The calculated three-second value and ten-minute value are available in the
Monitored data view through the outputs
3S_MN_UNB
and
10MN_MN_UNB
.
For VT connection = "Delta", the calculated zero-sequence voltage is
always zero, hence, the setting
Unb detection method = "Zero Seq" is
not applicable in this VT configuration.
Voltage unbalance detector
The three-second average value is calculated and compared to the set value
Unbalance start val. If the voltage unbalance exceeds this limit, the
MN_UNB_AL
output is activated.
The activation of the
BLOCK
input blocks
MN_UNB_AL
output.
Percentile calculation
The Percentile calculation module performs the statistics calculation for the level
of voltage unbalance value for a settable duration. The operation of the Percentile
calculation module can be described with a module diagram.
Observation
period
Statistics
recorder
Percentile
calculator
PCT_UNB_AL
OBS_PR_ACT
BLOCK
10MIN_MN_UNB
(from Average calculator)
3s_MN_UNB
(from Average calculator)
Figure 587: Percentile calculation
Observation period
The Observation period module calculates the length of the observation time for
the Statistics recorder sub-module as well as determines the possible start of a new
one. A new period can be started by timed activation using calendar time settings
Obs period Str year, Obs period Str month, Obs period Str day and Obs period Str
hour.
The observation period start time settings
Obs period Str year, Obs
period Str month, Obs period Str day and Obs period Str hour are used
to set the calendar time in UTC. These settings have to be adjusted
according to the local time and local daylight saving time.
A preferable way of continuous statistics recordings can be selected over a longer
period (months, years). With the
Trigger mode setting, the way the next possible
observation time is activated after the former one has finished can be selected.
Power quality measurement functions
1MRS757644 H
1110
620 series
Technical Manual
