How to Measure Aluminum Electrolytic Capacitance with Capacitance File of Digital Multimeter
First, the capacitance value of electrolytic capacitor cannot be measured online, because there are distributed factors in the circuit, which is inaccurate in most cases and must be measured after welding.
Second, if it is necessary to judge whether the electrolytic capacitor is invalid online, please use ESR meter (equivalent series resistance) to judge. On-line measurement of ESR value can quickly pick out the defective electrolytic capacitors.
Third, the measurement of electrolytic capacitance is not like measuring resistance. It is difficult to judge the quality of this electrolytic capacitance once. The error of measuring electrolytic capacitance in general digital multimeter capacitance file is relatively large.
The measurement of capacitors can only be judged accurately with a mechanical watch.
Turn the multimeter to 1K or 100 ohms, and connect the two probes to the two electrodes of the measured capacitor respectively. Observe the reaction of the hands. If the hands are close to zero soon, then slowly walk back (to infinity) and stop somewhere, it shows that the capacitor is basically good. The closer the return stop position is to infinity, the better the quality, and the farther it is, the more leakage. If the multimeter needle is set to zero or near zero soon, it means that the two poles of the capacitor have a short circuit fault and cannot be used. If the stylus does not move at all when the two poles of the capacitor are connected, it means that the internal connection of the capacitor has been disconnected and can not be used.
Which range to use for measuring capacitance with multimeter depends on the approximate size of the measured capacitance to select the corresponding range:
000p, suitable for measuring capacitance less than 2000pF;
20n, suitable for measuring the capacitance between 2000pF and 20nF;
200n, suitable for measuring the capacitance between 20nF and 200nF;
2μ file, suitable for measuring the capacitance between 200nF and 2μF;
20μ range, suitable for measuring the capacitance between 2μF and 20 μ f.
