The Transformer

Abstract

The transformer is a stationary appliance used to change the voltage of an a.c. supply without changing the frequency. For long distance transmission very high voltages are required; for distribution, much lower voltage; and for utilisation, say in the home, voltages of the order of 240 V. The transformer is essentially a ‘close-coupled’ mutual inductor, this meaning that almost of the whole of the flux set up by the primary m m f. links with the secondary winding, and almost of the whole of the flux set up by the secondary m.m.f. links with the primary winding. In other words, the leakage flux, the flux which links with one winding only, is very small. To ensure such close coupling the windings are arranged with their coils in close physical association and they are wound on a magnetic core.