Capacitor and withstand voltage?

Question

What factors influence the withstand voltage of a capacitor?

Answer 1

1 - The material; different materials can tolerate different voltages, for example, air breaks down around 30 to 100 volts per mil, whereas polypropylene can take about 17,000 volts per mil

2 - Thickness of insulator - obvious from the previous, i.e, 2 mils of air can stand off twice as much voltage as one

3 - Spacing of leads, tho of course, caps are normally designed with enough spacing between the leads such that the dielectric will breakdown long before the leads will arc

4 - Encapsulation method and material - it's possible that a cap can breakdown if the voltage can find a way AROUND the dielectric, rather than through it

That's all I can think of..... oh, maybe environment. Some dielectrics may have different breakdown at different temperatures, tho caps are specified as to environmental conditions and no guarentees are made beyond them...

Answer 2

You need a big enough capacitor to handle the Amps. Here Ya go--
Capacitors Work

by Marshall Brain



Table of Contents
Introduction to How Capacitors Work The Basics Farads Applications Lots More Information
The Basics
Like a battery, a capacitor has two terminals. Inside the capacitor, the terminals connect to two metal plates separated by a dielectric. The dielectric can be air, paper, plastic or anything else that does not conduct electricity and keeps the plates from touching each other. You can easily make a capacitor from two pieces of aluminum foil and a piece of paper. It won't be a particularly good capacitor in terms of its storage capacity, but it will work.
In an electronic circuit, a capacitor is shown like this:
When you connect a capacitor to a battery, here’s what happens:
The plate on the capacitor that attaches to the negative terminal of the battery accepts electrons that the battery is producing.
The plate on the capacitor that attaches to the positive terminal of the battery loses electrons to the battery.
Once it's charged, the capacitor has the same voltage as the battery (1.5 volts on the battery means 1.5 volts on the capacitor). For a small capacitor, the capacity is small. But large capacitors can hold quite a bit of charge. You can find capacitors as big as soda cans, for example, that hold enough charge to light a flashlight bulb for a minute or more. When you see lightning in the sky, what you are seeing is a huge capacitor where one plate is the cloud and the other plate is the ground, and the lightning is the charge releasing between these two "plates." Obviously, in a capacitor that large, you can hold a huge amount of charge!

Answer 3

if there is high enough potential between the two plates or whatever, the electrons will just start to jump across. if you stick something in between the plates however (a dielectric) it increases the breakdown voltage of the capacitor. they work by effectively increasing the electric field between the plates while themselves being very insulating in nature.

the response before saying stuff about current (or the unit of current amps) is crazy, current is what happens when the breakdown voltage of the capacitor has been exceeded.

Answer 4

The beauty of capacitor breakdown by excessive voltage is that once it goes - it goes big, because you bleed any charge stored in the capacitor through the short created by the blowout.

This can be quite spectacular....