MI 2893 / MI 2892 / MI 2885
Measurement methods
190
0
0
90
0
180
0
270
0
Ep-
Ep-
Ep+
Ep+
0
0
90
0
180
0
270
0
Eq+
Eq+
Eq-
Eq-
L
e
a
d
L
a
g
Active Energy
Fundamental Reactive Energy
L
e
a
d
L
a
g
Figure 154: Energy counters and quadrant relationship
Instrument has 3 different counters sets:
1.
Total counters are used for measuring energy over a complete recording. When recorder starts
it sums the energy to existent state of the counters.
2.
Last integration period counter measures energy during recording over last completed interval.
It is calculated at end of each interval.
3.
Current integration period
CUR
counter measures energy during recording over current time
interval.
Start of
Recording
Recording Intervals
1
2
3
m
m -1
Last interval
Current interval
Current
Time
LAST
CUR
Total Energy
TOT
Figure 155: Instrument energy counters
5.1.8
Harmonics and interharmonics
Standard compliance: IEC 61000-4-30 Class A (Section 5.7)
IEC 61000-4-7 Class I
Calculation called fast Fourier transformation (FFT) is used to translate AD converted input signal to
sinusoidal components. The following equation describes relation between input signal and its
frequency presentation.
