Re: Remote Tuned Primary (RTP) ideas...

Tesla List wrote:
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>

> 1.      Is mineral oil the best thing to use for insulation?  Or is there
> other substance (like silicone oil) that is really better?

Ordinary Transformer oil would work very well for what you're doing.

> 2.      There is one serious problem I have found.  Most small relays have
> little isolation distance between the switch elements and the coil.  An arc
> to the coil will probably blow up the control electronics (fiber optics
> prevents such a thing from blowing the operator ;-)).  Some small "safety
> relays" have a large distance between the coil and the switches that should
> work good.  They are usually pricey but they have cheap cousins.  However,
> perhaps someone knows of a perfect relay for such a use??  Big power
> contactors would be great but they are really too big for such a use.
> 3.      I would think there would be a cheap high voltage oil (or whatever)
> relay out there somewhere???  Kilovac makes HV reed relays (vacuum) but I
> think they would be over voltage and under current for this.  Is there a
> better commercial relay I could get for not too much money that would solve
> the problem straight away???  I would think a small high voltage oil relay
> would be cheap and easy to make commercially???  I have thought of putting
> the relays in a super high vacuum but that seems far too hard for me.  The
> specs are: 30KV isolation and switching, 100kHz, 2 amps RMS, and 70 amps
> peak.  The fiber optic cable isolation allows these specs to be abused
> wildly ;-)

Try using a solenoid attached to an insulating arm that will pull
up a bar that goes across the terminals.  Use a spring that will
insure solid contact when the solenoid is not engaged (bar across
the contacts).  Here is an ascii diagram of it.

                    | Solenoid |
          |     Contactor     Bar         |
           ----------     |       ----------
           | Contact |    |       | Contact |
           -----------    |       ----------
               |          |            |
               |        Spring         |    
            ===|          |            |====

Submerse everything under regular transformer oil.  Make
the conacts using 3/8" or 1/2" brass acorn nuts.  Make
the insulating rod about 2" to 2-1/2" long (metal to metal
distance).  Round the edges of the contactor bar (1/8" to 1/4"
x 1/2" brass or copper bar) nice and smooth.  Try and find a
solenoid with a minimum travel of 1/2".  This should give you an
"HV relay" good for 30 Kv.  These values are all for under
regular transformer oil such as Shell Dialax or Exxon Univolt 60.
Hope this helps!

David L. McKinnon
D&M's High Voltage