ENGINEERING ARTICLES

TRANSFORMER A transformer is an extended version of an inductor. The flux that is created inside the inductor is used here to induce voltages at other coil, which is termed as secondary coil. If the rate of change of flux can induce voltage across the primary coil, from which it is created, then it is also possible to induce voltage across secondary coil, provided that we can pull the flux to flow through the other coil. The rate of change of flux will induce voltage as many turn we use. If the turn is double the turn in primary then the voltage will also be double. If we increase the number of secondary coils, then voltage will be induced in all the secondary coils according to the number of turns present in each secondary coil. We can increase or decrease the secondary voltage level according to our requirement. If the secondary voltage is increased then it is called step up transformer and for the decreasing case it is called step down transformer. Each secondary voltage will...

Some small transformers for low-power applications are constructed with air between the two coils. Such transformers are inefficient because the percentage of the flux from the first coil that links the second coil is small. The voltage induced in the second coil is determined as follows. E=NdΦ/dt10 8 where N is the number of turns in the coil, dϕ/dt is the time rate of change of flux linking the coil, and ϕ is the flux in lines. At a time when the applied voltage to the coil is E and the flux linking the coils is ϕ lines, the instantaneous voltage of the supply is: Since the amount of flux ϕ linking the second coil is a small percentage of the flux from the first coil, the voltage induced into the second coil is small. The number of turns can be increased to increase the voltage output, but this will increase costs. The need then is to increase the amount of flux from the first coil that links the second coil.