GE D60 - Page 558

8-8 D60 Line Distance Protection System GE Multilin
8.1 DISTANCE ELEMENTS 8 THEORY OF OPERATION
8
Left Blinder RCA: 88°
Polarizing Current: Zero-sequence
Non-Homogeneity Correction Angle: 3°
Directional RCA: 88°
Z0/Z1 Magnitude: 4.55
Overcurrent supervision: 3 A
Z0/Z1 Angle: –12°
Distance Comparator limit angle: 75°
Z0M/Z1 Magnitude: 0
Directional Comparator limit angle: 75°
Assume the following signals are injected to the relay:
V
A
= 64.71 V 0.0° (pre-fault)
V
A
= 25.43 V –19.9°
V
B
= 80.22 V –133.5°
V
C
= 77.33 V 135.7°
I
A
= 4.47 A –107.8°
I
B
= 2.92 A 68.9°
I
C
= 2.93 A –51.1°
Based on the entered setting the relay calculates:
K0 = 3.58 –15.2°
K0M= 0
Z= 14.00  88°
Z
D
= 1  88°
Z
R
= 9.99  2°
Z
L
= 4.99  178°
For the assumed steady-state injection the relay calculates:
V
A
_1 = 58.83 V –2.1°
V
A
_1M = 64.71 V 0.0°
I_0 = 1.37 A –68.2°
I
A
_2 = 1.37 A –68.1°
–V_0 = 29.18 V 8.4°
(V
A
–V
B
)_1 = 93.35 V 32.0°
(V
A
–V
B
)_1M = 112.08 V 30.0°
I
A
–I
B
= 7.39 A –109.1°
b) MHO PHASE A TO GROUND ELEMENT (BEFORE MEMORY EXPIRES)
I
A
 Z + I_0  K0  Z + I
A
 K0M  Z – V
A
= 103.33 V –3.9°
V
A
_1M = 64.71 V 0.0°
I
A
_2  Z
D
= 1.37 V 19.8°
I_0  Z = 19.11 V 19.8°
I_0  Z
D
= 1.37 V 19.8°
• Overcurrent supervision: | 3  I_0 | = 4.09 A  3 A
• Mho difference angle = | –3.9° – 0° | = 3.9°  75°
• Reactance difference angle = | –3.9° – 19.8° | = 23.7°  75°
• Zero-sequence directional difference angle = | 19.8° – 0.0° | = 19.8°  75°
• Negative-sequence directional difference angle = | 19.8° – 0.0° | = 19.8°  75°
• Fault-type comparator difference angle = | 19.8° – 19.8° | = 0.0°  50°