GE D30 Instruction Manual page 452

8.1 DISTANCE ELEMENTS
Overcurrent supervision: | 3 × I_0 | = 4.09 A > 3 A
•
Mho difference angle = | –3.9° – (–2.1°) | = 1.8° < 75°
•
Reactance difference angle = | –3.9° – 19.8° | = 23.7° < 75°
•
Zero-sequence directional difference angle = | 19.8° – (–2.1°) | = 21.9° < 75°
•
Negative-sequence directional difference angle = | 19.8° – (–2.1°) | = 21.9° < 75°
•
Fault-type comparator difference angle = | 19.8° – 19.8° | = 0.0° < 50°
•
All four comparators and the overcurrent supervision are satisfied.
The Zone 1 MHO phase A ground element will operate for this fault.
• Zero-sequence directional difference angle for zones 2 and higher (phase A) = | 19.8° – 8.4° | = 11.4° < 90°.
Zones 2 and hihger phase A ground elements will pick-up, time-out and operate.
d) MHO AB PHASE ELEMENT
) × Z – (V
(I – I – V
A B A B
(V – V )_1M
A B
) × Z
(I – I
A B
) × Z
(I – I
A B D
• Overcurrent supervision: | (I
Mho difference angle = | –78.7° – 30.0° | = 108.7° > 75°
•
Reactance difference angle = | –78.7° – (–21.2°) | = 57.5° < 75°
•
Directional difference angle = | –21.2° – 30.0° | = 51.2° < 75°
•
The mho comparator is not satisfied.
The MHO AB phase element will not operate for this fault.
Repeating the above analysis one concludes that out of the six distance elements only the ground element in phase A will
operate for this fault.
e) QUAD PHASE A TO GROUND ELEMENT (BEFORE MEMORY EXPIRES)
I × Z + I_0 × K0 × Z + I
A
V _1M
A
j3
j × I_0 × e
_2 × Z
I
A D
I_0 × Z
D
× Z + I_0 × K0 × Z
I
A R R
× Z + I_0 × K0 × Z
I
A R R
I × Z + I_0 × K0 × Z
A L L
I × Z + I_0 × K0 × Z
8
A L L
Overcurrent supervision: | 3 × I_0 | = 4.09 A > 3 A
•
Reactance difference angle = | –3.9° – 24.8° | = 28.7° < 75°
•
• Zero-sequence difference angle = | –19.8° – 0.0° | = 19.8° < 75°
• Negative-sequence directional difference angle = | –19.8° – 0.0° | = 19.8° < 75°
Right blinder difference angle = | –93.0° – (–109.2°) | = 16.2° < 90°
•
Left blinder difference angle = | 82.9° – 108.7° | = 25.8° < 90°
•
• Fault-type comparator difference angle = | 19.8° – 19.8° | = 0.0° < 50°
All six comparators and the overcurrent supervision are satisfied.
The Quad Phase A ground element will operate for this fault.
8-10
= 88.65 V ∠–78.7°
)
= 112.08 V ∠30.0°
= 103.50 V ∠–21.2°
= 7.39 V ∠–21.2°
| = 4.27 A > 3 A
– I ) / 3
A B
× K0M × Z – V = 103.33 V ∠–3.9°
G A
= 64.71 V ∠0.0°
= 1.37 A ∠24.8°
= 1.37 V ∠19.8°
= 1.37 V ∠19.8°
× K0M × Z = 87.6 V ∠–109.2°
+ I – V
G R A
= 91.5 V ∠–93.0°
+ I × K0M × Z – V = 57.0 V ∠108.7°
G L A
= 45.8 V ∠82.9°
D30 Line Distance Protection System
8 THEORY OF OPERATION
GE Multilin