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N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
GROUPED ELEMENTS
CHAPTER 5: SETTINGS
5
5.7.6.2 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 simple
definite time element. The ground current input value is the quantity measured by the ground input CT and is the
fundamental 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 resets
according to the reset characteristic. For example, if the element reset characteristic is set to “Instantaneous” and the
element 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 N60. Inputs can be
selected 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 static
relays, which set the energy capacity directly to zero when the current falls below the reset threshold. The “Timed” reset
method 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 overcurrent
element.
GROUND TOC1 EVENTS
— This setting enables and disables the logging of ground time overcurrent events in the sequence
of events recorder.
GROUND TOC1
GROUND TOC1
FUNCTION: Disabled
Range: Disabled, Enabled
GROUND TOC1 SIGNAL
SOURCE: SRC 1
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
GROUND TOC1
INPUT: Phasor
Range: Phasor, RMS
GROUND TOC1
PICKUP: 1.000 pu
Range: 0.020 to 30.000 pu in steps of 0.001
GROUND TOC1
CURVE: IEEE Mod Inv
Range: see the Overcurrent Curve Types table
GROUND TOC1
TD MULTIPLIER: 1.00
Range: 0.00 to 600.00 in steps of 0.01
GROUND TOC1
RESET: Instantaneous
Range: Instantaneous, Timed
GROUND TOC1 BLOCK:
Off
Range: FlexLogic operand
GROUND TOC1
TARGET: Self-reset
Range: Self-reset, Latched, Disabled
GROUND TOC1
EVENTS: Disabled
Range: Disabled, Enabled
These elements measure the current that is connected to the ground channel of a CT/VT module. The conversion
range of a standard channel is from 0.02 to 46 times the CT rating.