Section 5 Protection functions
5.1 Three-phase current protection
5.1.1 Three-phase non-directional overcurrent protection
PHxPTOC
5.1.1.1 Identification
Table 58: Function identification
Different stages: Low stage High stage Instantaneous
stage
IEC 61850 identification: PHLPTOC PHHPTOC PHIPTOC
IEC 60617 identification: 3I> 3I>> 3I>>>
ANSI/IEEE C37.2 device number: 51P-1 51P-2 50P/51P
5.1.1.2 Functionality
The three-phase overcurrent protection PHxPTOC is used as one-phase, two-phase
or three-phase non-directional overcurrent and short-circuit protection for feeders.
The function starts when the current exceeds the set limit. The operate time
characteristics for low stage PHLPTOC and high stage PHHPTOC can be selected
to be either definite time (DT) or inverse definite minimum time (IDMT).The
instantaneous stage PHIPTOC 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.
5.1.1.3 Application
PHxPTOC is used in several applications in the power system. The applications
include but are not limited to:
1MRS756378 D Section 5
Protection functions
REF615 133
Application Manual
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