What is a Transformer?

An electric device used to transfer energy between two or more circuits through electromagnetic induction is a transformer. It works on the fact that if an alternating current flows through a coil of wire-that is, the primary winding-it generates changing magnetic field around it. That changing magnetic field can induce voltage in a nearby coil of wire, the secondary winding.

The transformers are mainly used to step up a voltage in order to increase the level of the given voltage, or step down a voltage to reduce its level in the power transmission.

Formula 

Transformer formula describes the interrelation of primary and secondary sides of a transformer, which is an electrical device used for transferring energy from one circuit to another through electromagnetic induction. The most important aspect related to this formula consists in expressions for transformations of voltage and current based on the ratio of windings turns.

The formula is given as,

Where

• Vp = main voltage,

• Vs = secondary voltage, 

• NP = number of turns in the primary

• NS = number of turns in the secondary

Solved Problems 

Problem 1:The number of primary and secondary windings is 60 and 100 respectively. The secondary voltage is given by 250V, determine the primary voltage.

 Solution:

 Given:

 Np = 60,

 Ns = 100

 Vs = 250V

The transformer formula is given by,

Vp / Vs = Np / Ns

Vp = Np / Ns × Vs

= 60 / 100 x 250

 Vp = 150 V

Problem 2: The number of primary and secondary windings is 100 and 350 respectively. The primary voltage is given by 200V, find the secondary voltage.

Solution:

Given:

Np = 100,

Ns = 350 and 

Vp = 200V

The transformer formula is given by,

Vp / Vs = Np / Ns

Vs = Vp×Ns / Np

Vs = 200 × 350 / 100

Vs = 700V

 

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