New here First Post Cap question 2x10nf 37.5kv

[HVfun]

I have a couple large box caps that are about 65mm x110mmx200mm They have (EFD Sp2512 2x10nF +/-10% 37.5KV 00/3 670) stamped on them. They have 3 wires coming out of them. If I measure the two outside wires it measures 5nf. If I go one outside and to center wire it reads 10nf.  I assume that I can only use either one at 10nf or together at 5nf.But not two single 10nf caps. Is this correct. Also the 35KV would that be for each side or in series? They came out of a 150kv X ray tank. These were in oil. I assume I would need to put them back in oil to be able to use them. Am I thinking correctly?


I would like to use them in a small TC. More on that later.

thanks in advance

[Mads Barnkob]

Hi HVfun and welcome to HVF!

I would assume that they are in series and the way the connections are arranged is to make it easier to construct a voltage doubler simply by adding diodes to the brass mounting holes / wires.

Unfortunately the EFD model numbers does not make much sense, there is a famous SP2550-2 capacitor (3.75uF 680Arms snubber capacitor), but that is way different from this.

Does it feel empty/hollow? I can follow your worries about them needing to be under oil when they got holes into it from where the wires come out.

[HVfun]

Yes it looks like this was part of a full wave voltage multiplier circuit. There was some diode boards that contained 11 c37-10 diodes in series per side. There were two of the diode boards and two small transformers that had large flat wire primary's and 30 awg secondaries. I think the secondaries were connected to the diodes and then to the caps in a multiplier circuit. The tank these came out of had a sticker 256v primary 1 phase 15khz.

See attached pics of diodes and small transformers.

I wonder what the output of the little transformer would be. I looks like it was ran through a Eupec 96amp SCR Doubler w/aux Cathode. I need to make a little tank to hold the transformer in oil I think to try it. Do you think it will work on 60hz mains thru a variac or only work at 15khz?

The large box caps seem hollow. Not potted. I can move the center wire around a bit and it moves a board or plate inside. I can jiggle the box and hear a thud as a plate or something is moving a little inside.

How do I tell what side is positive and what side is negative or does it matter for these caps?