Page 265 - Solutions Manual to accompany Electric Machinery Fundamentals

The resulting terminal characteristic is shown below:

A MATLAB program to calculate the terminal characteristic of this generator with armature reaction is
shown below:

% M-file: prob8_25d2.m
% M-file to calculate the terminal characteristic of a shunt
% dc generator with armature reaction.

% Get the magnetization curve. This file contains the
% three variables if_values, ea_values, and n_0.
clear all
load p87_mag.dat;
if_values = p87_mag(:,1);
ea_values = p87_mag(:,2);
n_0 = 1800;

% First, initialize the values needed in this program.
r_f = 20; % Field resistance (ohms)
r_adj = 10; % Adjustable resistance (ohms)
r_a = 0.18; % Armature + series resistance (ohms)
i_f = 0:0.005:6; % Field current (A)
n = 1800; % Generator speed (r/min)
n_f = 1000; % Number of field turns

% Calculate Ea versus If
Ea = interp1(if_values,ea_values,i_f);

% Calculate Vt versus If
Vt = (r_f + r_adj) * i_f;

% Find the point where the difference between the Ea
% armature reaction line and the Vt line is exactly
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