ABB REL670 2.2 IEC, Applications Manual

Page: 478 / 908

GlobalBaseSel : This is used to select GBASVAL function for reference of base
values.
The basic requirement is to assure selectivity, that is EFPIOC 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-earth faults and phase-to-
phase-to-earth faults shall be calculated as shown in Figure
258 and Figure 259 .
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
IEC09000022-1-en.vsd
IEC09000022 V1 EN-US
Figure 258: Through fault current from A to B: I
fB
IEC09000023-1-en.vsd
~ ~
Z
A
Z
B
Z
L
A B
IED
I
fA
Fault
IEC09000023 V1 EN-US
Figure 259: Through fault current from B to A: I
fA
The function shall not operate for any of the calculated currents to the protection.
The minimum theoretical current setting (Imin) will be:
 
Im ,
fA fB
in MAX I I

EQUATION284 V2 EN-US
(Equation 455)
Section 9
1MRK 506 369-UEN B
Current protection
472 Line distance protection REL670 2.2 IEC
Application manual