Hi,
I landed on a good tutorial I missed before with a great wye:wye ratio
graphic and neutral calculations. Scroll down to wye:wye voltage graphic,
nice.
http://www.electronics-tutorials.ws/transformer/three-phase-transformer.html
If interested...
Jim
> -----Original Message-----
> From: Jim Mora [mailto:wavetuner@xxxxxxxxx]
> Sent: Thursday, July 03, 2014 11:42 PM
> To: 'Tesla Coil Mailing List'
> Subject: Calculating the turns ratio in 3 phase HV
>
> Hi All,
>
> I have the Raytheon innards on the "bench" and the oil tank safely stowed
> and covered. The oil "looks" very good to me and amber clear; there is no
> sign of any water in the tank. It was probably well maintained until taken
> out of service. Anyway, since the transformer is out of the tank,
> measuring the transformer output with a voltage divider is no longer
> practical so I need to determine the turns ratio. I seem to remember with
> pigs, back feeding 120Vac into the HV was enough maybe to energize the
> core and measure the LV. So the question is - if I feed 120v into HV 1
> phase winding, I believe I read somewhere that LV 1 -N should reflect the
> direct turns ratio as in single phase. It is Wye:Wye, there is neutral on
> the primary but it is not on the schematic for the secondary as it is not
> needed in 6 pulse operation. I have to either find the secondary junction
> point or back feed 120 volts on a HV phase to another phase. I'm not too
> sure how to calculate it then. Would a like phase to phase LV be the
> correct voltage ratio value?
>
> If the transformer HV and six pulse calculates to the stated 24KV out,
> this would not be a good candidate for 6P resonant charging; and, I sure
> would like to know that at this juncture!
>
> Thanks,
> Jim Mora
>
> BTW, I found a tag that states "Ground Beacon", Federal Aviation...pulsed
> transmitter?
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