Transformer Ratio

Hello everyone, hope you all are doing great. You guys will get a detailed discussion on Transformer Ratio in today’s tutorial. I will provide you the information about the basics of transformer ratio or transformation ratio. The discussion will include its definition, mathematical expression to calculate this ratio, parameters required to calculate this ratio and all the relevant details. The relation between voltages and turns of the primary as well as secondary winding will also be the part of this discussion. Let’s get started with the today’s tutorial.

Basics of Transformer Ratio

In general, the transformation ratio can be defined as the ration of the voltage present at the secondary windings of the transformer to the voltage present at the primary windings of the same transformer. In simple words, it can also be said that the transformation ratio is the ratio of secondary voltage to the primary voltage. As we all know that the voltage is represented by the symbol “V”. The secondary voltage is represented by “VS. Similarly, the primary voltage is represented by “VP”. Transformation ratio can be represented by the mathematical expression as given below.

$$ Transformation Ratio =\frac{secondary voltage}{primary voltage} $$
$$ Transformer Ratio = \frac{V_S}{V_P} $$

Turns Ratio

As it is cleared from its name, the turn ratio can be defined as the ratio between the number of turns of secondary winding to the number of turns in the primary winding. The turns are usually represented in theoretical knowledge by “N”. The turns in primary winding can be represented by “NP whereas the turns in the secondary winding can be represented by “NS.
The expression to represent the turns ration can be given as:

$$Turns Ratio =\frac{secondary Turns}{primary Turns}$$
$$Transformer Ratio = \frac{N_S}{N_P}$$

Current Ratio

The current ratio can be defined as the ratio of the current flowing through the secondary winding of a transformer to the current flowing through the primary winding of the same transformer. In simple words, we can say that the ratio of the secondary current to the primary current is known as the current ratio. In theoretical expression, current is normally represented by the symbol “I”. The secondary current is represented by “IS and the primary current is represented by “IP. The transformer ratio can be represented by the expression shown below.

$$Current Ratio =\frac{secondary Current}{primary Current}$$
$$Transformer Ratio = \frac{I_S}{I_P}$$

Relation between Transformation, Turn & Current Ratio

The formulae for all the three transformation ration, turns ration and current ration can make strong relation with each other.
The relation between transformation ratio and turns ratio is below:
$$\frac{V_S}{V_P}=\frac{N_S}{N_P}$$
The relation between current ratio and the turns ratio is below:
$$\frac{N_s}{N_P}=\frac{I_P}{I_S}$$And
The relation between al the three parameters is:
$$\frac{V_S}{V_P}=\frac{N_S}{N_P}=\frac{I_P}{I_S}$$

Power Transformer Ratio

The transformer is basically a passive component that means it has no external power supply. Due to this specific reason, transformer is unable to generate more power at the output from secondary winding in comparison to its primary winding. Keeping in mind the above fact, if the voltage at the secondary winding is higher than the voltage at the primary winding of the transformer, the secondary current will be lesser than the primary current. If the voltage gets halved the current will be doubled correspondingly.

Important Parameters

There are several important parameters associated with the evaluation of transformation ratio, turns ratio, current ratio and power ratio. Below are the parameters with symbols.

Primary voltage = VP
Secondary voltage = VS
Primary current = IP
Secondary current = IS
No of turns in primary windings = NP
No of turns in secondary windings = NS
The important parameters discussed above is in the figure below .

Basic Parameters of Transformers
Basic Parameters of Transformers

This all from the article Transformer Ratio. I hope you guys have enjoyed the content and I hope it will be a lot helpful for you. If you have any sort of question or query, you can ask us anytime in the comment section. Our responsive team will surely respond you soon. Take care till my next tutorial 🙂

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1 thought on “Transformer Ratio”

  1. Sir
    I have requirment an elecrtomagnet of 220 volt a/c, please help me for its design…
    How mai i calculate plz help me

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