Re: [TCML] MOT Measurements

[tesla <tesla@xxxxxxxxxxxxxxx>]

Greetings Team

Well in the fist instance I used the resonance graph published recently
which showed 60Hz resonance with a capacitor of  just under 1.5uF. (close to
the value found in an operating MOT, no coincidence here I suspect)

I just solved f=1/(4pi^2f^2C) with
60Hz
C=1.5E-6
To give that 4.7Hy even if 50Hz environment still close to that value, would
not explain the 20 to 65Hy quoted below, I wonder what conditions this L is
measured at, I try to measure at high currents in the secondary (ie lots of
excitation to test it) so as to test it close to operating conditions. My
simple L meters measure around 40 to 100Hy on a secondary but I do not
believe those results

In the past as I'd said I've measured MOTs (600 watt type) with Pri SC I got
6Hy looking back into the secondary, I'll re-check tonite as it was a while
ago and advise results giving excitation voltage and resultant current.

Given the magnetising current required I long ago gave up using a meter to
measure large iron cored trannies and I'm not sure of the test freq either.

Best
Ted in NZ
Message ----- 
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, January 05, 2009 2:23 PM
Subject: Re: [TCML] MOT Measurements


> Hi Ted,
>
> Not that high. Terry's MOT measured 65H at L2. My own MOT measured 39.5H
> (although my MOT is a bit beefy compared). I would expect Herwigs MOT to
> be no lower than 20H. Your calculated value of 4.7uH is extremely low.
> How are you basing this value? Herwig is 230V 50Hz power environment.
> Are you assuming a 120V 60Hz situation?
>
> Take care,
> Bart
>
> tesla wrote:
> > Team
> > I noted the Value of Secondary L here of 30.4 Hy
> > I believe this is rather higher than I would expect.
> > Resonance at 1.5uF/60Hz puts this figure down to around 4.7Hy which is
> > in close agreement with experiments I've done (magnetic shunts intact).
> > Measured Secondary L with Pri Shorted (voltage generator source
> > situation as per mains input) and Secondary driven with a large 50Hz
> > AC voltage source and current measured technique
> >
> > Thanks, enjoying the dialogue on this matter
> > Ted in NZ
> >
> > SNIP
> >> - I am not so experienced in simulations as you are. Therefore I
> >> would like to accept your generous offer to run the simulation with
> >> my MOT data: no-load-output-voltage = 2232 Vrms, dc-resistance of
> >> secondary winding = 70 Ohms, calculated secondary inductance = 30,4
> >> H, all the other parts were copied from Piranha II.
> >> Take care,
> >> Herwig
>
> _______________________________________________
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> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla


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