RE: Primary Strikes, how serious/bad?

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

HI,

I would like to "sort of" agree with Gary...

A streamer does not have enough current or energy behind it to
substantially charge a primary cap to a significant voltage.  However, a
strike could promote a power arc to the AC or cause some transient (it is
like 250000 volts) that could break over insulation somewhere.  This gets
more tricky at RF frequencies with high voltage.  MMCs have taken direct
streamer strikes in mid string and have "liked it" :-))

I have done a lot of fault modeling and streamers hitting things are
"theoretically" pretty benign.  My coils do not have strike rails and are
designed to take streamer hits to the "stuff".  However, I tend not to get
primary strikes since I make my coils big enough ;-))

I have lots of MOVs and stuff and if a strike blew something up it would be
something really cool for me to study :-))  But it seems that things are
really tough and it is not a problem.  Marco has electronic switching power
supplies on his big coil and recently had a big "China syndrome" thing melt
one down due to a primary strike, but that is not typical for the rest of us.

I would install MOVs from line to line and each line to ground.  That
pretty much protects the AC line stuff and prevents the "AC outlet on fire"
thing...  A good RF ground is a giant help too since that provides a stable
place for energy to be dumped in the event of something going wrong.  My
filter's MOVs across the NST pretty much take car of problems there.

All coils, coiling places, and coilers are different so there are no
absolute answers.  But I would favor good grounds and lots of MOVs for
protecting against streamer hits to the AC and primary stuff...

http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/small_ACwiring.jpg

I have MOVs across all the AC stuff and have the $28.00 dual-stage Corcom
filters spread all around too...

Cheers,

	Terry




At 09:57 PM 7/20/2001 -0400, you wrote:
>I'd like to refute the suggestion that a primary strike could damage a tank
>cap.  I believe this is impossible.  The only way the cap could be damaged
>is if it were charged to too high a voltage.  No matter how or when a
>streamer strikes the primary, the tank cap cannot be charged to a voltage
>higher that what existed before the spark gap fires.
>
>I personally haven't yet made up my mind as to whether a strike ring is
>needed.  The down side of using it is that being the highest grounded point,
>it attracts streamers.  But yet it may provide cheap insurance against some
>other failure modes.  Possibilities include NST damage, and transients
>coupled into your AC power lines.
>
>Gary Lau
>MA, USA
>
>
>
>Original poster: "brian by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><ka1bbg1-at-mcttelecom-dot-com>
>
>Hi, sounds like its time to get a piece of 3/8 copper and make a strike
>ring! and yes it will destroy your caps and NST easily! cul brian f.
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Thursday, July 19, 2001 7:56 PM
>Subject: Primary Strikes, how serious/bad?
>
>
>> Original poster: "jpeakall by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><jpeakall-at-mcn-dot-org>
>>
>> Howdy All,
>>
>> Finally built a bigger torrid and got it tuned right. However, the
>increased
>> sparks are hitting parts of the primary circuit with fair regularity. I
>have
>> a Fritz RF filter and a carcom filter. Am I gonna toast my NST? Or will I
>> blow up things connected to the AC mains?
>>
>> Thanks,
>>
>> Jonathan Peakall
>>
>>
>>
>>
>
>