residual sum will have the same value as the remaining phase-to-ground voltage. See
Figure 65.
V
_
A
V
_
B
V
_
C
V
_
A
F
I
L
1
F
V
_
B
V
_
C
3
V
0
ANSI07000189-1-en.vsd
ANSI07000189 V1 EN
Figure 65: Ground fault in Direct grounded system
7.3.3.4 Settings for Two step residual overvoltage protection
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
Operation: Disabled or Enabled
VBase is used as voltage reference for the voltage. The voltage can be fed to the IED in
different ways:
1. The IED is fed from a normal voltage transformer group where the residual voltage
is created from the phase-to-ground voltages within the protection software.
2. The IED is fed from a broken delta connection normal voltage transformer group. In
an open delta connection the protection is fed by the voltage 3V0 (single input). The
1MRK 511 286-UUS A Section 7
Voltage protection
161
Application manual