The maximum three-second or ten-minute mean voltage unbalance is recorded
during the active observation period. The observation period start time
PR_STR_TIME
, observation period end time
PR_END_TIME
, maximum voltage
unbalance value during observation period active,
MAX_UNB_VAL
and time of
occurrence
MAX_UNB_TIME
are available through the Monitored data view. These
outputs are updated once OBS_PR_ACT deactivates.
Percentile calculator
The purpose of the Percentile calculator module is to find the voltage unbalance
level so that during the observation time 95 percent (default value of the
Percentile
unbalance
setting) of all the measured voltage unbalance amplitudes are less than
or equal to the calculated percentile.
The computed output value PCT_UNB_VAL, below which the percentile of the values
lies, is available in the Monitored data view. The PCT_UNB_VAL output value is
updated at the end of the observation period.
If the output PCT_UNB_VAL is higher than the defined setting
Unbalance start val
at the end of the observation period, an alarm output PCT_UNB_AL is activated.
The PCT_UNB_AL output remains active for the whole period before the next period
completes.
The BLOCK input blocks the output PCT_UNB_VAL.
Recorded data
The information required for a later fault analysis is stored when the Recorded data
module is triggered. This happens when a voltage unbalance is detected by the
Voltage unbalance detector module.
Three sets of recorded data are available in total. The sets are saved in data banks
1...3. The data bank 1 holds the most recent recorded data. Older data are moved
to the subsequent banks (1 to 2 and 2 to 3) when a voltage unbalance is detected.
When all three banks have data and a new variation is detected, the latest data set is
placed into bank 1 and the data in bank 3 is overwritten by the data from bank 2.
The recorded data can be reset with the RESET binary input signal by navigating to
the HMI reset ( Main menu> Clear> Reset recorded data> VSQVUBx) or through
tools via communications.
When a voltage unbalance is detected in the system, VSQVUB responds with the
MN_UNB_AL alarm signal. During the alarm situation, VSQVUB stores the maximum
magnitude and the time of occurrence and the duration of alarm MN_UNB_AL. The
recorded data is stored when MN_UNB_AL is deactivated.
Table 720: Recorded data
Parameter Description
Alarm high mean Dur Time duration for alarm high mean unbalance
Max unbalance Volt Maximum three-second voltage
Time Max Unb Volt Time stamp of voltage unbalance
1MRS758755 C Power quality measurement functions
REC615 & RER615
Technical Manual
733
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