GE D90 Plus Instruction Manual page 253

CHAPTER 7: PROTECTION
Neutral time overcurrent
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Block When Voltage Memory Expires
Range: Yes, No
Default: No
This setting is used to select the required operation upon expiration of voltage memory.
When set to "Yes," the directional element blocks the operation of any phase overcurrent
element under directional control, when voltage memory expires. When set to "No," the
directional element allows tripping of phase overcurrent elements under directional
control.
Events
Range: Enabled, Disabled
Plus
Default: varies with UR
This setting enables and disables the logging of phase directional overcurrent events in
the sequence of events recorder.
The figure shows the logic for the phase directional overcurrent 1 element. The logic is
identical for all phase directional overcurrent elements.
Figure 208: Phase directional overcurrent 1 scheme logic
The neutral 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
neutral current input value is a quantity calculated as 3I_0 from the phase currents and
can be programmed as fundamental phasor magnitude or total waveform RMS
magnitude as required by the application.
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.
-series model; see the EnerVista UR
GROUPED PROTECTION ELEMENTS
Plus
Setup software
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