GE D30 User Manual

9-10 D30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
DISTANCE ELEMENTS CHAPTER 9: THEORY OF OPERATION
9
I_0 = 1.37 A ∠–68.2°
IA_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°
9.1.6.2 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°
All four comparators and the overcurrent supervision are satisfied, so the MHO phase A ground element operates for this
fault.
9.1.6.3 Mho phase A to ground element (after memory expires)
After the memory expires, the relay checks the actual positive-sequence voltage and compares it with 10% of the nominal
voltage:
| V
A
_1 | = 58.83 V > 0.1 × 69.28 V
After the memory expires the relay uses the actual voltage for polarization.
I
A
× Z + I_0 × K0 × Z + I
G
× K0M × Z – V
A
= 103.33 V ∠–3.9°
V
A
_1 = 58.83 V ∠–2.1°
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° – (–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, so the Zone 1 MHO phase A ground element operates
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 higher phase A ground elements pick-up, time-out, and operate.
9.1.6.4 Mho AB phase element
(I
A
– I
B
) × Z – (V
A
– V
B
) = 88.65 V ∠–78.7°

GE D30 Specifications

General

Brand	GE
Model	D30
Category	Relays
Language	English