Single phase transformer is the static device or machine that is used to increase or decreases the A.C electrical power by the process of mutual induction at constant frequency. Main function of electrical transformer is to increase or decrease the supply voltage according to requirement.
Construction of single phase transformer
Core : core of transformer is the magnetic circuit that is usually made up of laminated Silicon Steel that provide low reluctance path for the magnetic field lines due to their high permeability property.
lamination is the arrangement of various thin sheets and each sheets are laminated by the coating of warnish. we provide lamination to reduce eddy current loss in the electrical machine. And we use Silicon Steel to reduce hysterosis loss due to low reluctance property in the Silicon Steel.
Primary winding : primary winding of single phase transformer is the coil of copper wire that wounded on the vertical limb of transformer core. Primary winding always connected to the input supply of single phase transformer. When primary winding get innergize by the alternating current it produces alternating magnetic field.
Secondary winding : it is coil of copper wire that wounded on vertical limb of the transformer core and it is always connected to the load. Secondary winding receives The induced voltage due to magnetic field created by the primary winding. Generally we use copper material for winding due to their good electrical conductivity.
We cannot identify primary and secondary winding in transformer when it is packed by the outer frame. to identify the windings in Transformers first we will have to open the frame and when we check which winding is connected to supply and which winding is connected to the load then we can identify primary and secondary winding of the Electrical Transformer.
Classification of single phase transformer
Step up transformer : Step Up transformer is consist with large number of turns in secondary winding compare with primary winding. it is used to convert low alternating voltage into high alternating voltage. When voltage increases then current decreases proportionally in secondary winding. Step up Transformer generally used in the generating station and transmission system to increase the generated voltage for long distance AC power transmission.
Step down transformer : step down transformer is consists with less number of turns in secondary winding compare to primary winding and it is used to convert high alternating voltage into low alternating voltage. We decrease the high alternating voltage to safely distributing the power to the home and for domestic purpose as well as for supplying the electronic devices that have requirement of low voltage.
Electrical Transformer consists with different important parts that we learn in next article of detailed construction of electrical Transformer.
Working principle of single phase transformer
First we give single phase AC supply in primary winding. Due to inductive coil of primary winding alternating magnetic flux produces and circulates around the core of transformer. When alternating magnetic field link with secondary winding or cut the winding then EMF induces in secondary winding by the principle of Faraday’s law of electromagnetic induction.
according to the principal of electromagnetic induction whenever varying nature of magnetic field or alternating field link with stationery conductor then EMF induces in the conductor or it’s vice versa. When stationary conductor is a close path then current will starts to circulate in that conductor.
therefore EMF is inducing in single phase transformer because alternating magnetic flux is circulating around the core of Transformers that links with the secondary winding that is a stationary coil. That’s why voltages inducing in the secondary winding.
if secondary coil will be connected to the load current will circulate and connected load will receive the supply. We connect primary coil to the supply and voltage induces in the secondary winding without any direct electrical connection , this phenomenon is known as mutual induction.
Thus an Electrical Transformer works, to increase the AC voltage we use step up Transformer in which number of turns in secondary winding is larger than primary winding. And to decrease the AC voltage we use step down transformer in which number of turns in secondary winding is less than number of turns in primary winding.