Transformers were the first set of electrical components invented in the 18th century. It was invented by Michael Faraday and was first produced industrially in 1831. It is use for stepping up or down AC but it can't be use for DC because DC don't produce oscillating magnetic field when connected to it. An electric transformer is made up of a primary and secondary coils wound on an iron core, the primary coil is where an alternating current is supplied to while the secondary coil is the voltage output phase.
Symbol of a transformer.
Working principles of a transformer.
When AC flows through a coil of certain lengths, varying electromagnetic field is produced around the coil, when a coil of wire is placed near it the electromagnetic field generated from the formal coil induces electric current into it. The amount of electricity is induced into the coil which is placed on a nearby coil of varying magnetic field depends on the distance between them, the nature of the core on which they are wound on and the amount of AC voltage applied to the coil
Types of transformers.
Basically, transformers are classified into two depending on the amount of voltage they produce at the secondary coil. There are basically two types of transformers which are Step down transformers: These type of transformers is use for stepping down an alternating voltage. It's primary has a much number of turns than it's secondary turn. The voltage produced is usually lower than the input voltage, but there is increase in current at the output. For example step down transformers can be made to produce 12v AC from 220v AC source. Step up transformers: they are use for stepping up AC voltage from a low AC source. For example, they can be made to step up 12vAC into 500vAC. The primary coil is made of few turns relative to the secondary coil having large number of turns. Due to the turn ratio of The secondary to primary coil, the output voltage is usually much more than the input meanwhile, the output current is usually always less than the input.
Difference between step down and stepup transformers.
Step down and step up transformers only differs only in the number of primary to secondary turns ratio. A step down transformer can be reversed to a step up by reversing the secondary coil as the primary coil and step up can be reversed to step down by also tell reversing the secondary coil into primary.
Common types of transformers.
1. Laminated iron core transformer. This type of transfomers are made by wounding copper coil on a laminated soft iron made into an E-I interlock.
Their core is usually laminated to reduce eddy current and iron losses by seperating the iron sheets with splint doblin or a non conductive gel. They're usually of small sizes and are usually having a low power rating of mili watt to mega watt making them to be used often in low power electronics.
2.Centre tapped transformers
They are usually laminated and are just a different version of laminated iron transformers. They only differ in the construction of their secondary coil. Their secondary coil is tapped at the middle to form there wire terminals. Their output voltage is usually written in form of 12v-0-12v, 6v-0-6v, 24v-0-24v. For example a transformer of 12v-0-12v rating at it end terminals it produces 12v while at the middle terminal to the end it produces 6v.
3.Torroidal transformers.
Torodial transformers are made in donut shape. They are cost to manufacture because the coils need to be wound by a very precise machine which needs to wound the coil in and out with low speed. Coils are wound in and out of a circular ferrite bead (containing a carbon iron composition) core. They consume less space compared to an E-I shaped core and usually mounted on bread boards with bolts and washers.
4. Leakage or stray field transformers.
These type of transfomers are the most inefficient, their coil are separated with much distance, and atr made from laminated soft iron and insulated copper cables. They are use as welding machine for producing low voltage and high current for heating.
5. Variable transformer.
Their output can be varied according to needs. Variable transformers can are commonly use in research labs and experiments where different AC voltage values are needed which can't be obtained from a normal transformer. It works by exposing part of the secondary winding coils and making the secondary connection vairable through a secondary connection by a sliding carbon brush.
6. Resonant transformers.
A resonant transformer is a transformer which has both it transmitter and reciever coil tuned by connecting a capacitor across their ends each. Examples are tesla coil and induction heaters. A Tesla coil converts few volts of electricity into thousands or milions of volts with the help of large number of secondary turns.
7. Ferrite core transformers.
It's coil usually made of ferrite is made in a E-I interlock. It occupies less space and are use in low power and portable electronics.
Appllications of transfomers.
1. They are use for stepping up or down AC voltage or current.
2. Center tapped transformers are use for converting DC to AC in inverters.
3. They are use for producing high current low voltage use for weldering metals.
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Basic Electronics