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Re: Rotary Spark Gap specs.


From: 	Benson_Barry%PAX5-at-mr.nawcad.navy.mil[SMTP:Benson_Barry%PAX5-at-mr.nawcad.navy.mil]
Sent: 	Sunday, November 23, 1997 2:00 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Rotary Spark Gap specs.


Hi Joshua, All,
     
     The following is a repost of the specs. for my
system using the H & R transformers.  I burned up two
of these transformers before I realized that the secondary
connections were too close together.  If you have the
lug type, remove one of the secondary wires.  Splice it
with solder to another wire and insulate them with teflon
heat shrink and a blob of silicone rubber.  The lugs are
too close together and will arc from transients thus
incinerating the secondary before you can turn off the
power.  I also put safety gaps across the secondarys
(wired in series with the low points grounded and
primaries reversed w.r.t. each other).  The gaps are set to
just not arc when the secondaries are operated without
any external load.  To keep the current down below the
20 Ampere circuit breaker limit I ran the secondaries
through a big choke consisting of two 100 turn windings
with RG 58 with the braid removed.  I haven't cooked
a transformer in 10 years of operation since.

     The cores of fried transformers make very good
chokes also.
     

"SYSTEMS, BARRY

Secondary Height=27"
Diameter=6"
Turns=~630
Wire diameter=#18 gauge (.0421")
Top terminal Type, Size=toroid, 5 high X 20"diameter
Resonant Frequency with terminal=~200khz
Q without terminal (optional)=haven't measured
Q with terminal (optional)=""""""

Primary cap value=.04
Peak primary cap voltage=14kv (2 5kv photocopier transformers in series x
1.414)
Breaks per sec=14 X 1750 / 60 = 408
Output length to grounded rod=56""

6.  I wrote an excel sheet to estimate my coil properties and was
wondering if anybody out in TC land has tried a coil with the H&R 10KV -at-
300mA xfmrs and knows good values for :
    Cap rating-----I use four ( 0.04uF) 30 kV DC rated capacitors
                             from CSI that are spec.d for 300 kHz operation 
in
                             induction heater service (polypropylene
                             with extended foil construction, 0.01 uF
                             each unit).
    Primary dimensions-----10" I.D. X 24" O.D., 6 turns of
                                             5/8" copper refridgeration 
tubing,
                                             tapped at the 5'th turn with a 
big
                                             gator clip.
    Secondary dimensions w/wo toroid-----see above
    Rotary gap ratings-----see above

CAUTION-----These transformers are very dangerous due to the
high current rating.  Keep the line cord in your pocket when
making adjustments!
                    Barry


I know that this is alot to swallow but if one of you experienced guys
can answer these for me, perhaps someday I'll be able to answer
questions for another newbie!!!!!

Thanks alot.
Sincerely,
Joshua Resnick