Digital voltmeter use precautions - Solutions - Huaqiang Electronic Network

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The digital voltmeter is a precision measuring instrument and must be operated strictly according to technical conditions. Otherwise, not only the measurement is inaccurate, but also the instrument may be damaged seriously. Therefore, pay attention to the following items:

(1) Adjustments and calibrations must be made prior to use. Otherwise it will not work properly. After the meter is energized and preheated according to the specified warm-up time, pre-adjustment can be performed. The models of the meters are different. The pre-adjustment methods are also different. The following are common situations:

1 Need to adjust the “positive and negative balance” and then calibrate the voltmeter. First set its calibration switch to “positive and negative balance” position, adjust the “balance” potentiometer to make the positive and negative values ​​of the table equal or within the allowable error range. Inside. Then place the calibration switch in the calibration position and the balance should be balanced. If it is unbalanced, it should be adjusted repeatedly to balance it and reach the specified correction voltage value.

2 Need to adjust the “zero balance” and then calibrate the voltmeter, first set the calibration switch to “zero balance” position, adjust the “zero balance” potentiometer, so that the display value changes around “O”. Then set the calibration switch to the “Calibration” position and adjust the “Correction” potentiometer to display the specified correction voltage value. At this time, the opposite polarity should also show this voltage value. If it does not overlap, the “zero balance” potentiometer should be adjusted repeatedly until the positive and negative values ​​show the same specified correction voltage value.

3 “zero adjustment” and “positive and negative calibration” respectively. The voltmeter should be placed in the “zero calibration”, “positive calibration” and “negative calibration” positions, and the corresponding adjustment potentiometer should be adjusted. When it is in each position, the corresponding indications "0", +UN and -UN are displayed.

4 If the above various zero adjustments and calibrations are still not up to the ideal value, they should be sent to the inspection department, and the professional can open the cover to adjust the internal “zero adjustment”, “calibration” and “range”. "The potentiometer to achieve the desired state."

5 In order to reduce the influence of zero current, some instruments have “zero current” regulation, and a zero current potentiometer should be adjusted as required to make it display zero. But adjust the zero current and adjust the zero voltage to take care of each other, do not get out of tune.

After pre-adjustment, the formal measurement work can be carried out after the requirements of the regulations are met.

(2) Pay attention to the ambient temperature and humidity when using. If the rules are violated, the error will increase and it will not work at all.

(3) There are instruments with standard batteries attached. It is strictly forbidden to tilt or invert at a large angle. It is best to remove the battery during transportation to prevent damage.

(4) The side dimension of the digital voltmeter should correspond to the type of the input signal. It is strictly forbidden to exceed the maximum input voltage specified by the instrument, otherwise the instrument will be damaged.

(5) Pay attention to shielding and grounding during use to reduce interference.

(6) Since the digital voltmeter has zero current and the input impedance is not infinite, pay attention to the error caused by the internal resistance of the signal source under test.

(7) If the digital voltmeter needs to be used with the printer, pay attention to the coding of the two, the level value of the logic state, and the consistency of the pulse width, polarity and waveform, otherwise the printer will not operate or malfunction.