Re: MMC corona

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

Original poster: "Trent Mullins by way of Terry Fritz <twftesla-at-uswest-dot-net>" <neontrent-at-earthlink-dot-net>

Hi Terry,

I drilled two holes in bottom of the box, put a couple brass bolts in, and
connected those bolts to the system's Rf ground.  Crude but functional.

Trent Mullins

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, December 14, 2000 9:43 PM
Subject: Re: MMC corona


| Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
|
| Hi Trent,
|
| Great to know the problem is solved!  However, I must ask, how in the
| world did you "ground" the plexiglass box?
|
| Cheers,
|
| Terry
|
|
| At 09:26 PM 12/14/2000 -0700, you wrote:
| >Terry,
| >
| >Thanks for the experiment.
| >
| >For the benefit of the rest of you, I recently had some terminal to
terminal
| >arcing on my new MMC.
| >It can viewed at:  http://hot-streamer-dot-com/TeslaCoils/MMCInfo/TrentMMC/
| >
| >There are 3 strings per perfboard.  While using 2 of the 3 strings, I had
| >arcing inside the box
| >from brass terminal to terminal.  The arcing was between the 2nd active
| >string and the 3rd inactive string right along the plexiglas box on the
| >inside.  Terry thought that maybe a static charge was building up inside
the
| >box.
| >
| >So,  I grounded the box and have since had NO problems  :-))  The
terminal
| >to terminal distance is 1 5/16".
| >
| >Thanks again Terry,
| >
| >Trent Mullins
| >
| >
| >----- Original Message -----
| >From: "Tesla list" <tesla-at-pupman-dot-com>
| >To: <tesla-at-pupman-dot-com>
| >Sent: Thursday, December 14, 2000 8:37 PM
| >Subject: MMC corona
| >
| >
| >| Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
| >|
| >| Hi All,
| >|
| >| While working on an experimental MMC, I hooked the Bertran directly
across
| >| two strings and charged the string ends to 24kV.  With my Olympus 3000
| >| digital camera I was able to take a pretty good picture of the corona
| >| between the strings:
| >|
| >| http://hot-streamer-dot-com/TeslaCoils/Misc/MMCglow.jpg
| >|
| >| This discharge starts at around 17kV and just gets worse as the voltage
is
| >| raised until it arcs over at about 25kV.  The terminals are 1.5 inches
| >| apart center to center.
| >|
| >| With a 15kV NST, the voltage between a dead and live string (this MMC
is
| >| specifically made to have selectable strings) would be only 11kV peak
AC.
| >| So It is probably ok but I thought I would share this info.
| >|
| >| Since it is really hard to solder up an MMC with ball solder joints to
| >| resist corona, there is probably a voltage level (~30kV) where
streamers
| >| will start to propagate or arcing will make an MMC impractical.  Thus
if
| >| one were to try and make an MMC for say a 50kV transformer, it would
need
| >| to be submersed in oil or something to stop this corona and the
inevitable
| >| destruction it would do at very high voltages regardless of the number
of
| >| caps per string.
| >|
| >| I should also mention that this was done at DC and the charging of the
| >| lexan and me was significant.  I could get steady 1/8 inch arcs about
once
| >| a second from my finger to a grounded object.  Some serious fields are
| >| present!  Also the negative side started corona much earlier than the
| >| positive as expected.
| >|
| >| A person had a problem with terminal to terminal arcing and this
| >experiment
| >| does not show any unusual problem.  However, perhaps my 1.5 inch
spacing
| >is
| >| greater than in his case?
| >|
| >| Cheers,
| >|
| >| Terry
| >|
| >|
| >|
| >|
| >
|
|
|
|