
M3x5/EN M/B
User Manual
Page 88
iSTAT M3x5
There are two different methods of calculating reactive energy, see Appendix D.
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Energy
12.4.1.7 MD values
MD values and their time stamp of occurrence are shown for:
Three phase currents
Active powers (import and export)
Reactive power (inductive and capacitive)
Apparent power
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MD values
Dynamic demands are continuously calculated according to set time constants and other
parameters.
Reset demands are maximum values of Dynamic demands since last reset.
12.4.1.8 Harmonic distortion
Device calculates different harmonic distortion parameters:
THD is calculated for phase currents, phase voltages and phase
−
to
−
phase voltages and
is expressed as percentage of high harmonic components regarding to fundamental
harmonic
TDD is calculated for phase currents
K-factor is calculated for phase currents
The device uses the measuring technique of real effective (rms) value that ensures exact
measurements with the presence of high harmonics up to 63rd harmonic.
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12.4.1.9 Flickers
Flickers are one of most important PQ parameters directly (through light flickering)
influencing human feeling.
Flickers are measured and statistically evaluated according to standard IEC 61000-4-15.
For basic flicker measurements on all three voltage phases 1200 readings per second are
taken. Instantaneous flicker sensation reduces this sampling rate 8 times (150
instantaneous flicker calculations per second) and uses approximately 3s averaging time.
With further statistical evaluation short term and long term flickers are calculated.
Pi
1-3
represents instantaneous flicker and is averaged and refreshed every 3 sec.
Pi
is
averaged from 500 instantaneous flicker calculations.
Pim
1-3
represents maximum value of instantaneous flicker
Pi
within 3 sec flicker averaging
interval and is refreshed every 3 sec. This value is displayed only on display. It is not
available on communication.
Pst
1-3
represents 10 min statistical evaluation of instantaneous flicker and is refresh every
10 minutes (x:00, x:10, x:20…)
Plt
1-3
represents 2 h statistical evaluation of short-time flicker
Pst
and is refreshed every
even 2 hours (0:00, 2:00, 4:00…)
Until the flicker value is calculated the symbol ‘
−
‘ is displayed.
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