Reasons for capacitor to burn?

Question

Reasons for capacitor to burn?

Answer 1

You are not charged by the word, why are you so unwilling to provide details?

A capacitor will smoke or burn out if you apply voltage in excess of it's rated voltage, or if you apply voltage of the wrong polarity to a polarized cap.

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Answer 2

In general this is because the capacitor shorts out. This is inevitably a result of dielectric failure.

There's several ways for this to happen:

* Overvoltage punches through the dielectric.

* Reverse voltage (for a polarized cap) heats the cap and destroys the dielectric.

* Overheating causes dielectric to break down.

The latter cause is a huge issue for power supplies: internal resistance in electrolytic caps will cause them to heat up. If they get too hot they literally explode (vent). Engineers and bean-counters often lock horns over the extra cost of low-ESR (equivalent series resistance) and extended temperature caps. Sometimes the good guys lose and this is the result.