Re: high voltage measurement w/ divider

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 2/4/03 9:11:56 PM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:
>Jim,
>
>I beg to differ. If one resistor fails (i.e. flashes over) the additional
>stress on the rest will start a chain reaction ending with a high energy
>discharge (but this is getting off topic).
>
>My 2-cents,
>Brian B.
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Tuesday, February 04, 2003 6:52 PM
>To: tesla-at-pupman-dot-com
>Subject: Re: high voltage measurement w/ divider
>
>
>Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><jimlux-at-earthlink-dot-net>
>
>No shrapnel involved.. Even if one resistor fails, the rest will limit the
>current, until they fail so you don't get the big peak currents needed for
>explosions.. Big snap, smoke, flames, but probably not explosions.
>
>That's not to say that one shouldn't be careful with large amounts of stored
>energy available.... There are plenty of other places for untoward rapid
>energy release..


Brian, Jim,

I have to go with Jim on this one :-) We're talking about (10) 10 mega
Ohm resistors in series. That's 100 megaOhms of resistance! So if one
of the resistors did fail as a direct short or 0 Ohms, that would still leave
90 megaOhms of resistance to "only" 10 kVDC. That would still only
allow 0.11 mA of current through the remaining 9 resistors. I don't
think that's going to cause any fireworks :-) BTW, from glancing at
Brian's attached page, it appears that the failure was caused by
flashover, not resistor failure. And yes, flashover failure in the multi-
kJ range is spectacular to say the least!

David Rieben