GE D30 Instruction Manual page 420

9.1 DISTANCE ELEMENTS
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:
= 64.71 V 0.0° (pre-fault)
V
A
= 25.43 V –19.9°
V
A
= 80.22 V –133.5°
V
B
= 77.33 V 135.7°
V
C
= 4.47 A –107.8°
I
A
= 2.92 A 68.9°
I
B
= 2.93 A –51.1°
I
C
Based on the entered setting the relay calculates:
K0 = 3.58 –15.2°
K0M= 0
= 14.00  88°
Z
= 1  88°
Z
D
= 9.99  2°
Z
R
= 4.99  178°
Z
L
For the assumed steady-state injection the relay calculates:
= 58.83 V –2.1°
V _1
A
= 64.71 V 0.0°
V _1M
A
= 1.37 A –68.2°
I_0
= 1.37 A –68.1°
I _2
A
= 29.18 V 8.4°
–V_0
= 93.35 V 32.0°
(V –V )_1
A B
= 112.08 V 30.0°
(V –V )_1M
A B
= 7.39 A –109.1°
I –I
A B
b) MHO PHASE A TO GROUND ELEMENT (BEFORE MEMORY EXPIRES)
 Z + I_0  K0  Z + I
I
A
V _1M
A
_2  Z
I
A D
I_0  Z
I_0  Z
D
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°
9 •
Negative-sequence directional difference angle = | 19.8° – 0.0° | = 19.8°  75°
•
Fault-type comparator difference angle = | 19.8° – 19.8° | = 0.0°  50°
•
All four comparators and the overcurrent supervision are satisfied.
The MHO phase A ground element will operate for this fault.
9-8
 K0M  Z – V = 103.33 V –3.9°
A A
= 64.71 V 0.0°
= 1.37 V 19.8°
= 19.11 V 19.8°
= 1.37 V 19.8°
D30 Line Distance Protection System
9 THEORY OF OPERATION
GE Multilin