[TCML] Another MMC question.

[huil888]

Hello Bart -

How were the "temperature rise" values determined for this chart? As a 
purely calculated value, it seems like you'd need to know the dielectric 
loss factor for the cap, the operating frequency, the thermal mass of the 
cap, etc.

Terry Fritz' original test setup used an RF power supply to pump 3.5A at 350 
KHz through the cap, and then measured the temperature rise after 15 
minutes. Terry's test setup can be seen at:

http://www.hot-streamer.com/TeslaCoils/MMCInfo/GeekCaps/GeekCaps.htm

Terry's formulas for determining the power handling capability of an MMC are 
at:

http://www.hot-streamer.com/TeslaCoils/MMCInfo/MMCPower4.html

I'm just curious how the temperature rise info was obtained, for use in 
calculating the temp rise for other types of capacitors.

Regards,
Scott Hanson





----- Original Message ----- 
From: "Barton B. Anderson" <bartb at classictesla.com>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Sent: Wednesday, December 12, 2007 9:14 PM
Subject: Re: [TCML] Another MMC question.


> Hi Michael, All,
>
> I deleted that old MMC Cap Chart. I created another chart in the way "I" 
> would do it for the 0.15uF CD cap which is so common. The chart is good 
> only for that cap. I basically added Vp and Temp Rise for a given 
> transformer type and then added combinations to meet the value for 
> Resonant, Static LTR, and SRSG LTR.
>
> Basically:
> The higher the voltage rating = the better the cap.
> The lower the Temp Rise = the better the cap.
>
> For a given NST type, I stopped when the MMC met or exceeded 2.5 x Vp and 
> if the temperature rise per cap in degrees centigrade was below 2 (when 
> both conditions were met). In all cases, the temp rise is either "good" or 
> "excellent". It's the standoff voltage really that is of the most concern 
> with this particular chart.
>
> Like I've said in the past, I don't use charts, but for those that prefer 
> a chart to get "as near as possible to stated LTR sizes", this one should 
> help (and if you can't understand if the string combo is good or bad, then 
> just ask the TCML). Due to the single cap value (0.15uF), the "nearest" 
> mmc value must be used. The old chart didn't really explain that. With 
> this chart, the value you see is the actual value of the mmc. Just 
> something I noticed while going through numbers on the old chart.
>
> http://www.classictesla.com/download/mmc_cap_chart.pdf
>
> This chart is 60Hz only. If there are "any" 50Hz coilers desiring the 
> same, just let me know. It's no big deal (but please ask while it's still 
> fresh in my brain).
>
> Take care,
> Bart
> _______________________________________________
> Tesla mailing list
> Tesla at www.pupman.com
> http://www.pupman.com/mailman/listinfo/tesla
>