Test Example 3 - GE T60 Instruction Manual

DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
Test Phase
Slope 1 A
B
C
Slope 1 A
B
C
Intermediate A
Slope 1 & 2
B
C
Intermediate A
Slope 1 & 2
B
C
Slope 2 A
B
C
Slope 2 A
B
C

8.2.4 Test example 3

8.2.4.1 Yg/D30° transformer with phase B to C fault on the Delta side
Transformer data — Y/D30°, 20 MVA, 115/12.47 kv, CT1 (200:1), CT2 (1000:1)
Figure 8-4: Current Distribution on a Yg/D30° transformer with an a to b fault on the LV side
8
Three adjustable currents are required in this case. The Phase A and C Wye-side line currents, identical in magnitude but
displaced by 180°, can be simulated with one current source passed through these relay terminals in series. The second
current source simulates the Phase B primary current. The third source simulates the delta "b" and "c" phase currents, also
equal in magnitude but displaced by 180°.
8-10
Injected current
W1 current W2 current
0.4435 ∠0° 1.6 ∠–180°
0 ∠0° 0 ∠0°
0.4435 ∠–180° 0 ∠0°
0.4425 ∠0° 1.7 ∠–180°
0 ∠0° 0 ∠0°
0.4425 ∠–180° 0 ∠0°
1.2 ∠0° 5 ∠–180°
0 ∠0° 0 ∠0°
1.2 ∠–180° 0 ∠0°
1.1 ∠0° 5 ∠–180°
0 ∠0° 0 ∠0°
1.1 ∠–180° 0 ∠0°
0.4 ∠0° 15 ∠–180°
0 ∠0° 0 ∠0°
0.4 ∠–180° 0 ∠0°
0.2 ∠0° 15 ∠–180°
0 ∠0° 0 ∠0°
0.2 ∠–180° 0 ∠0°
Displayed current
Differential Restraint
0.110 ∠0° 0.9026 ∠–180°
0 ∠0° 0 ∠0°
0 ∠0° 0 ∠0°
0.165 ∠0° 0.979 ∠–180°
0 ∠0° 0 ∠0°
0.165 ∠0° 0.979 ∠0°
0.675 ∠–180° 2.882 ∠–180°
0 ∠0° 0 ∠0°
0.675 ∠0° 2.882 ∠0°
0.860 ∠–180° 2.882 ∠–180°
0 ∠0° 0 ∠0°
0.860 ∠0° 2.882 ∠0°
7.915 ∠–180° 8.646 ∠–180°
0 ∠0° 0 ∠0°
7.915 ∠0° 8.646 ∠0°
7.918 ∠–180° 8.650 ∠–180°
0 ∠0° 0 ∠0°
7.916 ∠0° 8.650 ∠0°
T60 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: COMMISSIONING
Status
Block
I /I = 11.9%
d r
Operate
I /I = 16.8%
d r
Block
I /I = 23.4%
d r
Operate
I I
/ = 29.8%
d r
Block
I I
/ = 91.5%
d r
Operate
I /I = 95.7%
d r