Pocobor.

Exploding Capacitors

DISCLAIMER: This experiment was conducted in a controlled laboratory environment with the appropriate safety equipment and considerations. DON’T TRY THIS AT HOME!

It is often said that failure is the fastest way to success.  If you’ve ever mistakenly hooked up a capacitor backwards or exceeded the operational voltage, you’ll do your best to never do it again! With this in mind, I thought it would be interesting to intentionally trigger and document the failure of capacitors, an electronic component that we use every day at Pocobor.  I have chosen to focus on one very dramatic failure mode: explosion.  Capacitors don’t often explode, but when they do it is a remarkable event.  Capacitors all have a voltage rating that should not be exceeded (unless you want them to explode), and some capacitors, known as electrolytic capacitors, also have a preferred polarity  (one side is “+” and one side is “-“).  Reversing the polarity of these caps is an easy mistake to make and an easy way to produce an explosion. In this case it’s no mistake, but the result is the same.

In the video, I have intentionally connected two electrolytic capacitors in reverse polarity to induce an explosion.  As I slowly turn up the voltage (off camera), current starts to flow through the capacitor and heat up the interior.  DC current is not supposed to flow through capacitors, a sign of reverse polarity and looming failure.  As the heating causes pressure to build inside the capacitor, the capacitor’s end plug is pushed out of the housing, and it’s only a matter of time before the entire capacitor explodes.

Big takeaways:

  • Care must be taken to stay within a capacitor’s voltage rating  (both positive and negative)
  • Be careful to connect polar capacitors with the correct polarity
  • If care isn’t taken when using capacitors, they have the potential to be very dangerous
  • In the electronics world, capacitors are referred to as “passives”  (along with resistors, inductors, and the up-and-coming memristor), but there is nothing passive about these explosions.  Some very passive aggressive, aggressive passives?

    fail12

    10uF Electrolytic Capacitor (Reverse Polarity)

    fail2

    47uF Electrolytic Capacitor (Reverse Polarity)

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