The equations, constants, calculators and collections shown below are all related to the design of a transformer.

See the many related electrical equations in vCalc's Electrical Library.

What is a Transformer

A transformer transfers electrical energy between electrical circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force, the force that drives a current in a conductor when the conductor is exposed to time varying magnetic fields.

Transformers are used to increase or decrease the alternating voltages in electric power applications, thus they "transform" the voltage from one voltage level to another voltage level.

A varying current in the transformer's primary winding creates a varying magnetic flux in the transformer core and a varying field impinging on the transformer's secondary winding. See Figure 1

Varying magnetic field in a conductor causes motion of charge thus inducing voltage in the conductor.  In the transformer varying magnetic field at the secondary winding induces a varying electromotive force (EMF) or voltage in the secondary winding due to electromagnetic induction.

In other words, the varying current in the primary winding creates varying magnetic field in the secondary winding and that, in turn creates voltage in the secondary winding.

Since we distribute power over large distances using high voltage alternating current delivery wires, it is necessary to step the voltage down when it arrives at your home.  Thus transformers play an essential part in residential power delivery, among a myriad of other uses.

Transformer Design Elements

Figure 2 shows the dimensions of a simple transformer's core design.  The Core is the component of the transformer in which the magnetic flux is concentrated and around which the winding from from the primary and secondary circuits are wound.  The Core Geometry is a key transformer design element and is expressed in units of `"cm"^5`.