7.3.1 Identification
M14887-1 v4
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Instantaneous residual overcurrent
protection
EFPIOC
IEF V1 EN-US
50N
7.3.2 Application
M12699-3 v5
In many applications, when fault current is limited to a defined value by the object impedance,
an instantaneous earth-fault protection can provide fast and selective tripping.
The Instantaneous residual overcurrent EFPIOC, which can operate in 15 ms (50 Hz nominal
system frequency) for faults characterized by very high currents, is included in the IED.
7.3.3 Setting guidelines
IP14985-1 v1
M12762-44 v2M12762-4 v4
The parameters for the Instantaneous residual overcurrent protection EFPIOC are set via the
local HMI or PCM600.
Some guidelines for the choice of setting parameter for EFPIOC is given.
M12762-6 v7
GlobalBaseSel
: Selects the global base value group used by the function to define (
IBase
),
(
UBase
) and (
SBase
).
The setting of the function is limited to the operate residual current to the protection (
IN>>
).
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
48 and figure 49. 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 48: Through fault current from A to B: I
fB
1MRK 511 358-UEN A Section 7
Current protection
115
Application manual
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