Test Example 4 - GE T60 Instruction Manual
Transformer protection system ur series
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8 COMMISSIONING
TEST
PHASE
W1 CURRENT
Slope 2
A
8 –180°
B
C
D/D0° TRANSFORMER WITH PHASE B TO C FAULT ON THE SECONDARY DELTA WINDING.
Transformer: D/D0°, 20 MVA, 115/12.47 kv, CT1 (200:1), CT2 (1000:1)
I (f) = 0
A
A
I (f) = 0.866 pu –90°
B
B
C
I (f) = 0.866 pu –270°.
C
Figure 8–5: CURRENT DISTRIBUTION OF D/D TRANSFORMER WITH AN a TO b FAULT ON THE LV SIDE
TEST
PHASE
W1 CURRENT
Balanced
A
Condition
0.435 –90°
B
0.435 –270°
C
Min Pickup
A
0.09 –90°
B
0.09 –270°
C
Min Pickup
A
0.21 –90°
B
0.21 –270°
C
Slope 1
A
0.651 –90°
B
0.651 –270°
C
Slope 1
A
0.63 –90°
B
0.63 –270°
C
Intermediate
A
Slope 1 & 2
1.2 –90°
B
1.2 –270°
C
Intermediate
A
Slope 1 & 2
0.8 –90°
B
0.8 –270°
C
GE Multilin
INJECTED CURRENT
W2 CURRENT
4 0°
0 0°
0.6 0°
4 0°
0.6 –180°
D/d0° Transformer
H winding
∠
∠
INJECTED CURRENT
W2 CURRENT
0 0°
0 0°
0.8 –270°
0.8 –90°
0 0°
0 0°
0.23 –270°
0.23 –90°
0 0°
0 0°
0.486 –270°
0.486 –90°
0 0°
0 0°
1.39 –270°
1.39 –90°
0 0°
0 0°
1.39 –270°
1.39 –90°
0 0°
0 0°
4.63 –270°
4.63 –90°
0 0°
0 0°
4.63 –270°
4.63 –90°
T60 Transformer Protection System
8.2 DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
DISPLAYED CURRENT
DIFFERENTIAL
RESTRAINT
0 0°
0 0°
12.13 –180°
12.73 0°
12.13 0°
12.73 –180°
X winding
I (f) = 0.866 pu –90°
b
I (f) = 0.866 pu –270°
c
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°
STATUS
Operate
I
I
/
= 95.7%
d
r
> Slope 2 = 95%
8.2.5 TEST EXAMPLE 4
I (f) = 0
a
A
∠
B
F
C
∠
828739A1.CDR
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
8-11
8
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