2.12 Zero sequence voltage
protection U0> (59N)
2 Protection functions
Technical description
96
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VM259.EN007
Recorded values of the undirectional earth fault stages (8
latest faults) I
0
>, I
0
>>, I
0
>>>, I
0
>>>> (50N/51N)
Parameter
Value
Unit Description
yyyy-mm-dd
Time stamp of the recording, date
hh:mm:ss.ms
Time stamp, time of day
Flt
pu
Maximum earth fault current
EDly
%
Elapsed time of the operating time
setting. 100% = trip
SetGrp
1
2
Active setting group during fault
2.12.
Zero sequence voltage protection U
0
>
(59N)
The zero sequence voltage protection is used as unselective
backup for earth faults.
This function is sensitive to the fundamental frequency
component of the zero sequence voltage. The attenuation of the
third harmonic is more than 60 dB. This is essential, because
3n harmonics exist between the neutral point and earth also
when there is no earth fault.
Whenever the measured value exceeds the user's pick-up
setting of a particular stage, this stage picks up and a start
signal is issued. If the fault situation remains on longer than
the user's operation time delay setting, a trip signal is issued.
Two independent stages
There are two separately adjustable stages: U
0
> and U
0
>>.
Both stages can be configured for definite time (DT) operation
characteristic.
The zero sequence voltage function comprises two separately
adjust-table zero sequence voltage stages (stage U
0
> and U
0
>>).
Setting groups
There are two settings groups available for both stages.
Switching between setting groups can be controlled by digital
inputs, virtual inputs (mimic display, communication, logic)
and manually.