//Book - Power System: Analysis & Design 5th Edition //Authors - J. Duncan Glover, Mulukutla S. Sarma, and Thomas J. Overbye //Chapter - 10 ; Example 10.10 //Scilab Version - 6.0.0 ; OS - Windows clc; clear; Srated = 30; //power rating in MVA Vprtr = 34.5; //primary side of transformer voltage in kV Vsectr = 138; //secondary side of transformer voltage in kV IArated = (Srated*10^6)/(sqrt(3)*Vsectr*10^3); //Rated current on the 138-kV side of the transformer in Amperes CTratiosec = 150/5; //CT ratio on the 138-kV side IA = IArated/CTratiosec; //differential current in 138kV side in Amperes Iarated = (Srated*10^6)/(sqrt(3)*Vprtr*10^3); //Rated current on the 34.5-kV side of the transformer in Amperes CTratiopr = 500/5; //CT ratio on the 34.5-kV side Ia = Iarated/CTratiopr; //differential current in 138kV side in Amperes Iab = Ia*sqrt(3); //diffrential current in lefthand re-straining winding of figure 10.37 in Amperes crtratio = Iab/IA; //ratio of the currents in the left- to righthand restraining winding TA = 5; Tab = 10; tapratio = Tab/TA; //closest relay tap ratio %mismatch = (((Iab/Tab)-(IA/TA))/(Iab/Tab))*100; //percentage mismatch for tap setting printf('\nRated current on the 138kV side of the transformer is %f A',IArated); printf('\nRated current on CT ratio in 138 kV side of the transformer is %f A',IA); printf('\nRated current on the 34.5kV side of the transformer is %f A',Iarated); printf('\nRated current on CT ratio in 34.5kV side of the transformer is %f A',Ia); printf('\nThe percentage mismatch for the tap setting is %f',%mismatch);