import math
import cmath
#Variable declaration
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)
#Calculation
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)
#Result
print('Current, I = %.3f∠%.2f° p.u' %(abs(I),cmath.phase(I)*180/math.pi))
#Variable declaration
kV = 33.0 #Transmission line operating voltage(kV)
R = 5.0 #Transmission line resistance(ohm)
X = 20.0 #Transmission line reactance(ohm)
kVA_tr = 5000.0 #Rating of step-up transformer(kVA)
X_tr = 6.0 #Reactance of transformer(%)
kVA_A = 10000.0 #Rating of alternator A(kVA)
X_A = 10.0 #Reactance of alternator A(%)
kVA_B = 5000.0 #Rating of alternator B(kVA)
X_B = 7.5 #Reactance of alternator B(%)
#Calculation
kVA_base = kVA_A #Base rating(kVA)
X_gen_A = X_A*kVA_base/kVA_A #Reactance of generator A(%)
X_gen_B = X_B*kVA_base/kVA_B #Reactance of generator B(%)
X_trans = X_tr*kVA_base/kVA_tr #Reactance of transformer(%)
X_per = kVA_base*X/(10*kV**2) #X(%)
R_per = kVA_base*R/(10*kV**2) #R(%)
Z_F1 = (X_gen_A*X_gen_B/(X_gen_A+X_gen_B))+X_trans #Impedance upto fault(%)
kVA_F1 = kVA_base*(100/Z_F1) #Short-circuit kVA fed into the fault(kVA)
R_per_F2 = R_per #R(%)
X_per_F2 = X_per+Z_F1 #X(%)
Z_F2 = (R_per_F2**2+X_per_F2**2)**0.5 #Total impedance upto F2(%)
kVA_F2 = kVA_base*(100/Z_F2) #Short-circuit kVA fed into the fault at F2(kVA)
#Result
print('Case(a): kVA at a short-circuit fault between phases at the HV terminal of transformers = %.f kVA' %kVA_F1)
print('Case(b): kVA at a short-circuit fault between phases at load end of transmission line = %.f kVA' %kVA_F2)
print('\nNOTE: Changes in the obtained answer from that of textbook is due to more precision here & approximation in textbook')
#Variable declaration
kVA_a = 40000.0 #Capacity of transmission line(kVA)
x_a = 10.0 #Reactance of transmission line(%)
kVA_b = 20000.0 #Capacity of transmission line(kVA)
x_b = 5.0 #Reactance of transmission line(%)
kVA_c = 50000.0 #Capacity of transmission line(kVA)
x_c = 20.0 #Reactance of transmission line(%)
kVA_d = 30000.0 #Capacity of transmission line(kVA)
x_d = 15.0 #Reactance of transmission line(%)
kVA_e = 10000.0 #Capacity of transmission line(kVA)
x_e = 6.0 #Reactance of transmission line(%)
kVA_T1 = 150000.0 #Capacity of transformer(kVA)
x_T1 = 10.0 #Reactance of transformer(%)
kVA_T2 = 50000.0 #Capacity of transformer(kVA)
x_T2 = 8.0 #Reactance of transformer(%)
kVA_T3 = 20000.0 #Capacity of transformer(kVA)
x_T3 = 5.0 #Reactance of transformer(%)
kVA_GA = 150000.0 #Capacity of generator(kVA)
x_sA = 90.0 #Synchronous reactance of generator(%)
x_tA = 30.0 #Transient reactance of generator(%)
kVA_GB = 50000.0 #Capacity of generator(kVA)
x_sB = 50.0 #Synchronous reactance of generator(%)
x_tB = 17.5 #Transient reactance of generator(%)
V = 33.0 #Feeder voltage(kV)
#Calculation
kVA_base = 200000.0 #Base rating(kVA)
X_a = kVA_base/kVA_a*x_a #Reactance(%)
X_b = kVA_base/kVA_b*x_b #Reactance(%)
X_c = kVA_base/kVA_c*x_c #Reactance(%)
X_d = kVA_base/kVA_d*x_d #Reactance(%)
X_e = kVA_base/kVA_e*x_e #Reactance(%)
X_T1 = kVA_base/kVA_T1*x_T1 #Reactance(%)
X_T2 = kVA_base/kVA_T2*x_T2 #Reactance(%)
X_T3 = kVA_base/kVA_T3*x_T3 #Reactance(%)
X_sA = kVA_base/kVA_GA*x_sA #Synchronous reactance(%)
X_tA = kVA_base/kVA_GA*x_tA #Transient reactance(%)
X_sB = kVA_base/kVA_GB*x_sB #Synchronous reactance(%)
X_tB = kVA_base/kVA_GB*x_tB #Transient reactance(%)
X_eq_ab = X_a+X_b #Equivalent reactance of transmission lines a & b(%)
X_eq_abc = X_eq_ab*X_c/(X_eq_ab+X_c) #Equivalent reactance of transmission line c with series combination of a & b(%)
X_CF = (X_eq_abc+X_sA)*X_d/(X_eq_abc+X_sA+X_d) #Total reactance b/w sub-station C & F(%)
#Case(i)
X_tr_genA = kVA_base/kVA_GA*x_tA #Reactance in transient state of generator A(%)
X_T1_tr = kVA_base/kVA_T1*x_T1 #Reactance in transient state of transformer T1(%)
X_CF_tr = X_CF #Total reactance in transient state b/w sub-station C & F(%)
X_eq_tAF = X_tr_genA+X_T1_tr+X_CF_tr #Equivalent transient reactance from generator A to substation F(%)
X_tr_genB = kVA_base/kVA_GB*x_tB #Reactance in transient state of generator B(%)
X_T2_tr = kVA_base/kVA_T2*x_T2 #Reactance in transient state of transformer T2(%)
X_eq_tBF = X_tr_genB+X_T2_tr #Equivalent transient reactance from generator B to substation F(%)
X_eq_tF = X_eq_tAF*X_eq_tBF/(X_eq_tAF+X_eq_tBF) #Equivalent transient reactance upto substation F(%)
X_eq_tfault = X_eq_tF+X_T3 #Equivalent transient reactance upto fault point(%)
kVA_t_sc = kVA_base/X_eq_tfault*100 #Transient short circuit kVA(kVA)
I_t_sc = kVA_t_sc/(3**0.5*V) #Transient short circuit rms current(A)
I_t_sc_peak = 2**0.5*I_t_sc #Peak value of transient short circuit current(A)
#Case(ii)
X_S_genA = kVA_base/kVA_GA*x_sA #Reactance in steady state of generator A(%)
X_eq_SAF = X_S_genA+X_T1+X_CF #Equivalent steady state reactance from generator A to substation F(%)
X_eq_SBF = X_sB+X_T2 #Equivalent steady state reactance from generator B to substation F(%)
X_eq_SF = X_eq_SAF*X_eq_SBF/(X_eq_SAF+X_eq_SBF) #Equivalent steady state reactance upto substation F(%)
X_eq_Sfault = X_eq_SF+X_T3 #Equivalent steady state reactance upto fault point(%)
kVA_S_sc = kVA_base/X_eq_Sfault*100 #Steady state short circuit kVA(kVA)
I_S_sc = kVA_S_sc/(3**0.5*V) #Sustained short circuit rms current(A)
I_S_sc_peak = 2**0.5*I_S_sc #Peak value of sustained short circuit current(A)
#Result
print('Case(i) : Transient short circuit current at X = %.f A (peak value)' %I_t_sc_peak)
print('Case(ii): Sustained short circuit current at X = %.f A (peak value)' %I_S_sc_peak)
print('\nNOTE: Changes in the obtained answer from that of textbook is due to more precision here')
#Variable declaration
kVA_gen = 21000.0 #Generator rating(kVA)
kV_gen = 13.8 #Voltage rating of generator(kV)
X_tr_gen = 30.0 #Transient reactance of generator(%)
kVA_trans = 7000.0 #Transformer rating(kVA)
kV_trans_lv = 13.8 #LV voltage rating of transformer(kV)
kV_trans_hv = 66.0 #HV voltage rating of transformer(kV)
X_trans = 8.4 #Reactance of transformer(%)
l = 50.0 #Tie line length(miles)
x = 0.848 #Reactance of tie line(ohm/mile)
l_fault = 20.0 #Location of fault from station A(miles)
#Calculation
kVA_base = kVA_gen #Base rating(kVA)
X_A = X_tr_gen #Reactance of generator A(%)
X_B = X_tr_gen #Reactance of generator B(%)
X_T1 = 3.0*X_trans #Reactance of transformer T1(%)
X_T2 = 3.0*X_trans #Reactance of transformer T2(%)
X_1 = kVA_base/(10*kV_trans_hv**2)*x*l_fault #Reactance(%)
X_2 = X_1*(l-l_fault)/l_fault #Reactance(%)
X_AF = X_A+X_T1+X_1 #Resultant reactance A to F(%)
X_BF = X_B+X_T2+X_2 #Resultant reactance B to F(%)
X_eq_fault = X_AF*X_BF/(X_AF+X_BF) #Equivalent reactance upto fault(%)
kVA_SC = kVA_base/X_eq_fault*100 #Short circuit kVA((kVA)
I_SC = kVA_SC/(3**0.5*kV_trans_hv) #Short circuit current(A)
#Result
print('Short circuit current = %.f A' %I_SC)
print('\nNOTE: Changes in the obtained answer from that of textbook is due to more precision here')
#Variable declaration
MVA_G1 = 100.0 #Generator rating(MVA)
X_G1 = 30.0 #Reactance of generator(%)
MVA_G2 = 150.0 #Generator rating(MVA)
X_G2 = 20.0 #Reactance of generator(%)
MVA_G3 = 200.0 #Generator rating(MVA)
X_G3 = 15.0 #Reactance of generator(%)
MVA_T1 = 150.0 #Transformer rating(MVA)
X_T1 = 10.0 #Reactance of transformer(%)
MVA_T2 = 175.0 #Transformer rating(MVA)
X_T2 = 8.0 #Reactance of transformer(%)
MVA_T3 = 200.0 #Transformer rating(MVA)
X_T3 = 6.0 #Reactance of transformer(%)
MVA_T4 = 100.0 #Transformer rating(MVA)
X_T4 = 5.0 #Reactance of transformer(%)
MVA_T5 = 150.0 #Transformer rating(MVA)
X_T5 = 5.0 #Reactance of transformer(%)
Z_L1 = complex(0.5,1.0) #Line impedance(ohm/km)
L1 = 100.0 #Line length(km)
Z_L2 = complex(0.4,1.2) #Line impedance(ohm/km)
L2 = 50.0 #Line length(km)
Z_L3 = complex(0.4,1.2) #Line impedance(ohm/km)
L3 = 50.0 #Line length(km)
Z_L4 = complex(0.3,1.0) #Line impedance(ohm/km)
L4 = 60.0 #Line length(km)
kV_L1 = 220.0 #Voltage towards line(kV)
kV_L2 = 220.0 #Voltage towards line(kV)
kV_L3 = 132.0 #Voltage towards line(kV)
kV_L4 = 132.0 #Voltage towards line(kV)
#Calculation
MVA_base = 200.0 #Base rating(MVA)
X_d_G1 = (MVA_base/MVA_G1)*(X_G1/100) #Reactance of generator(p.u)
X_d_G2 = (MVA_base/MVA_G2)*(X_G2/100) #Reactance of generator(p.u)
X_d_G3 = (MVA_base/MVA_G3)*(X_G3/100) #Reactance of generator(p.u)
X_T_1 = (MVA_base/MVA_T1)*(X_T1/100) #Reactance of transformer(p.u)
X_T_2 = (MVA_base/MVA_T2)*(X_T2/100) #Reactance of transformer(p.u)
X_T_3 = (MVA_base/MVA_T3)*(X_T3/100) #Reactance of transformer(p.u)
X_T_4 = (MVA_base/MVA_T4)*(X_T4/100) #Reactance of transformer(p.u)
X_T_5 = (MVA_base/MVA_T5)*(X_T5/100) #Reactance of transformer(p.u)
Z_L1_base = kV_L1**2/MVA_base #L1 base impedance(ohm)
Z_L_1 = Z_L1*L1/Z_L1_base #Line impedance(p.u)
Z_L2_base = kV_L2**2/MVA_base #L2 base impedance(ohm)
Z_L_2 = Z_L2*L2/Z_L2_base #Line impedance(p.u)
Z_L3_base = kV_L3**2/MVA_base #L3 base impedance(ohm)
Z_L_3 = Z_L3*L3/Z_L3_base #Line impedance(p.u)
Z_L4_base = kV_L4**2/MVA_base #L4 base impedance(ohm)
Z_L_4 = Z_L4*L4/Z_L4_base #Line impedance(p.u)
#Result
print('p.u values of the single line diagram are as below')
print('Generators p.u reactances :')
print(' X_d_G1 = %.1f p.u' %X_d_G1)
print(' X_d_G2 = %.3f p.u' %X_d_G2)
print(' X_d_G3 = %.2f p.u' %X_d_G3)
print('Transformers p.u reactances :')
print(' X_T1 = %.3f p.u' %X_T_1)
print(' X_T2 = %.4f p.u' %X_T_2)
print(' X_T3 = %.2f p.u' %X_T_3)
print(' X_T4 = %.1f p.u' %X_T_4)
print(' X_T5 = %.3f p.u' %X_T_5)
print('Lines p.u impedances :')
print(' Z_L1 = (%.3f + %.3fj) p.u' %(Z_L_1.real,Z_L_1.imag))
print(' Z_L2 = (%.3f + %.3fj) p.u' %(Z_L_2.real,Z_L_2.imag))
print(' Z_L3 = (%.3f + %.3fj) p.u' %(Z_L_3.real,Z_L_3.imag))
print(' Z_L4 = (%.3f + %.3fj) p.u' %(Z_L_4.real,Z_L_4.imag))
print('\nNOTE: ERROR: (1). Reactance of T2 is 8 percent & not 1 percent as mentioned in the textbook problem statement')
print(' (2). Several calculation mistakes in the textbook')
#Variable declaration
kVA_gen = 21000.0 #Generator rating(kVA)
kV_gen = 13.8 #Voltage rating of generator(kV)
X_tr_gen = 30.0 #Transient reactance of generator(%)
kVA_trans = 7000.0 #Transformer rating(kVA)
kV_trans_lv = 13.8 #LV voltage rating of transformer(kV)
kV_trans_hv = 66.0 #HV voltage rating of transformer(kV)
X_trans = 8.4 #Reactance of transformer(%)
l = 50.0 #Tie line length(miles)
x = 0.848 #Reactance of tie line(ohm/mile)
l_fault = 20.0 #Location of fault from station A(miles)
#Calculation
kVA_base = kVA_gen #Base rating(kVA)
kV_base_lv = kV_trans_lv #Base voltage on L.V side(kV)
kV_base_hv = kV_trans_hv #Base voltage on H.V side(kV)
Z_gen_pu = 1j*X_tr_gen/100 #Impedance of generator(p.u)
Z_trans_pu = 1j*X_trans*3/100 #Impedance of transformer(p.u)
Z_F_left = 1j*x*l_fault*kVA_base/(kV_base_hv**2*1000) #Impedance of line to left of fault F(p.u)
Z_F_right = Z_F_left*(l-l_fault)/l_fault #Impedance of line to right of fault(p.u)
Z_AF = Z_gen_pu+Z_trans_pu+Z_F_left #Impedance(p.u)
Z_BF = Z_gen_pu+Z_trans_pu+Z_F_right #Impedance(p.u)
Z_eq = Z_AF*Z_BF/(Z_AF+Z_BF) #Equivalent impedance(p.u)
I_F = 1.0/abs(Z_eq) #Fault current(p.u)
I_base = kVA_base/(3**0.5*kV_base_hv) #Base current(A)
I_F_actual = I_F*I_base #Actual fault current(A)
#Result
print('Actual fault current = %.f A' %I_F_actual)
print('\nNOTE: Changes in the obtained answer from that of textbook is due to more precision here')
#Variable declaration
MVA_G1 = 50.0 #Generator rating(MVA)
kV_G1 = 15.0 #Voltage rating of generator(kV)
X_G1 = 0.2 #Reactance of generator(p.u)
MVA_G2 = 25.0 #Generator rating(MVA)
kV_G2 = 15.0 #Voltage rating of generator(kV)
X_G2 = 0.2 #Reactance of generator(p.u)
kV_T = 66.0 #Voltage rating of transformer(kV)
X_T = 0.1 #Reactance of transformer(p.u)
kV_fault = 66.0 #Voltage at fault occurence(kV)
kv_base = 69.0 #Base voltage(kV)
MVA_base = 100.0 #Base MVA
#Calculation
X_d_G1 = X_G1*MVA_base/MVA_G1 #Sub-transient reactance referred to 100 MVA(p.u)
E_G1 = kV_fault/kv_base #Voltage(p.u)
X_d_G2 = X_G2*MVA_base/MVA_G2 #Sub-transient reactance referred to 100 MVA(p.u)
E_G2 = kV_fault/kv_base #Voltage(p.u)
X_net = X_d_G1*X_d_G2/(X_d_G1+X_d_G2) #Net sub-transient reactance(p.u)
E_g = (E_G1+E_G2)/2 #Net voltage(p.u). NOTE: Not sure how this comes
I_fault = E_g/(1j*(X_net+X_T)) #Sub-transient fault current(p.u)
#Result
print('Sub-transient fault current = %.3fj p.u' %I_fault.imag)
print('\nNOTE: Changes in the obtained answer from that of textbook is due to more precision here')
import math
import cmath
#Variable declaration
X_d_st = 0.2 #Sub-transient reactance(p.u)
X_d_t = 0.4 #Transient reactance(p.u)
X_d = 1.0 #Direct axis reactance(p.u)
I_pu = 1.0 #Load current(p.u)
PF = 0.80 #Lagging power factor
#Calculation
V = 1.0 #Terminal voltage(p.u)
sin_phi = (1-PF**2)**0.5
I = I_pu*(PF-1j*sin_phi) #Load current(p.u)
E_st = V+1j*I*X_d_st #Voltage behind sub-transient reactance(p.u)
E_t = V+1j*I*X_d_t #Voltage behind transient reactance(p.u)
E = V+1j*I*X_d #Voltage behind direct axis reactance(p.u)
#Result
print('Voltage behind sub-transient reactance = %.2f∠%.2f° p.u' %(abs(E_st),cmath.phase(E_st)*180/math.pi))
print('Voltage behind transient reactance = %.2f∠%.2f° p.u' %(abs(E_t),cmath.phase(E_t)*180/math.pi))
print('Voltage behind direct axis reactance, E = %.2f∠%.2f° p.u' %(abs(E),cmath.phase(E)*180/math.pi))
#Variable declaration
kVA_G = 7500.0 #Generator rating(kVA)
kV_G = 6.9 #Voltage rating of generator(kV)
X_d_st = 9.0/100 #Sub-transient reactance of generator
X_d_t = 15.0/100 #Transient reactance of generator
X_d = 100.0 #Synchronous reactance of generator
kVA_T = 7500.0 #Transformer rating(kVA)
kV_T_delta = 6.9 #Voltage rating of transformer delta side(kV)
kV_T_wye = 115.0 #Voltage rating of transformer wye side(kV)
X = 10.0/100 #Transformer reactance
#Calculation
I_base_ht = kVA_T/(3**0.5*kV_T_wye) #Base current at ht side(A)
I_base_lt = kVA_T/(3**0.5*kV_T_delta) #Base current at lt side(A)
I_f_st = 1.0/(1j*(X_d_st+X)) #Sub-transient current after fault(p.u)
I_f_ht = abs(I_f_st)*I_base_ht #Initial fault current in h.t side(A)
I_f_lt = abs(I_f_st)*I_base_lt #Initial fault current in l.t side(A)
#Result
print('Initial symmetrical rms current in the h.v side = %.f A' %I_f_ht)
print('Initial symmetrical rms current in the l.v side = %.f A' %I_f_lt)
print('\nNOTE: Changes in the obtained answer from that of textbook is due to more precision here')
#Variable declaration
kVA_alt = 625.0 #Alternator rating(kVA)
V_alt = 480.0 #Voltage rating of alternator(V)
load = 500.0 #Load(kW)
V_load = 480.0 #Load voltage(V)
X_st = 8.0/100 #Sub-transient reactance
#Calculation
kVA_base = 625.0 #Base kVA
V_base = 480.0 #Base voltage(V)
I_load = load/kVA_base #Load cuurent(A)
V = 1.0 #Terminal voltage(p.u)
E_st = V+1j*I_load*X_st #Sub-transient voltage(p.u)
I_st = E_st/(1j*X_st) #Sub-transient current(p.u)
#Result
print('Initial symmetrical rms current at the generator terminal = (%.1f%.1fj) p.u' %(I_st.real,I_st.imag))
import math
import cmath
#Variable declaration
X_d_st_G = 0.15 #Sub-transient reactance of generator(p.u)
X_d_st_M = 0.45 #Sub-transient reactance of motor(p.u)
X = 0.10 #Leakage reactance of transformer(p.u)
V = 0.9 #Terminal voltage of the generator(p.u)
I_G = 1.0 #Output current of the generator(p.u)
PF = 0.8 #Power factor of the load
#Calculation
sin_phi = (1-PF**2)**0.5
I = I_G*(PF+1j*sin_phi) #Load current(p.u)
E_st_G = V+1j*I*X_d_st_G #Sub-transient voltage of the generator(p.u)
E_st_M = V-1j*I*X_d_st_M #Sub-transient voltage of the motor(p.u)
I_st_g = E_st_G/(1j*(X_d_st_G+X)) #Sub-transient current in the generator at fault(p.u)
I_st_m = E_st_M/(1j*(X_d_st_M-X)) #Sub-transient current in the motor at fault(p.u)
#Result
print('Case(a): Sub-transient current in the fault in generator = %.3f∠%.3f° p.u' %(abs(I_st_g),cmath.phase(I_st_g)*180/math.pi))
print('Case(b): Sub-transient current in the fault in motor = %.3f∠%.2f° p.u' %(abs(I_st_m),(180+cmath.phase(I_st_m)*180/math.pi)))
print('\nNOTE: ERROR: Sub-transient reactance of motor is 0.45 p.u & not 0.35 p.u as mentioned in textbook statement')
#Variable declaration
kVA_G = 625.0 #Generator rating(kVA)
V_G = 2.4 #Voltage rating of generator(kV)
X_st_G = 8.0/100 #Sub-transient reactance of generator
rating_M = 250.0 #Motor rating(HP)
V_M = 2.4 #Voltage rating of motor(kV)
n = 90.0/100 #Efficiency of motor
X_st_M = 20.0/100 #Sub-transient reactance of motor
#Calculation
kVA_base = 625.0 #Base kVA
input_M = rating_M*0.746/n #Each motor input(kVA)
X_st_m_pu = X_st_M*kVA_base/input_M #Sub-transient reactance of motor(p.u)
I_base = kVA_base/(3**0.5*V_M) #Base current(A)
Z_th = 1j*X_st_m_pu/3*X_st_G/(X_st_m_pu/3+X_st_G) #Thevenin impedance(p.u)
I_st = 1.0/Z_th #Initial symmetrical current at F(p.u)
I_st_g = I_st*(X_st_m_pu/3/(X_st_m_pu/3+X_st_G)) #Fault current rating of generator breaker(p.u)
I_st_m = (I_st-I_st_g)/3 #Fault current rating of each motor breaker(p.u)
#Result
print('Sub-transient fault current at F = %.2fj p.u' %I_st.imag)
print('Fault current rating of generator breaker = %.1fj p.u' %I_st_g.imag)
print('Fault current rating of each motor breaker = %.2fj p.u' %I_st_m.imag)