Re: Calibrating I Transfo

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 Te> Newsgroups: tesla.list

 Te> From wesb-at-VNET.IBM.COM Wed Apr  5 12:15 MDT 1995
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 Te> -0600 Date: Wed, 5 Apr 95 14:06:37 EDT
 Te> From: wesb-at-VNET.IBM.COM
 Te> To: tesla-at-objinc-dot-com
 Te> Subject: Calibrating I Transformer

 Te> Mark;

 Te> For the most part, your calibration procedure seems to be a reasonable
 Te> one. However, it leaves out an important point. Your statement:
 >Now you can adjust the turns on the coil to result in a .25 volt or 2.5 volt
 >or 25 volt reading on the meter connected to the winding which will be in
 >proportion to the current flowing through the line that runs through the
 >center of the core.

 Te> is correct in the absolute literal sense, but may lead others to draw
 Te> a false conclusion. More strictly, the voltage induced in the coil is
 Te> not proportional to i, but to di/dt. True, if we increase i by a
 Te> factor, di/dt will increase by the same factor, but di/dt will also
 Te> increase in proportion to frequency, even if i is not changed. This
 Te> means that a calibration done at one frequency will be invalid at any
 Te> other frequency, unless a frequency correction factor is employed.
 Te> Fortunately, the correction factor is simple to use. If the signal
 Te> being measured has a frequency that's n times the calibration
 Te> frequency, then the actual current will be n times the meter reading.
 Te> This shouldn't detract from the fine job you did in describing the
 Te> calibration procedure, but I hope it will help make it as useful as it
 Te> deserves to be. 
 MG> Agreed, and I thank you for pointing that out, I should have. But for     
     the most part I don't think an absolute measurement is what most are
     looking for, or is needed. More importantly is to be able to see the
     effect of circuit tuning, terminal changes, coupling changes, etc. on
     the base current of the secondary. In Tesla coil systems readings don't
     mean a whole lot unless all of them are taken the same way, there is no
     standard. Nor do I think there could be due to too many variables that
     are beyond our control. I think Harry says it best: Tune for most smoke!

                                Mark Graalman

... Alias, Mark the spark
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