Why is the capacitor exploding, what is the reason?

Explosion Site 2: Aluminum Electrolytic Capacitor Under Excessive Pressure

Explosion Scene 3: Short Circuit in Supercapacitor

Explosion Site 4: High Voltage Discharge

If a capacitor explodes, its power should not be underestimated. The following is a capacitor explosion test found online by Yirong.com. After reading it, you’ll realize that even small capacitors can be dangerous.

So, what are the main reasons for a capacitor to explode? Let’s take a closer look together.

1. Reversed Polarity

For polarized capacitors, such as tantalum capacitors, connecting them backwards can lead to serious damage. When the positive and negative terminals are reversed, the capacitor may overheat and eventually explode.

2. Poor Quality or Manufacturing Issues

Capacitors with poor manufacturing quality may have internal component failures, insulation damage, or other issues. These problems can lead to breakdowns or even explosions. Always choose reputable brands for reliable performance (you can check out quality capacitors on our website).

3. Poor Sealing and Oil Leakage

If the casing is not properly sealed, moisture can enter the capacitor, reducing insulation resistance. Oil leakage can also cause a drop in oil levels, leading to internal discharges or breakdowns inside the housing.

4. Internal Gas Build-Up and Bulging

When corona discharge or internal breakdown occurs, the capacitor may experience excessive gas buildup. This can increase internal pressure, causing the casing to bulge and potentially explode. This is especially dangerous under high voltage conditions.

5. Damage to External Insulation

Poorly manufactured high-voltage leads, such as those made from thin steel sheets, can develop sharp edges or bends. These imperfections can cause corona discharge, which breaks down the oil inside the capacitor, leading to expansion, reduced oil level, and eventual breakdown. Additionally, improper welding during assembly can burn the internal insulation, generating gas and lowering the voltage rating.

6. Closing with Residual Charge

It's critical not to close a capacitor bank while it still has a charge. If the capacitor is reconnected before it's fully discharged, the voltage at the moment of closing could be opposite to the residual charge, leading to an explosion. For capacitors above 160 kvar, automatic trip devices without voltage are typically required to prevent this.

7. Overheating Leading to Explosion

High temperatures can cause the electrolyte inside the capacitor to vaporize rapidly, increasing internal pressure and possibly causing the casing to rupture. Common causes include: 1) excessive voltage causing breakdown and sudden current surge; 2) ambient temperature exceeding safe limits; and 3) reversed polarity.

Now you understand why capacitors can explode and how to avoid these dangerous situations. If you have any questions about purchasing capacitors, resistors, inductors, or diodes, feel free to reach out anytime.