SKEE 4633

Mesin Elektrik

Department of Energy Conversion,

Universiti Teknologi Malaysia (UTM)

Assignment #1 (Group Assignment)

Answer all the questions given in this Tutorial Sheet.

Descriptive Questions:

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.

Q3. With the help of an appropriate equation, discuss briefly the mechanism of torque production in a doubly excited electromechanical energy system.

Due: 4/10/18

Sample of previous semester Assignment:

Question: Click here!                 Answer: Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9

Assignment #2 (Group Assignment)

Redo Examples 4.1 - 4.5. Use this graph paper for Figure 4.24. Click here!            

Descriptive Questions:

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.

Due: 15/11/18

Assignment #3 (Group Assignment)

Redo Examples 4.6 - 4.10. Use this graph paper for Figure 4.24. Click here!   

Descriptive Questions:

Q1. Why a starter is used for a DC motor? State and explain two main methods for starting DC motor.

Q2. Derive torque-speed equations for a separately excited DC motor and a series DC motor. Plot their torque-speed charateristics and explain their behaviour.

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.

Due: 29/11/18

Assignment #4 (Group Assignment)

Redo Examples 5.1, 5.2, 5.4 and 5.5. Use the approximate equivalent circuit of IM.

Descriptive Questions:

Q1. With 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.

Due: 20/12/18

Assignment #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:
supplying power at unity power factor, (ii) supplying power at lagging power factor, and (iii) supplying power at leading power factor.

Q2. With 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 are constants.

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.

No need to submitt

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