ABB RELION 620 Series Technical Manual page 561

1MRS757644 F
620 series
Technical Manual
I
zs1
A
I
zs1
B
I
zs1
C
Uzs
Operate for
internal fault
GUID-FAC5E4AD-A4A7-4D39-9EAC-C380EA33CB78 V2 EN
Figure 283: Current flow in all the CTs for an external fault
s
A
o
u
B
r
c
C
e
Ifault
Io
For internal fault
GUID-D5D712D4-2291-4C49-93DE-363F9F10801C V2 EN
Figure 284: Current flow in all the CTs for an internal fault
zone of
protection
Io
For external fault
Restrain for
external fault
zone of
protection
Uzs
Io
Operate for
internal fault
Section 4
Protection functions
I
a = 0
I I
b = 0 b = 0
I I
c = 0
I
N
Io
I
N Reference is Neutral
Current
I
N
I
N
Reference is Neutral
Current
Restrain for
external fault
a
b
c
I I
a = 0
a
I I
b = 0
b
I
c = 0
c
555