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Pole Mount Distribution Transformer Design

Hi everyone,

I'm currently trying to design a 20kVA (11kV - 230V) pole mount distribution transformer for a project. I'm having some difficulties deciding which core material and winding materials to use for the design.

How do i know what type of cold rolled grain oriented steel to use in the core and what thickness the laminations should be?

How do i know what the thickness and type (Aluminium,copper, round or square) of my winding materials (primary and secondary) should be? Finally, how much insulation should be placed between the winding layers?

Overall, i'm not really sure how to match my transformers application with suitable materials.

Any help would be very much appreciated. Or references to catalogues would be useful.

Thanks in advance slither

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Reply to
slither
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Reply to
John Fields

y,

h
d

It sounds like something I'd try and buy from someone who knew what they were doing. Why do you need to make it yourself?

George H.

Reply to
George Herold

Please tell me that this is a student project, and your design will never hang on the pole outside my house!

And folks wonder why we need licensed engineers.

Start with a good Electric Machines text, like "Electric Machines: Steady-State Theory and Dynamic Performance", M. S. Sarma, (C) William C Brown, 1986. It goes into the trade-offs between iron, iron sizes, wire, etc. Then get yourself a book that's _just_ about designing heavy-iron transformers.

The get yourself about five to ten years of experience in industry, helping to design these things, particularly in analyzing ones that have come back to the factory after incidents. Once you've spent some serious career time analyzing why the melt/burn/explode, then you'll be ready to set out and design one.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
Reply to
Tim Wescott

"slither"

** Wrong newsgroup - pal !!!!!!!!!!!!!!!!!!!!!

You need: "alt. suicidal.lunatics "

... Phil

Reply to
Phil Allison

Sure sounds like a homework question.

pick some figures and run the math see how much you loose in resistive losses, eddy currents, and the like.

adjust the figures, repeat.

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Reply to
Jasen Betts

y,

This is going to take some research into the economics. Your best core design depends on the relative cost of lost energy and the best specialty materials. You'll make a cost-amortization calculation.

The design of pole pig transformers includes cooling oil and enclosures, mechanical mount provisions, bird-tolerance, weather resistance, transient overvoltage and overload tolerance, etc.

Looking up steel formulations for the magnetic properties will only give you an idealized (fully-annealed unstressed) sample's properties, NOT the full as-manufactured performance of the finished product.

The stuff between windings is only PARTLY insulation; it's also mechanical stress relief.

Really designing one of these for mass-production is a daunting task. Have fun!

Reply to
whit3rd

If you check a catalog or actually open such a transformer up you'll find

aluminum primary, aluminum secondary would from flat straps, a step-lap core and insulation made of transformer paper, probably epoxy cured and then the tank filled with oil for cooling and insulation.

some places might still use copper, but it costs more so utilities don't care for that.

distribution transformers are designed to be efficient and to not rip into pieces if they experience a fault. the magnemotive forces can be quite high in such large devices.

Reply to
Cydrome Leader

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