Basler BE1-CDS220, Инструкция по эксплуатации

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D-2 Settings Calculations BE1-CDS220
Step 1. Determine the maximum CT secondary fault current for external faults at F (I
F3
for three-
phase, and I
FG
for single-phase). Refer to Figure D-1 for this example.
HIGH LOW
A 0 . 32
60
1916
I
F3
= =
A 66
160
10603
I
F3
= =
A 5 . 19
60
1171
I
FG
= =
A 70
160
11231
I
FG
= =
Step 2. Determine the worst case CT burden voltage for a three-phase fault (V
B3
).
For wye-connected CTs:
) R R ( I V
R L F3 B3
+ =
For delta-connected CTs, for three-phase fault:
) R R ( I 3 V
R L F3 B3
+ =
Note that the wye connection produces a lower burden on the CTs (see Setting Note 2).
Where:
Neglecting R
R
, use R
L
from Table D-1.
HIGH LOW
V 4 . 22 ) 7 . 0 )( 32 ( V
B3
= =
V 2 . 46 ) 7 . 0 )( 66 ( V
B3
= =
Step 3. Determine the worst case burden voltage for a line-to-ground fault (V
BG
).
For wye-connected CTs:
) R R 2 ( I V
R L FG BG
+ =
Where:
NOTE
This procedure uses the ANSI accuracy class method. See Setting Note 1 for
more information.
I
F3
= determined in Step 1
R
L
= one-way lead resistance in ohms
R
R
= relay resistance in ohms (< 0.05
Ω
)
I
FG
= determined in Step 1
R
L
= one-way lead resistance in ohms
R
R
= relay resistance in ohms