Re: Caps DC to AC rating

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi,

The version 2.2 does ask for the "DC" rating.  Pershaps there is on older
version that had it wrong but I thought it always asked for the "DC".  Let
me know if there is indded an error.

http://hot-streamer-dot-com/TeslaCoils/programs/Mmccalc2.zip

Cheers,

	Terry
	terrellf-at-qwest-dot-net

At 07:09 PM 1/17/2001 -0800, you wrote:
>Hi Terry,
>
>Seems we are "asking" for AC ratings in the various programs when we are
>concerned with DC ratings. I think we are assuming DC ratings in the calcs. I
>think the programs only require a simple label change for this particular 
>input.
>
>Bart
>
>Tesla list wrote:
>
>> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>>
>> Hi Kevin,
>>
>> At 08:58 PM 1/17/2001 +0000, you wrote:
>> >In Terry’s MMC calculator, I am asked for a caps AC voltage rating. Given
>> >the caps DC rating, how do I get the AC rating?
>>
>> The program askes for the DC voltage of each individual capacitor.  This
>> value is used as the maximum peak voltage on each cap.
>>
>> If one has say 10000 VAC the peak is 1.414 times that or 14140 volts.
>>
>> Vpeak = SQRT(2) x Vac     <--- Basic important equation
>>
>> So if you have a 15kV transformer and 1600 volt DC caps, the peak
voltage is:
>>
>> 15000 x 1.414 = 21213 volts
>>
>> The number of caps needed is 21213 / 1600 = 13.26 caps.
>>
>> Note that many people run the caps at a bit higher voltage to save money
>> since the caps don't seem to mind.
>>
>> The caps are actually rated around 630 volts AC for standard poly caps but
>> that rating is for full time AC use which really does not apply to us.  We
>> just worry about the peak voltage where they will start to break down.
>>
>> I hope that is what you were asking.
>>
>> Cheers,
>>
>>         Terry
>>
>> >I found a few references to
>> >this question in the archive. From what I could understand the AC rating
>> >will be somewhat lower than the DC rating. And the caps actual AC voltage
>> >rating is inversely proportional to frequency due to partial discharge and
>> >properties intrinsic of the dielectric. But I couldn’t find a definite
>> >equation. If anyone has an equation or at least a general guide, please
post
>> >it. Thanks, Kevin, thebiggiantkevin-at-hotmail-dot-com
>> >_________________________________________________________________
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>> >
>