METREL MI 2885, Manual

Page: 202 / 241

MI 2893 / MI 2892 / MI 2885 Measurement methods
202
Power
Combined Arithmetic average
Min, Avg, AvgOn, Max
Fundamental
Arithmetic average Min, Avg, AvgOn, Max
Nonfundamental
Arithmetic average Min, Avg, AvgOn, Max
Unbalance
U
+
RMS Min, Avg, AvgOn, Max
U
-
RMS
Min, Avg, AvgOn, Max
U
0
RMS
Min, Avg, AvgOn, Max
u- RMS
Min, Avg, AvgOn, Max
u0 RMS
Min, Avg, AvgOn, Max
I
+
RMS
Min, Avg, AvgOn, Max
I
-
RMS Min, Avg, AvgOn, Max
I
0
RMS
Min, Avg, AvgOn, Max
i- RMS Min, Avg, AvgOn, Max
i0 RMS Min, Avg, AvgOn, Max
Harmonics
DC, Uh
0÷50
RMS Avg, Max
DC, Ih
0÷50
RMS Avg, AvgOn, Max,
Interharmonics
Uh
0÷50
RMS Avg, Max
Ih
0÷50
RMS Avg, AvgOn, Max
Signalling U
Sig
RMS Min, Avg, AvgOn, Max
An active average value is calculated upon the same principle (arithmetic or RMS) as average value, but
taking in account only measurement where measured value is not zero:
RMS active average
N M A
M
A
M
j
j RMSact
 


;
1
1
2
(75)
Where:
A
RMSact
– quantity average over active part of given aggregation interval,
A – 10/12-cycle quantity value marked as “active”,
M – number of 10/12 cycles measurements with active (non zero) value.
Arithmetic active average:


 
M
j
j avgact
N M A
M
A
1
;
1
(76)
Where:
A
avgact
– quantity average over active part of given aggregation interval,
A – 10/12-cycle quantity value in “active” part of interval,
M – number of 10/12 cycles measurements with active (non zero) value.
Difference between standard average (Avg) and active average (AvgOn)
Example: Suppose we measure current on AC motor which is switched on for 5 min every 10 minutes.
Motor consumes 100A. User set recording interval to 10 minutes.
5min 10min 15min
100A