4 Protection functions
4.1 Three-phase current protection
4.1.1 Three-phase non-directional overcurrent protection
PHxPTOC (ANSI 51P-1, 51P-2, 50P)
4.1.1.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Three-phase non-directional over-
current protection, low stage
PHLPTOC 3I> 51P-1
Three-phase non-directional over-
current protection, high stage
PHHPTOC 3I>> 51P-2
Three-phase non-directional over-
current protection, instantaneous
stage
PHIPTOC 3I>>> 50P
4.1.1.2 Function block
Figure 197: Function block
4.1.1.3 Functionality
The three-phase non-directional overcurrent protection function PHxPTOC is used
as one-phase, two-phase or three-phase non-directional overcurrent and short-
circuit protection.
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.
Protection functions
1MRS759142 F
326 REX640
Technical Manual
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