I saw a site once that said toroids were much more efficient and much
smaller in height then equivalent E-I type transformers. Why do we not
see very many for mains conversion if this is the case?

"B...@gmail.com"
>
>I saw a site once that said toroids were much more efficient

** False.
The percentage efficiency of similar rated E-cores and toroiodals is the 
same.


> and much
> smaller in height then equivalent E-I type transformers.

** Makes them preferable in slim, rack style cabinets.
However, a U-core transforemer is just as low in height.
See pic:

http://www.ecraftsmen.com/user_files/images/Image/450-VA-Single-Phase-Transformer-sm.jpg


>Why do we not
> see very many for mains conversion if this is the case?

** Cos it is simply NOT the case   -  pal.

 Plus there are many drawbacks associated with toroidals.


.....   Phil 

"B...@gmail.com" <b...@gmail.com> wrote in message 
news:a...@h8g2000yqm.googlegroups.com...
> I saw a site once that said toroids were much more efficient and much
> smaller in height then equivalent E-I type transformers. Why do we not
> see very many for mains conversion if this is the case?

Cost, you can wind 10 EI or U cor transformer bobbins at once. ( right 
off the wire spools )
A toroid can only be done one at a time. (unless the machine can handle 
more than one)
A shuttle needs to be wound for each toroid.  toroid winding equipment 
cost more.

They do offer benefits, but the added cost is not justifiable in most 
cases.

Cheers
 

On Fri, 3 Jul 2009 12:38:46 +1000, "Phil Allison" <p...@tpg.com.au>
wrote:

>>
>>I saw a site once that said toroids were much more efficient
>
>** False.
>The percentage efficiency of similar rated E-cores and toroiodals is the 
>same.


  They are less leaky.  It stands to reason that any difference, even if
too small to consider major, would be in favor of the toroid.

On Jul 2, 9:38=A0pm, "Phil Allison" <phi...@tpg.com.au> wrote:
> "Bob.Jones5...@gmail.com"
>
>
>
> >I saw a site once that said toroids were much more efficient
>
> ** False.
> The percentage efficiency of similar rated E-cores and toroiodals is the
> same.
>
> > and much
> > smaller in height then equivalent E-I type transformers.
>
> ** Makes them preferable in slim, rack style cabinets.
> However, a U-core transforemer is just as low in height.
> See pic:
>
> http://www.ecraftsmen.com/user_files/images/Image/450-VA-Single-Phase...
>
> >Why do we not
> > see very many for mains conversion if this is the case?
>
> ** Cos it is simply NOT the case =A0 - =A0pal.
>
> =A0Plus there are many drawbacks associated with toroidals.
>
> ..... =A0 Phil

http://www.eea-trafo.com/toroidal.html

"Toroidal transformers typically are 90 to 95 per cent efficient;
whereas E-I laminates have a typical efficiency of less than 90 per
cent."

Of course they do not mention anything about mains/low frequency but
since they don't mention the frequency dependence I'd assume it is the
general case. After all the reason why E-I is less efficient is
because of the geometry which is probably frequency independent.

On Jul 2, 10:13=A0pm, "Martin Riddle" <martin_...@verizon.net> wrote:
> "Bob.Jones5...@gmail.com" <bob.jones5...@gmail.com> wrote in message
>
> news:a...@h8g2000yqm.googlegroups.com...
>
> > I saw a site once that said toroids were much more efficient and much
> > smaller in height then equivalent E-I type transformers. Why do we not
> > see very many for mains conversion if this is the case?
>
> Cost, you can wind 10 EI or U cor transformer bobbins at once. ( right
> off the wire spools )
> A toroid can only be done one at a time. (unless the machine can handle
> more than one)
> A shuttle needs to be wound for each toroid. =A0toroid winding equipment
> cost more.
>
> They do offer benefits, but the added cost is not justifiable in most
> cases.
>
> Cheers

This sounds like a much more reasonable answer.

"Martin Riddle"
> "B...@gmail.com"
>>
>> I saw a site once that said toroids were much more efficient and much
>> smaller in height then equivalent E-I type transformers. Why do we not
>> see very many for mains conversion if this is the case?
>
> Cost, you can wind 10 EI or U cor transformer bobbins at once. ( right off 
> the wire spools )
> A toroid can only be done one at a time. (unless the machine can handle 
> more than one)
> A shuttle needs to be wound for each toroid.  toroid winding equipment 
> cost more.


** Against that are facts like:

1.  C-cores come ready to use, instead of a box full of lams to be assembled 
after the bobbin is fully wound and terminated.

2.  C-core winding is very fast, inclding all the layers of plastic wrap.

3.  The winding wires can also be used to form the terminations in many 
cases.

4.  No metal mounting frames or bolts need be fitted by hand to assemble the 
final product.

5.  No resin coating or baking in an oven is needed to excluded moisture or 
make all the lams stick together.


Fact is, that in the majority of VA sizes and styles, a toroidal tranny 
takes LESS  time to complete than E-core types and uses less materials.



.....   Phil

"Dorothy with the Red Shoes on"...
 "Phil Allison"

>>>
>>>I saw a site once that said toroids were much more efficient
>>
>>** False.
>>The percentage efficiency of similar rated E-cores and toroiodals is the
>>same.
>
>
>  They are less leaky.

**  ??????????


> It stands to reason that any difference, even if
> too small to consider major, would be in favor of the toroid.

** For the same VA rating,  percentage efficiency ( under load) can go 
either way, by small margins.

  The subject is  MAINS  power toroidals  BTW.



.....  Phil 

"B...@gmail.com"
 "Phil Allison"
>
> >I saw a site once that said toroids were much more efficient
>
> ** False.
> The percentage efficiency of similar rated E-cores and toroiodals is the
> same.
>
> > and much
> > smaller in height then equivalent E-I type transformers.
>
> ** Makes them preferable in slim, rack style cabinets.
> However, a U-core transforemer is just as low in height.
> See pic:
>
> http://www.ecraftsmen.com/user_files/images/Image/450-VA-Single-Phase...
>
> >Why do we not
> > see very many for mains conversion if this is the case?
>
> ** Cos it is simply NOT the case - pal.
>
> Plus there are many drawbacks associated with toroidals.
>

http://www.eea-trafo.com/toroidal.html

"Toroidal transformers typically are 90 to 95 per cent efficient;
whereas E-I laminates have a typical efficiency of less than 90 per
cent."


** Complete pile of  MARKEING   bullshit  !!

 Lots of it to be found on the web  -   fool.

 So do not use it as  FACT  !!!



.....  Phil




.....  Phil

"B...@gmail.com"


This sounds like a much more reasonable answer.


**  Hey listen   -  DICKHEAD  !!!!

YOU   are in  NO  position to judge the answers.

Cos YOU are a know nothing wanker.



.....  Phil