Download Experiment 2 Magnetizing Characteristics of DC Generator

Bahçeşehir University
Name & Surname:
Faculty of Engineering
Electrical and Electronics Engineering Department
ID:
Electromechanical Energy Conversion Laboratory
Date:
Experiment 2
Magnetizing Characteristics of DC Generator
PRELIMINARY STUDIES
In this section you should read your lecture notes and answer following questions before coming to the laboratory. There
may be a quiz concerning these questions.
Q1.What are the types of DC machines according to their excitation circuits?
Q2.Draw the equivalent circuit of separately excited DC machine, and show current and power paths for generator
operation.
Q3.What are the ratings of the DC machine we study? How can we make use of them?
EXPERIMENT
A prime mover (a DC motor this week) will be employed to provide mechanical power input. It will be rotating at two
constant speeds (1200[rpm], 1500[rpm]) and these speed levels will be adjusted by instructors. The main point is to
operate a seperatly excited DC generator. So from our generator’s armature terminals we will just read the produced
voltage, thus only a voltmeter connection is needed.
To obtain magnetization characteristic of a seperatly excited DC generator, we must determine the induced voltage as a
function of the field current. So, armature voltage values at different excitation current settings are to be acquired. For
seperate excitation, an independent DC source is needed and for different values of excitation current a rheostat is to be
connected between the field terminals and the DC source. The DC source for excitation must be constant at its rated
value and field current must vary between 0.25 - 0.45[A]. Induced voltage versus field current values must be recorded
both when increasing and decreasing the excitation current. Everyone has to fill Tables.
Part.1. Simulation
In first part experiment will be simulated using Matlab/Simulink. Using the given machine and simulation diagram in the
figure below, adjust field current to the mentioned values by changing resistance and record your readings to the table.
Prepared by F.Kemal BAYAT
Page 1 of 3
Bahçeşehir University
Faculty of Engineering
Electrical and Electronics Engineering Department
Electromechanical Energy Conversion Laboratory
Q4.Plot measurements of at two different speeds below, increasing and decreasing readings together on the same
graph.
@ 1000 rpm
Prepared by F.Kemal BAYAT
@ 1800 rpm
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Bahçeşehir University
Faculty of Engineering
Electrical and Electronics Engineering Department
Electromechanical Energy Conversion Laboratory
Q5.For both of the graphs you plotted, is there a difference between the increasing curve and the decreasing curve? If
there exists a difference, try to comment.
Part.2. Hardware
In this section you will do the experiment in a same manner with the simulation. The difference in the configuration is the
prime mover which substitutes speed input of the generator.
Q6.Plot measurements of at two different speeds below, increasing and decreasing readings together on the same
graph.
@ 1200 rpm
@ 1500 rpm
Q7.For both of the graphs you plotted, is there a difference between the increasing curve and the decreasing curve? If
there exists a difference, try to comment.
Prepared by F.Kemal BAYAT
Page 3 of 3