Large transformer design

[peterson76]

Hello,

I need to build a large mains transformer, around 10 kva. Does anyone know of a free basic design program for a transformer such as this? The programs I see are for high frequency flyback and such...

Thanks,
Eric

 

[svhb]

Do you have some laminations available? Why would you like to build this yourself?

Anyway, you have to start with a certain estimated lamination size, see how much primary windings you need for a certain maximum induction (this sets the 'core'-losses and depends on the kind of laminations used). Then you calculate the number of secondary windings goes together with that.

Knowing the number of windings for secondary and primary, try to find a wire diameter for both that fits the available winding area. Calculate the 'copper'-loss for nominal load (on primary AND secondary). If the copper loss + the 'core' loss is too high for the estimated form factor, choose the next bigger form factor for the laminations and start over again...

For a lot of these steps, you will need some information about the laminations used, the nominal power a certain size of transformer can dissipate before starting to smell bad, ....

My advice, try to get some information from a specialized company, and maybe order the tranformer over there too.

Stefaan

 

[peterson76]

Thanks,

Ya, I have several large toroid core laminations around from similar transformers. I have had some made in the past and the cost is the holdup. I would like try my own first. I just needed a starting point for inductance, etc because I hate to waste that much wire on a bad design.

Can you give me an example calculation for inductance and turns based on 50-60 hz 240v input and 2000v output @ 5 amps (10 kva). I really just need to know where to start on the primary turns count. The other stuff is not a problem.

I don't have spec for the laminations that i have. Is there a quick and dirty method for getting some characteristics of the core using a scope and some windings?

Thank you.

 

[svhb]

If you understand some basic magnetic properties, you can do a lot yourself. You can even measure some material characteristics of your core material.

**broken link removed**
https://en.wikibooks.org/wiki/Electronics/Transformer_Design
https://en.wikipedia.org/wiki/Transformer