// 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 1: SYMMETRICAL SHORT CIRCUIT CAPACITY CALCULATIONS // EXAMPLE : 1.1 : // Page number 466-467 clear ; clc ; close ; // Clear the work space and console // Given data V = 500.0 // Generator voltage(V) rating = 10.0 // Rating of the generator(kVA) n_up = 1.0/2 // Turns ratio of step-up transformer Z_line = complex(1.0,2.0) // Transmission line impedance(ohm) n_down = 10.0/1 // Turns ratio of step-down transformer load = complex(2.0,4.0) // Load(ohm) // Calculations V_base_gen = V // Base voltage(V) kVA_base_gen = rating // Base rating(kVA) I_base_gen = kVA_base_gen*1000/V_base_gen // Base current(A) Z_base_gen = V_base_gen/I_base_gen // Base impedance(ohm) V_base_line = V_base_gen/n_up // Voltage base of the transmission line(V) kVA_base_line = rating // Base rating of transmission line(kVA) I_base_line = kVA_base_line*1000/V_base_line // Base current of transmission line(A) Z_base_line = V_base_line/I_base_line // Base impedance of transmission line(ohm) Z_line_1 = Z_line/Z_base_line // Impedance of transmission line(p.u) V_base_load = V_base_line/n_down // Base voltage at the load(V) kVA_base_load = rating // Base rating of load(kVA) I_base_load = kVA_base_load*1000/V_base_load // Base current of load(A) Z_base_load = V_base_load/I_base_load // Base impedance of load(ohm) Z_load = load/Z_base_load // Load impedance(p.u) Z_total = Z_line_1+Z_load // Total impedance(p.u) I = 1.0/Z_total // Current(p.u) // Results disp("PART III - EXAMPLE : 1.1 : SOLUTION :-") printf("\nCurrent, I = %.3f∠%.2f° p.u", abs(I),phasemag(I))