MI 2883 Energy Master
Theory and internal operation
143
∆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 s
ystems, the ∆Uss is
the
largest ∆Uss on any channel.
5.1.15
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 5.14: 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.
(57)
Arithmetic average:
N
j
j
avg
A
N
A
1
1
(58)
