Day 4: Transformers Definition of a Transformer Transformer Windings Transformer Operation using Faraday’s Law Step-up & Step-down Transformers Turns Ratio Examples of Transformer Use

Definition of a Transformer A transformer is a device for increasing or decreasing AC voltage A transformer consists of two independent coils wrapped around a common ferrite core. The input winding is called the primary winding, and the output winding is called the secondary winding

Transformer Operation A transformer is designed so that a change in magnetic flux in the primary coil, passes through the secondary coil. Energy losses through the core are minimal An AC voltage applied to the primary coil, produces a ΔΦ B and induces an AC voltage of the same frequency in the secondary coil The voltage in the secondary coil is dependent upon the ratio of the turns in the coils in the transformer

Step-up & Step-down Transformers If the secondary coil has more turns (loops) than the primary, it is called a step-up transformer If the secondary coil has less turns (loops) than the primary, it is called a step-down transformer Energy conservation requires that (neglecting core losses) that the primary power equals the secondary power.

Transformer Operation Transformers only work with AC current. A DC current in the primary coil does not produce a changing magnetic flux, therefore it does not induce an EMF in the secondary coil. A voltage step applied to the primary coil, will only induce a voltage spike in the secondary coil.

Examples of Transformer Use Cell phone chargers Car ignition coil Power company HV Transformers

Examples of Transformer Use