Page 240 - Solutions Manual to accompany Electric Machinery Fundamentals

% curve. Specify cubic spline interpolation to provide
% good results with this sparse magnetization curve.
e_a0 = interp1(mmf_values,ea_values,f,'spline');

% Calculate the motor's speed from Equation (9-13).
n = (e_a ./ e_a0) * n_0;

% Calculate the induced torque corresponding to each
% speed from Equations (8- 55) and (8-56).
t_ ind = e_a .* i_a ./ (n * 2 * pi / 60);

% Plot the torque-speed curve
figure(1);
pl ot(t_ind,n,'b-','LineWidth',2.0);
hold on;
xlabel('\bf\ tau_{ind} (N-m)');
ylabel('\bf\itn_{m} \rm\bf(r/min)');
title ('\b fSeries DC Motor Torque-Speed Characteristic');
%axis([ 0 700 0 5000]);
grid on;
hold off;
The resulting torque-speed character istic is shown below:

8-15. A 300-hp 440-V 560-A, 863 r/min shunt dc motor has been tested, and the following data were taken:
Blocked-rotor test:

V  14.9 V exclusive of brushes V  440 V
F
A
I  500 A I  7.52 A
F
A
No-load operation:

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