[Prev][Next][Index][Thread]
Re: Re. Cheap 20nF 20kV pulse caps - If it would work??
>>Because of the very long effective Rleakage*C time contants, this effect
>>only shows after extended DC operation. For Tesla Coil operation, each
Well, one situation where this can happen is this: you charge the cap
and have no discharging it. It will discharge through internal leakage.
Then you perhaps discharge it by shorting the terminals. One of the caps
might still be charged although net voltage is zero.
So, now you reconnect it to a psu having same polarity as before. (Same
ac half cycle) Every cap will be charged to some more voltage - including
the one that did not get empty before! Bang, dead cap.
This kind of situation can also happen due to dielectric adsorpsion too.
Using a dc signal to test caps is one very easy way to blow them up.
The first ac cycle will do the damage in this method. Much like the
problem described above.
>at first. I am going to leave the balance resistors in since they don't
>hurt anything and I want to run them in air where corona, finger prints,
I'd do that too. They are cheap and can prevent many problems you might
not think of. They'd also act as a discharging resistor for the cap at
no extra cost or effort.
>It will be easy to experiment with blowing this cap up since it is very
>cheap and easy to repair. Perhaps I can gain some insight as to why
Depends on how you blow it up. When one cap of a chain has been blown
up there is more voltage stress to the rest of the chain. If caps are
similar rest of the chain will fail too one by one at increasing speed.
Well, all you'd have to do is to replace one of the chains. Easy repair
perhaps, depends on how you see it.
I'd go for rated voltage myself too!
--
Harri Suomalainen mailto:haba-at-cc.hut.fi
We have phone numbers, why'd we need IP-numbers? - a person in a bus