Basler BE1-CDS220, Instruction Manual

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BE1-CDS220 Settings Calculations D-1
APPENDIX D
•
SETTINGS CALCULATIONS
GENERAL
These settings calculations are provided to assist in developing the required settings for the BE1-CDS220
Current Differential System. To develop these settings, the paragraphs in this section discuss each task.
•
Verify CT Performance
•
Determine Tap Settings
•
Calculate Minimum Pickup Restraint Setting
•
Select Unrestrained Pickup Setting
•
Calculate Slope
•
Select Harmonic Restraint Settings
For additional information on selected examples, see the associated Setting Notes.
EXAMPLE - TWO WINDING TRANSFORMER
Verify CT Performance
Refer to Figure D-1 and Table D-1 for the application parameters used in this example.
11-05-99
D1873-21
(3)
1916 (3
∅
)
1171 (1
∅)
300/5T
600/5MR
Z
S
=2%@100MV
A
+10%LTC
Z
T
=5%@12MVA
69 kV
12/20MVA
12.47 kV
(3)
1200/5MR
800/5T
10,603 (3
∅
)
11,231 (1
∅
)
LOAD
F
S
Figure D-1. Two-Winding Transformer Relay Setting Calculation Example
Table D-1. Two-Winding Transformer Relay Setting Calculation Example
Specifications High Side Low Side
Nominal Voltage 69 kV 12.47 kV
No-Load Taps
70.725 kV
72.450 kV
69.000 kV
67.275 kV
65.550 kV
12.47 kV
MVA 12/20 12/20
CT Ratio 600:5 1200:5
CT Tap 300:5 800:5
CT Accuracy Class 400 800
One-Way Lead Burden (
Ω
)
0.7 0.7
XFMR Connection
∗
DELTA WYE
CT Connection WYE WYE
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
°
.