How to Choose a Digital Multimeter?

Digital multimeter means a mainstream multimeter, which is mainly used to test and measure capacitance value, triode magnification, diode voltage drop, etc. There are several aspects to consider when choosing a multimeter. The specific analysis is as follows:

Function

In addition to the five functions of measuring AC and DC also has functions such as digital calculation, self-test, reading hold, error readout, diode detection, and word length selection. , It should be selected according to the specific .

Range and range

Digital multimeters have many ranges, but the basic range is the most accurate . Many digital multimeters have automatic range function, no need to manually adjust the range, making the measurement convenient, safe and fast . There are also many digital multimeters with over-range capabilities. When the measured value exceeds the range but has not reached the maximum display , it is not necessary to change the range, thereby improving accuracy and resolution.

Accuracy

The maximum error allowed by a digital multimeter depends not only on its variable error, but also on its fixed error. When choosing, , and whether the resolution meets the requirements.

Input resistance and zero current

If the input resistance of the digital multimeter is too low and the zero current is too high , it will cause measurement errors. The key depends on the limit value allowed by the measurement device, that is, the internal resistance . When the signal source impedance is high, an instrument with high input impedance and low zero current should be selected so that its influence can be ignored.

Display form and power supply

The display form of the digital multimeter is not limited to numbers, but can also display charts, text and symbols, so as to facilitate on-site observation , operation and management. According to the dimensions it can be divided into four categories: small, medium, large and super large. The power supply of the digital multimeter is generally 220V, and some new digital multimeters have a wide power supply range, which can be between 1100V and 240V. Some small digital multimeters can be used with batteries.

Response time, measurement speed, frequency range

The shorter the response time, the better, but some meters have a longer response time , and it takes a while for the reading to stabilize . The measurement speed should be based on whether it is used in combination with the system test. If it is used in combination, the speed is very important, and the faster the better . The frequency range can be appropriately selected according to the needs.

AC voltage conversion form

AC voltage measurement is divided into average value conversion, peak value conversion and effective value conversion. When the waveform distortion is large, the average conversion and peak conversion are inaccurate, but the effective value conversion can not be affected by the waveform, so that the measurement results are more accurate.

Resistor connection

There are four-wire system and two-wire system for resistance measurement wiring. When measuring small resistance and high precision, the resistance measurement wiring method with four-wire system should be selected.