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Transformer Wire Sizing

10/30/2017 9:27 AM

Hello

I was thinking about something the other day. Is it fairly common to have different wire sizes on a transformer?

For example say you have a 480 / 110 transformer

15 KVA so full load on the 480 side is only 30 A and on the 110 size is around 130Amps

So when sizing the wire for each side would we just select an appropriate size for the 30A and then pick again for the 130 A?

Stupid question but for some reason this popped into my head the other day.

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#1

Re: Transformer Wire Sizing

10/30/2017 9:40 AM

Using the same size wire would in principle add unnecessary weight and volume, unnecessary first cost, and therefore unnecessary uncompetitiveness.

The forum cannot answer the question that involves an undefined <...we...>.

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#2
In reply to #1

Re: Transformer Wire Sizing

10/30/2017 10:18 AM
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#3
In reply to #2

Re: Transformer Wire Sizing

10/30/2017 10:41 AM

this forum never stop amazing me

I ask a very specific wire size question and you send me a link to generic transformer page. That was REALLY HELPFUL!

Dont bother posting unless yo are going to make a valiant effort.

This was a generic question for a hypothetical situation.

Sending me to a link that discusses hysteresis is not helpful and not even on the subject.

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#5
In reply to #3

Re: Transformer Wire Sizing

10/30/2017 10:48 AM

Don't insult people who are trying to help you!

Why not ask your instructor if you need help.

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#7
In reply to #5

Re: Transformer Wire Sizing

10/30/2017 11:21 AM

Insult people that are trying to help me?

You are not trying to help me in any sense of the word

Ask my instructor? That is hilarious

Im 50 year old PE that went to a D1 school.

That is the problem with this forum. You old farts are to busy trying to play college police rather then talk about actual engineering.

As a PLC programmer i very seldom talk about wire size. So excuse me for asking a question on a forum designed to ask questions.

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#9
In reply to #7

Re: Transformer Wire Sizing

10/30/2017 11:46 AM

As far as I can see, you would do well to read this!

The 20 Etiquette Lessons Every Child Needs to Know - Etiquette ...

Good luck!

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#11
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Re: Transformer Wire Sizing

10/30/2017 11:55 AM

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#10
In reply to #7

Re: Transformer Wire Sizing

10/30/2017 11:54 AM

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#6
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Re: Transformer Wire Sizing

10/30/2017 10:56 AM

I thought the link that Lyn provided answered your question quite well. (especially the section on wire sizing).

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#8
In reply to #6

Re: Transformer Wire Sizing

10/30/2017 11:23 AM

Ah yes, one old fart to rescue and stick up for the other. Standard operational procedure for CR4 forum

Now i remember why i dont come here anymore. A bunch of retired key board warriors who have never done any real engineering in there life

And the wire sizeing section is talking about the magnet wire to wind a transformer. But as usual your butting your nose in where it doesn't belong

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#12
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Re: Transformer Wire Sizing

10/30/2017 11:57 AM

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#17
In reply to #6

Re: Transformer Wire Sizing

10/30/2017 2:19 PM

I agree that Lyn's link does provide a very good answer to the question. However, the link does accurately use some critical jargon (circular mils per ampere, CGS, watts, volt-amperes) that require the reader to understand the meaning of this jargon. At the same time, this jargon does differentiate the engineers from the chaff.

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#18
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Re: Transformer Wire Sizing

10/30/2017 3:43 PM

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#4
In reply to #1

Re: Transformer Wire Sizing

10/30/2017 10:41 AM

Thanks

All of which i was thinking. Thanks for confirming my thoughts.

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#13

Re: Transformer Wire Sizing

10/30/2017 12:41 PM

The answer is yes.In most cases different wires are uses for different currents.

There are some exceptions such as weight and price of tranaformer being very small compared with the whole project, or when the same winding can be used by making series and parallel connections.

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#15
In reply to #13

Re: Transformer Wire Sizing

10/30/2017 1:30 PM

Thank you for your reply sir

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#23
In reply to #15

Re: Transformer Wire Sizing

10/31/2017 4:27 AM

Are you certain that user is male?

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#14

Re: Transformer Wire Sizing

10/30/2017 12:43 PM
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#16
In reply to #14

Re: Transformer Wire Sizing

10/30/2017 1:30 PM

Thank you for your reply sir

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#22
In reply to #16

Re: Transformer Wire Sizing

10/31/2017 4:06 AM

Are you certain that user is male?

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#19

Re: Transformer Wire Sizing

10/30/2017 4:36 PM

More amps, bigger wire, less amps, smaller wire. Copper costs money, don't use more copper than you need.

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#20

Re: Transformer Wire Sizing

10/30/2017 4:41 PM

I am by no means an E.E. But I found this. I believe this pertains to your original question, as does this link.

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#26
In reply to #20

Re: Transformer Wire Sizing

11/03/2017 2:40 PM

That, I believe adequately answers his question.

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#21

Re: Transformer Wire Sizing

10/30/2017 7:05 PM

Generally speaking, yes, the turns ratio of the transformer determines the (inverse) ratio of the wire sizes. There are many exceptions though, especially when considerations such as impedance, temperature rise, voltage drop, size, weight, cost, short-circuit strength, operating frequency, insulation class, cooling means, etc., etc., are in play.

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#24

Re: Transformer Wire Sizing

10/31/2017 10:40 AM

I was going to try to take a stab at this question, but after reading some of the comments, I'm not sure which wires you're talking about. At first, I thought you were talking about the windings, then it looked like you were talking the leads. Are you trying to design the transformer itself, or just hook up an existing one? The devil's in the details. If you think this is just hot air, that's because I'm an old-fart, too.

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#25

Re: Transformer Wire Sizing

10/31/2017 11:00 AM

I decided to skip all the insults and bickering so forgive me if someone else already said this. Here are some observations.

The wire size will determine the number of turns per inch and the overall volume of space needed to get the desired turns ratio.

Magnetic flux density in the primary is proportional to current times the number of turns. The length of the primary wire and the iron core will affect the impedance of the primary, which will determine the current at a given voltage. The secondary current and voltage will then be based on the ratio of primary turns to secondary turns.

There is a lot more science (and some say art) to it than that but that should give you something to think on about the size of the wire.

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