Re: Higher input voltage

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

Original poster: Ed Phillips <evp-at-pacbell-dot-net> 

Tesla list wrote:
 >
 > Original poster: dhmccauley-at-spacecatlighting-dot-com
 >
 > Yes, people have gone higher than 15kV.  The biggest reason people stick to
 > 14.4kV, is availability of pole transformers.  There are higher voltage pole
 > transformers
 > and potential transformers, but higher voltage pole transformers are more
 > rare, and most potential transformers of higher voltage almost always have
 > 120VAC seconday, not
 > 240VAC.  So running large coils with potential transformers at high power is
 > more difficult with the 120VAC as the current can get very high.
 >
 > Also, with higher voltage tesla systems, corona leakage and voltage
 > stand-off becomes much more an issue.  So design can be somewhat more
 > trickier.
 >
 > Dan
 >
 >  >      I just had a quick question.  I look at a lot of the designs out
 > there
 >  > and I see that most people use NST's up to 15 kV, or lower voltage MOT's,
 >  > or pole pigs around 15 kV as well.  My question is, has anyone ever
 >  > designed a coil with a larger input voltage than 15 kV?  Maybe using 
30 or
 >  > 40 kV or even higher.  Is there a reason that most people don't go much
 >  > higher than 15 kV of input power?  Is it due to the availability of such
 >  > high voltage sources or more of the complexity involved in engineering TC
 >  > components to withstand the higher voltages?  Thanks in advance!
 >  >
 >  > Jeremy Gassmann
 >  > Cincinnati, Oh

	Cost primarily; certainly the big commercial stations used higher
voltage.  In the "good old spark days" of ham radio most guys were
restricted to a frequency GREATER than 1500 kHz and a single-turn
primary was necessary with the typical 0.01 ufd capacitors in common
use.  In the quest for higher power some well-heeled guys did go to 25
kV and there were both capacitors and transformers available
commercially.  All this happened just at the end of the spark era
(~1921) and I've never seen any of that stuff in person.

Ed