Re: 37XR inductance range

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>

Thanks everyone for the explanation. When I next get around to testing these
xfmr's, I'll run them near true operating conditions and apply the math. I
pretty much already knew the formulaes, but didn't think about core
permeability. I just was hoping for an easy measuring method, OH BOY! ,I CAN
MEASURE THIS WITH MY NEW METER!
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, January 06, 2006 11:40 AM
Subject: Re: 37XR inductance range


> Original poster: Finn Hammer <f-h@xxxx>
>
> Mike,
>
> You can trust the meter., however notice that the meter probably
> measures mH at 1kHz, and H at 50hZ.
>
> Also note: From posts I made 28-12-05
> Mike,
>
> Pls. notice that few LCR meters can supply enough current to produce
> a usefull measurement on iron cored inductors. By exciting the
> windings with a typical LCR meter, the iron will be operating in the
> low "initial permeability" area of the B-H curve, and the readings
> will turn out to be too small.
>
> Instead, you should connect the windings across a variac, with a
> Ammeter in series, and calculate inductance according to:
> u = wLi
>
> W = Omega = 2*pi*frequency = 2 * 3.14 * 60 = 377
>
> Cheers, Finn Hammer
>
> Yes, "u" is voltage across inductor being measured.
> u = wLi
>
> Rearrange for L you get:
>
> L=u/wi
> And can see that for a given current, voltage across
> inductorincreases with L and for the same voltage across inductor:
> current decreases with inductance. Which is what you`d expect.
>
> Tesla list wrote:
>
> >Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
> >
> >I recently purchased the Meterman 37XR per the list members
> >favorable use. I was just measuring the inductance of my variable
> >ballast, and a few hig power isolation xfmr I have laying around.
> >One measured 365 mh. When I changed ranges to henrys, it
> >dramatically changed to 0.260H ! Does anyone else notice this vast
> >discrepincy? Can I trust the meter?
> >
> >
> >
>