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5-7-3 Setting Internal Gain with ACTL LOAD
The DPM-900/950 series can set the internal gain with the ACTL LOAD (actual load). When using an
extension cable, set the internal gain with ACTL LOAD for more accurate measurement.
Follows are the setting procedures of the optimum internal gain with the ACTL LOAD.
1) Set the DPM-900/950 series to the ACTL LOAD mode. (Press and hold the ACTL LOAD switch to
lights up.)
2) Connect the strain gage, strain gage transducer, or external calibrator to the input and conduct bridge
check.
3) Press the BAL switch twice. (Conduct balance adjustment in no load state.)
4) Input the actual load or strain of the external calibrator.
5) Set the VOLTAGE OUT switch to the desired voltage.
6) Press the SET switch twice.
7) Press the BAL switch twice with no load. (The DPM-900/950 series becomes measuring state after
balancing.)
While correctly setting the internal gain, appears on the monitor.
When the
appears on the monitor, it is indicating the setting error. Read “9-4 TROUBLE
SHOOTING.”
5-8 LOW-PASS FILTER
The DPM-900/950 series provides a secondary Butterworth type low-pass filter.
Five cutoff frequencies are provided, including 10, 30, 100, 300 Hz and 1 kHz, in addition to “FLAT.”
At the point of a cutoff frequency selected, the amplitude is attenuated by about 70%.
The cutoff characteristic is rated at -12 dB/Oct. It means that the amplitude attenuates to 1/4 when
frequency is doubled in the cutoff region in excess of a cutoff frequency.
The low-pass filter plays the following roles.
1) Removes the unnecessary high-frequency components from a strain signal.
2) Determines the overall characteristic of a measuring system including a strain gage or a strain gage
transducer.
3) Unities the characteristics of data paths for simultaneous multi-point measuring.
For the setting method of the low-pass filter, read “4-6-2 Setting Low-pass Filter.”
When strain signals vary in the form of sine wave (sin-functionally), set the low-pass filter to a cutoff
frequency from 2 to 5 times larger than the signal frequency or strain signals that are to be measured.
For the characteristic of the low-pass filter, read “9-2 LOW-PASS FILTER.”
Press and hold the SET switch in the ACTL LOAD mode. The
scrolls on the monitor.
It is the amount of the strain that is input to the DPM-900/950 series.
When the input strain is 10000 m/m at the time of internal gain setting, the calibration signal
corresponds to the input cannot be set.
Maximum calibration signal is 9999 m/m.
In addition, the built-in software version is scrolled horizontally on the monitor if the
SET
switch is pressed and hold in the “Normal Mode.”
With a low-pass filter having the Butterworth characteristic, the phase delay becomes
unproportional to the frequency nearby a cutoff frequency in use. Accordingly, fast rising or
falling signals that pass the filter will cause an overshoot. To prevent it, set the low-pass filter to a
cutoff frequency about 10 times larger than the frequency of strain signals.
NOTE
MEMO
