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Re: [Amps] Test versus working voltage for oil filled capacitor

Subject: Re: [Amps] Test versus working voltage for oil filled capacitor
From: Alan Ibbetson <>
Date: Thu, 16 Apr 2015 19:28:03 +0100
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My original post had a misleading typo: my capacitors weigh 10Kg not 10lb each. Sorry. They sound very similar to the CDE ones from Henry that Jim describes.

I have tested each unit for temperature rise when carrying 3A ripple current at 50Hz, using a carefully fused variac on UK mains. I clamped a temperature probe to the case for hands-free measurement. The bottom line is I can't see any temperature rise in one hour - confirmed by hand after removing the mains connection. I don't doubt these things are not purpose made for HT PSU applications but as far as ripple current goes they seem fine.

I do not yet have the means to charge the caps to 3KV in finite time for hi-potting so I will need to scratch build a PSU using a junk box transformer I have.

Thanks to everyone for your help.

73, Alan G3XAQ

On 15/04/2015 14:38, Jim Thomson wrote:
##  They will run fine at 3 kv no load.   Dunno about 2A ripple current though.
They are light.  Mine were from henry radio, made by CDE.   8 x 4 x 12  and 
30 lbs each, rated at 42 uf @ 4500 V.     Mount them vertically.
Also insulate them from any metal chassis, and metal sidewalls....and also from
the 2nd oil cap.     IE:   Treat them  like hv electrolytics.  If you see oil 
stating to leak
around the insulators, stop using them.  Your caps are no doubt pulse type 
rated caps,
and they usually have high ESR.  On any pulse rated oil cap, don’t runt them at 
any more than
60% of their stamped rating.

Jim  VE7RF

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