blob: 6c44ab73ad89232a62d129a1d01cce4a5168c826 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
// A Texbook on POWER SYSTEM ENGINEERING
// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar
// DHANPAT RAI & Co.
// SECOND EDITION
// PART IV : UTILIZATION AND TRACTION
// CHAPTER 1: INDUSTRIAL APPLICATIONS OF ELECTRIC MOTORS
// EXAMPLE : 1.17 :
// Page number 699
clear ; clc ; close ; // Clear the work space and console
// Given data
hp = 50.0 // DC shunt motor rating(hp)
V = 440.0 // Voltage(V)
I_b = 150.0 // Breaking current(A)
N_reduce = 40.0 // Speed of motor fallen by(%)
R_a = 0.1 // Armature resistance(ohm)
I_a_fl = 100.0 // Full-load armature current(A)
N_fl = 600.0 // Full-load speed(rpm)
// Calculations
E_b = V-I_a_fl*R_a // Back emf of motor(V)
V_a = V+E_b // Voltage across armature when braking starts(V)
R_b = V_a/I_b // Resistance required(ohm)
R_extra = R_b-R_a // Extra resistance required(ohm)
T_fl = hp*746*60/(2*%pi*N_fl) // Full-load torque(N-m)
T_initial_b = T_fl*I_b/I_a_fl // Initial breaking torque(N-m)
E_b2 = E_b*(100-N_reduce)/100 // Back emf at new speed(V)
I = (V+E_b2)/R_b // Current(A)
EBT = T_fl*I/I_a_fl // Torque when motor speed reduced by 40%(N-m)
// Results
disp("PART IV - EXAMPLE : 1.17 : SOLUTION :-")
printf("\nBraking torque = %.1f N-m", T_initial_b)
printf("\nTorque when motor speed has fallen, E.B.T = %.1f N-m\n", EBT)
printf("\nNOTE: ERROR: Calculation mistakes in the textbook solution")
|
