Re: Help please - info on big CDE pulse caps?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>


----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, January 09, 2005 11:08 AM
Subject: Re: Help please - info on big CDE pulse caps?


> Original poster: FIFTYGUY@xxxxxxx
>
> In a message dated 1/9/05 11:24:51 AM Eastern Standard Time,
> tesla@xxxxxxxxxx writes:
> Also, don't neglect the possibility that it's a one of a kind for some
> special purpose.
>
>      Well, I believe there were about a dozen of these in the particular
> lot. Not to mention that they are serial numbered past the "100" range,
and
> apparently in multiple series. They also have what appear to be federal
> stock numbers. All that would appear to point to a standardized part for a
> large system.

Not necessarily.  If you were to open up, for instance, the two Mars Rovers
Spirit and Opportunity, you'd see one-of-a-kind amplifiers with serial
numbers beginning at 100 or 200, and with custom part numbers, that we had
assigned (and told the mfr to put on there with excruciating detail with
type of paint, size of letters, etc.etc.etc.).

Many, many projects require that the supplier provide the parts with part
numbers that fit our particular project numbering scheme, so that our parts
lists look consistent.  This is pretty common practice in aerospace (and
makes figuring out what that piece of surplus gear actually is quite
difficult).

Also, if there were any special inspection, test, or delivery requirements,
it's likely that the mfr would want to assign a special part number to
distinguish the part from run-of-the-mill parts.

Such things are what results in $600 toilet seats and $500 hammers.  In the
"big picture" it costs less because all the part numbers are in the same
format, etc.  For instance, part numbers might be assigned in such a way
that the subassembly that the part will go into is part of the number, or,
that the part number indicates the mfr of the part (If you've ever looked
through W.W. Grainger catalogs or McMaster Carr, you'll have seen this
technique).  Saves money at a higher level of integration, even if it drives
up the piece part costs in some ways.



>      I realize the tall insulators are at odds with high-current discharge
> ratings, but at 120KV that would be an awkwardly large diameter for a flat
> insulator on caps of this size.

High voltage pulse caps  (the kind in steel cans) use a flat insulator with
multiple ridges (to get the needed creepage distance) and are designed to
operate immersed in oil (or, possibly SF6).  Check out old Maxwell Labs
datasheets, for instance.

>

> -Phil LaBudde
>
>