The structure and use of digital multimeter in detail
Multimeter, also known as multipurpose meter, multi-meter, triple meter, complicated meter, etc., is an indispensable measuring instrument in power electronics and other departments, generally to measure voltage, current and resistance as the main purpose.
Multimeter is divided into pointer multimeter and digital multimeter according to the display mode. It is a multifunctional, multi-range measuring instrument, generally the multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc. Some can also measure AC current, capacitance, inductance and some parameters of semiconductors (e.g., β), etc. The multimeter is a kind of measuring instrument with a rectifier, which can be used for the measurement of voltage and resistance.
Multimeter is a kind of magneto-electric instrument with rectifier, which can measure various electrical parameters such as AC and DC current, voltage and resistance. For each electrical quantity, there are generally several ranges.
Also known as a multi-meter or simply multi-meter. A multimeter consists of a magneto-electric ammeter (meter head), a measurement circuit, and a selector switch. By changing the selector switch, a variety of electrical parameters can be easily measured. The main basis for circuit calculation is the closed circuit Ohm's law. There are many types of multimeters, which should be selected according to different requirements.
Multimeter to MF30-type pointer multimeter and DT840-type digital multimeter as an example, to understand its structure and performance, learn to use the multimeter to correctly measure the voltage, current, resistance and other basic power methods, familiar with the use of precautions.
1. Structure of Pointer Multimeter
Mainly by the head, measuring line, switch three parts. The structure is shown in Figure 3.12.
The use of pointer multimeter, the main attention to the following points:
(1) Before use, the head pointer should be zeroed.
(2) Before measurement, according to the item and size of the measured power, the transfer switch should be dialed to the appropriate position.
(3) Measurement is complete, the transfer switch should be dialed to the highest AC voltage file, some multimeter (such as 500 type) should be dialed to the transfer switch labeled "." The neutral position.
2, AC voltage measurement
(1) Before measurement, switch to the corresponding AC voltage range. If you do not know the size of the measured voltage, the range should be placed in the highest grade to avoid damage to the meter head.
(2) When measuring, connect the meter pens in parallel to the measured circuit or the measured components. It is strictly prohibited to toggle the changeover switch to select the range during the measurement.
(3) When measuring voltage, develop the habit of one-handed operation and concentrate your attention highly.
(4) As the dial AC voltage scale is calibrated according to sinusoidal AC, if the measured quantity is not sinusoidal, the error will be larger.
(5) The frequency range of measurable AC voltage is generally 45HZ ∽ 1000HZ, if more than the range, the error will increase.
