[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Vegas pole pigs can't take the heat (fwd)

---------- Forwarded message ----------
Date: Sat, 7 Jul 2007 17:55:53 -0500
From: D.C. Cox <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Vegas pole pigs can't take the heat (fwd)

The answer is simple.  There is no "excessive current" that is causing the 

Normal current under high temps --- the oil can not adequately handle the 
cooling requirements of the xmfr and the core gets hotter and hotter as the 
day progresses, especially if the xmfr is operating at full load but yet not 
in overcurrent conditions.  The xmfr oil and case can not dissipate the heat 
into the surrounding ambient air fast enough to prevent core overheating.

Excessive thermal problems under normal load conditions, aggrevated by high 
heat, produce problems.

A lot like the human body.  Under "normal loads" it does fine.  Throw it in 
Iraq or some other high-temp area and it can not function at "full-load" 
without encountering some problems.  Extra precautions have to be taken.  In 
this example, adding more water and more salt help.  In the case of the poor 
pole xmfr it has to survive on what it has --- it doesn't get extra help. 
As a former U.S. Marine in Vietnam during the late 60's I know all to well 
how these thermal effects can overload a human.  Same applies to xmfrs.

Dr. Resonance
Resonance Research Corp.

----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, July 07, 2007 11:00 AM
Subject: Re: Vegas pole pigs can't take the heat (fwd)

> ---------- Forwarded message ----------
> Date: Fri, 6 Jul 2007 15:23:09 -0700 (PDT)
> From: G Hunter <dogbrain_39560@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Vegas pole pigs can't take the heat (fwd)
> This is a puzzle.  I'm no engineer, but I think pole
> transformers are protected from overload by a
> "blowout" fuse or a mechanical recloser.  If too many
> customers switch on the AC, why don't these protect
> the transformer from excessive current?
> I lived on an Air Force base in the deep south for
> many years.  Every year on the first really hot day of
> summer, a large polemount (supported on a trestle
> between two poles) transformer would fail at the
> hottest part of the afternoon.  Even though this pole
> unit was 2 or 3 blocks away, I could hear it fail just
> before my base housing unit lost power.  I recall the
> distinctive growling sound of power arcing so loud it
> echoed around the base.  Once or twice I actually saw
> the flicker of blue-white light playing off nearby
> trees and structures, even in the brassy summer
> sunshine.  Once it actually burst into a smokey,
> spectacular fire, flaming oil dripping to the ground.
> Fortunately, the errant unit was in an open area away
> from houses and streets.
> This was between 1984-95, and I've forgotten exactly
> how many times it failed, but it happened often enough
> that I came to expect it every year--sort of like the
> 4th of July.  After one such summer failure, I noticed
> the replacement unit was much bigger than before.  The
> transformer never failed again.  I guess somebody
> finally got a clue.
> If the smaller, failure-prone unit was overloaded by
> peak summer demand, why didn't the protective devices
> kick in?
> Cheers,
> Greg
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>> ---------- Forwarded message ----------
>> Date: Fri, 06 Jul 2007 17:59:39 +0000
>> From: David Rieben <drieben@xxxxxxxxxxx>
>> To: tesla@xxxxxxxxxx
>> Cc: drieben@xxxxxxxxxxx
>> Subject: Vegas pole pigs can't take the heat
>> Hi all,
>> Although this is not directly Tesla coil related, I
>> thought that
>> some of the collective knowledge of this list would
>> be able
>> to address this question, assuming that the
>> moderator fore-
>> bares to let this through. I noticed in the recent
>> news that some
>> of the pole transformers in Las Vegas were failing
>> and catch-
>> ing fire, supposedly due to the increased demand of
>> running
>> A/Cs. My question is that although 116*F is a bit
>> warm, even
>> by Las Vegas summer standards, Las Vegans (including
>> their
>> local electrical utility) are certainly no strangers
>> to triple digit
>> summer temperatures and I would think that the A/Cs
>> are go-
>> ing to be running a plenty whether it's 116*F or
>> "only" a more
>> typical 105*F.? I can see where the entire power
>> grid, as a
>> whole, would be under additional strain due to above
>> average
>> temperatures, but not the individual pole
>> transformers, at least by
>> that much. We coilers talk all of time about how
>> pole pigs are built
>> very robust and can easily handle 2 to 3 times their
>> nameplate rating
>> for short duty cycles and can even be ran like 50%
>> above their
>> nameplate rating continuously. It sounds to me like
>> the said trans-
>> formers in Las Vegas may have been a bit underrated
>> to begin with and/
>> or they may have been toward the end of, or even
>> past their useful life
>> cycle and the current heat wave may have been the
>> "straw that broke
>> the camel's back". Any more qualified comments?
>> David Rieben
> ____________________________________________________________________________________
> Moody friends. Drama queens. Your life? Nope! - their life, your story. 
> Play Sims Stories at Yahoo! Games.
> http://sims.yahoo.com/