How to work out the turn ratio on a transformer

In summary, the turns ratio on a transformer can be calculated by dividing the primary voltage by the secondary voltage. In real transformers, the turns ratio may be slightly higher than this calculated value. To improve accuracy, a primary voltage that is only 10% of the rated voltage can be used. There are two types of transformers, step-up and step-down, with different turns ratios depending on the type. The output voltage of a transformer can be calculated using the turns ratio and input voltage. However, if the turns ratio is unknown, it must be measured using the primary and secondary voltages.
  • #1
speedy46
46
0
I would like to know how to work out the turn ratio on a transformer from having just the input and output voltages.
 
Last edited:
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  • #2
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
For example = 244 / 9.88 = 24.6

So the turn ratio is 24 - 6
 
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  • #4
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
speedy46 said:
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
ws0619 said:
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
Thank you

How do you calculate the out put voltage of a transformer when you only know the input voltage
 
  • #8
speedy46 said:
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
Is there a formula for working this out please
 
  • #11
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
thank you
 

1. What is a transformer?

A transformer is an electrical device that transfers energy between two or more circuits through electromagnetic induction.

2. Why is turn ratio important in a transformer?

The turn ratio in a transformer determines the voltage and current output of the secondary circuit in relation to the input voltage and current of the primary circuit.

3. How do you calculate the turn ratio of a transformer?

The turn ratio is calculated by dividing the number of turns in the secondary coil by the number of turns in the primary coil.

4. What factors affect the turn ratio of a transformer?

The turn ratio of a transformer is affected by the number of turns in the primary and secondary coils, the magnetic permeability of the core material, and the frequency of the input voltage.

5. How does the turn ratio affect the efficiency of a transformer?

A higher turn ratio in a transformer will result in a higher output voltage and a lower input current, which can lead to increased efficiency. However, if the turn ratio is too high, it can cause excessive voltage stress on the insulation of the windings, reducing the lifespan of the transformer.

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