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*To*: tesla@xxxxxxxxxx*Subject*: Re: Current Limiting and Impedence/Phase angle of an 18khz argon discharge?*From*: "Tesla list" <tesla@xxxxxxxxxx>*Date*: Wed, 27 Apr 2005 13:28:53 -0600*Delivered-to*: testla@pupman.com*Delivered-to*: tesla@pupman.com*Old-return-path*: <teslalist@twfpowerelectronics.com>*Resent-date*: Wed, 27 Apr 2005 13:29:08 -0600 (MDT)*Resent-from*: tesla@xxxxxxxxxx*Resent-message-id*: <PO1Dr.A.osG.Cg-bCB@poodle>*Resent-sender*: tesla-request@xxxxxxxxxx

Original poster: Harvey Norris <harvich@xxxxxxxxx>

--- Tesla list <tesla@xxxxxxxxxx> wrote: > Original poster: "Gerald Reynolds"

> >Instead we must break down the Z's into R, and X > > > >Z1^2 = R1^2 + X1^2 > >Z2^2 = R2^2 + X2^2 > > > >And must assign the correct sign for X in case both > inductive and > >capacitive reactance is present. > > > >Then > > > >Z^2 = (R1 + R2 + ...)^2 + (X1 + X2 + ...)^2 > > YES, this is correct > > > >I'm not sure this solves my problem, because in my > case the R's were > >near zero and the X's were inductive. I will go > back and recalculate.

Hi Gerald, I had a similar problem where two impedances were added in series, and I was wondering if the following data would provide enough information to determine the acting phase angle of a gas discharge, which in this case was a 2 ft argon tube. First let me digress a bit about what I have seen with gas disharges. We all know that a gas discharge must be current limited or ballasted. But why is this specifically true, shouldnt the gas discharge itself have a high resistance? Apparently not initially upon preliminary firing where ionization first occurs, it may have to do with the so called negative resistance portion of operation. I play around with AC alternators a bit, and I have a pole pig. I decided to put a 2 ft neon as a solitary secondary output on the pole pig, and power it by an alternator. I put an amperage meter on the pole pig primary and used 480 hz available from the alternator to go through the pole pig primary. What happened next showed the need for ballasting. The neon breifly lit, and then everything went dead. Inspection of the problem showed that the primary must have experienced a large amperage surge, as the fuse in the amperage meter had blown. It would require at least 10 amps to do this. So next I limited the neon current by putting it in series with about 2 nf available from a plexiglass plate capacity. This doesnt sound like much but recall that at 480 hz a capacity will have 8 times less reactance then it would have at 60 hz. Having a variac control of the alternator voltage output I gradually increased the input voltage until the neon lit. Then I measured both the voltage across the capacity, and the voltage across the neon, but unfortunately I dont recall measuring the voltage across both elements in series. What I found was that at this lowest ionization level where the bulb first fires, the voltage across both elements were almost equal, with the neon disharge having a slightly higher voltage. I think it will be important to repeat this procedure and measure the total voltage across both elements because of the following thought. The neon contains impedance, but what kind of impedance? I would think that it should be inductive reactance, not capacitive reactance. And since I was using capacitive reactance to limit the current, it might seem possible that since intially the voltages were almost equal, that perhaps the reactances might be cancelling, as occurs in series resonance. If this were the case the voltage across both elements at the pole pig secondary would be less then opposing voltages inside the circuit across each element, and then we could even find a q ratio according to that ratio of inside vs outside voltages. Now what I did next was to increase the intensity of the neon disharge by increasing the primary voltage of the pole pig, since the DC field of the alternator was regulated by means of variac control thus the AC voltage output of the alternator connected to the pole pig primary could be guadually increased. When this was done the voltage across the limiting capacity went way down, and then most of the voltage was across the neon. What this seems to tell me is that if the neon has a phase angle of operation, its phase angle must change according to its volume of current, or intensity of discharge. Now for something completely different which comes to my problem. I have some small 4 inch neon bulbs that fire at smaller voltages, so I could actually scope out the neon discharge. I found that the solid state NST advertised as 20,000 hz output would fire the bulb around 200 volts, where at 60 hz it would fire at 260 volts. The scoping however showed that the AC signal was not sinusoidal but triangular shaped, but more importantly the frequency showed itself as 18,000 hz, not 20,000 hz. I do not know if this was just an idiosyncrasy of the scopes internal capacity reacting with measuring a high input frequency or what, but for the purposes here I will use 18khz as the input frequency. Incidentally the higher input frequency has quite a bit to do with errors encountered in measuring instruments, which are probably designed to give accurate answers at the conventional 60 hz, not something as high as 18 khz. An analogue needle voltage meter will give a different answer for the voltage across the 4 inch neon on each different scale setting. It will only read ~ 50 volts if set to the smallest scale, but it reads accurate at the highest scale showing 200 volts, this is known because at that scale both the scope and meter agree on the voltage across the bulb. Another factor here in the problem is that because of the higher freq, and the triangular AC form showed with the signal, no amperage meter was placed on the output. If I knew the amperage changes involvolved with this problem, the answer might be easily found, but because of these extraneous matters, I wouldnt trust an amperage meter on a gas discharge circuit at 18 khz, so I didnt use one. So the question becomes can I determine what phase angle exists on a 18 khz 2 ft argon bulbs discharge, by adding a known inductive reactance in series with the discharge? For the known inductive reactance I used a 20.5 mh solenoidal winding of 1500 ft of 14 gauge wire on a sonotube form, (thus R is so miniscule in comparison to Z that we can call this a predominantly inductive reactance, and thus R is ignored) Here is the data and speculations I had made from records, with further comments contained in brackets[],

"Since we are given the information that 590 volts is enabling the solitary argon discharge with a 120 ma input on primary, but we cannot actually measure the secondary amperage for fear of meter damage, or totally off whack readings because of that high frequency now shown to be 18,000 hz on secondary end, we can still establish some comparisons by calculating what the 20.5 mh coils impedance would be at 18 khz. This would be 2317 ohms, by the inductive reactance formula X(L) = 2 pi *F* L. Now we have no idea what the impedance of the argon discharge would be at this frequency, but it is accepted that it consists of primarily a phase angle of inductive reactance with a small amount of resistance in that phase angle, whereas the impedance of the 20.5 mh coil is primarily all inductive reactance X(L) of 2317 ohms. We also know that when the coil was placed in series with the bulb, the voltage across the bulb went from 590 volts to 515 volts, with an extra 140 volts appearing across the coils inductive reactance, so the voltage dropped to 87.3 % of the former level without anything except the amperage changing on the primary side. Now the primary amperage dropped from 120 ma to 90 ma when more impedance was added to the secondary side. It dropped to 3/4 of the former level. This is then equivalent to stating that for the unknown impedance of the bulb to have more impedance to be added in series, if a linear primary/secondary amperage relationship exists for the solid state transformer, the addition of the known impedance of 2317 ohms to the secondary side, for the amperage to drop to 3/4 of the former level, 4/3 more total impedance must be present on the secondary side.

Now since we have speculated that 4/3 more additional impedance has been added to the secondary side, than what the bulb itself delivers, if both the bulb and the coil were ~ all inductive reactance, this would mean that the voltage across the bulb should drop to about three quarters of its former level, or 75%. Then the distribution of series voltages would also sum to equal the first case for a total of 590 volts. But this did not occur, the voltages in series sum to a total higher value, and the voltage drop across the bulb was instead 87.3% of its former value, or about 7/8 ths of what it was in solitary operation. [Note; this fact in of itself shows that the argon discharge MUST NOT be all inductive reactance and that it should have a phase angle when driven at 18 khz. Furthermore what we are trying to determine here is that the gas discharge does HAVE a real resistance coordinate, despite some misunderstandings concerning what is called the negative resistance portion of operation. It is my speculation that this portion of operation only occurs near the point of initial ionization, and that as the intensity of the discharge increases this ALSO changes its operational phase angle. A simple proof of that would be made by driving the solid state NST at the recomended 240 volts, instead of household 120 AC volts as was done here, and then repeating the voltage mesurements across each component to see if this same ratio exists. If the ratio remained the same the phase angle would not have changed, but I suspect that would not occur.] Without knowing what the actual secondary amperage was, this indeed poses a confusing problem to find "what phase angle" the gas discharge itself consists of..

Let us also speculate that with the coil and bulb in series, the total impedance from the unknown phase angle consists of 4 * 2317 ohms or 9268 ohms. The coil contributes little or no resistance for the X coodinant, but the gas discharge does. [proven by voltage distributions adding to a higher total then what exists for the bulb alone] By the pythagorean theorem we then speculate that 9268 = sq rt{ x^2 + y^2} The Y portion of the equation consists of Y = { X(L) as coil= 2317 ohms + X(L) as gas discharge = ?} R for the gas discharge as X coordinant is also unknown, thus with two unknowns here, the equation still presents a great problem.

Truly baffling problem here. Perhaps it is only appearing that way because of how the problem itself is being presented, and we are being deceived by a sort of mirage. Let us form a phase angle so that the higher impedance of the gas disharge WILL have 75% of its Y coordinate value as the total inductive reactance on the Y axis. Let us also use 100 volts for this example instead of 590 volts, to make the math simpler. We then know that the vector magnitude, (determined by pythagorean theorem) will be 87.3, and its y coordinate will be 75. The sin function is the y coordinant divided by the vector magnitude or the sin of this unknown angle will be 75/87.3 = .859 radians. Dividing this by 2pi= 6.28 radians/360 degrees we obtain a phase angle of 49.25 degrees, where the cosine of this angle will be .653.

Now let us return to the original problem then where 590 volts are across the bulb alone. We theorize that the resistance x coordinant will consist of 65.3 % of the total impedance of the bulb, and its inductive reactance will consist 85.9 % of the bulbs impedance, with all of this based on the assumption that the discharge itself has a 49.25 degree phase angle. Now we will add 1/3 more inductive reactance added by putting the coil in series with the bulb. This will change the total resultant phase angle.

I think [perhaps] I have made some serious miscalculations here, and have approached this problem in a totally incorrect fashion. I think the whole problem needs to be back engineered so that the total RESULTANT phase angle would be that 49.25 degrees, and then by then knowing that information, the actual phase angle of the bulb discharge itself might be known. So before this problem drives me nuts, I'm just going to put it on the back burner for future consideration. If anyone can fathom an answer from this information, please post it, as I am rusty concerning phase angle mathemathematics.

The problem breifly reformulated is this. 590 volts appears across a bulb, at a frequency of 18,000 hz. We do not know the amperage consumption or the phase angle of that impedance load. Then a known purely inductive reactance of 2317 ohms made at 18,000 hz is added in series, whereby we then speculate that the unknown amperage consumption on the secondary has decreased to 3/4 of its former level, indicating the addition of 4/3 more impedance on the secondary, with a new unknown phase angle made by that addition in series for all practical purposes, a purely inductive reactance. These facts are predicted from observing the primary amperage consumption differences of 120 ma for bulb alone, and 90 ma for coil in series with bulb on secondary, on the solid state 18 khz transformer secondary, with primary amperage differences being known, but not the secondaries. Now the voltage across the bulb decreases to 7/8 of its former value, and not the lesser 3/4 of its former value, which would occur if both impedances were predominantly inductive. The new voltage distribution from the former 590 volts total now becomes 515 across the bulb and 140 volts across the pure inductive reactance of the coil. What, if any phase angle considerations can be gleaned from the above information? A phase angle of 45 degrees would mean that both the X(L) inductive reactance, and R resistance would be equal, and for conventional frequency determinations at 60 hz would actually involve a fairly huge inductance. But here because the frequency is already so high we can speculate that the inductive reactance from the gas discharge itself would be high, as that current going through the bulb does also produce a magnetic field that causes a higher inductive reactance to be present as a component of its resultant phase angle."

Postnote; I thought I would also mention the following use of the solid state NST. They are very cheap in cost compared to a signal generator, I think I only paid 20-25 dollars for the ones I purchased. One might wonder why I would go about putting a coil in series with a gas bulb in the first place, driven by a high frequency solid state NST. Richard Hull notes the following; "If we place a quantity of electrical energy into the coil and do it quickly enough, the coil will ring at its natural resonant frequency, much like a bell. Voltage nodes and peaks will appear along the coil. If the coil is floating in free space, it will tend to oscillate at its natural 1/2-wavelength resonant frequency, and each end of the coil will exhibit a voltage peak while a voltage nodal point will exist in the exact center of the coil. If, however, we ground the base of the coil, this is a forced nodal point and the coil will oscillate at its natural 1/4-wave resonant frequency. "

The key here appears to be doing it "quickly enough". The 20khz solid state NST can do this quickly enough so that the scoping of the coil in series with the gas discharge will show harmonics riding on the source frequency, and then this becomes a method to scope out the natural resonant frequency of a solenoid.

In fact it would seem that when we scope out that coil in series with the gas bulb, we can find higher harmonics riding on the AC signal, and by finding the higher frequency riding on the lower frequency of the 20khz solid state input, this is a signpost of that coils natural resonant frequency, so we should be able to use the solid state NST as an indicator of a coils natural resonant frequency. In the 20.5 mh solenoidal coil I used I applied Ed Harris' formula found at <http://www.pupman.com/listarchives/1996/june/msg00227.html> When I scoped out the cited coil in series with the argon tube driven by the solid state NST the harmonics gave about the same answer as Harris' formula gives. This scoping and other solid state NST work is shown at http://groups.yahoo.com/group/teslafy/message/517 Further references on this same phase angle problem http://groups.yahoo.com/group/teslafy/message/1000

I also tried this with my 26 gauge secondary having a resonant freq ~ 330,000 hz and found that some of the scope forms were uncohered or rapidly moving across the screen. However by taking a quick digital picture of the scope form it showed a small slice in time of an AC oscillation that was identical in answer to the resonant frequency of the secondary. Sincerely HDN

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