document. The configuration can be written to the protection relay once the
mismatch is corrected.
4.2.10.5 Operation principle
The
Operation
setting is used to enable or disable the function. When selected “on”
the function is enabled and respectively “off” means function is disabled.
The operation of
Touch voltage-based earth-fault current protection IFPTOC
can be
described by using a module diagram (see figure below). All the modules in the
diagram are explained in the next sections.
BLOCK
CB_CL_CMD
I3P
U3P
URES
IRES
EF_IND
Fault
current
estimation
and
validity
check
Touch
voltage
estimation
Faulted
phase
identifi-
cation
Intermittent
earth fault
protection
Cross-
country
fault
protection
Fault
resistance
estimation
OPERATE
START
PEAK_IND
INTR_EF
TRIGG_REC
Recorded
data
EXT_RELEASE
U_A
U_B
U_C
U_AB
U_BC
U_CA
I_A
I_B
I_C
Uo
Io
VALID_EF
XC_FLT
Blocking
logic
OP_INTR
ST_INTR
OP_SOTF
ST_SOTF
ST_EF
OP_EF
ST_XC
OP_XC
Trip logic
Switch
onto fault
protection
General
fault
criterion
Earth-fault
current &
touch
voltage
protection
Figure 335: Functional module diagram
General fault criterion
The General fault criterion (GFC) module monitors the presence of earth fault in the
network. It is based on the value of the fundamental frequency residual voltage
1MRS759142 F
Protection functions
REX640
Technical Manual
585
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