Kikusui PFX2000 Series, Руководство по эксплуатации

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A-2 Appendix PFX2000
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Noise rejection and sampling interval
On the voltage sensing line, there are various noise components that are superim-
posed on the signal in addition to the DC voltage that needs to be measured.
To minimize the effects of hum noise, this unit measures voltage in synchronization
with the commercial power supply period as illustrated by Fig. A-2. Therefore, the
measurement interval (sampling interval) is equal to the power supply period
(except during pulse operation). This makes stable measurement possible even
when the voltage sensing line is extended to 7 m.
Fig. A-2 Measurement Interval
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Auto fi ne function
The auto fi ne function brings the current value set by the constant current operation
and the current that actually fl ows closer together through automatic adjustment.
You can eliminate the error caused by the accuracy of the constant current setting by
enabling this function. This function is effective when you need higher accuracy of
constant current performance or when you wish to suppress the current error
between channels.
Operating principle
As explained in section A.1.1, “Overview,” this unit is equipped with a high-resolu-
tion A/D converter. The auto
fi ne function uses the highly accurate current measure-
ment performance to correct the D/A converter output so that “measured current =
constant current setting” is achieved. By adopting a correction converter as shown
in Fig. A-3, the resolution of the D/A converter is effectively increased to approxi-
mately the same level as the resolution of the A/D converter.
Voltage waveform of the AC line applied to the unit (for 50 Hz)
= Voltage
measurement
10 ms
Point near the zero-crossing
where the hum noise is reduced
= Current
measurement
Values used as measured voltage
230
µ
s 230
µ
s
Time
* Current measurement is performed at arbitrary times.