In my house, most, if not all, 120 volt circuits come off of one leg of my utility pig (ground hog actually) and lighting circuits come off the other. Since my breaker box is in my garage,I could run a circuit off the second leg for my second NST. I have a 15 kV 120 ma NST, that needs more than 20 amps when cranked up to 140 volts. Given the low duty cycle, I could easily install a larger breaker on 12 AWG wire, but have been upgrading to PTs, then a 14.4 kV 25 kVA pig, so I installed a 100 amp breaker to an industrial disconnect, so I can padlock it.
From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wednesday, April 8, 2015 7:28 AM
Subject: Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)?
Typo 120 volts, not 1230 volts
From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wednesday, April 8, 2015 7:25 AM
Subject: Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)?
One NST PRIMARY goes from NEUTRAL to one HOT. The other goes from NEUTRAL to the other HOT. Each gets 1230 volts input. I don't think y'all are reading my original post.
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Wednesday, April 8, 2015 12:03 AM
Subject: Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)?
On 4/7/15 10:17 AM, Yurtle Turtle via Tesla wrote:
> There's no reason both NSTs have to be paralleled on a single 120 volt circuit. If you have 240 volts or can buy a breaker and run a circuit, you can run the two NSTs in series, but you'll have to rephase the secondaries.
>
Au contraire...
you can series NSTs if you have a isolation transformer with 7.5 kV
insulaton resistance.
Think about it..
Call the first NST the "low" one.. the two terminals are at 7.5kV
relative to ground, and the NST has insulation that can hold off, say,
8kV. The center tap of the secondary, connected to the case, is roughly
at the primary voltage.
Now connect the secondary of the second NST to the first one. So one
secondary terminal is at 7.5 kV, the center tap connected to the case,
is at 15 kV, and the other secondary terminal is at 22.5kV.
So that makes the primary of the second transformer floating at around 15kV.
The insulation of the NST isn't good enough to do that.
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