GE T35 Instruction Manual page 526

DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
Figure 8-5: Current distribution of D/D transformer with an a to b fault on the LV side
Test Phase
Balanced A
Condition
B
C
Min Pickup A
B
C
Min Pickup A
B
C
Slope 1 A
B
C
Slope 1 A
B
C
Intermediate A
Slope 1 & 2
B
8
C
Intermediate A
Slope 1 & 2
B
C
Slope 2 A
B
C
Slope 2 A
B
C
8-12
Injected current
W1 current W2 current
0 ∠0° 0 ∠0°
0.435 ∠–90° 0.8 ∠–270°
0.435 ∠–270° 0.8 ∠–90°
0 ∠0° 0 ∠0°
0.09 ∠–90° 0.23 ∠–270°
0.09 ∠–270° 0.23 ∠–90°
0 ∠0° 0 ∠0°
0.21 ∠–90° 0.486 ∠–270°
0.21 ∠–270° 0.486 ∠–90°
0 ∠0° 0 ∠0°
0.651 ∠–90° 1.39 ∠–270°
0.651 ∠–270° 1.39 ∠–90°
0 ∠0° 0 ∠0°
0.63 ∠–90° 1.39 ∠–270°
0.63 ∠–270° 1.39 ∠–90°
0 ∠0° 0 ∠0°
1.2 ∠–90° 4.63 ∠–270°
1.2 ∠–270° 4.63 ∠–90°
0 ∠0° 0 ∠0°
0.8 ∠–90° 4.63 ∠–270°
0.8 ∠–270° 4.63 ∠–90°
0 ∠0° 0 ∠0°
0.315 ∠–90° 8.33 ∠–270°
0.315 ∠–270° 8.33 ∠–90°
0 ∠0° 0 ∠0°
0.18 ∠–90° 8.33 ∠–270°
0.18 ∠–270° 8.33 ∠–90°
Displayed current
Differential Restraint
0 ∠0° 0 ∠0°
0 ∠0° 0.8 ∠–270°
0 ∠0° 0.8 ∠–90°
0 ∠0° 0 ∠0°
0.065 ∠0° 0.230 ∠–270°
0.065 ∠0° 0.230 ∠–90°
0 ∠0° 0 ∠0°
0.102 ∠0° 0.486 ∠–270°
0.101 ∠0° 0.486 ∠–90°
0 ∠0° 0 ∠0°
0.195 ∠0° 1.39 ∠–270°
0.195 ∠0° 1.39 ∠–90°
0 ∠0° 0 ∠0°
0.233 ∠0° 1.39 ∠–270°
0.233 ∠0° 1.39 ∠–90°
0 ∠0° 0 ∠0°
2.44 ∠–270° 4.63 ∠–270°
2.44 ∠–90° 4.63 ∠–90°
0 ∠0° 0 ∠0°
3.18 ∠–270° 4.63 ∠–270°
3.18 ∠–90° 4.63 ∠–90°
0 ∠0° 0 ∠0°
7.77 ∠–270° 8.33 ∠–270°
7.77 ∠–90° 8.33 ∠–90°
0 ∠0° 0 ∠0°
8 ∠–270° 8.33 ∠–270°
8 ∠–90° 8.33 ∠–90°
T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: COMMISSIONING
Status
Not Applicable
Block
I
= 0.065 < Min PKP
d
Operate
I
= 0.101 > Min PKP
d
Block
I I
/ = 14% < 15%
d r
Operate
I I
/ = 16.8% > 15%
d r
Block
I I
/ = 52.6%
d r
< 60%
computed
Operate
I / I = 68.8%
d r
> 60%
computed
Block
I / I = 93.2%
d r
< Slope 2 = 95%
Operate
I I
/ = 96%
d r
> Slope 2 = 95%