Method and precautions for the measurement of resistance with a digital multimeter
During the measurement, the positive power supply is charged to the measured capacitor Cx through the specification resistor R0, and the display shows "000" because Vc = 0 at the beginning of the charging moment. As Vc gradually grows higher, the display value increases. When Vc = 2VR, the meter starts to display the overflow symbol "1". Charge time t for the display value from "000" changes to overflow time required, the time distance can be measured by quartz meter. The use of DT830-type digital multimeter to estimate the capacitance of 0.1μF ~ thousands of microfarads capacitors, in accordance with Table 5-1 selection of resistance gear, the table gives the range of measurable capacitance and the corresponding charging time.
Digital multimeter resistance measurement method
When measuring the resistance, the reading should be seen on the scale marked with "ω" (because the current through the meter head is not proportional to the measured resistance, so the resistance scale on the dial is not uniform). The actual value of the measured resistance is equal to the reading on the scale multiplied by the multiple indicated by the knob. Before measurement, the two pens should be shorted and the zeroing potentiometer should be turned so that the pointer is at the position of 0ω, and then the appropriate stop should be selected to ensure the accuracy of the measurement. Every time you change a measurement limit, you should re-zero. In addition, the resistance measurement, must be no source and no other parallel branch circuit. After the resistance (or current) measurement is completed, the changeover switch should be rotated to the high voltage stop, which is a good habit to prevent the misuse of ohmmeter (or current stop) voltage measurement.
Precautions for digital multimeter resistance
The digital multimeter will be dialled to the appropriate resistance file, the red and black pens are differentiated to contact the two poles of the measured capacitor Cx, then the display value will be gradually increased from "000" until the display overflows with the symbol "1". If constantly display "000", marking the capacitor internal short circuit; if constantly display overflow, it can be when the capacitor internal inter-pole open circuit, can also be enough when the selected resistance file is not suitable. Test electrolytic capacitors must pay attention to, the red pen (positively charged) connected to the positive terminal of the capacitor, the black pen connected to the negative terminal of the capacitor.
