[Amps] Hipersil, the myth and the truth. (Updated)

[Will Matney]

Colin,

I was thinking the same thing because here in the U.S., that goes on a bunch. It's who can grease the politicians hand the most. The U.S. military has also been known to buy things just because someone higher up just wanted them whether it was for the best or not. I hesitated to say this earlier, but since you did, might as well.

See to me, for any of the claims to hold water, they would about have to go against the laws used in electronics where it just dont add up. There is nothing without a loss and there are things that increase those losses. That would completely throw out the formulas used to calculate cores I would think in some areas. The fundamental formula to calculate either core area, turns, voltage, etc. only include flux density, area, frequency, voltage, and using the factor 4.44 for a sine wave, and 4.0 for a square wave. There's nothing more to it. So having a major difference between two transformers with the same core size, frequency, flux density, and voltage just dont add up. The same formulas are used for gaps, and for losses no matter what the shape. These are the same used to construct the watts per pound loss curves, and the flux density curves. Also, tests on each material giving the BH loops, etc. done by the steel manufacturers. Each steel has to have the exact same content to be classified with an AISI number too. This means the BH loop has to be the same, no matter the shape. Plus, if using a C-core whos legs and core are longer, and window wider than a stock EI core, the reluctance will go up instead of down, just like adding more resistance to a series circuit. Those EI core forms were designed for the most economical stamping without scrap, plus the most efficiency they could squeeze out of them, and still get at least two windings in the coil.

They were also designed so that each lamination could be interleaved to kill off any gap. Even though an EI core can be gapped by butt stacking the lams. Then, the C-core still has a gap no matter how well they fit them up, and gap = reluctance, no way around it. Plus, I have several books written by Westinghouse engineers on the subject and they all say the same thing. Thay still have to be designed the same, with the same formulas, whether the original formula, or the WA product which should equal each other in the end.

That's my view on it though and others may see it different.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 4/18/05 at 11:49 AM Colin Lamb wrote:

>Peter asked:
>
>"Can you think of a reason why, at least over here, the military
>especially  
>seemed for many years to go for C cores rather than the conventional E and
> I?"
>
>There is an implication in the question that the military would have
>chosen the C cores because of some inherent quality.  I am not convinced
>that military procurmenet decisions are always that rational.  Over here,
>some military decisions have been proven to to be less than rational, and
>sometimes they are even based upon politics.  So, when I saw your
>question, I wondered if the manufacturer of Hypersil transformers in
>England had made campaign contributions to the political party in office,
>or if someone had arbitrarily determined that since the Hypersil
>transformers were more expensive, they were better, since price is no
>object for the military.  
>
>I realize that it may be heresy to doubt the wisdom of  the English
>military, but I recall a few details in the history books that raised a
>slight bit of doubt.   And, our family tree shows similar questions were
>raised 300 years ago when my family members left your country for the new
>world.  They never mentioned Hypersil, however.   
>
>Colin  K7FM     
> 
>
>
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