GE D30 Instruction Manual page 467

CHAPTER 9: THEORY OF OPERATION
Normally, in order to respond to the fault shown in the figure, a distance relay is applied at the relaying point X. The table
outlines the relay input signals at this location.
Table 9-10: Relay input signals at location X
Input Primary
VA 100.4 kV ∠–7.32°
VB 97.23 kV ∠–53.4°
VC 181.8 kV ∠–150.0°
IA 1.288 kA ∠–27.6°
IB 1.288 kA ∠152.4°
IC 0
If installed at the location X, the relay uses the following input signals for its phase AB distance element:
V = V = 77.402 kV ∠57.5° primary or 29.49 V ∠57.5° secondary
AB
I = I – I = 2.576 kA ∠–27.6° primary or 42.93 A ∠–27.6° secondary
A B
And consequently it sees an apparent impedance of
Z = V / I = 30.05 Ω ∠85° primary or 0.687 Ω ∠85° secondary
app
If applied at location H, the relay sees the following input signals:
Table 9-11: Relay input signals at location H
Input Primary
7.584 kV ∠–5.59°
VA
6.269 kV ∠–120.1°
VB
7.751 kV ∠125.5°
VC
IA 16.976 kA ∠–27.6°
IB 33.952 kA ∠152.4°
IC 16.976 kA ∠–27.6°
The relay is set as follows:
= "Dy11"
XFMR VOL CONNECTION
= "Dy11"
XFMR CUR CONNECTION
D30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 9-5: Sample system configuration
150 MVA, 10%
13.8kV/315kV
delta wye, 330 lag
H X
VT = 13.8kV/120V VT = 315kV/120V
CT = 8000:5 CT = 300:5
2.57Ω∠88.4°
Secondary
38.25 V ∠–7.32°
37.04 V ∠–53.4°
69.26 V ∠–150.0°
21.47 A ∠–27.6°
21.47 A ∠152.4°
0
Secondary
69.95 V ∠–5.59°
54.52 V ∠–120.1°
65.84 V ∠125.5°
10.61 A ∠–27.6°
21.22 A ∠152.4°
10.61 A ∠–27.6°
PHASE DISTANCE APPLIED TO POWER TRANSFORMERS
°
AB
Z = 30.11 Ω∠ 85°
L
Ω∠
0.688 85°
837727A2.CDR
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