Measurement methods and precautions for the use of multimeters
Digital table measurement accuracy, wide measurement range, can measure voltage, current, resistance, inductance, capacitance, frequency, transistor, etc., so in recent years is very popular.
1, digital meter display commonly used for more than 31/2, 41/2, etc., its range to 2 as the base, such as 200mV (display 199.9mV), 2V (display 1.999V), 20Ω (display 19.99Ω), 200mA (display 199.9mA), and so on, so the choice of range should be as close as possible to the fullness of the value.
2,Digital meter display accuracy is greatly affected by the battery voltage, so if you find abnormal readings in use, you should check the battery in time.
3,Digital meter range, gear interval is dense, so we must develop the habit of checking the range carefully before testing.
4,If you are not sure about the voltage and current of the test, you should choose the highest range first.
5,As with the pointer meter, it is absolutely forbidden to change the gear when the machine is electrified.
6, pointer meter precautions digital meter most useful.
(1) Before using the multimeter to calibrate the mechanical zero and electrical zero, if you want to measure the current or voltage, you should adjust the mechanical zero of the meter pointer first; if you want to measure the resistance, you should adjust the electrical zero of the meter pointer first to prevent the voltage of the battery inside the meter from dropping and generating measurement errors.
(2) Before measurement, make sure to select the right gear, i.e. voltage gear, current gear or resistance gear, and also select the right range. The initial selection should be from large to small, so as not to break the pointer. It is prohibited to switch the range with electricity. Range selection principle is "U, I in the upper part, R in the middle of the more accurate", that is, the measurement of voltage, current, the pointer in the dial more than 1/2, the measurement of resistance, the pointer in the middle of the dial to be accurate.
(3) When measuring DC, pay attention to the polarity of the pen. Measurement of high voltage, the red and black pens should be inserted into the "2500V" and "-".
and "-" jacks, put the multimeter on the insulated bracket, and then use an insulated tool to touch the pen to the measured conductor.
(4) When measuring transistors or integrated devices, do not use R×1 and R×10k range gear.
(5) Care should be taken to prevent short-circuit and electric shock accidents during charged measurement.
(6) When not in use, the toggle switch should not be stopped in the ohm range to prevent the battery from being discharged when the meter pen is shorted.
