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Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
I just remembered that I have 25x 100nF polypropylene capacitors. I tried to get some information from the datasheet, but they don't look like high quality caps. I don't quite understand the voltage derating graph, but it doesn't look good to me. So the big question, can they be used for induction heating and how much power could I force through them? They're the 630V/250VAC type. I thought if I immersed them in oil I could keep the temperature under control.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
The "knee" in the voltage derating curve, where it changes from flat to dropping 6dB/octave, tells you the RMS current rating of the cap. You just take the voltage shown on the curve at the knee point, and multiply it by 2 pi times the frequency times the capacitance.
It's also the frequency you want to run at to get the maximum kVA, since at this frequency the cap is working at its maximum rated voltage and its maximum rated current.
I agree that those Celem capacitors are rather good I got mine on Ebay.
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
That gave me about 8A per cap, so 200A with all 25 in parallel. That's only at 20kHz though.... Did you just buy your caps from celem directly and what was the shipping like, HFsstc-freak?
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
HFsstc-freak wrote ...
But he told me they are starting to fail one by one.
My celem caps costed me around 30 bucks each.
Didn't you get those at ebay, IIRC?
Does anyone actually have reliable price list of at least some celem caps? I know they are expensive, but I think lots of people would appreciate that.
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