GE D90 Plus Instruction Manual page 272

Line distance protection system

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GROUPED PROTECTION ELEMENTS

validated, neither forward nor reverse indication is given. In addition, the negative-

sequence current (or zero-sequence current) must be greater than the

setting value specified in the Protection > Power System > AC Inputs – Current menu. The

following figure explains the usage of the voltage polarized directional unit of the element.

Figure 224: Negative-sequence directional characteristics

The forward-looking function is designed to be more secure as compared to the reverse-

looking function, so use the forward-looking function for the tripping direction. The

reverse-looking function is faster compared to the forward-looking function and is to be

used for the blocking direction. This allows for better protection coordination. Take this bias

into account when using the negative-sequence directional overcurrent element to

directionalize other protection elements.

Select the Settings > Protection > Elements > Group 1 > Current > Negative Sequence

Directional OC menu to open the negative-sequence directional overcurrent

configuration window.

LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL

CHAPTER 7: PROTECTION

Current Cutoff Level