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Recycled: Measuring Coupling Coefficients
From: Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: Wednesday, November 26, 1997 6:58 AM
To: Tesla List
Cc: terryf-at-verinet-dot-com
Subject: Recycled: Measuring Coupling Coefficients
>
>
> From: terryf-at-verinet-dot-com[SMTP:terryf-at-verinet-dot-com]
> Sent: Tuesday, November 25, 1997 4:23 PM
> To: Tesla List
> Subject: Measuring Coupling Coefficients
>
> Hi All,
> I have been playing with measuring coupling coefficients lately. I
> was just wondering if anyone has a relatively easy way to accurately measure
> this elusive factor?
> I have tried measuring the coils in series so that the inductances
> add and then subtract and then applying the formula M=(La-Lb)/4. However,
> due to the large difference in the primary and secondary inductances (two
> orders of magnitude) this formula can introduce substantial error.
> I have been able to load the output with a 10K ohm resistor and use
> a 50 ohm voltage source to determine K. However, the frequency needs to be
> carefully selected to insure an accurate reading, the math involved in the
> calculation is very complex (the compter does all the work:-)), and it takes
> substantial test equipment to perform. So far this is the best method I
> have found and it seems to work very well but I just want to be sure I
> haven't missed some simpler method.
>
> Any thoughts / comments welcome.
>
> Terry
> terryf-at-verinet-dot-com
>
>
Here's a recycled post that may be of some help to you
or maybe some other coiler who is seeking to determine K.
Hope this help.
Fr. Tom McGahee
From: Edward V. Phillips[SMTP:ed-at-alumni.caltech.edu]
Sent: Friday, August 08, 1997 2:50 PM
To: tesla-at-pupman-dot-com
Subject: Re: Mutual Inductance and Coupling Measurement
Here is a pretty fundamental way to measure the mutual
inductance, provided you have a millivoltmeter. Feed a known
60 cycle current (say power line in series with 100 watt light
bulb) through one winding and measure the induced voltage
across the other. Suppose, for instance, that the mutual
inductance is 100 microhenries. This represents a reactance
of 0.0377 ohms at power line frequency, so the voltage will
be omega x M x I = 377 x 100 E-6 x 1 =37.7 millivolts.
Having measured M the coupling factor k is the
mutual inductance M divided by the square root of L1 x L2,
where L1 and L2 are the winding inductances.
Ed
>