Fireworks are still dangerous. Let’s take a deeper look at the causes of electrolytic capacitor explosions.

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

1. 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

1. 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

1. 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.

4.Capacitor Explosion Caused by Charging While Live

1. Capacitor banks of any rated voltage must not be reconnected to a live circuit. Each time a capacitor bank is reconnected, it must be fully discharged for at least 3 minutes with the switch open. Otherwise, the polarity of the instantaneous voltage upon closing may be opposite to the residual charge on the capacitor, leading to an explosion.

5. High Temperature Triggering a Capacitor Explosion

1. If the temperature of the electrolytic capacitor is too high, the internal electrolyte will rapidly vaporize and expand, eventually bursting the shell and causing an explosion. The common reasons for this are:
   • Excessive voltage leading to breakdown and a rapid increase in current flow through the capacitor.
   • Ambient temperature exceeding the capacitor’s allowed operating temperature, causing the electrolyte to boil.
   • Reversed polarity connection.

Now that you understand the causes of electrolytic capacitor explosions, it’s crucial to address the root causes to avoid such failures. Proper storage is also essential. If capacitors are exposed to direct sunlight, significant temperature differences, corrosive gases, high temperatures, or humidity, the performance of safety capacitors may degrade. If a safety capacitor has been stored for over a year, be sure to inspect its performance before use. YMIN capacitors are always reliable, so Capacitor Solutions，Ask YMIN for your applications!