4
Protection functions
4.1
Three-phase current protection
4.1.1
Three-phase non-directional overcurrent protection
PHxPTOC
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/51P
4.1.1.2
Function block
Figure 118: 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.
1MRS757644 H
Protection functions
620 series
Technical Manual
239