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// ELECTRICAL MACHINES
// R.K.Srivastava
// First Impression 2011
// CENGAGE LEARNING INDIA PVT. LTD
// CHAPTER : 4 : DIRECT CURRENT MACHINES
// EXAMPLE : 4.18
clear ; clc ; close ; // Clear the work space and console
// GIVEN DATA
V = 500; // Operating voltage of the DC series motor in Volts
P_hp = 10; // Operating Power in HP
Il = 40; // Lower currents limit in Amphere
Ih = 60; // Higher currents limit in Amphere
f = 0.5/100; // Motor flux rises by 0.5% per amphere
Rt = 0.8; // Motor terminal resistance in Ohms
eta = 90/100; // Motor efficiency
// CALCULATIONS
E1 = V-Il*Rt; // Induced EMF E1 in Volts
// Induced EMF, E2 = 500-60(0.8+r4) = 500 - 60*R4 where r4 is the fourth-step resistance, and R4 = 0.8+r4 and E1 = 1.1*E2 , 500 - 40*0.8 = 1.1*(500-60(0.8+r4)), 500-32 = 550-66*R4 thus we get, R4 = (550-500+32)/66 refer page no. 197
R4 = (V-(E1/1.1))/Ih;
r4 = R4 - Rt; // Fourth-step resistance in ohms
R3 = (V-((V-Il*R4)/1.1))/Ih;
r3 = R3 - R4; // Third-step resistance in ohms
R2 = (V-((V-Il*R3)/1.1))/Ih;
r2 = R2 - R3; // Second-step resistance in ohms
R1 = (V-((V-Il*R2)/1.1))/Ih;
r1 = R1 - R2; // First-step resistance in ohms
// DISPLAY RESULTS
disp("EXAMPLE : 4.18: SOLUTION :-");
printf("\n (a) The resistance steps in series motor stater are %.3f Ohms,%.4f Ohms, %.3f Ohms and %.2f Ohms \n",r1,r2,r3,r4)
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