ABB RELION REX640 Technical Manual page 1650

Section 10
Power quality measurement functions
1644
The calculated three-second value and ten-minute value are available in the
Monitored data view through the outputs 3S_MN_UNB and 10MIN_MN_UNB.
3S_MN_UNB values are updated every three seconds and
10MIN_MN_UNB is updated every minute.
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
3s_MN_UNB
(from Average calculator)
10MIN_MN_UNB
(from Average calculator)
BLOCK
GUID-023E300F-5516-4CD0-860A-577278B32A92 V1 EN
Figure 848: 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.
period
Statistics
Percentile
calculator
recorder
1MRS759142 C
OBS_PR_ACT
PCT_UNB_AL
REX640
Technical Manual