What is a transformer? How does it works ?

What is a transformer? How does it works ?

Transformer is a constant power, frequency, flux device. This converts voltage from step up to step down or vice versa. This works on the principle of mutual induction.

A transformer is an electrical device which converts alternating current from one voltage to another. It can be designed to "step-up" or "step-down" voltages and works on the magnetic induction principle. A transformer has no moving parts and is a completely static solid state device which insures, under normal operating conditions, a long and trouble-free life. A transformer consists of two or more coils of insulated wire wound on a laminated steel core. When voltage is introduced into one coil (called the primary), it magnetizes the iron core. As a result, a voltage is induced into the secondary or output coil. The change of voltage (voltage ratio) between the primary and secondary depends on the turn’s ratio of the two coils.

A transformer operates on the principle of magnetic induction. Each transformer consists of two or more coils of insulated conductor (wire) wound on a laminated steel core. When a voltage is supplied to the PRIMARY (input) coil, it magnetizes the steel core, which in turn induces a voltage on the SECONDARY (output) coil. The voltage induced from the primary to the secondary coils is directly proportional to the turn’s ratio between the two coils.

For example, if a transformer's input or primary leg has twice as many turns of wire as the secondary, then the ratio would be 2:1. Therefore, if you applied 200 volts to the primary, 100 volts would be induced in the secondary. This is an example of a two winding "step-down" transformer. If the voltage is to be "stepped-up" or increased, the same transformer could be turned around and connected so that the input side would have the 100 volts and the output would be 200 volts. Standard transformers rated at 3kVA and larger can be used for either step-up or step-down service. Transformers rated 2kVA and below have compensated windings and should not be used in reverse feed applications.

Formulas:

Transformation ratio (k) = N2/N1       N1: primary turns, N2: secondary turns

                                     = E2/E1         E1: primary induced EMF, E2: secondary induced EMF

Induced EMF (RMS) E1 = 4.44 Φ fN1         Φ: Maximum flux, f = frequency, N1 = Total Turns on primary

Induced EMF (RMS) E2 = 4.44 Φ fN2         Φ: Maximum flux, f = frequency, N2 = Total Turns on Secondary