# Tranny question...

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From:  davmckin [SMTP:davmckin-at-ix-dot-netcom-dot-com]
Sent:  Monday, January 26, 1998 3:12 AM
To:  Tesla List
Subject:  Re: Tranny question...

Tesla List wrote:

> ----------
> From:  Dan Ressler [SMTP:danz_da_man-at-hotmail-dot-com]
> Sent:  Sunday, January 25, 1998 2:13 AM
> To:  tesla-at-pupman-dot-com
> Subject:  Tranny question...
>
> Hey,
> I have aquired a 15kv/30ma tranny and have have noticed
> a......suspicious quality.  Upon testing the tranny for resistance I
> found that the resistance of one secondary output to the ground was
> different than the resistance of the other secondary output to the
> ground.  Arent they supposed to be the same?  I got the tranny for free
> and Im wondering if this is the reason why....on the other hand Im not
> wise in the way of these things so Im asking all you.  Please give me
> some input, and thanks.
> Dan

Dear Dan & all,

How much different are the resistances you measured?  If you're able
to measure, using a multitester, any significant difference in resistance
(should be less than approx. 5%)  between each sides of the NST then
something is probably wrong with the transformer.  The lower of the
resistances possibly has some windings shorted (unless one of the
windings themselves had been mechanically opened - whereupon you
would measure an infinite or several hundred Mohms of resistance).  If
you apply a voltage to the secondary say 15 VAC, you should measure
7.5 VAC (exactly 1/2 of the applied voltage - or close to it) between
each winding and case (ground on a NST).  Also, you should have
continuity between both of the high voltage terminals and both of the
high voltage terminals to ground.

I would recommend applying a voltage (15VAC or some low level test
voltage -at- 60Hz) between the High Voltage secondary terminals and
measuring their respective voltages with respect to the case ground.  You
should measure 1/2 of the voltage that you apply between the high voltage
terminals and ground (case) - and please note that the test voltages are to

be applied to the High Voltage terminals NOT the low voltage (115VAC)
terminals!!!  If anything I've said isn't 100% clear - please let me
know!!!

David L. McKinnon
HV / Transformer Engineer

E-mail:  DavMcKin-at-ix-dot-netcom-dot-com