Re: Pole Pig Question: (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 25 May 2007 10:40:53 -0400
From: Jonathon Reinhart <jonathon.reinhart@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Pole Pig Question: (fwd)

OK, I guess I was a *little* off... but the general idea was right... I
think... :-P

Sorry for any confusion...

Jonathon

On 5/25/07, Tesla list <tesla@xxxxxxxxxx> wrote:
>
> Original poster: List moderator <mod1@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Fri, 25 May 2007 08:24:11 -0400
> From: Jonathon Reinhart <jonathon.reinhart@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Cc: rrreinhart@xxxxxxxxx
> Subject: Re: Pole Pig Question: (fwd)
>
> I always thought it was best to look at it first as just what you said: 1
> Primary (HV) = 1 Secondary.
>
> X1            X2
> O             O
> |                |
> vvvvvvvvvvvvvv   HV
> =========
> ^^^^^^^^^^^^^^   LV
> |        |       |
> O      O     O
> L1     N     L2
>   \     / \     /
>    120   120
>
> Remember the secondary coil is center-tapped, so for now, just think about
> the secondary coil as a whole. The voltage waveform across L1 and L2 will
> look exactly like the waveform across X1 and X2, just as one would expect.
> The tricky part comes in when you add that centertap, and the confusion is
> this:  Voltage is relative.  Now without any grounds connected, all of
> these
> voltages on the LV side are simply relative to each other (I think they
> might float at whatever actual voltage they wish).  But L1-L2 is 240VAC,
> L1-N is 120VAC and L2-N is 120VAC.
>
> Now, we ground one of the terminals so that the voltage is stable and has
> a
> reference point. We COULD (but don't), decide to ground L1.  In this case,
> we could get 120V to ground at N, and 240V to ground at L2.  In this case,
> when N was at +120V, L2 would be at +240V (and same for the negative
> side).
>
> However, it makes much more sense to ground that centertap.  Now the
> difference between L1-N is 120VAC and L2-N is 120VAC, but at a given
> instant
> when L1 is at +120V to ground, and L2 is at -120V to ground, because they
> are wound the same direction, but on opposite sides of the centertap.  We
> ground this center tap, because now, we can still get 240VAC by connecting
> to L1 and L2, but we can never get more than 120V to ground, which is
> safer.
> The only way to get a 240V shock is to touch both L1 and L2, which is
> well,
> pretty unlucky.
>
> Hope this helped,
>
> Jonathon
>
> On 5/24/07, Tesla list <tesla@xxxxxxxxxx> wrote:
> >
> > Original poster: List moderator <mod1@xxxxxxxxxx>
> >
> >
> >
> > ---------- Forwarded message ----------
> > Date: Thu, 24 May 2007 16:14:32 -0500
> > From: Jim < branley1@xxxxxxxxxxx>
> > To: tesla-request@xxxxxxxxxx, Tesla list <tesla@xxxxxxxxxx>
> > Subject: Pole Pig Question:
> >
> >
> > Hi Folks:
> >
> > I have received from you a bucket truck load of insightful input on pole
> > pigs that has helped me to better understand them, thanks.
> > What seems to be evading me is  How can a single primary feed create 2 -
> > secondaries that are alternating in current.
> > I always assumed that 1 - primary feed equals 1 - secondary wave form
> > not 2 - alternating wave forms.
> >
> > Your help is greatly appreciated,
> >
> > Jim
> >
> >
> >
> >
>
>
>