MI 2892 Power Master
Theory and internal operation
172
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.
Figure 5.17: Avg vs. Avgon, switching load current
After 10 minutes values will be:
Irms (rms average) = 50A
Irms (rms AvgOn) = 100A
AvgOn takes into account only those measurements where current is greater than zero.
Power and energy recording
Active power is aggregated into two different quantities: import (positive-consumed P+) and export
(negative-generated P-). Nonactive power and power factor are aggregated into four parts: positive
inductive (i+), positive capacitive (c+), negative inductive (i+) and negative capacitive (c-).
Consumed/generated and inductive/capacitive phase/polarity diagram is shown on figure below:
5min
10min 15min
100A
