TRANSFORMER NOISE ITS CAUSES AND LIMITATIONS

Abstract

111th the instail~ti~n of an ever increasing number of transformer sub-stations in built un Rreas. the noise emitted by the transformer has bec-)me a nrnri (,m of or-~'rir- concern. Tn this dissertati-)n; an a at t-met is made to revie7r the r.resent day kno1arledge on the subject of transformer n~iso. Though all the major sources of noise are listed, -particular attention is given t) the ma--netostriction nro-)erties of the core material., since m<agnetostriction is 'ono rn to be the chief source of dob1e fref7uenc., "hum" emitted by the transformer. Theoretical and design considerations affecting the level of transformer noise are discussed in some detail and the characteristics of noise with na.rticular reference to the human ear are examined critically. Various methods of limitation and reduction of transformer noise are described and it is shown that economic considerations do not usually permit the uuse of very lov noise levels in commercial transformers.