ELEN 140 ELECTRICAL CIRCUITS II Winter 2013 Professor: Stephen O Loughlin Prerequisite: ELEN 130 Office: C234B Co-requisite: none Office Ph: (250) 762-5445 ext 4376 Lecture: 3.0 hrs/week Email: soloughlin@okanagan.bc.ca Lab: 2.5 hrs/week Description: Advanced analysis of resistive and reactive passive networks, under direct and alternating current excitation. Topics include Thevenin s and Norton s theorems; loop current and node voltage analysis; superposition; delta-wye transformations; non-ideal transformers; resonant circuits; DC and AC bridges; T and π pad coupling networks; Z and Y two port parameters; filters; bode plots; and threephase systems. Laboratory projects provide experience with testing representative networks. General : Upon completion of this course the student should be able to: 1. Analyze and test practical AC networks using basic principals and techniques. 2. Predict output waveforms for passive circuit configurations with sinusoidal inputs. 3. Predict and analyze the behaviour of resonant circuits. Major Topics: 1. INDUCTION AND CAPACITANCE IN AC CIRCUITS Inductive Reactance Capacitive Reactance The practical inductor Frequency Response of RL circuits Impedance triangles and the phasor domain Effective Resistance OBJECTIVES 1.1 Describe inductive reactance (XL) and capacitive reactance (Xc). 1.2 Given the operation frequency (f) and the value of inductance (L), calculate the inductive reactance (XL) of a simple circuit. 1.3 Describe the effect of the phase relationship between current (I) and voltage (V) in both an inductive circuit and a capacitive circuit. 1.4 Draw a simple phasor diagram representing AC current (I) and voltage (V) in an inductive circuit. 1.5 Given the operating frequency (f) and the value of capacitance (C), calculate the capacitive reactance (Xc) of a simple AC circuit. 1.6 Draw a simple phasor diagram representing AC current (I) and voltage (V) in a capacitive circuit. 1.7 Define impedance (Z). 1.8 Given the values for resistance (R) and inductance (L) and a simple R-L series AC circuit, calculate the impedance (Z) for that circuit. ELEN 140 Course 2013 Okanagan College 1
1.9 Given the values for resistance (R), capacitance (C) and a simple R-C series AC circuit, calculate the impedance (Z) for that circuit. Given a simple R-L-C series AC circuit and the values for resistance (R), inductive reactance (XL), and capacitive reactance (XC), CALCULATE the impedance (Z) for that circuit. 2. IMPEDANCES IN SERIES AND PARALLEL Series LRC circuits Parallel LRC circuits Series-parallel equivalent circuits Impedance triangles Admittance triangles : 2.1 Become familiar with the characteristics of series and parallel ac networks and be able to find current, voltage and power levels for each element and use Ohms law to analyze simple circuits. 2.2 Apply the voltage divider rule to determine the voltage across any element in a series or parallel network. 2.3 Be able to find the total impedance of any series or parallel ac network and sketch the impedance and admittance diagram for each. 2.4 Apply Kirchhoff s current and voltage laws to any series or parallel configuration. 2.5 Determine the series and parallel equivalent of any network comprising a combination of resistors, inductors and capacitors. 3. SERIES AND PARALLEL RESONANCE Series resonant circuits; Parallel resonant circuits; Sensitivity and Selectivity Q factor Filter networks 3.1 Become familiar with the frequency response of a series or parallel resonant circuit and determine the resonant frequency and bandwidth of the circuit. 3.2 Be able to calculate a tuned network s quality factor (Q), bandwidth, voltages, currents and power levels at important frequency levels. 3.3 Sketch the impedance, current and power of elements in a resonant circuit. 3.4 Design a resonant circuit for a given set of parameters 3.5 Convert a series RL network into an equivalent parallel network for a given frequency. 4. METHODS OF CIRCUIT ANALYSIS Superposition; Loop and Nodal analysis; Delta-Wye conversions. Thevenin and Norton equivalent circuits Mesh Analysis; : 4.1 Be able to apply the superposition theorem to ac networks and determine the voltage across or current through any component in the given circuit. ELEN 140 Course 2013 Okanagan College 2
4.2 Become proficient in applying Thevenin s theorem and determine the Thevenin equivalent of circuits having dependent and/or independent sources. 4.3 Determine the Norton equivalent of circuits having dependent and/or independent sources. 4.4 Understand the conditions to be met for maximum power transfer to a load in a given circuit and apply the theorem to determine the load impedance in the circuit. 4.5 Define and explain the steps used in Nodal and Mesh Analysis to develop a set of simultaneous linear equations. 4.6 Convert an ac voltage source into its equivalent current source and conversely convert a current source into its equivalent voltage source. 4.7 Solve for the current or voltage in a circuit having either a dependent current source or a dependent voltage source. 4.8 Perform delta-to-wye and wye-to-delta conversions for circuits having reactive elements. 4.9 Be able to define the relationship between the elements in an ac circuit that will establish a balanced condition. 5. POWER IN REACTIVE CIRCUITS The power triangle; Power factor; True power, reactive power, apparent power; Power factor correction; 5.1 Define and determine the active, reactive and apparent power to a load in a given circuit. 5.2 Construct and use the power triangle to analyze power to complex loads. 5.3 Measure the power in single phase circuits 5.4 Compute the power factor (Fp) and apply power factor correction techniques to the circuit. 5.5 Explain why equipment is rated in VA instead of Watts 6. THE NON-IDEAL TRANSFORMER The non-ideal transformer; The linear power supply; The capacitive loaded transformer Efficiency and Regulation The equivalent circuit, core and copper losses 6.1 Describe the basic construction and operation of a transformer. 6.2 Define and explain the relationship between the transformer ratio, voltage ratio, current ratio, and impedance ratio. 6.3 Use the dot convention to determine transformer phasing. 6.4 Determine and explain the relationship between the voltage and power developed in the primary and secondary windings of a transformer. 6.5 Define reflected impedance and the concept of an equivalent circuit with just the reflected load. 6.6 Use transformers to impedance match load. 6.7 Find the transformation ratio to deliver maximum power to a load and compute the iron-core transformer efficiency. 6.8 List and explain several practical applications of transformer 6.9 Understand and measure the non-ideal characteristics of a transformer. ELEN 140 Course 2013 Okanagan College 3
7. COUPLING NETWORKS Impedance (Z) parameters; T networks; Admittance (Y) parameters; networks 7.1 Use T-pads and π-pads to attenuate signals 7.2 Derive the s parameters for the π-network. 7.3 Design the equivalent circuits for both the t-network and π-network. 8. DECIBEL, FILTERS AND BODE PLOTS The Decibel; The R-C Low-Pass Filter; Simple RC and RL Transfer Functions Filters The R-C High-Pass Filter 8.1 Evaluate the power gain and voltage gain of a given system and express in decibels. 8.2 Identify and design simple RL and RC low-pass and high-pass filters and explain the principles of operation of each type of filter. 8.3 Write the standard form of a transfer function for a given filter. 8.4 Compute the time constant (Tc) and use it to determine the cut-off frequency(ies) and sketch the bode plots showing the frequency response of voltage gain and phase shift of any first-order filter. 9. THREE-PHASE SYSTEMS Three phase voltage generation; Basic three-phase relationships; Measure Power in three-phase circuits; Power system loads Basic three phase circuit connections Power in a balanced system Unbalanced loads 9.1 Become familiar with the operation of a three phase generator and the magnitude and phase relationship between three-phase voltages. 9.2 Represent three phase voltages and currents in phasor form. 9.3 Compute active, reactive and apparent power in a three-phase system (Y or Delta connected). 9.4 Calculate the voltages and currents for a three-phase Y-connected generator and Y-connected load or a delta-connected generator and a delta-connected load. 9.5 Measure power using the two-wattmeter and three-wattmeter methods. 9.6 Analyze simple unbalanced three-phase circuits and determine the line and phasor voltages and currents and power across each line or phasor elements. ELEN 140 Course 2013 Okanagan College 4
Course Materials: 1. Textbook: Introduction to Electric Circuits, 9e, Herbert W. Jackson, Oxford 2. Lab Manual: none Marks Distribution: Class Assignments 15% Lab Reports and Tests 15% Term Tests 30% Final Exam 40% Calculators: You may use any calculator you wish for the course. A calculator that supports the use of both polar and rectangular modes for complex numbers is strongly recommended. The ELEN department has a class set of the CASIO FX991 MS basic scientific calculator. You may wish to purchase one of these for yourself, or at least make yourself familiar with their operation in case your own calculator dies and you need to borrow one of them for a quiz or an exam. No other devices are allowed during exams such as MP3 players, cell phones or PDA s. Labs & Assignments: Students are to hand in, on time, a neat copy of all assignments and lab reports. Students handing any work in late (labs, assignments), will have their mark for that work de-rated. Students arriving late for any lab will have their mark for that lab de-rated. ELEN 140 Course 2013 Okanagan College 5