core sizing Re: DC charging reactor

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

>>Imagine slicing through your core with a knife. Looking at

>> the end view of the core you just sliced through, you will

>> be looking at the cross sectional area, ie, cutaway view.

>> If the core measures 5 inches wide x 4 inches high
>>then the 5 x 4 in = 20 sq. inches of cross sectional area.

>>This is what they are talking about --- the rectangular or

>>square cross section area of the core material.  The larger

>> the cross sectional area the more lines of magnetic flux

>>lines that can be produced, and a highermagnetic flux

>> produces more power per unit area.

>     Hmmm. I'm still having trouble picturing this in my head,

> the part about slicing through the core.  There are about 6

> dimensional ways

	?  3, i should think.

> of doing this and I'm not sure which way you mean...

	Mag flux is by definition/observation at right
	angles to electric current flow.  So its the
	dimension/area at right angles to the windings.

> If I throw out an example can you elaborate?
> For my reactor I cut an MOT core into its 'E' and 'I'

> sections. I sawed the middle leg out of the E, turning it

> into a 'C'. I split the C into 2 piles of laminations and

> stuck these end to end forming a rectangular ring.
> It measures 6.5 inches long by 4.5 inches wide.

	The 'other' area is what's needed.  How Thick is
	the stack?
	

> The ring width is about 1 inch and the laminiations are

> 1 inch thick.

	Is this the 'thickness of the pile'?
	That's the principal item of interest.


> So it's as if I took a 1"x1" iron bar

	THAT is the area that is of interest.

> and bent it 90 degrees four times forming a 4.5 x 6.5 rectangle.
> There is a winding on each of the 6.5" sections.


>     So is the 'cross sectional area' simply 6.5 x 4.5?

	'cross' here means crossways to the long dimension.
	(Cross ways to the mag flux: right angles to the
	windings.)


> Surely the thickness of the laminations (read overall iron

> mass) has to figure into this somewhere.

	Good intuition.
	Mass is less important than _area_ tho the two are,
	coincidentally, proportional.

> Help, I'm geometrically challenged and I can't get up ;)

	Yer doing fine...
	This is Much Easier with pictures.
	(Possibly obfuscating, but true:
	It is possible to draw a real analogy between mag
	flow in a mag circuit  and current flow in an
	electric circuit:  In each case, there MUST be
	'enough' area to keep out of trouble.

	There are differences:
	In the mag case, there is generally a step change
	(saturation) rather than things just generally
	getting hotter, as in the electrical case.
	Also, mag flux will flow thru air (unlike
	(LV) electric current).

	The magnetic equations use different _names_ (to
	'assist' people in keeping the concepts seperate,
	but if all the equations are set out, the analogy
	is exact.
	)

	best
	dwp

...the net of a million lies...
	Vernor Vinge
There are Many Web Sites which Say Many Things.
	-me