I've had very misleading results when trying to determine the turns ratio
by energizing the secondary with a known line voltage. This has been
discussed in the past and I'm not sure that an underlying cause or
workaround has been identified. Anyone else?
Gary Lau
MA, USA
On Wed, Apr 20, 2016 at 7:27 PM, Ed <evp@xxxxxxxxxxx> wrote:
> I strongly suggest a modification to this test, and that is to feed line
> voltage into the secondary and measure the resulting primary voltage.
> Safer and no chance of damaging the voltmeter.
>
> Ed
>
>
> On 4/16/2016 2:52 PM, Kurt Schraner wrote:
>
>> There are just 2 fundamental tests, which allow the determination of most
>> importent transformer parameters: The open circuit test, and the short
>> circuit test. In Jim Lux' HV-book you find a nice description of all what
>> is needed; please click the following link:
>>
>> http://home.earthlink.net/~jimlux/hv/xfmrmeas.htm
>>
>> Regards, Kurt
>>
>> -----Ursprüngliche Nachricht----- From: Brian Hall
>> Sent: Friday, April 15, 2016 8:44 PM
>> To: Tesla Coil Mailing List
>> Subject: [TCML] Determining a transformer's voltage and current
>>
>>
>> I posted a question similar to this a couple weeks ago, but it was a bit
>> cluttered or may have just gotten lost in the shuffle - there were no
>> replies.
>>
>> To simplify:
>> Given a 120v 60Hz primary high voltage transformer (looks like it could
>> have come from a bug zapper or similar device), but there is no plate or
>> markings indicating the HV output voltage, current, or manufacturer:
>>
>> 1) How could I determine the output voltage?
>> I got a cord and wire nuts, and hooked it up to 120v 60Hz AC to get a max
>> spark of 1.8mm between the sharp ends of two bolts. What is the scale in mm
>> for room temperature (20 degrees C) and still air on that max spark gap?
>>
>> 2) How could I determine the output current?
>>
>> I have a variac and some decent power resistors, if putting in say 10 or
>> 20 volts on the primary side, then a resistive load on the hv side would
>> help along with Ohms Law for finding the current on the HV output.
>> Just wondering if anyone else has encountered this and already knows how
>> to find such answers, and has advice on how to determine with some degree
>> of accuracy the HV side voltage and current values of an unmarked
>> transformer.
>>
>> ----------------------------------
>> Brian Hall
>>
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>>
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