The four main causes of CBB film capacitors failure

Under normal circumstances, if a CBB capacitor is purchased of qualified quality and is selected and used correctly, its lifespan is particularly long. For example, KYET's CBB capacitors are generally designed to have a lifespan of up to 100,000 hours and are generally not damaged. However, if the selection and use are improper, it is easy to cause damage to CBB film capacitors. Below are the four most common reasons that cause CBB capacitors to be damaged.

1. High Temperatures Cause CBB Capacitor Damage.

Most electronic components are sensitive to high temperatures, and CBB capacitors are no exception. If the operating temperature of a CBB capacitor is too high, it can easily lead to rapid damage.

Generally, film capacitors made of high-temperature resistant materials can operate normally in temperatures ranging from -40℃ to +105℃. However, exceeding this operating temperature range accelerates the thermal aging of the film capacitor, reducing its service life and, in severe cases, causing it to explode. In fact, the vast majority of damage to qualified CBB capacitors is caused by excessively high operating temperatures.

2. Caused by excessive operating current.

When selecting CBB capacitors, their current rating must also be considered. The current in the circuit must be less than the allowable current of the film capacitor; otherwise, the film capacitor will overheat. Over time, this will not only shorten the lifespan of the film capacitor but may also cause it to explode and ignite in severe cases.

3. Caused by excessively high operating voltage.

When selecting CBB capacitors, pay attention to their rated voltage. If the voltage applied to the circuit is too high, far exceeding the rated operating voltage of the film capacitor, partial discharge will occur inside the film capacitor, causing it to break down and become unusable. Therefore, allow for a larger margin in voltage withstand to prevent damage to the CBB capacitor.

Also, be aware that many inferior CBB capacitors on the market are commonly sold with substandard voltage ratings, meaning low-voltage CBB capacitors are passed off as high-voltage ones. This results in insufficient voltage withstand margin in the circuit, further damaging the circuit due to excessively high voltage. When selecting CBB capacitors, avoid choosing neutral capacitors without a brand name printed on them; instead, choose reputable, brand-name CBB capacitors.

4. Presence of Harmonic Currents

When selecting components, in addition to considering the normal current, we also need to consider the presence of harmonic currents. For example, the superposition of higher-order harmonic currents with the fundamental current can lead to an increase in the total current flowing into the film capacitor.

Higher-order harmonics can cause parallel resonance between the system's inductive reactance and the film capacitor's capacitive reactance, potentially causing the film capacitor to withstand higher and larger currents.

Local series resonance of the film capacitor with respect to a certain higher-order harmonic can cause overload, internal expansion of the film capacitor, and ultimately, an explosion leading to failure.