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2 Analysis of heat transfer in a single-phase transformer

2 Analysis of heat transfer in a single-phase transformer

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Assignment 2 6-6Code that shows the formulation <strong>of</strong> thermal equivalent circuit and the elements <strong>in</strong> the circuit% thermal equivalent circuit - topology matrix% [element(1) node(n) node(m) thermal conductivity]Tec = [ 1 1 2 0.5*h_c * 0.5*w_s / (0.5*l_c/tc_fe+<strong>in</strong>s/tc_<strong>in</strong>s+0.5*l_w1/tc_w<strong>in</strong>);2 2 3 0.5*h_c * 0.5*w_s / (0.5*l_w1/tc_w<strong>in</strong>+<strong>in</strong>s/tc_<strong>in</strong>s+0.5*l_w2/tc_w<strong>in</strong>);3 3 4 0.5*h_c * 0.5*w_s / (0.5*l_w2/tc_w<strong>in</strong>+<strong>in</strong>s/tc_<strong>in</strong>s+0.25*l_c/tc_fe);4 4 5 0.5*h_c * 0.5*w_s / (0.25*l_c/tc_fe+1/Aconv);5 1 6 0.5*h_c * 0.5*l_c / ((0.5*w_s+0.25*l_c)/tc_fe);6 2 7 0.5*h_c * l_w1 / ((0.5*w_s-<strong>in</strong>s)/tc_w<strong>in</strong>+<strong>in</strong>s/tc_<strong>in</strong>s+0.25*l_c/tc_fe);7 3 8 0.5*h_c * l_w2 / ((0.5*w_s-<strong>in</strong>s)/tc_w<strong>in</strong>+<strong>in</strong>s/tc_<strong>in</strong>s+0.25*l_c/tc_fe);8 6 7 0.5*h_c * 0.25*l_c / ((0.5*l_c+<strong>in</strong>s+0.5*l_w1)/tc_fe);9 7 8 0.5*h_c * 0.25*l_c / ((0.5*l_w1+<strong>in</strong>s+0.5*l_w2)/tc_fe);10 8 4 0.5*h_c * 0.5*l_c / ((0.5*w_s+0.5*l_c)/tc_fe);11 6 9 0.5*h_c * 0.5*Ltr / ((0.25*l_c)/tc_fe+1/Aconv);];2.5 FE modelF<strong>in</strong>ite element model has been given <strong>in</strong> EMK_task_1.lua.The xy-plane cross-section <strong>of</strong> a shell type <strong>of</strong> <strong>transformer</strong> is the base geometry for the <strong>heat</strong> <strong>transfer</strong>analysis. Notice that the loop calculations are commented out and <strong>in</strong>itially the relative slot open<strong>in</strong>gis selected 50%.2.6 AssignmentBased on the outcome from FE and EC model (that takes at least 5 m<strong>in</strong>utes)― Show Jcm=f(ks) for these deferent models― Calculate a <strong>transfer</strong>red power P=f(ks) for these deferent models― Calculate copper and core losses and the sum <strong>of</strong> these losses Ploss=f(ks)― Estimate the efficiency for these deferent modelsAnalyze the outcome <strong>of</strong> the FE analysis and if necessary <strong>in</strong>troduce additional calculations <strong>in</strong> orderto evaluate the thermal conductance shown below:a)ϑ cuQ cuG th1ϑ ambc)ϑ cu1Q cu1G th1ϑ ambb)G th3ϑ cuQ cuG th1ϑ ambG th6ϑ cu2Q cu2G th4G th2G th5Q feϑ feG th2ϑ feQ feG th3Carry out this study for an optimal <strong>transformer</strong> and as far you are able i.e. start from circuit a,cont<strong>in</strong>ue with b and if you are able then also circuit c.AAV0090 Electrical Drives - project, TTU, 2008

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