Technical description
2 Protection functions
2.7 Directional overcurrent protection
Idir> (67)
VM259.EN007
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79
Inverse operation time
Stages I
dir
> and I
dir
>> can be configured for definite time or
inverse time characteristic. See chapter 2.24 for details of the
available inverse delays. Stages I
dir
>>> and I
dir
>>>> have
definite time (DT) operation delay. The device will show a
scaleable graph of the configured delay on the local panel
display.
Inverse time limitation
The maximum measured secondary current is 50xI
N
. This
limits the scope of inverse curves with high pick-up settings.
See chapter 2.24 for more information.
Cold load and inrush current handling
See chapter 0.
Setting groups
There are two settings groups available for each stage.
Switching between setting groups can be controlled by digital
inputs, virtual inputs (mimic display, communication, logic)
and manually.
Figure 2.7-4 shows the functional block of the Idir> stage.
Figure 2.7-4.Block diagram of the three-phase overcurrent stage I
dir
>
Parameters of the directional overcurrent stages
I
dir
>, I
dir
>> (67)
Parameter
Value
Unit
Description
Note
Status
-
Blocked
Start
Trip
Current status of the stage
F
F
TripTime
s
Estimated time to trip
SCntr
Cumulative start counter
Clr
TCntr
Cumulative trip counter
Clr
SetGrp
1 or 2
Active setting group
Set