How to work out the turn ratio on a transformer

  • Thread starter speedy46
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  • #1
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I would like to know how to work out the turn ratio on a transformer from having just the input and output voltages.
 
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Answers and Replies

  • #2
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For an ideal transformer (that is, no losses in the windings or in the core), the turns ratio is just N = Vp/Vs where
N = turns ratio
Vp = primary Voltage (rms)
Vs = secondary Voltage (rms)

In real transformers, the turns ratio will be slightly higher (typically about 2%) than what is calculated by this formula. One way to improve the accuracy of the calculation is to use a primary Voltage that is only about 10% of the rated Voltage.
 
  • #3
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For example = 244 / 9.88 = 24.6

So the turn ratio is 24 - 6
 
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  • #4
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There are two types of transformers,step-up transformer(sut) and step-down transformer(sdt),the turns ratio for (sut)is bigger than 1 and for (sdt) is less than 1.
 
  • #5
rbj
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For example = 244 / 9.88 = 24.6

So the turn ratio is 24 - 6
what? isn't it 246 to 10? or 24.6 to 1?
 
  • #6
stewartcs
Science Advisor
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There are two types of transformers,step-up transformer(sut) and step-down transformer(sdt),the turns ratio for (sut)is bigger than 1 and for (sdt) is less than 1.
There are quite a few more types of transformers than just step-up and step-down (e.g. autotransformers, buck-boost, isolation).

CS
 
  • #7
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Thank you

How do you calculate the out put voltage of a transformer when you only know the input voltage
 
  • #8
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Thank you

How do you calculate the out put voltage of a transformer when you only know the input voltage
its based on the ratio as stated
 
  • #9
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Is there a formula for working this out please
 
  • #11
1,041
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The formula is in post #2. But, you can only solve for one unknown when you have only one equation. If you don't know the turns ratio, you must measure the primary and secondary Voltages.
 
  • #12
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thank you
 

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