Skillfully Using the Resistance Range of a Multimeter to Test Capacitor Performance

Common faults of capacitors during use include breakdown, leakage, and failure. We can use the resistance range of a multimeter to test the performance of capacitors, and this detection method mainly utilizes the principle of capacitor discharge. The specific detection methods are as follows:

1. During detection, if the multimeter pointer swings once and then quickly returns to the "∞" position, it indicates that the capacitor performance is normal.

1. If the multimeter pointer swings once but fails to return to the "∞" position, instead pointing to a certain resistance value, it means the capacitor is leaking. This resistance value is the leakage resistance of the capacitor. Normally, the leakage resistance of small-capacity capacitors is about several tens to several hundreds of megohms. If the leakage resistance of a capacitor is less than several megohms, it cannot be used.

1. If the multimeter pointer does not move and stays at the "∞" position all the time, it indicates that the capacitor has an internal open circuit. However, for small-capacity capacitors with a capacity of less than 5000pF, this is due to the insignificant charging and discharging, so it cannot be regarded as an internal open circuit.

1. If the multimeter pointer swings to the "0" position, it indicates that the capacitor has broken down and short-circuited, and thus cannot be used.

1. If the multimeter pointer swings to a certain position in the middle of the scale and stops, and when the test leads are exchanged for re-testing, the pointer still stays at that position, just like a resistor, it means the capacitor has failed.

Precautions for detection:

1. Fixed capacitors with a capacity smaller than 10pF are too small. With a pointer multimeter, only whether they are leaking, have an internal short circuit, or are broken down can be detected.

1. For capacitors with a capacity ranging from 10pF to 0.01uF, a pointer multimeter can only detect whether they are leaking or have an internal short circuit, but cannot detect the presence of charging and discharging phenomena.

1. For capacitors with a capacity larger than 0.01uF, when measuring with a multimeter, an appropriate range must be selected according to the capacitance of the capacitor to make a correct judgment.

For measuring capacitors with a capacity of more than 300uF, the R100 ohm or R1 ohm range can be selected; for measuring 10-300uF capacitors, the R100Ω range can be used; for measuring 0.47-10uF capacitors, the R1KΩ range is applicable; for measuring 0.01-0.47uF capacitors, the R*10KΩ range can be chosen.