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4.1.2.3
Functionality
The three-phase overcurrent protection function (F)DPHxPDOC is used as
one-phase, two-phase or three-phase directional overcurrent and short-circuit
protection for feeders.
(F)DPHxPDOC starts up when the value of the current exceeds the set limit and
directional criterion is fulfilled. The operate time characteristics for low stage
FDPHLPDOC and high stage DPHHPDOC can be selected to be either definite time
(DT) or inverse definite minimum time (IDMT).
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.
4.1.2.4
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of (F)DPHxPDOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 120: Functional module diagram
1MRS758755 C
Protection functions
REC615 & RER615
Technical Manual
237