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*To*: tesla@xxxxxxxxxx*Subject*: Re: Racing Spark Prediction*From*: "Tesla list" <tesla@xxxxxxxxxx>*Date*: Wed, 03 May 2006 15:58:46 -0600*Delivered-to*: testla@xxxxxxxxxx*Delivered-to*: tesla@xxxxxxxxxx*In-reply-to*: <118340673.20060507001411@xxxxxxxxxxxxx>*Old-return-path*: <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>*References*: <6.2.3.4.2.20060502180118.01e35990@xxxxxxxxxxxxxxxxxxxxxxx> <118340673.20060507001411@xxxxxxxxxxxxx>*Resent-date*: Wed, 3 May 2006 15:44:56 -0600 (MDT)*Resent-from*: tesla@xxxxxxxxxx*Resent-message-id*: <czt5X0Y1b_P.A.YCG.YRSWEB@chip1>*Resent-sender*: tesla-request@xxxxxxxxxx

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx> Hi,

==============

Subject: Best Method to Find Coupling Coefficient All, I have tried all the suggestion I have received (Thanks Malcolm, Fr.

The mutual inductance is found by: M = V / (w * I) Where: M = Mutual inductance in Heneries.

I = The measured current in the primary in amps AC. V = The measured secondary voltage in volts AC. As an example:

0.100 / (377 * 10 ) = 26.52 uH for the mutual inductance. k can then be found by using the formula: k = M / sqrt(L1 * L2) Where L1 and L2 are the inductances of the primary and secondary coils.

Terry ======================= Cheers, Terry At 11:14 AM 5/6/2006, you wrote:

Hallo John. > Original poster: FutureT@xxxxxxx > Seems that when using the aiding and bucking inductances method > for measuring k, along with the typical formula that's generally used > (I can't remember it offhand), the higher couplings give wrong results. > It makes the k seem tighter than it really is. something like "measure the series inductance twice, once with one coil reversed (a1 and a2), subtract one result from the other, and solve the resulting expression for M.", then M=|a1-a2|/4 ? yeah, i`ve read about this gotcha in archives, but i think this method prone to errors with any value of k - coz Lpri is about 3 order of magnitude smaller than Lsec. Marco Denicolai had used this method while playing with his Thor, he make it even simplier - used only one msmt instead of 2 - measured only a1, then M=|a1-(L1+L2)|/2 : D > Using the 60 Hz AC current method you mentioned, then all is > accurate for k measurements. so no problemo here : ) i prefer measuring instead of calculating k not because i don`t trust JAVATC or INCA for example - no, just coz i know for sure, that it would be impossible for me to wind a primary exactly flat, or exactly at 30 deg, etc, etc, so at the end i would not have rights to compare my real transformer with simulated one, that`s all % )

**References**:**Re: Racing Spark Prediction***From:*Tesla list

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