Ground Time Overcurrent Protection (51G) - GE 845 Instruction Manual

PROTECTION
Ground Time
Overcurrent
Protection (51G)
4–180
The 845 is equipped with the Ground Time Overcurrent protection element. The settings of
this function are applied to the ground input current to produce Trip or Pickup flags. The
Ground TOC Pickup flag is asserted when the ground current is above the PKP value. The
Ground TOC Trip flag is asserted if the element stays picked up for the time defined by the
selected inverse curve and the magnitude of the current. The element drops from Pickup
without operation if the measured current drops below 97 to 98% of the Pickup value
before the time for operation is reached. When Definite Time is selected, the time for
Ground TOC operation is defined only by the TDM setting.
FUNCTION
Range: Disabled, Trip, Alarm, Latched Alarm, Configurable
Default: Disabled
INPUT
Range: Phasor, RMS
Default: Phasor
PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.000 x CT
CURVE
Range: IEEE Extremely/Very/Moderately Inverse,
ANSI Extremely/Very/Normally/Moderately Inverse,
Definite time IEC A/B/C and Short Inverse,
IAC Extremely/Very/Inverse/Short Inverse
FlexCurve A/B/C/D, I2t, I4t
Default: IEEE, Moderately Inverse
TDM
Range: 0.05 to 600.00 in steps of 0.01
Default: 1.00
RESET
Range: Instantaneous, Timed
Default: Instantaneous
DIRECTION
Range: Disabled, Forward, Reverse
Default: Disabled
BLOCK
Range: Off, Any FlexLogic operand
Default: Off
OUTPUT RELAY X
For details see Common
EVENTS
Range: Enabled, Disabled
Default: Enabled
TARGETS
Range: Self-reset, Latched, Disabled
Default: Self-reset
Setpoints.
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS