Talking about the Use of Digital Multimeter
The multimeter was originally used to measure the three physical quantities of voltage, resistance, and current, so it is also called a multimeter. With the advancement of science and technology, the functions of multimeters have been continuously improved, and the new multimeters have added functions such as temperature measurement, frequency measurement, diode measurement, and triode measurement; the types of multimeters have also expanded from pointer types to numbers that can directly display measurement results Mode. Nowadays, digital multimeters are widely used because of their advantages of simple operation, portability, and quick readings. They are often used in electrical technology for circuit maintenance, electrical component diagnosis, and circuit wiring. This article is aimed at operations such as digital maintenance, electrical component diagnosis, and circuit wiring. This article discusses the use of digital multimeters, in order to provide valuable reference for beginners in electrician.
1 Precautions for use
(1) Carefully read the instruction manual to understand the structure of each part of the digital multimeter, and master its various functions and parameter limits during use.
(2) Determine the measurement items before measurement, determine the measurement method, and select the appropriate range. When measuring an unknown voltage or current, first turn the rotary switch to the maximum range, and then select a suitable range after a test.
(3) Before each measurement, check whether the sockets of the red and black test leads are correct, whether they are in the required function position, and whether the selection of the measuring range is appropriate.
(4) During the measurement process, it is strictly forbidden to switch the function gear at will. If it is really necessary to switch the function gear, the two test leads should be removed before the operation. Similarly, after the measurement, the test leads should be removed first and then switched to the OFF position.
(5) When measuring, use one hand to hold the insulating part of the red and black test leads for operation.
2. Basic usage
voltage measurement
When measuring DC voltage, firstly insert the black and red test leads into the common port and the V function jack; then turn the rotary switch to V- or mV-position (Note: If the measured DC voltage is unknown, you should first turn the rotary switch Turn to V- position); Finally, connect the two test leads in parallel to the two ends of the electric component or power supply. At this time, it should be noted that the red and black test leads correspond to the positive and negative poles of the electric component or power supply. After the value is stable, the value of the measured DC voltage will be displayed on the LCD.
The measurement method of AC voltage is basically the same as that of DC voltage, the difference is that the knob should be turned to V~ or mV~, and there is no difference between positive and negative voltage when measuring.
2.2 Measurement of current
When measuring DC current, first insert the black test lead into the COM public port, and the red test lead into the 10A or mA jack (note: if the current is greater than 400mA, choose the 10A jack, and if the current is less than 400mA, choose the mA jack); then turn the knob switch to A- or mA- or uA- (Note: If the measured DC current is unknown, first turn the knob to A-); finally, connect the digital multimeter to the circuit under test. At this time, attention should be paid to the The red and black test leads should correspond to the high potential and low potential of the circuit under test respectively.
The measurement method of AC current is basically the same as that of DC current, the difference is that the knob should be turned to A~ or mA~ or uA~, and the test leads have no polarity
2.3 Measurement of Resistance
When measuring resistance, firstly insert the black and red test leads into the common port and the Ω functional jack; then turn the rotary switch to Ω; finally connect the test leads to both ends of the measured resistance in parallel. At this time, it should be noted that the measured resistance should be in an open circuit, and the hands should not touch the metal part of the test lead. After the value is stable, read the resistance value and unit on the display.
2.4 Diode measurement
Digital multimeters are widely used in diode measurement, and can measure the quality, polarity, and conduction voltage drop of diodes. First, insert the black and red test leads into the public port and the diode function jack respectively; then turn the rotary switch to the diode function position;
For a good diode with known polarity, connect the red and black test leads to its positive and negative poles respectively, and the value on the display at this time is the conduction voltage drop of the diode.
