Hi all,
I made a 'post' a while back about my Ricci transformer that wouldn't work.
After trying long it turned out to be working fine. It is a 9-50 trafo.
Resonant cap value is 0.017684 uF. (I live in EU)LTR is then: 0.026526 uF.
My first question is concerning the LTR value. Is it safer to go higher than this value? Or does it have no impact on safety (and performance)?
I did some calculations using a 0.15 uF 2kV cap for the MMC. If I use 2 strings in parallel with 12 caps in series I get a capacitance of 0.0249 uF. Using 11 in one string gives a capacitance of 0.0272 uF.
These options are both very realistic to me but which is the better setup? 2 caps more doesn't really disadvantage me in terms of costs. However a 3 string of 17 is really goes to the boundary. (It would give 0.0264 uF)
For the MMC I want to use the most popular caps but they seem to be out of stock in my country. I decided to look for similar ones. I found one from Kemet.
This is the link: https://nl.mouser.com/ProductDetail/Evox-Rifa-KEMET/PHE450SR6150JR06L2?qs=sGAEpiMZZMv1cc3ydrPrF85GIl804cbNdYhnhUR0dRE%3d
Life time is missing from this page while it is present on the CD 940C series caps. https://nl.mouser.com/ProductDetail/Cornell-Dubilier-CDE/940C20P15K-F/?qs=11kF6y5Z3OhbthK%252bpYczHA%3D%3D
It does have a higher VAC of 700. Is this beneficial? And most importantly has anyone ever used these? If so can you recommend them? They are significantly cheaper.
In the TCML archives there was already one asking the same. As a reply someone answered: "I don't think those capacitor will work for Tesla coils. If you look at the curves of applied voltage vs frequency on the web site, these capacitors roll off at much lower frequencies than we work with. In other words we couldn't apply a high voltage to them at primary/secondary frequencies."Links that were provided by him and other repliers do not work anymore. (http://www.kemet.com/kemet/web/homepage/kechome.nsf/file/PHE450%20Series/$file/F3294_PHE450.pdf).
However Bert Hickman said the following about the caps: "The series is rated for high frequency applications with high current stress. Sounds like a potential TC MMC app to me... :^)."
I did find a page containing the information however I do not know if this is the same that was on the site once.
After some digging I found it in someone's PhD Thesis. In the datasheets is the page it's about the PHE450 series. To find it quickly for you it's on page 8 of the Datasheets. The Datasheets begin on page 259. ; )
This is the link of the paper: https://dspace.lib.cranfield.ac.uk/bitstream/1826/8574/.../Aldhaher_S_Thesis_2014.pdf
This person used one of the PHE450 series: https://www.youtube.com/watch?v=Uh3sLMV2jeY (The caps don't look similar to the picture on Mouser)
From what I see on Mouser it should be fine except for that some data is not there, for example ESR value. So should I wait for the most popular or go with these? It is the first time I am building a MMC so please forgive my lack of understanding.
I hope I have provided enough information.
My kind regards,
Yesn
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