Re: Capacitor safety questions

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "volitan712003" <volitan@o...>
wrote:

Divid:

Look for my comments below.

> Hello,
>
> I just ordered a 12,000uF x 100V capacitor for my power supply. I know
> capacitors can be deadly but I have no concept of what a micro farad
> is. If this cap is fully charged, is this thing big enough to kill?

Yes, it is if the voltage it's charged to is high enough.

> Another question is how can I check it so I know it's discharged. I'm
> guessing it would have too much power to hook my volt meter up
> directly.

No, voltmeters just measure voltage, they don't know anything about
power. Your voltmeter will read the voltage across the capacitor just
fine. Just STAY on VOLTAGE. The best way to discharge a capacior is
with a resistor. For that size cap I would suggest a 100 ohm 10 watt
wirewound resistor. When first connected it will draw 1 amp. The
current will drop as the voltage decreases so the resistor won't hive
time to get hot.

Good power supply design has a bleeder resistor connected across all
large capacitors to discharge them when power is removed. For this,
the resistor is always drawing current so you will want a larger
value. A 1000 ohm 20 watt resistor would be a good choice. It will
draw 100ma. from the power supply but that should not be noticable.

Regards;

Ken

> Thanks!
> David

David: