GE D90 Plus Instruction Manual page 267

CHAPTER 7: PROTECTION
Negative-sequence time overcurrent
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Events
Range: Enabled, Disabled
Plus
Default: varies with UR
This setting enables and disables the logging of ground instantaneous overcurrent
events in the sequence of events recorder.
The figure shows the logic for the ground instantaneous overcurrent 1 element. The logic is
identical for all ground instantaneous overcurrent elements.
Figure 219: Ground instantaneous overcurrent scheme logic
The negative-sequence time overcurrent element can be used to determine and clear
unbalance in the system. The input for calculating negative-sequence current is the
fundamental phasor value.
Two methods of resetting operation are available: "Timed" and "Instantaneous." 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.
Select the Settings > Protection > Elements > Group 1 > Current > Negative Sequence
TOC menu to open the negative-sequence time overcurrent configuration window.
Figure 220: Negative-sequence time overcurrent configuration settings
The following settings are available for each negative-sequence time overcurrent element.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the negative-sequence time overcurrent protection
element.
-series model; see the EnerVista UR
GROUPED PROTECTION ELEMENTS
Plus
Setup software
257