branch. R
s
increases the impedance of the protection relay; hence the name high-
impedance differential scheme.
GUID-1AB5D686-3B9C-413F-9D0A-215BFCA224B4 V1 EN
Figure 278: Phase-segregated bus differential protection based on high-impedance
principle
CT secondary winding resistances (R
in
) and connection wire resistances (R
m
/2) are also
shown in Figure 279.
Figure 279 demonstrates a simplified circuit consisting only of one incoming and
outgoing feeder. To keep it simple, the voltage-dependent resistor (R
u
) is not included.
The wiring resistances are presented as total wiring resistances R
m1
and R
m2
.
R
m1
is the maximum wiring resistance concerning all incoming feeder
sets, whereas R
m2
is the maximum wiring resistance concerning all
outgoing feeder sets.
Section 4 1MAC059074-MB A
Protection functions
554 615 series ANSI
Technical Manual
To Next Page
Loading...
