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Re: [TCML] Nonlinear nst behave and LTR caps

Sorry for the typos. I am not familiar how to use the mail list. I meant "nonlinear NST behaviour"  of  when the SGTC operates with LTR caps. I don't know if  I am asking stupid questions as I am new to electrical and electronics. The magnet shunt is supposed to limit the current but I read that it does not  always happens under maximum load, so it draws lots more apparent power than the reactive power stated on the name plate even with power factor correction cap in place. On the name plate of a Fart 10kv 50ma it states 65mA  and Fart web site states "Potenza assorbita", or absorb power, is equal to 282W for the 10kv 50ma model. So I got a bit puzzled when it actually draws 700W  with a power correction cap of 25 mircroFarads during the operation with my SGTC. 282W divided by 700W giving a factor of only 0.4.  I was expecting at least 0.6. Anyway I am going to measure the power correction factor  with a newly purchased energy monitor and increase the power factor cap to 35 microFarads to see the difference in power drawn.   However, I am not sure if Richard Hull measurements in the link below  is relevant to a tesla coil? Or I compare an apple to an orange? His two-third rule is based on pure resistive load and hence not applicable to a tesla coil? Link and his paper is here:


Neon transformers - Fusor Forums<http://www.fusor.net/board/viewtopic.php?f=19&t=7945>
How loadings affect this type of transformer and how the amateur scientist/experimenter must go about applying them in their work. Richard Hull

From: Tesla <tesla-bounces@xxxxxxxxxx> on behalf of SING LO <singhonlo@xxxxxxxxxxx>
Sent: 09 May 2018 04:11:07
To: tesla@xxxxxxxxxxxxxxxxxx
Subject: [TCML] Nonlinear nst behave and LTR caps

   My first post here. I have successfully built my first 3" SGTC powered by 10kv 50ma 230V  50hz Fart using RQ gaps with 35mm copper pipes plus terry filter.  It gave 63cm arches in first light (not bad) with 19" spun aluminium toroid using 25nF MMC which 1.6 x resonance caps. I power it with a 3kw variac.  I am very puzzled by two observations:

1. The spark gaps breakdown voltage is very low with the variac set to 50v to 70v, the RQ starts to arc. This is 20% of the full input voltage. I measured the NST output to the terry filter using a 40kv high voltage probe.  It rises up to near 10kv even the variac input is 50v to 70v. This looks like resonance rise to me but at x 1.6???? How is this possible?

2. I use 25 micro farads pfc caps recommended  by Fart' product guide ( calculated is 39 micro farads), the coil draws between 650 to 700w.  I dont read italian, it mentions 282W for the Fart 10kv 50am. I assume it means real power output if you input 500w.  Now i dont understand why it can draw more than 500w with pfc caps. Then i read Gary Lau web site about core saturation of NST with LTR caps with the poor quenching of his sucker gap.  The question i got very good quenching with the RQ gaps due to the oversize 35mm copper pipes and powerful fan, so is it normally the nst draws 700w??  According to Richard Hull in Fusor forum, he said NST can supply only 2/3 of the rate current and 2/3 of the output voltage on the name nst plate.

I am going to put two 10kv 50ma in parallel with a new coil using much higher primary impedance ( and lower resonance frequency at 150khz ) to reduce the primary cap size and spark gap loss. I have built a sucker gaps with coxial 1cm diametee pure tungsten rods inside copper pipes with thermal mass but i am not confident testing it yet based on Gary Lau experience on sucker gap.  Any insight would be appreciated.

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