GE D90 Plus Instruction Manual page 255

CHAPTER 7: PROTECTION
Ground time overcurrent
NOTE:
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 212: Neutral directional overcurrent 1 scheme logic
The ground time overcurrent element can provide a desired 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. When the element is blocked, the time accumulator will reset
according to the reset characteristic. For example, if the element reset characteristic is set
to instantaneous and the element is blocked, the time accumulator will be cleared
immediately.
These elements measure the current that is connected to the ground channel of an AC
module. This channel may be equipped with a standard or sensitive input. The conversion
range of a standard channel is from 0.02 to 46 times the CT rating. The conversion range of
a sensitive channel is from 0.002 to 4.6 times the CT rating.
Select the Settings > Protection > Elements > Group 1 > Current > Ground TOC menu
item to open the ground time overcurrent configuration window.
GROUPED PROTECTION ELEMENTS
245