EXAMPLE TWO – TWO WINDING TRANSFORMER
Verify CT Performance
Refer to Figure D-3 and Table D-3 for the application parameters used in this example.
Figure D-3. Two Winding Transformer Relay Setting Calculation Example
Table D-3. Example 2 Specifications
SPECIFICATIONS
HIGH SIDE
LOW SIDE
Nominal Voltage
69 kV
12.47 kV
Taps
70.725 kV
+2.5%, 5%
12.47 Kv
+10% Auto
MVA, SC, FA
12/20
12/20
XFMR connection
Delta Wye
CT connection
Wye
Wye
CT ratio
600:5
1200:5
CT tap
300:5
800:5
CT accuracy class
400
800
One-way lead burden (ohms) †
0.7
0.7
Input #
1
2
Fault current (three-phase)
1,916
10,603
Fault current (single-phase)
1,171
11,231
Standard connection: High voltage leads the low voltage by 30
.
†
L
T
resistance at tap and lead resistance (R
L
+ R
CT
).
NOTE
Please read the discussion at the start of Example 1 calculations.
D-12
BE1-CDS240 Settings Calculations
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Summary of Contents for BE1-CDS240
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