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Old 17th November 2008, 04:40 PM   #1
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Default Power transformer design paper

I'd promised to make this available a long time ago. This is a copy of a hand out I got when I was doing my post graduate course in advanced electronic design at IISc in Bangalore some 25 years ago ! With design software available nowadays this might seem unnecessary. Bit it IS interesting and those who do not have software , they might find it illuminating .

I completed typing out the material from the frayed cyclostyled papers just now and so it might have typo's or some small errors . I did go through it quickly twice but it might have some small errors.

There are a few graphs that go along with it but they look bad as the papers are faded and have splotches on them . I need to clean them up ( digitally ) before putting them up.

The question is , should I really spend time doing this ? Would enough people be really be interested in this document today ?
I find it interesting enough to go through through them again.
Could be useful to those who want to wind their own special transformers or modify some they have .

Let me know if I should put up the cleaned up charts also .

To SY and other moderators . The document is just a set of cyclostyled papers. It doesn't mention an author's name ( or editor ) and there is no copyright mentioned either. It does give a course number ( ES6-217 - IISc Bangalore ) . It was compiled by Swiss industry experts .
So I guess it's OK to put this up on this forum ?
Cheers,
Ashok.
Attached Files
File Type: pdf design of power transformers.pdf (51.6 KB, 230 views)
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Old 17th November 2008, 05:19 PM   #2
AndrewT is offline AndrewT  Scotland
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I would like to see/have the whole document.

Thanks, for what you have posted.

I note the current density 5.5A/sqmm of winding cross section.
Most of the new toroids I have are around 3 to 3.5A/sqmm.
Could this account for the reduced regulation that we see for a toroid cf. EI transformer? Older toroids operate with an even lower current density due to the relatively lower price of copper two or three decades ago.
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Old 17th November 2008, 06:03 PM   #3
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Hi Andrew,
Today has been a late night for me. It is about 20 mins past midnight . I decided to check my mail just before turning in when I saw your reply to my post.

I must say that you are probably quite right about guys using higher current densities nowadays . My older transformers did run cooler ! The line between electrically optimum and commercially optimum is very hazy. They must be veering towards the commercial requirement with todays high prices of raw materials.

I'll clean up all the files and charts and post them together if possible tomorrow or latest before the week end.

Glad to see that it is of interest to at least someone. I find it interesting to go through it again after so long. The last time I poured over it really intently was when I was ( also !) concerned about grades !
I'll be using the info again as I'm working on some new transformer designs. One local manufacturer is willing to make one off or small numbers of transformers wound to my specs at very reasonable rates.
I just wound my first power supply choke ( 5 H ) and will be doing more experimentation on chokes soon. I can also buy them as wound coils ( my specs ) with separate core material at pretty affordable rates. I'm not sure if they offer this service to everyone. I know them since they started business around 20 years ago.
Cheers,
Ashok.
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Old 17th November 2008, 08:41 PM   #4
Ghianni is offline Ghianni  Greece
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Interesting! Waiting for the complete document.

Thanks for posting that.
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Old 22nd November 2008, 09:30 PM   #5
kevinkr is offline kevinkr  United States
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Interesting document, thanks for posting it, and I look forward to seeing the rest. Ashok I think a lot of tube guys would be very interested in this paper, and I am going to post a link to this thread there.
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Old 27th November 2008, 10:05 PM   #6
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Hi I am also interested in the whole paper. Thank you.

Regards all

Nico
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Old 28th November 2008, 12:57 AM   #7
AKSA is offline AKSA  Australia
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Thank you Ashok,

I too would be interested in the full paper, if you get time!

Hugh
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Old 28th November 2008, 01:18 AM   #8
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Sorry for the delay. We have been having unusual stormy weather with it's associated flooding in our area ( and plenty of other areas too !). Something like 5 times the usual amount of rain in just a few days. Never seen rain come down so heavily.

I'll put up the whole paper as soon as possible. They say the worst is over and that by Saturday the heavy downpours will stop.
Cheers.
Ashok.
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Old 29th November 2008, 11:09 AM   #9
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Hello

Me also I am interested in the full paper.

I was using formula with maximum core flux measured in maxwell for Bmax because it is from an old transformer making book.

Thank

Gaetan
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Old 1st December 2008, 08:43 AM   #10
gpapag is offline gpapag  Greece
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I am also interested. Thanks in advance.

Take your time. Family priorities first.
Good luck with the flooding.

Regards
George
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