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Resistance of a pole pig
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From: John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent: Saturday, April 11, 1998 4:53 PM
To: Tesla List
Subject: Re: Resistance of a pole pig
At 12:43 AM 4/8/98 -0500, you wrote:
>
>----------
>From: Jim Fosse [SMTP:jim.fosse-at-bjt-dot-net]
>Sent: Tuesday, April 07, 1998 1:24 AM
>To: Tesla List
>Subject: Re: Resistance of a pole pig
>
>Hi Jim,
>
>[snip]
>>DC resistance can be measured with an ohmmeter....
>>The reactance is a little trickier. Measure the AC resistance at 60 Hz,
>>remove the contribution of the DC resistance, and you'll have the
>>reactance, unloaded. Of course, this doesn't measure the leakage
>>inductance.
>
>I was going to post about using the "short the secondary" and measure
>the primary inductance method, but using JUST hand tools;) requires
>one to measure the primary current from the mains! The local
>electrical utility would not be happy.
--------------------------- big snip
Jim, All -
The local electric utility would be little affected when you test your
transformer for percent impedance if you do it correctly. It is actually a
simple test and requires very little current. The percent impedance is used
by electrical engineers to find the short circuit current of the transformer.
A schematic diagram and an example is shown in my Tesla Coil Design
Manual. There is also much more Tesla coil information shown in the Manual.
The percent impedance is important for Tesla coils because a lower
impedance will give you a longer output spark, other parameters being equal.
This is why you should not compare a spark output from a 5 KVA (full load)
transformer to one from a 10 KVA that appears to be operating at 5 KVA.
John Couture