Re: RSG gap at side of electrode.

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

Original poster: "tesla by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-paradise-dot-net.nz>

Thanks Terry.
This was the site I used to find the expansion coeff and I can see that I
mis read the number and my note was in error the expansion will be 4.5 times
the figure I quoted. Still a small number thought
Tnx
Ted L Out
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, November 26, 2002 12:37 PM
Subject: Re: RSG gap at side of electrode.


 > Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
 >
 > Hi Ted,
 >
 > http://www.webelements-dot-com/webelements/elements/text/W/heat.html
 >
 > tells more about elements than anyone really wants to know ;-))
 >
 > For tungsten, the magic number is 4.5 E-6 / C.
 >
 > For every degree C you raise the temperature, it will expand 0.0000045 of
 > what it was.  +4.5 x10^-6 / C
 >
 > So if I have a 1 inch tungsten block and I heat it from 25C to 1000C it
 > will end up at...
 >
 > 1.0043875 inches...
 >
 > Your calculations are correct.  I would worry more about any plastics
 > expanding or deforming from centrifugial forces and such.  But, we are
 > still talking the thickness of a sheet of paper...
 >
 > Cheers,
 >
 >          Terry
 >
 >
 > At 11:59 AM 11/26/2002 +1300, you wrote:
 > >Hi Ed
 > >Ted in NZ here
 > >Looking at the thermal coefficient of expansion for Tungsten (assuming
that
 > >is what you use) is 1 part per million per deg kelvin.
 > >So if a 200mm rotor heats up by an average of 100deg delta L is 0.02mm
 > >
 > >I'm not a mechanical engineer dealing in this stuff so forgive me if I've
 > >stuffed up but as you can see with tungsten delta L is pretty small.
 > >
 > >Other designs with other metals will be quite different but all in all
 > >expansion is relatively small and only a problem with high power, longer
 > >rotors and very close gaps. Again my problem was with brass rotor of 5mm
dia
 > >220mm long running over 5kva and I'd set up the gaps very tight.
 > >
 > >Best
 > >Ted L in NZ
 > >----- Original Message -----
 > >From: "Tesla list" <tesla-at-pupman-dot-com>
 > >To: <tesla-at-pupman-dot-com>
 > >Sent: Tuesday, November 26, 2002 11:08 AM
 > >Subject: Re: RSG gap at side of electrode.
 > >
 > >
 > > > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
 > ><Esondrmn-at-aol-dot-com>
 > > >
 > > > In a message dated 11/24/02 2:09:50 PM Pacific Standard Time,
 > > > tesla-at-pupman-dot-com writes:
 > > >
 > > >
 > > >
 > > > >Subject: RSG gap at side of electrode.
 > > > >
 > > > >Tnx Pete I think that would work well and might have other advantages
 > >too.
 > > > >I would not want to over state the expansion problem, it arose for me
at
 > > > >very high power and in special circumstances (ie brass rod rotor) and
is
 > > > >very easily accounted for with a small extra amount of clearance to
the
 > > > >fixed electrodes.
 > > > >Best
 > > > >Ted L
 > > >
 > > >
 > > > Since I am in the process of building a new rotary gap, I find this
 > > > discussion interesting.  With the stationary electrodes set to the
outside
 > > > of the rotating electrodes - will the diameter of the rotating
electrodes
 > > > increase when comparing the static dimension to the clearance when it
 > >comes
 > > > up to speed?
 > > >
 > > > Ed Sonderman
 > > >
 > > >
 > > >
 >
 >
 >
 >