ABB Relion 620 Series - Page 591

Figure 311: Example for busbar differential protection
Bus data:
U
n
20 kV
I
n
2000 A
I
kmax
25 kA
10 feeders per protected zone including bus coupler and incomer.
CT data is assumed to be:
CT
2000/1 A
R
in
15.75 Ω
U
kn
436 V
I
e
<7 mA (at U
kn
)
R
m
1Ω
The stabilizing voltage is calculated using the formula:
1MRS757644 H
Protection functions
620 series
Technical Manual
591