Application of digital multimeter in measuring resistance in automotive circuits
In the process of measuring resistance, the digital multimeter must follow the same process as the above measurement of current and voltage to obtain more accurate results. However, when measuring the resistance, when selecting the range at the beginning, the minimum range of resistance should be selected first. Insert the red test lead in the digital multimeter into the red jack indicating the resistance, and the black test lead is the same as the above insertion method. The digital multimeter itself has a certain resistance, and the internal resistance of the digital multimeter needs to be exploded and measured, so as to provide a basic guarantee for the accuracy of the measurement results of other circuit resistances in the later stage. Then, for the measurement of the digital multimeter's own resistance, it is mainly to overlap the two test leads, and the display of the digital multimeter's own resistance is mainly distinguished according to the functions of different multimeters. Generally, a normal DMM has a resistance of less than 2 ohms. Under such normal conditions, the internal resistance value of the digital multimeter itself can be measured, and the actual measurement of the external circuit can also be carried out.
In the later stage of the measurement, separate the connected test leads, adjust the resistance gear to the maximum range, and verify that there is no loading voltage in the measured circuit, then the negative pole of the battery must be disconnected. At this time, a certain method can be used to cut off the measured circuit from other circuits, so that the measured circuit exists independently. A clear resistance value can be obtained, which represents the sum of the resistance of the digital multimeter itself and the circuit under test. When the actual resistance value is two to three digits after the decimal point, it means that the range of the resistance selected before is too large. You can disconnect the test leads of the digital multimeter and convert the range of the resistance to
In the lower value, a more prepared resistance value can be obtained. The resistance value of the measured circuit can be obtained by subtracting its own resistance value from the resistance value measured in Europe.
When using a digital multimeter to carry out the resistance measurement of the measured element, it is also necessary to pay more attention to various matters. First of all, it is necessary to ensure that the battery power of the digital multimeter itself is sufficient, and to verify that there is no voltage in the measured circuit or component, and to ensure that they exist alone. When measuring, there is also a certain voltage in the human body. Therefore, it is necessary to prohibit the use of the body to touch the digital multimeter, which will affect the resistance of the digital multimeter [4]. In addition, the resistance of some airbags cannot be measured with a digital multimeter, otherwise it will cause adverse consequences. When the resistance value display is less than zero during the measurement process, the resistance range selection should be adjusted. When reading the resistance value, pay attention to the resistance symbol behind.
