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Re: A primary concern...
Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>
I think you have emphatically shown why it is not a good
idea to ground any mains connected eqpt. to the RF ground. ALL amins
connected equipment should be earthed to the mains earth since it
provides the lowest impedance back to the grounded neutral wire.
Sorry to hear about your variacs. Others out there take note.
On 9 Mar 01, at 16:46, Tesla list wrote:
> Original poster: "BunnyKiller by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <bigfoo39-at-telocity-dot-com>
> Hi All...
> after a week of playing around with the dual piggie setup, I've come
> to the conclusion that the higher voltage output (280V-at-120X = 30KV+)
> is more trouble than what it is worth. To start, insulating properties
> and wiring is pushed to its limits. Since I dont have 30KV rated wire,
> any point ( even semi conductive (( dry wood)) ) that is within 1" of
> the wire becomes a path to ground. Previous safety gap settings are
> way too small, and the spark gaps require major reconsiderations.
> Also, if the RF ground wire is ANYwhere near the pig, it creates nasty
> feedback problems to the variacs. ( yes I fried my variacs :( all
> it took was one good discharge to the safety gap and POOF goes the
> Variacs, and this was at 40% of the dial , the only thing i can think
> of was that the wire leading from the center ball of the safety gap
> was about 1/2" from the pig case, the safety gap fired which hi volted
> the case which in turn high volted the straps inside the case that
> feed the variac voltage to the transformers. Thus the hi potential of
> the case went for the lower potential ( the 240 feed) and OOOOPS.
> Lesson learned here, ground out the pig case to either a dedicated
> ground or to the system ground, not the RF ground.
> I like challenges but i dont like frying my equipment... so I think
> ill do the parallel piggies instead of series piggies after I rebuild
> the variacs.....
> done some math and 14400 -at- 1.4A = 30KV -at- .6A approximately...
> now since I've bored yall to death here is a question....
> I'm thinking of taking 1/2" Cu tubing and running it thru a roller
> press to flatten it into a ribbon, this should result in a width of
> .8" approximately. What I have planned is to do this for 3/4's of the
> length and leave the other 1/4 length as tubular form ( for tapping)
> what we would have here is 3/4's of the primary as a ribbon form and
> the last 1/4 as a tubular form ( this is mainly an idea to reduce the
> overall primary diameter). How would this affect the mag field of the
> primary??? Would it be detrimental or no difference?
> thinking again .....
> Scot D