310102jA Fundamentals of Alternating Current Part A 2015 (TF)
Fundamentals of Alternating Current
General Overview
Topic: Alternating Current (ac)
Focus on Circuit Properties
Presented by: Tiisley & Lovo
Course: Instrumentation Technician
Page 1: Introduction to AC
Definition of Alternating Current (ac)
Key concepts will be explored in subsequent pages, including generation, properties, and behaviors in circuits.
Page 2: Understanding Magnetic Fields and AC
Magnetic Field:
Direction indicators: North (N) and South (S)
Circular Motion of Conductor:
Conductor cuts across magnetic lines of force at different angles (0°, 90°, 180°, 270°, 360°)
Positive and Negative Alternations explained.
Voltage and Cycles:
One complete cycle includes one positive and one negative alternation.
Page 3: Course Objectives
Explain the generation of an ac sine wave.
Determine the output frequency of an ac generator.
Calculate standard ac sine wave values.
Demonstrate the relationship between sine waves and phasor diagrams.
Page 4: Generation of Alternating Current
Principle of Generation:
Relative motion between conductor and magnetic flux induces electromotive force (emf) or voltage.
Factors affecting emf generated:
Density of Magnetic Flux
Length of Conductor
Rate of Conductor's Motion (Velocity)
Formula: E = βLV
Where β = Magnetic Flux Density, L = Length of Conductor, V = Velocity
Page 5: Motion of Conductor Analysis
Emphasizes the interaction of a circular conductor within a magnetic field.
Equation Explaining emf: E = B × L × V
Understanding peaks and different positions throughout the electrical cycle.
Page 6: Cutting Lines of Force
Rate of Cutting:
Non-cutting (0°), Medium, and Maximum Cutting Rates (90°, 145°)
Seen through varying conductor positions within a magnetic field.
Importance of angle in the rate of emf generation.
Page 7: Understanding Alternation in Cycles
Breakdown of a single electrical cycle:
Positive Alternation (0° to 180°)
Negative Alternation (180° to 360°)
Visual representation of conductor positions and voltage changes.
Page 8: Voltage Waveform Representation
Graphical Representation:
Positive peak and negative peak generated by the waveform.
Key positions and states summarized in graphical format.
Page 9: AC vs. DC Current
Comparison Graphs: Current vs Time in AC and DC Circuits
Key Point: Ohm’s law applies in resistive circuits, illustrating current's proportionality to voltage.
Page 10: Sine Wave Development
Explaining the development of a sine wave indicating:
Voltage Peak (Emax) = 170V
Voltage values at angles (0°, 20°, 45°, 90°), demonstrating varying instantaneous voltage levels using sine calculations (e.g., e = Emax × sin(angle)).
Page 11: Mechanical vs Electrical Cycles
Analysis of 4-pole machine behavior:
Produces one cycle while rotating through 180 mechanical degrees.
Understanding the conversion between mechanical and electrical degrees.
Page 12: Advanced Cycles of 4-pole Machine
Illustrated explanation of cycles generated by a 4-pole machine:
720 electrical degrees as it travels through 360 mechanical degrees represents two complete electrical cycles.
Page 13: 8-pole Machine Cycles
In-depth analysis of an 8-pole machine and cycle generation:
Produces 4 cycles through 360 mechanical degrees.
Page 14: Frequency and Speed Comparison
Comparative graph showing frequency and rotational speeds:
2-pole: 60 r/min = 1 Hz
4-pole: 60 r/min = 2 Hz
120 r/min for both = 4 Hz, emphasizing the relationship between pole numbers and frequency.
Page 15: Frequency Calculation Formula
Frequency (f) Calculation:
f = [Number of poles] × [Speed]
Key visual representations of generated frequencies and conditions for electrical cycles.
Page 16: Frequency Measurement
Definition of Frequency:
Measured in electrical cycles per second (hertz).
Important Relationships:
Frequency calculations for 15 cycles in 100 ms yielding 150 Hz.
Page 17: Voltage Values in Electrical Cycle
Explaining variables:
Vm, Em: Maximum voltage values
e: Instantaneous voltage values during 360° electrical cycle.
Vrms: root mean square value for practical voltage reading.
Page 18: Instantaneous Values of Voltage
Exploration of instantaneous voltage values at different angles within one cycle, along with peak values for sine waveforms.
Page 19: Detailed Sine Wave Properties
Detailed breakdown of sine wave characteristics and voltage development at various degrees throughout the cycle.
Page 20: Sine Wave Example - 100 V
Visual representation of a sine wave with E = 100 V and measurements for instantaneous voltage along with the degree angles.
Page 21: Maximum and RMS Values
Explanation of maximum (Em) and effective (Ems) values in the context of alternating current:
Example: Em = 100 V, Ems = 70.7 V at specific angles.
Page 22: Conclusion of Objectives 1, 2 & 3
Recap of learning objectives achieved through the lessons learned in this material.
Page 23: Phasor Representation of Sine Waves
Introduction to phasors, simplifying the representation of sine waves and their properties.
Page 24: Different RMS Value Phasors
Illustrative figures showcasing phasors indicating various RMS values representing different sine waves.
Page 25: In-Phase Currents
Visual representation of in-phase currents accentuating points of alignment (or origin references) within the cycle.
Page 26: Out-of-Phase Voltage Representation
Visualizing voltages that are out of phase, understanding their implications on circuit behavior.
Page 27: Two Voltages Out-of-Phase Representation
Diagrams illustrating the behavior of two voltages separated by a 90° phase difference, demonstrating their interaction.
Page 28: Alterations in Reference for Out-of-Phase Voltages
Review of the same two voltages with a different reference, showcasing phase interrelations visually.
Page 29: Drawing Phasors
Techniques for visually representing phasor relationships and their associated angular measurements within the electrical cycle.