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// Example 2.12
// Computation of (a) Core loss (b) Core loss if operated at rated current and
// 0.860 power factor from 375V, 50 HZ supply (c) Efficiency for condition in (b)
// (d) Efficiency if the load is disconnected
// Page No. 72
clc;
clear;
close;
// Given data
Srated=50000; // Transformer power rating
VHS=450; // High side voltage
RPU=0.0125; // Percent resistance
XPU=0.0224; // Percent reactance
FP=0.86; // Power factor lagging
eta=0.965 // Efficiency
Hl=0.71 // Hysteresis loss
Vt60=375 // Supply voltage
f1=60; // Transformer frequency
f2=50; // Supply frequency
// (a) Core loss
IHS=Srated/VHS;
// Using high-side values
Req_HS=RPU*VHS/IHS; // Equivalent high-side resistance
Pout=Srated*FP; // Output power
Pin=Pout/eta; // Input power
Pcore=Pin-Pout-(IHS^2*Req_HS) // Core loss
// (b) Core loss if operated at rated current and 0.860 power factor from
// 375V, 50 HZ supply
Ph60=Hl*Pcore; // Hysteresis loss
Pe60=Pcore-Ph60; // Eddy current loss
Pe50=Pe60*(Vt60/VHS)^2; // Eddy current loss
Ph50=Ph60*(f2/f1)*(Vt60/VHS*f1/f2)^1.6;
Pcore50=Pe50+Ph50; // Core loss
// (c) Efficiency
Pout=Vt60*IHS*FP; // Output power
etanew=Pout/(Pout+Pcore50+IHS^2*Req_HS);
// (d) Efficiency with the load is disconnected
// Display result on command window
printf("\n Core loss = %0.1f W", Pcore);
printf("\n Core loss at 375V, 50 Hz supply = %0.2f W",Pcore50);
printf("\n Efficiency = %0.1f Percent", etanew*100);
printf("\n Efficiency = 0 with the load is disconnected as Pout=0" )
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