EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: MRMILSTAR on December 04, 2018, 04:40:06 am
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A few months ago I bought a used DRSSTC (dual resonant solid state tesla coil). There was no documentation with it, so no schematic. Upon studying the circuitry, I noticed that there are three 1500 uF electrolytic capacitors connected in parallel for a total of 4500 uF. The mysterious thing is that the 120 volt 60 Hz AC power line is connected directly across the terminals, so for each half cycle the polarity is wrong. The DRSSTC works well, so apparently this odd arrangement works. My question is, why don't these capacitors explode from the reverse polarity?
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They are probably Bipolar Electrolytic Capacitors.Do they have BP or NP on them anywhere?
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4500uF would have a reactance at 60Hz of 0.59 ohms, and if wired between Line and Neutral would draw a current of 195A from a 115V AC line. Even if you consider their possible ESR, its unlikely the impedance would be over 1 ohm so the current would be significantly over 100A.
That's patently ridiculous, so either your capacitors are *NOT* of the value you think they are and probably not electrolytic (e.g. could they be 1500nF oiled paper, in aluminum cans?), or you've traced the connections incorrectly and they are *NOT* directly across the AC supply.
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A photo of the capacitors might help.