Is it possible to use an electrolytic capacitor in a high voltage application without causing problems ? If so what are the advantages and disadvantages to doing so .

 

What do you consider high-voltage? 300VDC? 1000Vdc?

hgmjr

 

above 24 V

 

I just checked digi-key and they sell a 180uFd at 500V. Now the rule of thumb is that the voltage rating of a capacitor is derated at least by a factor of 2 which means this particular capacitor will provide many years of reliable service when used in a circuit that never subjects it to a voltage greater than 250VDC.

One thing to be avoided when it comes to any polarized capacitor be it electolytic or tantalum or whatever is applying reverse voltage across the capacitor.

hgmjr

 

hgmjr gave you great scoop - he was just in a hurry to give it to you before I beat him to the punch.

But to somewhat emphasize what he's talking about:

The voltage rating of a capacitor is derated at least by a factor of 2; which means this particular capacitor will provide many years of reliable service, when used in a circuit that never subjects it to a voltage greater than 250VDC.

One thing to be avoided when it comes to any polarized capacitor, be it electolytic, tantalum or other, is applying reverse voltage across said capacitor.

If that happens, expect pops, flashes, and smoke.

 

50V electrolytics are very common, as long as you aren't applying a reverse voltage you're fine.

 

Now the rule of thumb is that the voltage rating of a capacitor is derated at least by a factor of 2

This applies mostly to tantalums -- they are vey voltage sensitive. Aluminum electrolytics can be operated at up to 80% of the rated voltage -- it is operating temperature that ages them faster. Designers often overlook the ripple current rating of them and end up reducing their lifetime -- ripple current causes heating. Many capacitor manufacturers have derating guidelines on their website.

 

This applies mostly to tantalums -- they are vey voltage sensitive. Aluminum electrolytics can be operated at up to 80% of the rated voltage -- it is operating temperature that ages them faster. Designers often overlook the ripple current rating of them and end up reducing their lifetime -- ripple current causes heating. Many capacitor manufacturers have derating guidelines on their website.

Well put! Many other students at school that are working on their first designs are shocked to find out there is more to voltage rating and capacitance when selecting a capacitor. It's amazing how such a small and simple device can have so many parameters that are essential to respect and be aware of for a successful and reliable circuit.

 

Thanx for the info. I'll be sure to keep these things in mind when designing my next circuit.