How to use the multimeter and precautions for using the multimeter

How to use the multimeter and precautions for using the multimeter
1. Be familiar with the meaning of the symbols on the dial and the main functions of the knobs and selector switches. The selection of the range should try to deflect the pointer to about 2/3 of full scale. If you do not know the magnitude of the measured voltage in advance, you should first select the highest range, and then gradually reduce to the appropriate range.
a. Measurement of AC voltage
b. Measurement of DC voltage:

2. Measuring current:
When measuring DC current, put one switch of the multimeter in the DC current block and the other switch on the appropriate range of 50ua to 500ma. The current range selection and reading method are the same as the voltage. When measuring, you must first disconnect the circuit, and then connect the multimeter to the circuit under test in accordance with the direction of the current from "+" to "-", that is, the current flows in from the red meter pen and flows out from the black meter pen. If the multimeter is connected in parallel with the load by mistake, the internal resistance of the meter head is very small, which will cause a short circuit to burn the meter. The reading method is as follows:
Actual value = indicated value × range / full deviation

3. Resistance measurement: When measuring resistance with a multimeter, the following methods should be used:
a. Select the appropriate override gear. The scale line of the multimeter ohm block is not uniform, so the selection of the multiplier block should make the pointer stay at the thinner part of the scale line, and the closer the pointer is to the middle of the scale, the more accurate the reading. In general, the pointer should be between 1/3 and 2/3 of the scale.
b. Ohm zero adjustment. Before measuring the resistance, the two test leads should be short-circuited, and the "ohmic (electrical) zero adjustment knob" should be adjusted so that the pointer just points to the zero position on the right side of the ohmic scale. If the pointer cannot be adjusted to zero, it means that the battery voltage is insufficient or there is a problem in the instrument. And every time the magnification gear is changed, the ohm zero must be adjusted again to ensure accurate measurement.
c. Reading: The reading of the meter is multiplied by the magnification, which is the resistance value of the measured resistance.

4. Matters needing attention:
a. When measuring current and voltage, it is not allowed to change the range with power on;
b. When selecting the range, first select the large one and then select the small one, try to make the measured value close to the range;
c. When measuring resistance, it cannot be charged. Because when measuring resistance, the multimeter is powered by an internal battery. If the measurement is live, it is equivalent to connecting an additional power supply, which may damage the meter head.
d. After use, the transfer switch should be in the maximum gear or neutral gear of AC voltage.

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