Test Example 4 - GE T60 Instruction Manual
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8 COMMISSIONING
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
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
C
Intermediate
A
Slope 1 & 2
B
C
Slope 2
A
B
C
Slope 2
A
B
C
GE Multilin
Courtesy of NationalSwitchgear.com
D/d0° Transformer
H winding
∠
∠
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°
T60 Transformer Management Relay
8.2 DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
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°
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°
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
Block
I
I
/
= 93.2%
d
r
< Slope 2 = 95%
Operate
I
I
/
= 96%
d
r
> Slope 2 = 95%
8-11
8
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