How do you test a failed capacitor?

Meters such as the Fluke 110, 170, and 180 series can provide the required data necessary to determine the presence of a failed capacitor. Although other test methods are available, such as live testing, this technical note is centered on testing capacitors in their de-energized state.

How to know if a film capacitor is failing?

For film capacitors, the typical failure mode is capacitance decrease due to self-healing, so it is possible to diagnose the life expectancy by understanding the capacitance change. Capacitors fabricated with reliable technology and strictly controlled processes can enhance the performance and reliability of electronic circuits.

How do you know if a capacitor is faulty?

As with externally fused capacitors, IEEE Std. 18 specifies capacitance readings in the 0 to +10% range. In reality, internally fused capacitors will be in the 0 to +2% range. These capacitors will show signs of failure in the following three ways:

How to prevent a capacitor failure?

Such failures can be avoided with preventive maintenance action such as replacing the capacitor. For film capacitors, the typical failure mode is capacitance decrease due to self-healing, so it is possible to diagnose the life expectancy by understanding the capacitance change.

How do you test a capacitor?

Due to their relatively low capacitance (0.20uF to 100.00uF), testing of the capacitors can be done with many standard digital multi-meters (DMM's). Meters such as the Fluke 110, 170, and 180 series can provide the required data necessary to determine the presence of a failed capacitor.

What type of capacitor is most likely to fail?

Mica and tantalum capacitors are more likely to fail in the early period of use (early failure), while aluminum electrolytic capacitors are more likely to experience wear-out failure due to aging use. In the case of film capacitors, when a local short circuit failure occurs, the shorted area may temporarily self-heal.