GE T60 Instruction Manual page 449

CHAPTER 5: SETTINGS
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.
This channel can be equipped with a standard or sensitive input. The conversion range of a sensitive channel is
from 0.002 to 4.6 times the CT rating.
5.7.9.4 Restricted ground fault (ANSI 87RGF, IEC PNDF)
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  GROUND CURRENT  RESTRICTED GROUND FAULT
1(6)
 RESTRICTED GROUND
 FAULT 1
As of T60 firmware revision 3.20, the definition of the restraining signal has been significantly changed compared
to previous versions. The restraint during external faults is generally not lower, and often much higher, compared to
the previous definition of the restraining signal (enhanced security). The restraint on internal faults has been greatly
reduced compared to previous versions (enhanced sensitivity), particularly during low-current internal faults. Using
time delay as a means of dealing with CT saturation is no longer obligatory; pickup and slope are the primary
means of addressing CT saturation. Increasing the slope setting is recommended when migrating from the 3.1x or
earlier firmware revisions. The default value for the slope has been changed from 10% to 40%.
T60 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 5-149: Ground IOC1 logic
RESTD GND FT1

FUNCTION: Disabled
RESTD GND FT1

SOURCE: SRC 1
RESTD GND FT1

PICKUP: 0.080 pu
RESTD GND FT1

SLOPE: 40%
RESTD GND FT1 PICKUP

DELAY: 0.10 s
RESTD GND FT1 RESET

DELAY: 0.00 s
RESTD GND FT1 BLOCK:

Off
RESTD GND FT1

TARGET: Self-reset
GROUPED ELEMENTS
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: 0.005 to 30.000 pu in steps of 0.001
Range: 0 to 100% in steps of 1
Range: 0.00 to 600.00 s in steps of 0.01
Range: 0.00 to 600.00 s in steps of 0.01
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
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