4-28
IM 760301-01E
Explanation
For details, see section 2.3.
Excluding the cases when the screen is set to the displays listed below, the selected
interval is used pass the numeric data to the D/A output and communication output as
well as storing the numeric data (to the internal memory).
• Waveform display
• Split display including a waveform display
• Display Position of the Data Update Rate
The data update rate is displayed in the upper right corner of the screen when the
UPDATE RATE key is pressed.
Data update rate
Computing method
• Limitation on the Data Update Rate by Measurement Modes
• Normal Measurement Mode, Waveform Computation Mode, and FFT Mode
Select from the choices below. The numeric data is updated at the selected
interval. To capture relatively fast load fluctuations in the power system, select a
fast data update rate. To capture relatively low frequency signals, select a slow
data update rate.
50 ms, 100 ms, 250 ms, 500 ms, 1 s, 2 s, 5 s, 10 s, and 20 s
• Wide Bandwidth Harmonic Measurement Mode and IEC Harmonic
Measurement Mode
The data update rate setting is invalid. The data update rate is determined
automatically by the fundamental frequency of the PLL source and the number of
periods of the PLL source used for the analysis.
• Voltage Fluctuation and Flicker Measurement Mode
The data update rate is fixed to 2 s.
• Cycle-by-Cycle Measurement Mode
The data update rate setting is invalid. The data update rate is automatically
determined by the fundamental frequency and the number of measurement cycles
of the synchronization source.
Note
•
In some cases, the display update rate of the numeric data and waveform data that are
displayed on the screen may take longer than the data update rate.
•
The lower frequency limit of the AC signal that can be measured varies depending on the
data update rate. The measured value may not be stable if an AC signal of a frequency lower
than the lower limit of measurement frequency (see section 12.4) is measured.
•
The WT3000 automatically switches the method of computing the measured values according
to the data update rate. For details, see appendix 7.
•
The data update rate of the FFT is determined automatically from the number of FFT points.
For details, see chapter 11 in the
Extension Function User’s Manual IM760301-51E
.
•
The display update interval in waveform computation mode and FFT mode is the data update
rate + computation time.
4.10 Selecting the Data Update Rate