GE D90 Plus Instruction Manual page 565

CHAPTER 15: THEORY OF OPERATION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 469: Example system configuration
Plus
The D90 input signals at point X are shown in the following table.
Table 26: Input signals at point X for example system with power transformers
Input
V
A
V
B
V
C
I
A
I
B
I
C
If installed at location X, the D90
distance element.
= 77.402 kV ∠57.5° primary or 29.49 V ∠57.5° secondary.
V = V
AB
= 2.576 kA ∠–27.6° primary or 42.93 A ∠–27.6° secondary.
I = I – I
A B
And consequently, the D90
= V / I = 30.05 Ω ∠85° primary or 0.687 Ω ∠85° secondary.
Z
APP
If applied at location H, the D90
Table 27: Input signals at point H for example system with power transformers
Input
V
A
V
B
V
C
I
A
I
B
I
C
The following settings are applied in the D90
Transformer Voltage Connection
Transformer Current Connection
PHASE DISTANCE APPLIED TO POWER TRANSFORMERS
Primary
100.4 kV ∠–7.32°
97.23 kV ∠–53.4°
181.8 kV ∠–150.0°
1.288 kA ∠–27.6°
1.288 kA ∠152.4°
0
Plus
uses the following input signals for its phase AB
Plus
would see the following apparent impedance.
Plus
input signals are shown below.
Primary
7.854 kV ∠–5.59°
6.269 kV ∠–120.1°
7.751 kV ∠125.5°
16.976 kA ∠–27.6°
33.952 kA ∠152.4°
16.976 kA ∠–27.6°
Plus
.
: "Dy11"
: "Dy11"
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°
21.11 A ∠152.4°
10.61 A ∠–27.6°
557