Changing the X/R ratio of a transformer

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chimp1

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Palm Bay, FL US
I was told you can increase the power of a transformer by changing its x/r ratio. You don't need a larger transformer to produce more power just change the x/r ratio. Is this true?
 

jim dungar

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Wisconsin
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I was told you can increase the power of a transformer by changing its x/r ratio. You don't need a larger transformer to produce more power just change the x/r ratio. Is this true?

The X/R ratio of a transformer is determined by its design and construction. After it is built there is nothing for you to change.
 
The X/R ratio of a transformer is determined by its design and construction. After it is built there is nothing for you to change.

That is true, mostly.

I had a 3MVA trasnformer core/coil inspection and it failed the X/R ratio. So they went back to make adjustments and managed to bring it into range. Granted the adjustmens that can be made are minor and has to do with clamping and tightness, but SOME things can be done.
 

jim dungar

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I had a 3MVA trasnformer core/coil inspection and it failed the X/R ratio. So they went back to make adjustments and managed to bring it into range. Granted the adjustmens that can be made are minor and has to do with clamping and tightness, but SOME things can be done.

But all they did was bring it back to its design X/R. They did not change it with the end result being to change the output of the transformer.

If they could not restore the specified X/R, what ould have been the next step?
 
But all they did was bring it back to its design X/R. They did not change it with the end result being to change the output of the transformer.

If they could not restore the specified X/R, what ould have been the next step?

Yes Jim, that's why I said: "That is true, mostly."

Certainly the 'tightening' of the X/R ratio slightly changes the transformers capacity, but not to the degree the OP implied his needs, which he did not state with any quantitative values.
 

beanland

Senior Member
Location
Vancouver, WA
X/R is physical

X/R is physical

The R can be lowered by using larger wire in the windings, but that cannot be fixed after it is built. The X has to do with the proximity and coupling between windings, the tighter the windings are coupled, and coupled through the core, the lower the X. You can lower X by tweaking the windings but only a little. The X/R ratio and impedance are things that need to be designed into the transformer.
 

jim dungar

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Location
Wisconsin
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PE (Retired) - Power Systems
Certainly the 'tightening' of the X/R ratio slightly changes the transformers capacity, but not to the degree the OP implied his needs, which he did not state with any quantitative values.

I was interested in what you would have done if they could not bring the X/R ratio back into specifications.
 
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