ABB REC650 - Page 109

GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
The setting of the function is limited to the operate residual current to the protection
(Pickup).
The basic requirement is to assure selectivity, that is EFPIOC (50N) shall not be allowed
to operate for faults at other objects than the protected object (line).
For a normal line in a meshed system single phase-to-ground faults and phase-to-phase-
to-ground faults shall be calculated as shown in figure
40 and figure 41. The residual
currents (3I
0
) to the protection are calculated. For a fault at the remote line end this fault
current is I
fB
. In this calculation the operational state with high source impedance Z
A
and
low source impedance Z
B
should be used. For the fault at the home busbar this fault current
is I
fA
. In this calculation the operational state with low source impedance Z
A
and high
source impedance Z
B
should be used.
~
~
Z
A
Z
B
Z
L
A B
IED
I
fB
Fault
ANSI09000022-1-en.vsd
ANSI09000022 V1 EN
Figure 40: Through fault current from A to B: I
fB
1MRK 511 286-UUS A Section 6
Current protection
103
Application manual