setting specifies the ground time overcurrent pickup level in per-unit values.GROUND TOC1 CURVE — This setting selects the inverse time overcurrent curve style.GROUND 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.GROUND 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.GROUND TOC1 BLOCK — Assertion of the operand assigned to this setting blocks operation of the ground time overcurrentelement.GROUND TOC1 EVENTS — This setting enables and disables the logging of ground time overcurrent events in the sequenceof events recorder. GROUND TOC1 GROUND TOC1FUNCTION: DisabledRange: Disabled, Enabled GROUND TOC1 SIGNALSOURCE: SRC 1Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6 GROUND TOC1INPUT: PhasorRange: Phasor, RMS GROUND TOC1PICKUP: 1.000 puRange: 0.020 to 30.000 pu in steps of 0.001 GROUND TOC1CURVE: IEEE Mod InvRange: see the Overcurrent Curve Types table GROUND TOC1TD MULTIPLIER: 1.00Range: 0.00 to 600.00 in steps of 0.01 GROUND TOC1RESET: InstantaneousRange: Instantaneous, Timed GROUND TOC1 BLOCK:OffRange: FlexLogic operand GROUND TOC1TARGET: Self-resetRange: Self-reset, Latched, Disabled GROUND TOC1EVENTS: DisabledRange: Disabled, EnabledThese elements measure the current that is connected to the ground channel of a CT/VT module. The conversionrange of a standard channel is from 0.02 to 46 times the CT rating.
