What Do I Do?
Date: Fri, 23 Jun 2006 17:42:39 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
I am trying to get a transformer and ballast set up with just a spark gap for
now. It is multi gap copper tube set up, 8 tubes total, 5 tubes in use @ .050
each .200 gap. The first ballast try was with a roll of 12 ga w/steel core and
a NST transformer core with just the primary, when I ramped up the supply
voltage it would barely fire when I got up to 95% on the voltage at the
transformer input. I added 7 turns of 10ga for a secondary on the
NST core, now I get good sparks at 60% voltage. Can any one tell me why ? I am
using the roll of wire and NST core to limit my transformer to 1.95Kva max. It
is all trial and error at this end , should I add more turns on the NST
secondary until I get null spot. I am getting actual 8 amp at the input of the
transformer at 140v, max s/b 8 amp at 240v. I have a volt and amp meter at the
transformer input. I think I would be better off with more volts and less amps
or ????.
Rich , from the middle of Missouri
Date: Sat, 24 Jun 2006 08:05:37 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Gerry
Reynolds" <gerryreynolds@earthlink.net>
I suspect the problem is the NST with primary only. The inductance would be
high with little current going thru it if you removed the secondary and didn't
add any gap to the EI core. The current allowed would be the same as the
current thru a working NST of the same design with the secondary opened
(probably not much current). When you added a secondary using 7 turns of 10
gauage (presumably shorted), this allowed current to flow thru the primary.
Gerry R
Date: Sat, 24 Jun 2006 08:09:16 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Christoph
Bohr" <cb@luebke-lands.de>
Hello Rich.
> I am trying to get a transformer and ballast set
up with just a spark
> gap for now. It is multi gap copper tube set up,
8 tubes total, 5
> tubes in use @ .050 each .200 gap.
hm, would nice to know the type of transformer for better help, but this is of
course possible...
> The first ballast try was with a roll of 12 ga
w/steel core and a NST
> transformer core with just the primary,
both in series configuration? If you have an unballasted transformer in you
setup, you can do the following: connect only the ballast across your variac and
measure the current, modify the ballast until you reach the
desired current. This will be (pretty much) the propper setting for your setup
with you transformer
connected, cause the transformer will add zero Ohms to the loop when its output
is shorted out by the arc.
> when I ramped up the supply
> voltage it would barely fire when I got up to
95% on the voltage at
> the transformer input. I added 7 turns of 10ga
for a secondary on the
> NST core, now I get good sparks at 60% voltage.
> Can any one tell me why ?
when you add a shorted turn or winding to the core, this will lower the over all
inductance of the ballast, this increasing current. You might as well add an
airgap or remove primary turns or withdraw the steel core from the
wire spool.
> I am using the roll of wire and NST core to
limit my transformer to
> 1.95Kva max. It is all trial and error at this
end , should I add
> more turns on the NST secondary until I get null
spot.
More turns won't lead to more current, rather less turns but with 7 turns you
are already pretty low. You can try to remove some of the steel core in your
other ballast. I am not sure what NST you have and whether it
will be able to supply 1.95KVA at all, the wire spool probably will... Why
1.95KVA? just curious....
> I am getting actual 8 amp at the input of the
transformer at 140v
> , max s/b 8 amp at 240v.
140V is probably a miss-measurement. With open load there should be almost 240V
at this end and with shorted output zero.... that’s what the ballast is for. You
simply need less ballast inductance and you are done.
Exact values might differ, as the devices are not mathematically perfect.
> I have a volt and amp meter at the transformer
input.
> I think I would be better off with more volts
and less amps or ????.
I think you are allright, you just stopped experimenting too early ;-)
Lower the ballast inductance until you reach 1.95KVA..... done.
regards
Christoph Bohr
Date: Sat, 24 Jun 2006 09:57:11 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: RE: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
Can a gap be added with a saw??? This is an old Jefferson and does not have an
EI core and no visible shunts.
Rich
Subject: Re: What do I do ?
Original poster: "Gerry Reynolds" <gerryreynolds@earthlink.net>
I suspect the problem is the NST with primary only. The inductance would be
high with little current going thru it if you removed the secondary and didn't
add any gap to the EI core. The current allowed would be the same as the
current thru a working NST of the same design with the secondary opened
(probably not much current). When you added a secondary using 7 turns of 10
gauge (presumably shorted), this allowed current to flow thru the primary.
Gerry R
Date: Sat, 24 Jun 2006 09:57:29 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: RE: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
Subject: Re: What do I do ?
Original poster: "Christoph Bohr" <cb@luebke-lands.de>
Hello Rich.
> I am trying to get a transformer and ballast
set up with just a spark
> gap for now. It is multi gap copper tube set
up, 8 tubes total, 5
> tubes in use @ .050 each .200 gap.
hm, would nice to know the type of transformer for better help, but this is of
course possible... Transformer is a standard EI core 240v in 13Kv out, Tag says
1.95 Kva, it is non NST , no shunts or current control.
> The first ballast try was with a roll of 12 ga
w/steel core and a NST
> transformer core with just the primary,
both in series configuration? If you have an unballasted transformer in you
setup, you can do the following: connect only the ballast across your variac and
measure the current, modify the ballast until you reach the
desired current. This will be (pretty much) the proper setting for your setup
with you transformer
connected, cause the transformer will add zero Ohms to the loop when its output
is shorted out by the arc.
> when I ramped up the supply
> voltage it would barely fire when I got up to
95% on the voltage at
> the transformer input. I added 7 turns of 10ga
for a secondary on the
> NST core, now I get good sparks at 60% voltage.
> Can any one tell me why ?
when you add a shorted turn or winding to the core, this will lower the over all
inductance of the ballast, this increasing current. You might as well add an
airgap or remove primary turns or withdraw the steel core from the
wire spool. The steel wire core was made with thread all in the center so I can
do this.
> I am using the roll of wire and NST core to
limit my transformer to
> 1.95Kva max. It is all trial and error at this
end , should I add
> more turns on the NST secondary until I get
null spot.
More turns won't lead to more current, rather less turns but with 7
turns
you are already pretty low. You can try to remove some of the steel core in your
other ballast. I am not sure what NST you have and whether it will be able to
supply 1.95KVA at all, the wire spool probably will...
Why 1.95KVA? just curious.... Well the tag says it is rated at 1.95Kva
> I am getting actual 8 amp at the input of
the transformer at 140v
> , max s/b 8 amp at 240v.
140V is probably a miss-measurement. With open load there should be almost 240V
at this end and with shorted output zero.... that’s what the ballast ist for.
You simply need less ballast inductance and you are
done. Exact values might differ, as the devices are not mathematically
perfect. I have a good Simpson panel meter and a cheap DVM on it now, I have a
good Fluke RMS DVM but I am protective of it and now realize the $3
meter might not give good voltage readings
regards
Christoph Bohr
Date: Sat, 24 Jun 2006 13:04:35 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Dr. Resonance"
<resonance@jvlnet.com>
The individual laminations in the core are usually varnished, ie, insulated
from each other to prevent eddy current losses. If you saw through the
laminations the sharp edges usually end up shorting each
other out so the core may run hotter than normal due to the eddy currents. You
will get away with this if you keep your run time short.
Epoxy a 50 mil plastic spacer into the cut or it will buzz like heck.
Dr. Resonance
Date: Sun, 25 Jun 2006 08:04:27 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Gerry
Reynolds" <gerryreynolds@earthlink.net>
Hi Rich,
I would suspect so. The problem might be if you cut the gap too wide, it would
be hard to close it again. I personally would try to play with a shorted
secondary first to see if your current levels can be obtain. You might
experiment with the number of turns on the secondary being shorted. I would not,
however, take turns off of the primary as this could cause the core to saturate.
In this application, volts per turn and core area are the major factors
determining where saturation occurs.
Gerry
Date: Sun, 25 Jun 2006 20:53:34 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: RE: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
Thanks Gerry
I think I am getting to workable solution, my little cheap DVM is reading a
voltage that would be expected then as I raise it the gap fires, at that point
the voltage drops dramatically. That is why I reported the 140v when it s/b 220
to 240. Would I be better off with a standard panel meter than the DVM when try
to read the input at the
transformer. I have a complex voltage supply system and can feed the transformer
from O to approx 300v.I am using a 0 to 140 Variac, 120/208/277 , step up trans
, then the ballast, the HV trans has 208/220/240 taps. It sounds like a mess but
my 240 Variac is tied up on something else.
Rich
Subject: Re: What do I do?
Original poster: "Gerry Reynolds" <gerryreynolds@earthlink.net>
Hi Rich,
I would suspect so. The problem might be if you cut the gap too wide, it would
be hard to close it again. I personally would try to play with a shorted
secondary first to see if your current levels can be obtain. You might
experiment with the number of turns on the secondary being shorted. I would not,
however, take turns off of the primary as this could cause the core to saturate.
In this application, volts per turn and core area are the major factors
determining where saturation occurs.
Gerry
>Original poster: "Rich & DJ" <rdj@wildblue.net>
>
>Can a gap be added with a saw??? This is an old
Jefferson and does not
>have an EI core and no visible shunts.
>
>Rich
>
>Subject: Re: What do I do ?
>
>Original poster: "Gerry Reynolds" <gerryreynolds@earthlink.net>
>
>I suspect the problem is the NST with primary
only. The inductance
>would be high with little current going thru it
if you removed the
>secondary and didn't add any gap to the EI core.
The current allowed
>would be the same as the current thru a working
NST of the same
>design with the secondary opened (probably not
much current). When
>you added a secondary using 7 turns of 10 gauage
(presumably
>shorted), this allowed current to flow thru the
primary.
>
>Gerry R
>
> >Original poster: "Rich & DJ" <rdj@wildblue.net>
> >
> >I am trying to get a transformer and ballast
set up with just a
> >spark gap for now. It is multi gap copper tube
set up, 8 tubes
> >total, 5 tubes in use @ .050 each .200 gap.
> >The first ballast try was with a roll of 12 ga
w/steel core and a
> >NST transformer core with just the primary,
when I ramped up the
> >supply voltage it would barely fire when I got
up to 95% on the
> >voltage at the transformer input. I added 7
turns of 10ga for a
> >secondary on the NST core, now I get good
sparks at 60% voltage.
> >Can any one tell me why ?
> >I am using the roll of wire and NST core to
limit my transformer to
> >1.95Kva max. It is all trial and error at this
end , should I add
> >more turns on the NST secondary until I get
null spot.
> > I am getting actual 8 amp at the input of
the transformer at 140v
> > , max s/b 8 amp at 240v.
> >I have a volt and amp meter at the transformer
input.
> >I think I would be better off with more volts
and less amps or ????.
> >
> >Rich , from the middle of Missouri
> >
Date: Sun, 25 Jun 2006 22:39:57 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Gerry
Reynolds" <gerryreynolds@earthlink.net>
Good question.
Many use panel meters as the are much more robust in these applications. My
panel meter uses two pair of Simson meters (each pair 300Vac and 50Aac). I have
noticed the amp meters are susceptible to H fields created from high current
routes, so it may be best to route high current and return current wires
together as pairs.
Gerry R.
Date: Mon, 26 Jun 2006 22:00:14 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Barton B.
Anderson" <bartb@classictesla.com>
Hi Gerry,
Regarding the H fields on amp meters: A couple years ago I rewired my control
cabinet and routed the high current lines to and from the amp together, but this
made no difference. They are routed side by side.
Maybe a twisted-pair solution is necessary to reduce the H field influence?
Take care,
Bart
Date: Tue, 27 Jun 2006 07:35:48 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Gerry
Reynolds" <gerryreynolds@earthlink.net>
Hi Bart,
I think a twisted pair would be a better solution. Maybe we ought to use RG8
coax :o)) I did improve my measurements by reducing the current loops but then
again, I had some pretty large loops to begin with.
Gerry R.
Date: Tue, 27 Jun 2006 11:35:55 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: RE: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
Well I don't have much problems with current loops as my meters are with
in a few inches of my HV transformer, but I do have lots of RG8 and RG11
I could use. I do have a new question today for all you EE guys today.
Update on my set up I added a GE AC 300 volt panel meter. If you
remember before I said when the gap was sparking I was getting a reading
of about 140v with the cheap DVM.
I added the AC meter and have played with my inductive ballast. Now I am
at the point where I am up to about 190v at the input of the
transformer. The transformer is tapped at 208V in.
Try to hold at approx 8 to 10 amp amps, I can increase the voltage
reading by increasing the spark gap. Is this what I should be seeing ,
volts in, rise as the gap opens??
Next question , should I run a test , ramping up the voltage slowly when
I add the MMC and primary or wait until the secondary and top load is
complete?
Rich , from the middle of Missouri
Date: Wed, 28 Jun 2006 09:55:38 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Scott Hanson"
<huil888@surfside.net>
Bart -
I have a number of military analog meters (AC voltmeters and AC ammeters) that
have drawn metal "cups" (magnetic shields) that completely enclose the portion
of the meter case that projects behind the panel. I don't know if they are steel
or some more exotic material like mu metal, but I suspect they are just drawn
from soft steel.
Regards,
Scott Hanson
Date: Wed, 28 Jun 2006 09:56:26 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do ?
Original poster: "Gerry
Reynolds" <gerryreynolds@earthlink.net>
Hi Bart,
I monitor the current in two places - right out of the variac and going into the
pig. Without any PFC, the two currents should be the same and they aren't. I
have reduced the difference by changing the wire routing but I also suspect the
two meters just plain "don’t read the same". When I get to it, I will swap the
meters to see if the difference follows the meters or is dependent on where the
meters are located. Anyway, let us know if the twisted pairs helps.
Gerry R.
Date: Wed, 28 Jun 2006 09:57:36 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: RE: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
-----Original Message-----
From: Tesla list [mailto:tesla@pupman.com]
Sent: Tuesday, June 27, 2006 12:36 PM
To: tesla@pupman.com
Subject: RE: What do I do ?
Original poster: "Rich & DJ" <rdj@wildblue.net>
Well I don't have much problems with current loops as my meters are with in a
few inches of my HV transformer, but I do have lots of RG8 and RG11 I could use.
I do have a new question today for all you EE guys today. Update on my set up I
added a GE AC 300 volt panel meter. If you remember before I said when the gap
was starting to spark I was getting a reading of about 140v with the cheap DVM.
I added the AC meter and have played with my inductive ballast. Now I am at the
point where I am up to about 190v at the input of the
transformer. The transformer is tapped at 208V in. Try to hold at approx 8 to
10 amp amps, I can increase the voltage reading by increasing the spark gap. Is
this what I should be seeing, volts in, rise as the gap opens??
Next question , should I run a test , ramping up the voltage slowly when I add
the MMC and primary or wait until the secondary and top load is complete?
Rich , from the middle of Missouri
Date: Wed, 28 Jun 2006 19:20:56 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: What do I do?
Original poster: "Dr. Resonance"
<resonance@jvlnet.com>
If you try to run the primary circuit in a resonant condition without a
secondary load the large rise in Q factor will blow your caps and/or
transformer. Set up your entire system, use a discharge rod off the toroid to
see the spark length, and only run at 30-40% power level until you get the
circuit in tune. Also a good idea to set the
sparkgap at 1/2 it's normal setting until you are in resonance. This keeps the
resonant potential to a lower value and will prevent stress on the caps and
xmfrs.
Dr. Resonance
>Next question , should I run a test , ramping up
the voltage slowly when
>I add the MMC and primary or wait until the
secondary and top load is
>complete?
>
>Rich , from the middle of Missouri