# ELEN 214 Electrical Circuit Theory

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```					ELEN 214 Electrical Circuit Theory Spring 1999 Sections 501,502 MWF 08:00-09:15 ZACH Rm 104

Description: Credit 4 (3-3). Fundamentals of electric circuit theory and analysis of resistive and complex circuits will be introduced. This course will develop and analyze circuit laws such as nodal and mesh analysis, magnetically coupled circuits, sinusoidal steady state and AC energy systems, as well as switching transients. Emphasis will be placed on conservation of charge, conservation of flux and circuit laws. An introduction to DSP analysis will be included. Prerequisites: PHYS 208; Math 308 or registration therein. Lecturer: Dr. N. C. Griswold, Professor ELEN phone (409) 845-7404, e-mail griswold@ee.tamu.edu, office 216-L, office hours to be announced. Introduction to Electric Circuits: Richard C. Dorf & James A. Svoboda 4th edition John Wiley and Sons, 1998. Reading and homework assignments will be made in class. Class time will be used for explanation, clarification and in class solutions to problem sets using the Electronic Workbench, simulations and team projects. Problem sessions will be used to specifically give the student practice in problem solving. Extended use of Electronic workbench will be made. Standard ELEN 214 laboratory. Homework and quiz average---------------------------------------15% individual Laboratory Reports---------------------------------------------------15% team grade Midterm and Final Exam @ 25% each---------------------------50% individual In Class Team Reports-----------------------------------------------20% team grade Approximately one week (two class periods) will be spent on each of the following. Variations in timing will be determined by the instructor. Electric Circuit Variables Electric Circuit Elements Resistive Circuits Methods of Analysis of Resistive Circuits Circuit Theorems Operational Amplifier Energy Storage Elements (inductors and capacitors) Complete Response of RL and RC Circuits Complete Response of RLC Circuits Sinusoidal Steady State Analysis AC Steady State Power Three Phase Circuits Introduction to DSP solutions Introductions to DSP continued

Textbook:

Problem Sessions:

Topics by week:

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Team Projects: Classroom activities will usually include team projects and/or analysis as part of each week. Two outside class projects will also be assigned. A team grade will be assigned for this activity.

Instructor notes:

The following are suggested emphasis areas

Chapter 1: Please emphasize the need to understand and have correct units. Students should be used to this from Physics and Chemistry but experience indicates they do not understand the reasoning nor do they get the units correct. Many times they give answers to questions for finding current and voltage and do not label. Once they learn to label and keep track of units they typically can tell if they have made the correct analysis (ie. if something should be Watts then it had better be Joules/sec). Students seem to have difficulty with polarity as defined by Electrical engineers. This arises out of electron flow concepts in Physics. Voltage and current polarity must be made absolutely clear. In electrical engineering the positive terminal is always understood to mean current flows into that terminal of a circuit element. This current is assumed in the wire connecting elements and once chosen must not be changed for the analysis. This will aid them later in doing Mesh and Nodal analysis. The students have a tendency to change the current direction as they work around the mesh or node. Instantaneous power and energy must be completely understood. For team exercises they need to form the teams and get familiar with Electronic Workbench operation quickly. Make sure everyone in the team can do it so as not to rely solely on one computer wizard.

Chapter 2 Independent and dependent sources should be clearly defined. A suggested example of what a dependent source means and where it fits into the analysis of circuits helps the student feel more confident with these types of sources. Students will need to understand the ramifications of Ohm's law and terminology used such as ohms ands conductance (G). Obviously Kirchhoff's law must be completely understood. Traditionally the students seem to catch on to summing voltages in Mesh analysis but have more difficulties with Nodal analysis. Stress Nodal analysis and point out that under certain conditions the Mesh analysis can fail while Nodal analysis does not. The students ability to work quickly with 3x3 type matrices should be stressed without the use of a calculator. Students need to begin to judge that the calculated answer is correct based on quick estimates so that they begin to see what is reasonable. The units drill will help them with this. I have also suggested that a perspective on household wiring will keep their interest. The first Team task concerns turning a basic resistive load (a light bulb) on from three different rooms. The key is the 4-way switch discussed in problem 2-29. While this deals with AC as opposed to DC the wiring connections help them understand resistive loading. It also helps in reminding them that this is not just a DC course. Do not bring up AC power at this time or impedance concepts. Just the wiring connections from a source. Chapter 3 Resistive networks are a fundamental starting place. Voltage divider and current divider equivalents will help the student reduce the work load but more importantly help them to see how things are connected and where and where not to break circuits for analysis. The students should be able to derive the voltage divider and current divider formulas (not just rely on the text or memorizing). When they can do that they begin to understand resistive networks. The measurement of voltage and current is fundamental to our analysis and the students need to understand need to appreciate analog measuring devices even though in the laboratory they will undoubtedly use digital equipment. The team project in this section is the ohm meter measuring device. They will see this many times in their work and at home just measuring for continuity. They need to have an understanding of how an ohm meter works. Even in cases where they use a digital ohm or multi-meter the concept of switching resistors for full scale deflection is important. Chapter 4 Circuit analysis with resistive networks is where the student needs just a lot of drill. It will take as many different circuits as can be dreamed up to give them confidence. The many variations for both Nodal and Mesh analysis should require an extra amount of homework. Generally the student wants a cook book approach. The large assignments in this section will help them see a wide variety of circuits. They will need to reduce the networks without getting confused with such concepts as a super node or super mesh. Students generally do not grasp this well the first time through. The source transformations are of vital importance to understanding the Thevenin and Norton equivalent circuits and it will be used in AC as well as with Laplacian methods in circuit analysis later. I have suggested two weeks on this section to give sufficient time for drill and classroom discussion. The team efforts on the electronic workbench will help see the real aspects of Norton and Thevenin. Let them work out the results by hand and then work on the Electronic Work Bench (EWB) to see that the simulation with resistive networks is the same for measuring the Thevenin resistance and open circuit voltage as well as the short circuit current. They should draw the circuits with EWB and place the measurement device in the propoer polarity to verify the answers derived by manual means. This concept will feed into maximum power transfer which would be more difficult if they can't make a Thevenin or Norton equivalent circuit.

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