MI 2892 Power Master
Theory and internal operation
170
∆Umax is the maximum absolute difference between any of the U
Rms(1/2)
values during the RVC event and the final arithmetic mean 100/120 U
Rms(1/2)
value just prior to
the RVC event. For poly-phase systems, the ∆Umax is the largest ∆Umax on any channel.
∆Uss is the absolute difference between the final arithmetic mean
100/120 U
Rms(1/2)
value just prior to the RVC event and the first arithmetic mean
100/120 U
Rms(1/2)
value after the RVC event. For poly-phase systems, the ∆Uss is the largest ∆Uss
on any channel.
5.1.16
Data aggregation in GENERAL RECORDING
Standard compliance: IEC 61000-4-30 Class A (Section 4.5)
Time aggregation period (IP) during recording is defined with parameter Interval: x min in GENERAL
RECORDER menu.
A new recording interval commence at real time clock thick (10 minutes
half cycle, for Interval: 10
min) and it last until next real time clock plus time needed to finish current 10/12 cycle measurement. In
the same time new measurement is started, as shown on next figure. The data for the IP time interval
are aggregated from 10/12-cycle time intervals, according to the figure below. The aggregated interval is
tagged with the absolute time. The time tag is the time at the conclusion of the interval. There is
overlap, during recording, as illustrated on figure below.
RTC
End of
Interval
10/12 cycles
10/12 cycles
10/12 cycles
10/12 cycles
10/12 cycles
10/12 cycles
1
2
3
i
j
k
overlap
10 min interval (x)
10 min interval (x+1)
Figure 5.16: Synchronization and aggregation of 10/12 cycle intervals
Depending from the quantity, for each aggregation interval instrument computes average, minimal,
maximal and/or active average value., this can be RMS (root means square) or arithmetical average.
Equations for both averages are shown below.
RMS average
N
j
j
RMS
A
N
A
1
2
1
Where:
A
RMS
– quantity average over given aggregation interval
A – 10/12-cycle quantity value
N – number of 10/12 cycles measurements per aggregation interval.
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