How do we measure the internal resistance of an electrolytic capacitor?

I. Multimeter test

1, with a multimeter ohm file (R × 10k or R × 1k file, depending on the capacity of the capacitor), when the two pens were touching the container of the two leads, the needle first clockwise direction (to the right) swing, and then slowly to the left to return to the vicinity of ∞ position, the process of charging the capacitor.

2, when the meter needle is stationary resistance value is the capacitor leakage resistance (R). In the measurement, such as the needle from infinity farther, indicating that the capacitor leakage is serious, can not be used. Some capacitors in the measurement of leakage resistance, the needle back to infinity position, and clockwise swing, which indicates that the capacitor leakage is more serious. General requirements for leakage resistance R ≥ 500k, otherwise it can not be used.

3, for capacitors with capacity less than 5000pF, the multimeter can not measure its leakage resistance.

Second, the capacitor break

Capacitor break (also known as open circuit), breakdown (also known as short circuit) detection detection capacity of 6800pF ~ 1mF of capacitors, with R × 10k file, red, black meter stick were connected to the two pins of the capacitor, in the meter stick connected to the moment, you should be able to see the needle has a very small swing process.

If you do not see the needle swing, red and black meter stick can be interchanged once after the test, the needle swing should be slightly larger, if the needle in the above detection process, no swing, indicating that the capacitor has been disconnected.

If the needle swings to the right at a great angle, and the needle stops there (i.e., no regression phenomenon), indicating that the capacitor has been broken or serious leakage.

Note: In the detection of fingers do not touch the two sticks at the same time, in order to avoid the impact of human body resistance on the test results, at the same time, the detection of large capacitors such as electrolytic capacitors, due to its large capacity, charging time is long, so when measuring electrolytic capacitors, according to the size of the capacitor capacity, the appropriate choice of range, the smaller the capacitance, the more the range R should be put small, otherwise the capacitor charging is mistakenly thought to be breakdown.

Detection of capacitors with a capacity of less than 6800pF, due to the capacity is too small, the charging time is very short, the charging current is very small, the multimeter detection can not be seen when the needle deflection, so this time can only detect the presence of capacitor leakage fault, and can not determine whether it is open, that is, in the detection of such small capacitors, the meter needle should not be biased, if the deflection of a larger angle, indicating that the capacitor leakage or breakdown. Regarding whether there is an open-circuit fault in this type of small capacitor, it cannot be detected by this method. Can be used instead of the inspection method, or with the measurement of capacitance function of the digital multimeter to measure.

Third, the judgment of the polarity of electrolytic capacitors

Use the multimeter to measure the leakage resistance of electrolytic capacitors, and note down the size of this resistance, and then the red and black meter stick to the opposite side and then measure the leakage resistance of the capacitor, will be the two measured resistance value comparison, leakage resistance is small one time, the black meter stick contacted by the negative pole.