What points should be paid attention to when using the instrument correctly?

In order to avoid errors caused by imperfect measurement methods, attention must be paid to the correct use of the instrument, mainly the following points:

(1) Select the instrument type according to the nature of the measurement object. First, DC or AC is measured so that DC meter or AC meter can be selected. If you measure the AC volume, you should also pay attention to whether it is a sine wave or a non-sine wave; when measuring, you should also distinguish whether the measured value is the average value, effective value, instantaneous value or maximum value. For the AC volume, you should also pay attention to the frequency.

(2) Select the instrument grade according to the actual needs of the measurement object. According to the nature of the project, as long as the error of the measurement results is within the actual allowable range of the project. For example, in commonly used standards and some precision measurements, instruments with an accuracy of 0.1-0.2 can be used; in experimental measurements, instruments with a level of 0.5-1.5 can be used; in factory production, instruments with a level of 1.0-5.0 can be used.

(3) Select the internal resistance of the instrument according to the resistance of the measurement object and the measurement line. For a voltmeter that measures voltage, the larger the internal resistance, the better. The internal resistance of the voltmeter is required to be 100 times larger than the object being measured. For ammeters that measure current, the smaller the internal resistance, the better. The internal resistance of an ammeter is often less than 100 times that of the object being measured.

(4) Select the allowable rating of the instrument according to the measurement object. Do not use a large-range instrument to measure small values to avoid inaccurate readings. Of course, you cannot use small-range instruments to measure large amounts of electricity to avoid damaging the instrument. Therefore, when selecting instruments, you must carefully observe the rated voltage, rated current and rated power allowed by the instrument and equipment.