Transformer Voltage Ratio Calculation Calculator

The transformer voltage ratio is defined as the ratio of primary voltage to secondary voltage. The transformer has two winding – primary and secondary winding. The primary and secondary voltage is denoted as Vp and Vs respectively.

Derivation of Transformer Voltage Ratio

The transformer functions on the principle of Faraday’s law of electromagnetic induction. The voltage induced in the primary and secondary depends on the number of turns in the primary and secondary winding.

derivation of transformer voltage ratio

From equations (1) and (2), we get

formula of voltage ratio of transformer

The ratio of primary to secondary voltage is the transformer voltage ratio(VR).

Relationship between Voltage & Turn Ratio

The other name of the transformer voltage ratio is the transformer turn ratio(TTR), where TR is the ratio of primary turns to secondary turns.

Transformer Voltage Ratio Calculation
from the above equation(6), it is clear that the transformer voltage ratio is equal to the transformer turn ratio.

The voltage ratio of 1:3 means the secondary voltage is 3 volts for 1 volt of primary voltage. If the primary voltage is 100 volts, then the secondary voltage is 300 volts. The voltage ratio of 1:3 shows that the secondary voltage is more than the primary voltage, and the transformer is called a step-up transformer. In other words, we can say that the transformer that has a voltage ratio of 1:3 will have three times the number of secondary turns than the primary turns.

The voltage ratio of 3:1 means the secondary voltage is 1 volt for 3 volts of primary voltage. If the primary voltage is 90 volts, then the secondary voltage is 30 volts. The voltage ratio of 3:1 shows that the secondary voltage is less than the primary voltage, and the transformer is called a step-down transformer. In other words, we can say that the transformer that has a voltage ratio of 3:1 will have one-third numbers of secondary turns than the primary turns.

Transformer Voltage Ratio Calculator

  • Input Primary Voltage
  • Input Secondary Voltage
  • Press Calculate button
  • The calculated value will be shown on the Voltage Ratio Field
  • Reset for next calculation


Numerical problems

A transformer steps down the voltage from 440 volts in the primary to 44 volts in its secondary. Find the transformer’s voltage ratio.

Given Data-
Vp= 440 Volts
Vs = 44 Volts

Transformer Voltage Ratio Calculation:

solved problem-1  on transformer voltage ratio calculation

A transformer has 1000 turns & 200 turns in its primary and secondary respectively. Find its voltage ratio.

Given data:
Np = 1000
Ns= 200

solved problem-2  on transformer voltage ratio

The voltage ratio of a transformer is 4:1, if the transformer’s primary voltage is 1000 volts, calculate its secondary voltage.

Given Data:
VR = 4:1
Vp= 1000 Volts

solved problem-3  on transformer voltage ratio
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