ABB RELION REX640 Technical Manual page 1653

1MRS759142 C
REX640
Technical Manual
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 1466: Recorded data
Parameter
Alarm high mean Dur
Max unbalance Volt
Time Max Unb Volt
Power quality measurement functions
Description
Time duration for alarm high mean unbalance
Maximum three-second voltage
Time stamp of voltage unbalance
Section 10
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