4.2
Earth-fault protection
4.2.1
Non-directional earth-fault protection EFxPTOC
4.2.1.1
Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Non-directional earth-fault protection,
low stage
EFLPTOC
Io>
51N-1
Non-directional earth-fault protection,
high stage
EFHPTOC
Io>>
51N-2
Non-directional earth-fault protection,
instantaneous stage
EFIPTOC
Io>>>
50N/51N
4.2.1.2
Function block
EFLPTOC
Io
BLOCK
START
OPERATE
ENA_MULT
EFHPTOC
Io
BLOCK
START
OPERATE
ENA_MULT
EFIPTOC
Io
BLOCK
START
OPERATE
ENA_MULT
A070432 V2 EN
Figure 72:
Function block
4.2.1.3
Functionality
The non-directional earth-fault protection function EFxPTOC is used as non-
directional earth-fault protection for feeders.
The function starts and operates when the residual current exceeds the set limit. The
operate time characteristic for low stage EFLPTOC and high stage EFHPTOC can be
selected to be either definite time (DT) or inverse definite minimum time (IDMT). The
instantaneous stage EFIPTOC always operates with the DT characteristic.
In the DT mode, the function operates after a predefined operate time and resets when
the fault current disappears. The IDMT mode provides current-dependent timer
characteristics.
The function contains a blocking functionality. It is possible to block function outputs,
timers or the function itself, if desired.
1MRS757454 D
Section 4
Protection functions
611 series
161
Technical Manual
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