Electrolytic Capacitor Explosion: A Different Kind of Firework
When an electrolytic capacitor explodes, its power should not be underestimated. Here are the most common causes of capacitor explosions, so be cautious during assembly!
1. Reverse Polarity
- For polarized capacitors like bullhorn capacitors, connecting the positive and negative terminals in reverse can cause the capacitor to burn out in mild cases, or lead to an explosion in more severe cases.
2. Bulging
- When partial discharge, dielectric breakdown, and severe ionization occur inside the capacitor, the overvoltage reduces the starting ionization voltage below the working electric field strength. This triggers a series of physical, chemical, and electrical effects, accelerating insulation degradation, gas production, and creating a vicious cycle. The increasing internal pressure causes the capacitor shell to bulge and potentially explode.
3.Damaged Insulation of the Shell
- The high-voltage side of an electrolytic capacitor‘s leads is made of thin steel sheets. If manufacturing quality is poor—such as uneven edges, burrs, or sharp bends—the sharp points can cause partial discharge. This discharge can break down the oil, cause the casing to expand, and lower the oil level, leading to insulation failure. Additionally, if the corner welds are overheated during sealing, it can damage internal insulation, producing oil stains and gas, drastically lowering voltage and causing failure.