4.1.4.2 Function block
Figure 148: Function block
4.1.4.3 Functionality
Directional three-independent-phase directional overcurrent protection function
DPH3xPDOC is used as one-phase, two-phase or three-phase directional
overcurrent and short circuit protection for feeders.
DPH3xPDOC starts when the value of the current exceeds the set limit and
directional criterion is fulfilled. Each phase has its own timer. The operation time
characteristics for the low stage, DPH3LPDOC, and the high stage, DPH3HPDOC,
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 operation 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.
4.1.4.4 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "On" and "Off".
The operation of DPH3xPDOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
1MRS757644 H
Protection functions
620 series
Technical Manual
299
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