[Amps] Re: White Smoke

[R.Measures]

On Aug 28, 2004, at 2:05 AM, Harold B. Mandel wrote:

> Dear Rich,
>
> Thanks for the reply.

ur welcome
>
> The schematic of the xfmr, as supplied by PWD, shows the dual
> primary windings "side by side" (however vertically) with the
> associated pin-outs corresponding to the original ALPHA 77
> transformer plug. This means that the uppermost winding
> has pin 6 on one side of the coil and pin 12 on the other, or lower
> side of the coil. The lower set of primary windings has pin 9 at the
> top and pins 7&10 both bonded to the lower coil wire.
>
> This arrangement matches the pin out of the ALPHA xfmr plug
> exactly, wherein the pins 9 & 12 are jumpered together for 240vac
> service.
>
> Before connecting any a.c., a resistance check was made to
> verify continuity and lack of continuity between specific leads
> just in case there was a primary-to-frame short, and to verify the
> two primaries were indeed being connected correctly.
>
> If a phase reversal occurred in winding the xfmr, the error was
> embedded and the leads extended so that following the diagram
> produced the damage.
>
> (Yes, no, Maybe???)

Yes.  The moral to the story is, to avoid smoke, put a 100w lightbulb 
in series with the mains when testing transformer  Primary  
winding-phasing.

chers, Hal
>
> Thanks,
> Hal
>
>>>
>>>         Doing a bench test of my new P.W.Dahl custom-wound
>>> filament transformer with no loads attached the breaker was on
>>> for under five seconds before the unit burned out.
>>>
>>>         A small puff of white smoke, a nasty smell and now
>>> a fried transformer.  All the connections matched the PWD
>>> schematic and the voltage was as specified for the primary
>>> windings. The transformer had dual 120-vac windings that
>>> jumper together just like the original ALPHA xfmrs so
>>> 120 or 240 vac service could be selected.
>> --  Were the dual 120vac windings connected in-phase or out of 
>> phase?
>
>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org