#1 (Group Assignment)
Answer all the questions given in this Tutorial Sheet.
Q1.With the help of appropriate equations and and
diagram, discuss briefly the process of energy conversion occurs in a basic electromechanical system.
Q2. With the help of appropriate equations and
diagram, discuss briefly the production of torque in a singly excited electromechanical
energy system based on the change of the field stored energy and co-energy.
the help of an appropriate equation, discuss briefly the mechanism of
torque production in a doubly excited electromechanical
Sample of previous semester Assignment:
Question: Click here! Answer: Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9
#2 (Group Assignment)
Redo Examples 4.1 - 4.5. Use this graph paper for Figure 4.24. Click here!
Q1. What is armature reaction? State and explain two main
methods to minimize the effect of armature reaction.
Q2. State and explain the causes of voltage drops occur in
shunt DC generator.
Q3. State and explain the conditions for voltage build-up in
shunt DC generator.
Q4. Starting from e = Blv, derive an expression for the induced
voltage in a DC generator.
#3 (Group Assignment)
Redo Examples 4.6 - 4.10. Use this graph paper for Figure 4.24. Click here!
Q1. Why a starter is used for a DC motor? State and explain two main methods for starting DC motor.
Derive torque-speed equations for a separately excited DC motor and a
series DC motor. Plot their torque-speed charateristics and explain
Q3. State and explain three methods for controlling speed of DC motor. Highlight their pros and cons.
Q4. Starting from f = Bli, derive an expression for the developed torque in a DC motor.
#4 (Group Assignment)
Redo Examples 5.1, 5.2, 5.4 and 5.5. Use the approximate equivalent circuit of IM.
the help of the simple stator winding diagrams, show the production of
the rotating magnetic field. What happen to the direction of rotor
rotation if the phase sequence of the three phase
winding is changed.
Q2. Describe briefly the working principle of
three-phase induction machine.
Q3. Based on the approximate equivalent circuit of induction machine, write expressions for the torque produced by the motor
as a function of circuit parameters. Plot torque-speed characteristics of the induction motor. Label key quatities.
#5 (Group Assignment)
Problem 6.3 From the Textbook
Q1. Sketch the equivalent circuit of synchronous
generator having Xs
synchronous reactance per phase with circuit parameters and electrical
variables fully labeled. Then, draw the phasor diagrams of the synchronous
generator for each of the following conditions:
(i) supplying power at unity power factor, (ii) supplying power at lagging power factor, and (iii) supplying power at leading power factor.
the help of phasor diagram, describe the
effect of the excitation on the synchronous generator behavior when the
generator real power output, frequency and terminal voltage
Q3. Explain briefly the test needed to be performed
on the synchronous machine to obtain the synchronous reactance. Support your answer with the proper
plots of the tests.
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