Hioki 3286-20, Инструкция по эксплуатации

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23
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Chapter 2 Measurement Procedure
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Sample Measurements
I U 1
φ
P Meter
λ
1
φ
PF Meter
λ
1.000 1.000
*
0.847 0.750
* Distorted waveforms with crest factor of 1.9.
[Difference in
λ
between 1
φ
P Meter and 1
φ
PF Meter]
For distorted waveforms, the value of power factor
λ
may differ between the 1
φ
P meter and 1
φ
PF meter.
The difference is due to the fact that the 1
φ
P
meter calculates
λ
from active power and apparent
power, while the 1
φ
PF meter assumes a sine wave
and calculates
λ
from the phase angles of the
voltage waveform and current waveform of that sine
wave. Therefore, phase-angle measurement serves
as the basis for the 1
φ
PF meter. Distorted
waveforms and those with noise superimposed may
prevent the meter from measuring power factors
accurately or even at all. Therefore, use
λ
of the 1
φ
P meter for distorted waveforms.
Power factor
λ
of the 3
φ
PF meter is also obtained
from the phase angles of voltage waveform and
current waveform of an assumed sine wave.
Therefore, accurate measurements may also not be
conducted with distorted waveforms or those with
noise superimposed. The following example shows
the measurement of power factor
λ
from power
values on a three-phase circuit.