Core lamination

[tommy1000]

This is an old style core lamination plate. The center tap is bended in order to insert it into the bobbin. What is the pros and cons of of this type/style of plate? Thanks

[Juergen Knoop]

fama says equal or better specs than toroids, but expensive - cause not easily machinable

[djQUAN]

I've seen it mentioned here:
Practical Transformer Winding

Not all laminations follow the "economy" proportions, though. Here is an example of a lamination that comes in one piece, instead of being divided into an E and an I, and that has the windows proportionally much larger than the E-I lamination shown above. Such a lamination is a bit more expensive to make, because the steel cut from the windows is wasted, unless the manufacturer can find some other use for it. But being able to accomodate a much large winding assembly, it has some advantages in certain cases.

These "non-economy" laminations were quite usual in Europe, many years ago, but nowadays copper is so much more expensive than steel, that transformers are usually designed to use more steel and less copper. And for that goal, the economy lamination is very well suited. So you won't very often come across a lamination like this, unless you are restoring antique equipment.

[pieter t]

Originally Posted by Juergen Knoop

fama says equal or better specs than toroids, but expensive - cause not easily machinable

Hm Juergen, that is romantic nonsense.
Please see and read this (your own language).
Shouldn't be too difficult for Tommy to read too I hope.

[Juergen Knoop]

hm pieter, what are you referring too? According to your document the MD cut outperforms the EI and M cuts. And I have an article lying around somewhere promising lower inner resistance even than toroids while having a comparable strayfield and size.

[pieter t]

Originally Posted by Juergen Knoop

hm pieter, what are you referring too? According to your document the MD cut outperforms the EI and M cuts. And I have an article lying around somewhere promising lower inner resistance even than toroids while having a comparable strayfield and size.

Juergen,
I just took a quick look at that Waasner document, haven't read the whole story.
In my opinion with whatever EI, M or MD core type you will never reach the same level of power "economics" as is possible for toroids, because of the simple fact that with all stamped laminates the corn orientation is not everywhere "in line" with the magnetic field.
Only c-cores and r-cores can approach toroids in that respect.
Also strayfields with non-toroids will always be larger because part of the core is exposed to the outside world; only with toroids, where the coil surrounds the whole core, strayfields are small, especially when it is a low T design.
Toroids have their own drawbacks however.
I'd be interested in the article you have laying around somewhere.

[tommy1000]

Interesting, according to the Waasner document it is possible to get 60% more power using the MD cut for the same steel weight, compared to M or EI cut, due to better utilization of the grain orientation when using MD cut.

[Tony]

power is a function of temperature rise, did that document say what levels of temperature rise is the 60% comparable to?

[Tony]

Originally Posted by tommy1000

This is an old style core lamination plate. The center tap is bended in order to insert it into the bobbin. What is the pros and cons of of this type/style of plate? Thanks

the obvious, there is just one gap compared to EI's 2......

[Juergen Knoop]

Originally Posted by Tony

power is a function of temperature rise, did that document say what levels of temperature rise is the 60% comparable to?

the document says "equal size and temperature rise"