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Re: break-rate/power tests over weekend
to: John
Good post John. I have also noted that 120 bps synchro seem to produce nice
results. Try this sometime: Take a camera time exposure wide open f1.2 at
4 sec duration. Do this with both a synchro and non-synchro gap. You will
notice the photos of the synchro are very thick, bright, and have a very
unique "bushy" characteristic. The synchro RSG delivers much more current
into the discharge. The proof is in the photographs. This experiment can
be done with almost any size or style of TC.
Regards,
Dr.Resonance
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Wednesday, February 17, 1999 2:55 AM
Subject: break-rate/power tests over weekend
>Original Poster: FutureT-at-aol-dot-com
>
>All,
>
>Over the weekend, I decided to tackle the input power question again
>for various break-rates. My questions were; is my wattmeter accurate
>at high break-rates, and how efficient are the high break rates? To
>find the answer, I first "calibrated" a thermocouple ammeter using a
>resistive load instead of a Tesla coil.
>
>I used a household toaster for the resistive load, and applied 1080
>watts as measured with my wattmeter. I also noted that a regular
>ammeter read 4.4 amps, (240 volts). The thermocouple ammeter
>(TCA) read 55. This number 55 means nothing in itself, it's simply
>a reading on the meter. The thermocouple meter is also non-linear.
>The thermocouple meter can read any kind of current waveform;
>distorted, high frequency, etc.
>
>Next I ran the Tesla coil at a break-rate of 400 BPS (approx) and
>turned up the power until the TCA read 55, this means the
>true input current is 4.4 amps (based on chart below showing the
>toaster tests). The regular ammeter read 4.3 amps, so it was very
>close. Next I read the wattmeter which read 1000 watts. This too
>was very close to the reading with the toaster.
>
>The conclusion is that the regular ammeter seems to read OK, and
>the wattmeter seems to read OK at 400 BPS in this Tesla coil,
>based on comparisons with a resistive load. If the power factor was
>bad, (which might confuse the issue), the wattmeter would pick it up.
>But it seems the power factor is pretty good. I figure that this
>method of cross checking the meters, and calibrating first with
>a resistive load should give a reasonable assurance of the general
>accuracy of the measurements. I'm not looking for 1% accuracy,
>I'm satisfied with 10%. My original concern was that the wattmeter
>might be reading with a 50% or 100% error at the high break-rates,
>but that doesn't seem to be the case.
>
>I also did a number of other runs at different break-rates, different
>calibrations with the toaster load, etc., as shown in the following
>chart:
>
>BPS Watts Amps TCA ballast set toroid spark inches
>
>(est.)
>120 600 3 25 3 10" 28
>120 600 4 60 5 10 28
>400 1000 4.3 55 5 10 30
>800 1000 5 70-80 5 10 15
>T 600 2.5 20
>T 1000 4 48
>T 740 2.8 25
>T 1080 4.4 55
>T 1220 5.1 70
>120 620 3 20"
>42"
>400 1000 5 20
>44" (?)
>
>Notes: BPS at 400 and 800 are approx., watts read on wattmeter,
>amps read on regular ammeter, TCA stands for thermocouple
>ammeter. Prior tests showed that the wattmeter is accurate at 120
>BPS based on TCA comparisons, T indicates toaster load (no TC).
>Most likely the wattmeter is reasonably accurate at 800BPS also,
>and is showing a poorer power factor.
>
>I used my 42" spark TC, but I used a 3" by 10" spun smooth toroid
>instead of the usual 5" by 20" dryer duct toroid, because I did some
>other tests of spark coalescence etc. The power was deliberately
>held back in the tests discussed in this posting.
>
>It appears that my TC is actually drawing high power levels at the
>high break-rates, without any real increase in spark length*. In other
>tests, I ran the coil at higher power levels. At 600 watts at 120
>BPS, sparks were 32" long, and multiple streamers formed. At
>800 watts at 400 BPS, sparks were still 32" long, but were much
>brighter. At 1000 watts at 800 BPS, the sparks coalesced into one
>very bright streamer, of the same length. I could tell that the
>capacitors were charging to a much lower voltage at the higher
>break-rates, because the variac had to be turned up higher to
>make the gaps fire. However, at 120 BPS, at very low power,
>multiple streamers were still produced, which suggests that the
>coalescence resulted more from the high break-rate than from the
>lower capacitor voltage. *It should be noted that the average spark
>length was shorter at 120 BPS, than at the higher break-rates, but
>the sparks occasionally reached out and hit 32" despite the much
>lower input power, and multiple streamers. So there is more
>variability to the spark length at low break-rates; the sparks
>occasionally grow to long lengths. Also, the brightness of the high
>break-rate sparks makes them appear longer than they are, in a
>sense. Both low break-rate and high break-rate sparks struck the
>ground with equal frequency, despite the longer average length of
>the high break-rate sparks. Of course the high break-rate sparks
>required a lot more input power.
>
>It is possible that the losses in the ballast or transformer are much
>higher at the high break-rates although the 1500 watt rated potential
>transformer should not have a great problem charging the small
>.007uF tank cap. It has been suggested to me that larger transformers
>will show lower relative losses at the higher break-rates. Thus, larger
>systems should better tolerate the higher break-rates, but for small
>systems, up to two kilowatts or so perhaps, I don't see how high
>break-rates can offer good "efficiency". It seems to me, that in a
>small system using traditional power supplies, longest sparks using
>minimum input power will always be achieved at low break rates. I
>don't know what will happen for larger coils, but I wouldn't be surprised
>if low break-rates were more efficient also.
>
>But if the brightest possible sparks are desired (especially with a
>small toroid), then a high break-rateshould be used, but this will
>demand more power. Most TC's will give longer sparks of course,
>if the break-rate is increased, but the power input will rise greatly.
>To obtain the best results from a low break-rate system, a larger
>toroid may be needed than a comparable high break-rate system.
>This will help keep the sparks brighter and longer despite the low
>power input.
>
>Although a high break-rate may create a bright, coalescent streamer
>using a small toroid, the sparks will still be a lot shorter than when
>using a larger properly sized toroid. At 120 BPS, I get a 32" spark
>at 800 watts with the small 10" toroid, but with a 20" toroid, I get 42"
>sparks at only 620 watts at the same break-rate, and the sparks are
>much brighter. At 400 BPS, I get a 32" spark at 1000 watts with the
>10" toroid, but with a 20" toroid, I get 44" sparks at 1000 watts or so.
>
>It is interesting to note that using the small toroid, the longest spark
>length did not increase at high break rates, but with the larger toroid,
>the spark length did increase by a couple of inches at high break-
>rates. Maybe the small toroid does not store enough energy to
>effectively feed the streamer even at high break-rates, whereas
>a large toroid provides enough stored energy to the streamer to allow
>it to benefit from a high break-rate, although it only increases by a
>couple of inches, despite the much higher input power. If this is
>true, then larger coils with large toroids might benefit more from
>higher break-rates than smaller coils with smaller toroids. This
>might be the explanation for the good performance of some large
>coils at high break-rates rather than the theory of lower transformer
>losses in large coils. This is getting speculative here though. More
>tests are needed.
>
>The general principles mentioned in this post should apply
>to mostly all coils using standard power supplies, although some
>variation might occur at higher powers, or especially with different
>capacitor sizes relative to the input power.
>
>If anyone wishes to modify their TC for 120 BPS operation, it's
>possible that a larger tank capacitor and toroid, and different ballast
>setting will be required for best results. The components must be
>carefully "matched for synergy" at 120 BPS, because there will no
>longer be the option to use changes in break-rate to find the coil's
>"sweet spot". Rather than adjusting break-rate to match the coil,
>the coil will need to be matched to the break-rate at 120 BPS.
>This may explain the reports of poor results with 120 BPS operation
>that are sometimes heard.
>
>Comments are welcome,
>
>John Freau
>
>