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KPM1000
App. A
Display Update Interval and
Measurement Period
The KPM1000 measurement period is determined by the zero crossing points of the
synchronization source and the display update interval (which can be selected on the configuration
menu). The figure below shows the temporal relationship between the display update interval and
the measurement period.
Synchronization source
You can set the synchronization source to voltage input (factory default setting) or current input. The
points in time when the amplitude crosses the zero level on the rising slope are known as zero
crossings.
If the synchronization source waveform is distorted or if it contains harmonics, the KPM1000 may
not be able to accurately detect the zero crossings. In this situation, change the synchronization
source (switch between voltage and current input), or turn the frequency filter on. If the KPM1000
cannot accurately detect the zero crossings, the measured values may not be stable.
Measurement period
The KPM1000’s measurement period is defined as the time between (1) the zero crossing
immediately before the display is updated (t-na) and (2) the zero crossing immediately before the
display is updated the next time (t-nd).
If the synchronization source has been turned off or if zero crossings could not be detected because
the input is not at a valid input level even though the synchronization source has been turned on,
measurements will be performed asynchronously. In this situation, the measurement period is the
same as the display update interval (t-na equals t-nb and t-nd equals t-ne).
Consecutive measurements
For example, in a measurement between two zero crossings (t-nc and t-nd) within the display
update interval, there is a gap between the display update interval and the next measurement
period (from t-na to t-nc). To perform consecutive measurements with no gaps between them, the
KPM1000 sets the measurement period as the time between (1) the zero crossing immediately
before the display is updated (t-na) and (2) the zero crossing immediately before the display is
updated the next time (t-nd).
Measurement period n
Zero crossing
Synchronization source
n-1
t-na t-nb t-nc
t-nd
t-ne
t-na
t-nb
t-nd
t-ne
t-na: Immediately before the display is updated (t-nb)
t-nd: Immediately before the display is updated (t-ne)
n+1
n-2
n
Display update interval n-1
Summary of Contents for IB022853
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