// A Texbook on POWER SYSTEM ENGINEERING // A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar // DHANPAT RAI & Co. // SECOND EDITION // PART III : SWITCHGEAR AND PROTECTION // CHAPTER 9: PROTECTION OF TRANSFORMERS // EXAMPLE : 9.3 : // Page number 636 clear ; clc ; close ; // Clear the work space and console // Given data V_lv = 11.0*10**3 // LV side voltage of transformer(V) V_hv = 66.0*10**3 // HV side voltage of transformer(V) ratio_CT = 250.0/5 // CT ratio on LV side of transformer // Calculations V_hv_phase = V_hv/3**0.5 // HV side phase voltage(V) ratio_main_T = V_hv_phase/V_lv // Ratio of main transformer I_2 = 250.0 // Primary CT I_1 = I_2/(ratio_main_T*3**0.5) // Primary line current(A) CT_sec = 5.0 // Secondary CT secondary_side = CT_sec/3**0.5 // HV side CT secondary // Results disp("PART III - EXAMPLE : 9.3 : SOLUTION :-") printf("\nRatio of CTs on high voltage side = %.1f : %.1f = (%.f/%.2f√3) : (%.f/√3) ", I_1,secondary_side,I_2,ratio_main_T,CT_sec)