CAD CAM EDM DRO - Yahoo Group Archive

Re: [CAD_CAM_EDM_DRO] Re:Transformer Workin's

on 2002-02-17 15:37:32 UTC
The reason power transformers have laminations is to contain the magnetic
field. In a typical " E - I " transformer, changing (i.e. alternating)
current in the primary coil creates a magnetic field that's north-oriented
in the area inside the center of the coil, and south-oriented outside the
coil. (Nose-to-Tail, they add to each other, so-to-speak). Since the coil
is mounted inside the EI configuration, virtually all the magnetic field is
"trapped". As the field expands, or becomes more intense, while the
current is increasing, the magnetic "lines of force" subsequently cut
across the secondary coil(s), and induces a current in them, if there's a
"load" attached to them. There is a "downside" to the effect, though...
Even as the primary coil is causing the field to "expand", the field is
cutting across the very coils that initiated the force, and a "back-EMF"
(electro-motive force) is generated. This manifests itself as
Inductance...

At least, that's how I remembers my physics class... when I weren't lookin'
at the girls sittin' at the next table.

----------
> From: John H. <johnhe-uk@...>
>
> This wasn't explained to us in physics for some reason. You have two
coils
> opposite each other in your transformer. The field expands and collapses
> over the coil opposite. The laminate stops it turning the supports into
part
> of the equation, fine. But if you look down on a transformer from the top
it
> looks like 50% of each coil is pointing the 'wrong' way. The field is
> emitted in a spiral shape up each coil which should also be present
_behind_
> the coil pointing away from the other coil. We were told that we should
> assume transformers to be close to 100% efficiency. Does the presence of
> another coil somehow shape the field? This has been annoying me for a
good
> while, that means it's probably a really simple answer.
>
> Regards,
> John H.

Discussion Thread

Raymond Heckert 2002-02-17 15:37:32 UTC Re: [CAD_CAM_EDM_DRO] Re:Transformer Workin's