2.15 Zero sequence voltage protection
U0> (59N)
2 Protection functions
Technical description
78
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VM50.EN004
Parameter Value
Unit Description
Note
t> s
Operation time. Actually the
number of cycles including
faults x 20 ms. When the time
between faults exceeds 20 ms,
the actual operation time will
be longer.
Set
Io input
Io1Peak
I
01
Connectors X1-7,8,9
Set
Intrmt
s
Intermittent time. When the
next fault occurs within this
time, the delay counting
continues from the previous
value.
Set
For details of setting ranges see chapter 9.3 .
Set = An editable parameter (password needed)
C = Can be cleared to zero
F = Editable when force flag is on
Recorded values of the latest eight faults
There is detailed information available of the eight latest
detected faults: Time stamp, U
0
voltage, elapsed delay and
setting group.
Recorded values of the directional intermittent transient
earth fault stage (8 latest faults) I
0T
> (67NT)
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 detected earth fault
current
EDly
%
Elapsed time of the operating time
setting. 100% = trip
Uo
%
Max.
U
0
voltage during the fault
SetGrp 1
2
Active setting group during fault
2.15.
Zero sequence voltage protection U
0
>
(59N)
The zero sequence voltage protection is used as unselective
backup for earth faults and also for selective earth fault
protections for motors having a unit transformer between the
motor and the busbar.
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.