Distance Elements Analysis - GE L90 Instruction Manual

9.3 DISTANCE ELEMENTS
The same desirable effect of memory polarization applies to the directional comparator of the quadrilateral characteristic.
Figure 9–11: DYNAMIC SHIFT OF THE MEMORY-POLARIZED DIRECTIONAL 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 not affect the L90 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, reac-
tance and blinder characteristics.
a) DESCRIPTION
This subsection shows how to analyze the operation of the distance elements in steady states using the results of short cir-
cuit 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:
9
Phase Rotation: ABC
Right Blinder Reach: 10 
Nominal Secondary Voltage: 69.28 V
Right Blinder RCA: 88°
Distance Reach: 14 
Left Blinder Reach: 5 
Distance RCA: 88°
9-26
X
Self-polarized mho
Figure 9–10: DYNAMIC SHIFT OF THE MHO CHARACTERISTIC
X
Self-polarized
837724A1.CDR
L90 Line Current Differential System
9 THEORY OF OPERATION
Memory-polarized mho
(Reverse fault)
Memory-polarized mho
(Forward fault)
R
837719A1.CDR
Memory-
polarized
(Reverse fault)
R
Memory-
polarized
(Forward fault)

9.3.5 DISTANCE ELEMENTS ANALYSIS

GE Multilin