# Transformation ratio Vs Voltage ratio

#### panthripu

##### Member
What is the difference between transformation ratio and voltage ratio ? Why are they not identical ?

#### LarryFine

##### Master Electrician Electric Contractor Richmond VA
What is the difference between transformation ratio and voltage ratio ? Why are they not identical ?
In theory, they are. In reality, there are resistive losses, reactive losses, magnetic losses, etc.

" Transformation ratio is defined as the ratio of secondary voltage to the primary voltage. It can also be defined as the ratio of number of turns in the secondary winding to the number of turns in the primary winding. "

" A transformer turns ratio is the division of the number of turns in the primary winding by the number of turns in the secondary winding by the equation TR = Np/Ns. This ratio should also equal the voltage of the primary winding divided by the voltage of the secondary winding, as given by Vp/Vs. "

" The transformation ratio is defined as the ratio of the secondary voltage to primary voltage. And Turns Ratio would be the number turns of the primary winding to the secondary winding. Some transformers have multiple secondary windings as well to create multiple outputs. "

• Julius Right and Carultch

#### Julius Right

##### Senior Member
I agree with LarryFine: transformer ratio is the ratio between number of turns primary and secondary and then it is ratio between primary emf [electromotive force] and secondary emf. In no load condition the terminal voltage ratio will be very close to emf ratio, but in the load condition, due to transformer internal voltage drop the difference may be 1 to 20%.