4.2.2.2
Function block
Figure 188: Function block
4.2.2.3
Functionality
The directional earth-fault protection function DEFxPDEF is used as directional
earth-fault protection for feeders.
The function starts and operates when the operating quantity (current) and
polarizing quantity (voltage) exceed the set limits and the angle between them
is inside the set operating sector. The operate time characteristic for low stage
(DEFLPDEF) and high stage (DEFHPDEF) 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.
4.2.2.4
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of DEFxPDEF can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 189: Functional module diagram
Protection functions
1MRS757644 H
388
620 series
Technical Manual
