Transformer Core Lamination Thickness

...otherwise the manufacturer would not have offered two options. GA

really this manufacture give us the lowest price ( less than next offer by half million dollar ) and he have great reference in my country

so after i give him 120000 dollar i still have a good deal

i already send to manufacture letter to ask him about the saving due to modification and ask him about the increasing in the weight.

See reply #1 - I suggest you also ask the manufacturer what core losses he will guarantee commercially with each lamination thickness. You can then compare your long time savings with extra initial cost.

ok i will thanks for you

I suspect the extra cost is more due to the use of non-standard material than anything else. A transformer this size will require a large quantity of cold rolled silicon gain oriented steel, scheduling a special run of thinner than normal sheet steel for a transformer that size is not out of the question, but an extra cost to the builder. Plus, it is likely the mechanical design of the core probably has to be modified slightly.

your supplier appears to be eager to please, others probably would not have gone through the exercise to give you exactly what you asked for...

thanks for your help i really wait for his response and i will send to you the supplier repaly

thanks for your great help really i use your guide and i send to him to give me the increasing in volume and weight and the saving

whet you think roughly about the range of increasing in weight if possible

Here's the answer, "we require the core thickness lamination equal or less than 0.3 mm."

Your specification does not require 0.027 mm, so why would you consider it?

Ask the person who wrote the spec if it is worth it.

Lyn's answer is the correct one; if your unit does not require smaller thickness, then do not purchase it because is expensive, but if the unit requires smaller lamination thickness then purchase regardless the price.

i really ask him but as you know 0.27 more better

the specification mentioned 0.3 to make less cost but really according to transformer price the 12000 will not equal to 1.5% of total price so my boss accept if the manufacture send to me the saving and we find this worth but my problem increasing of weight or vol;ume due to change lamination

Secondary Effects can Become Primary Cost Issues

I agree with lyn and pcchatur to use the literal specifications
as a first order consideration for any purchase choice.
However, one should always consider ALL the why's for a choice
in analyzing the motivations behind a specification. Pcchatur
hints at one of these by noting the brittleness of higher silicon
steels. That would lead me to ponder if brittle steel might (beyond
manufacturing cost issues) impact the problem-free lifetime of the
transformer.

One question to ask is if your specs consider such
things as load/age triggered cracking of laminations and the
electrical performance if lamination cracks diminish the magnetic
capacity of the iron loop. Another question is whether there could
be a noise issue precipitated by cracked laminations. A third
consideration is whether there might be internal corrosion aggravated
by cracking. A fourth consideration is whether there are cross terms
with other specifications such as the generation of waste heat from
your transformer and whether the transformer has robust means of
preventing the accumulation of waste heat in hotspots in the
laminations.

Waste heat issues might be particularly pertinent in
locations with solar hotspots on the case, extreme overall
temperatures, or extreme swings in temperature. Locations such as
Saudi Arabia if, indeed the installation is to be in your listed
location, might be important for creating an accurate evaluation of
total costs of providing the power you plan to provide.
Specifically with regard to temperature, the problem-free lifetime
may be highly dependent on the installation climate. The total
costs might also be highly dependent if the transformer is to be
installed in an air conditioned space. The cost of the direct
electrical losses may be less than the cost to remove the heat
produced in the space occupied. If not actively cooled, then
the heat accumulation during high load might be an issue. If
the transformer comes with builtin fans, are they up to the
task with which they will be presented ? If laminations start
cracking, are the fans still adequate with the additional losses
due to the accumulating cracks ?

So, look to the specifications, but do not glibly discount
apparent secondary effects on other specifications for your
purchase. Long term reliability and waste heat removal efficiency
can have major impacts on lifetime total cost of ownership of
your purchase. I am aware that many transformers perform well
even with cracked laminations when their designs include some
tolerance by using more/better iron in the magnetic loop than
strictly required for the magnetic power conveyed through the
oscillating magnetic loop. Hopefully, those with practical
statistics regarding the industry practices and experience will
have some insight with respect to installations in extreme temp
locations. You may want to give them at least some details
about the actual physical installation temperature conditions
and the thermal strategies employed for your transformer.

__________________
thewildotter

What is all this about "laminations cracking"?

I have worked with transformers for 61 years and have yet to find a used transformer with cracked laminations? The laminations may short out, but crack? NEVER!

When I say that steel becomes brittle, doesn't mean that it would crack. All steel specifications call for bend test. This restricts the amount of silicone to be added.

It is partly correct that thinner steel will have lower Eddy loss. This is true only when other chemical composition remaining the same. But manufacturer can always vary alloying elements to improve specific loss. I have used steel with same speecifsloss with different steel thickness

thanks for your valuable help really

i really talk with manufacture about the saving and the income from the modification and i want to ask you if the weight or volume will increase due to this change and the expected increase ( the manufacture will replay at the end of this month ) and i really afraid from chines manufacture although he has great reference

Hi

Transformer performance is affected by the thickness and the composition of the steel used and several other factors as well. If you don't know how to specify the transformer for procurement, employ a consulting engineer to do this properly. You should not be seeking this advice over a web forum (and professional engineers should not be giving it in this way either)

So, a decision worth <...120000 dollar...> is going to be based upon the replies received to a global, anonymous Engineering internet forum?

Wow. This is a post worth watching!

:<subscribes>

How come an incompetent person is given the assignment to decide the purchase of a multi-million dollar transformer?

To answer your question, . . . you care about the CORE LOSS in the transformer. The 0.27mm laminations will have a lower loss.

The supplier must have quoted guaranteed core losses. You will save power and energy over the service life of the transformer by using the transformer with lower losses. Add up the KWH, . . . multiply by energy pricing, . . . and this will be your savings for using the lower-loss core in the transformer. Is it worth paying the extra . . ? ? ?

is that 500MVA or 500MW

the voltage 500 KV

and rating 500 MVA three separate single phase auto transformer

I would like to state that the stacking factor for thinner laminations would be lower than that of thicker laminations. In this case stacking factor of 0.27 mm thick lamination would be lower. Number of layers of 0.27 mm thick laminations would be 10% more than the number of layers of 0.3mm laminations for the same iron core area. Each layer is coated with insulating varnish (about 8-10 microns each side). So lower sacking factor of thinner laminations with more number of layers (with varnish) would result in reduced net iron length of the core thereby increasing the flux density and so the iron losses. Otherwise to maintain the same net iron length, flux density and the losses, extra layers will have to be added. This would result in corresponding increase in weight, cost and (the dimensions to some extant). All these factors result in additional cost.