An electrical transformer is a device that transfers power or electric energy from one circuit to another through electromagnetic induction. Michael Faraday first discovered electromagnetic induction in the 1830s. Faraday found that every time the magnetic field around an electromagnet was built and broken down by the closing and opening of the circuit of which it was a part, an electric current was produced in a nearby separate conductor. Moving a permanent magnet in and out of a coil of wire also induced a current in the wire while the magnet was in motion. As long as the conductor moves near a stationary permanent magnet, current will flow through the wire. However, there are many different types of transformers, each designed for several applications. Here are some of the most common types of transformers and their applications.
A transformer typically consists of two coils of wires wound around an iron core. Each coil is a part of a different circuit. When alternating current flows through the primary coil, it magnetizes the iron core. Since the current is alternating current, the magnetic field of the iron core is constantly reversing. Alternating current flows through the primary winding, creating a variable magnetic flux. The resulting magnetic field strikes the second winding and generates an alternating voltage through electromagnetic induction.
Vp = Primary Voltage Vs = Secondary Voltage
Ip = Primary Current Is = Secondary Current
Np = Primary Turns Ns = Secondary Turns
Step-up transformers are used when the power output (and voltage) is low. Moreover, Step-up transformers are essential for distributing electricity to the public. These transformers allow the power plant to increase its supply voltage high enough to operate efficiently over long distances.
Step-down transformers reduce the voltage of received currents at the local distribution level. In the case of a step-down transformer, the second coil has fewer turns than the first, allowing a voltage drop in the current flowing.
Step-up and step-down transformers illustrate the basic principles of electromagnetic induction and voltage variation. However, there are many other transformers for specific applications, including audio, electrical, instrumentation, and others. These transformers operate on induction in the alternating current but differ in their construction to suit their particular functions.