Name of the: A. Siva Sankar, L/E staff memberBranch: Electrical and Electronics Engg.Institution : Govt.Polytechnic,ProddaturSemester: IVTopic : Single Phase TransformersSubTopic:Practical transformer with winding resistancesSub.Coe:EE-!" # $% &achines-I!uration:'! min.Teachin" Ais:PPT, $nimations1 EE 403.13!epartment of Technica# EucationAnhra $raesh%ECA$(Ideal transformer (Pro)lems on transformer on load&b'ective:*n com+letion of this +eriod, youwill )e a)le to understand( ,eal transformer with windingresistances( Phase or diagrams for the real transformer( Transferring resistance from one side of transformer tothe otherside3 EE 403.13%ea# or $ractica# Transformer( )ith )inin" resistances on#*+($ +ractical transformer has coils of finite resistance. The effect of resistance is to cause voltage dro+s in the two windings.( -et ,. and ,/ )e the resistances of the +rimary winding and secondary winding res+ectively. 0ence, the I.,. and I/,/ re+resent the corres+onding voltage dro+s in the windings4 EE 403.131ig .: Practical transformer with winding resistances5 EE 403.131 1 1 1R I V E =Primary induced e.m.f.2 2 2 2R I V E + =Similarly, Secondary induced e.m.f.2riting the 3V- e4uations for the +rimary and secondary loo+s we have6 EE 403.13$hasor ia"rams for ifferent #oas$hasor ia"rams for ifferent #oasI2V2I2R2E2I01E I1R11I12I01V1,i" -: $hasor ia"ram for resistive #oa7 EE 403.131E E2I0I2V2I2R21I212II1R101V1,i" .: $hasor ia"ram for inuctive #oa8 EE 403.13I2V2I2R2E2I012I1E I1R11I01V1,i" /: $hasor ia"ram for capacitive #oa9 EE 403.13E0uiva#ent %esistance(Tomodelatransformer,itisim+ortanttounderstand how resistances or im+edances are transferred from one sidetoanother,thatis+rimarytosecondaryor secondaryto+rimary.,esistanceor im+edance transfer hel+s to calculate the current5voltage easier and get ride of the ratio for the rest of the calculation.(The resistances of the windings can )e transferred from -V to 0V or vise versa on the )asis of e4ual +ower loss i.e. co++er losses 10 EE 403.13( The co++er loss in the secondary winding is.This loss is su++lied )y +rimary winding current. Ifis the e4uivalent resistancein the +rimary which would have the same loss as within the secondary, Then221222122121221 222KRRRIIRR I R I== =222R I1I12R2R21IIK =12RwhereTheis called the secondary resistance referred to +rimary.E0uiva#ent %esistance(The total resistance of the +rimary ,Similarly, if we +roceed in the same way, the e4uivalent +rimary resistance when referred to secondary is o)tained.The total resistance of the secondary,22112 1 02KRRR R R+ =+ = 2 12211 02R R KR R R+ =+ = 12 EE 403.131ig ':Total resistance of the transformer referred to +rimary13 EE 403.131ig: 6Total resistance of the transformer referred to +rimary14 EE 403.13It is to be note from the above iscussion that.. In order to shift resistance from +rimary to secondary multi+ly the +rimary resistance ,. )y 3/./. In order to shift resistance from secondary to +rimary divide the secondary resistance ,/ )y 3/". 0ence, in general, any im+edance transferred from secondary side to +rimary side must )e multi+lied )y thes4uare of the turns-ratio, a/.15 EE 403.13Summar*::2e have discussed a)out(0ow a real transformer with winding resistances is re+resented.(The +hasor diagrams of the transformer at different loads vi7., 8P1, lagging and leading +ower factors considering the resistances of the windings only.(The derivation of the formulae to transfer resistancefrom one side to the other )ased on e4ual +ower loss.16 EE 403.13.. The secondary load resistance ,- can )e re+resented on the +rimary side asKRAL)LR B)LR K C2)2)KRDL17 EE 403.13/. The relation for e4uivalent resistance of a transformer is o)tained )ased on------A) co++er losses9: iron losses%: hysterisis losses;: eddy current losses18 EE 403.13". ". The resistance of +rimary of a //!!5//! V, '!07 ,The resistance of +rimary of a //!!5//! V, '!07 , single/ turns in +rimary and $ transformer has >. and >/ turns in +rimary andsecondary windings res+ectively. Its secondary windingsecondary windings res+ectively. Its secondary winding resistanceof , resistanceof ,/ /= =, when referred to +rimary,, when referred to +rimary, is------------------ is------------------= =2122)NNR A122)NNR B2212)NNR C212)NNR D20 EE 403.13,re0uent#* Aske 1uestions.. ;erive the relation for e4uivalent resistance of a transformerwhen a: referred to +rimary and ): referred to secondaryE?+lain with neat s@etches./. ;raw the +hasor diagrams of a transformer for resistive andinductive loads assuming the windings have only resistances.21 EE 403.13". 2hat are the effects of winding resistances of a transformerA. E?+lain thenecessity of transferring resistances5 im+edances from one side of a transformer to the other22 EE 403.13,re0uent#* Aske QuestionsEE 403.13 23T0$>3 B*8