ABB RELION 620 Series Technical Manual page 490

Section 4
Protection functions
484
Y
2000/1A
2.......7
2000/1A
GUID-97462931-644F-4EFD-8C9A-AF61A3C870B8 V1 EN
Figure 228: Example for busbar differential protection
Bus data:
V 20 kV
n
I 2000 A
n
I 25 kA
kmax
10 feeders per protected zone including bus coupler and incomer.
CT data is assumed to be:
CT 2000/1 A
R 15.75 Ω
in
V 436 V
kn
I <7 mA (at U )
e kn
R 1Ω
m
2000/1A
Bus coupler
2000/1A
Stabilizing
resistor R
s
Differential protection Differential protection
(87A, 87B, 87C) for (87A, 87B, 87C) for
Zone A
1MAC504801-IB E
Y
2000/1A
Stabilizing
resistor R
s
Zone B
Technical Manual
620 series ANSI