Distance Elements Analysis - GE D90 Plus Instruction Manual

CHAPTER 15: THEORY OF OPERATION

Distance elements analysis

PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 549: Dynamic shift of the memory-polarized quadrilateral characteristic
Mutual zero-sequence compensation may raise concerns regarding directional integrity
on reverse faults in the situation when the relay gets overcompensated. This problem does
Plus
not affect the D90 because its ground distance elements use zero-sequence and
negative-sequence currents in extra directional comparators. Both the currents are from
the protected line and are not affected by any compensation as the latter applies only to
the reach defining comparators: the mho, reactance, and blinder characteristics.
This subsection shows how to analyze the operation of the distance elements in steady
states using the results of short circuit studies. All quantities are secondary ohms, volts,
and amperes. Ground phase A and phase AB distance elements are analyzed. Assume the
following settings have been entered in the Settings > Protection > Elements > Group 1 >
Ground Distance menu.
Plus
THE D90 DISTANCE ELEMENTS
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