M3 Electrical Fundamentals B1 B2 PDF

Module FOR B1 & B2 CERTIFICATION 03 ELECTRICAL FUNDAMENTALS Aviation Maintenance Technician Cer...

Module FOR B1 & B2 CERTIFICATION 03 ELECTRICAL FUNDAMENTALS Aviation Maintenance Technician Certification Series - Electron Theory - Resistive (R), Capacitive (C) and, - Static Electricity and Conduction Inductive (L) Circuits - Electrical Terminology - Transformers - Generation of Electricity - Filters - DC Sources of Electricity - AC Generators - DC Circuits - AC Motors - Restistance/Resistor - Power - Capacitance/Capacitor - Magnetism - Inductance/Inductor - DC Motor/Generator Theory - AC Theory  MODULE 03 FOR B1 & B2 CERTIFICATION ELECTRICAL FUNDAMENTALS Aviation Maintenance Technician Certification Series  FORWARD PART-66 and the Acceptable Means of Compliance (AMC) and Guidance Material (GM) of the European Aviation Safety Agency (EASA) Regulation (EC) No. 1321/2014, Appendix 1 to the Implementing Rules establishes the Basic Knowledge Requirements for those seeking an aircraft maintenance license. The information in this Module of the Aviation Maintenance Technical Certification Series published by the Aircraft Technical Book Company meets or exceeds the breadth and depth of knowledge subject matter referenced in Appendix 1 of the Implementing Rules. However, the order of the material presented is at the discretion of the editor in an effort to convey the required knowledge in the most sequential and comprehensible manner. Knowledge levels required for Category A1, B1, B2, and B3 aircraft maintenance licenses remain unchanged from those listed in Appendix 1 Basic Knowledge Requirements. Tables from Appendix 1 Basic Knowledge Requirements are reproduced at the beginning of each module in the series and again at the beginning of each Sub-Module. How numbers are written in this book: This book uses the International Civil Aviation Organization (ICAO) standard of writing numbers. This method displays large numbers by adding a space between each group of 3 digits. This is opposed to the American method which uses commas and the European method which uses periods. For example, the number one million is expressed as so: ICAO Standard 1 000 000 European Standard 1.000.000 American Standard 1,000,000 SI Units: The International System of Units (SI) developed and maintained by the General Conference of Weights and Measures (CGPM) shall be used as the standard system of units of measurement for all aspects of international civil aviation air and ground operations. Prefixes: The prefixes and symbols listed in the table below shall be used to form names and symbols of the decimal multiples and submultiples of International System of Units (SI) units. MULTIPLICATION FACTOR PReFIx SyMbOL 1 000 000 000 000 000 000 = 101⁸ exa E 1 000 000 000 000 000 = 101⁵ peta P 1 000 000 000 000 = 1012 tera T 1 000 000 000 = 10⁹ giga G 1 000 000 = 10⁶ mega M 1 000 = 103 kilo k 100 = 102 hecto h 10 = 101 deca da 0.1 =10-1 deci d 0.01 = 10-2 centi c 0.001 = 10-3 milli m 0.000 001 = 10-⁶ micro µ 0.000 000 001 = 10-⁹ nano n 0.000 000 000 001 = 10-12 pico p 0.000 000 000 000 001 = 10-1⁵ femto f 0.000 000 000 000 000 001 = 10-1⁸ atto a International System of Units (SI) Prefixes  EASA LICENSE CATEGORY CHART A1 B1.1 B1.2 B1.3 B2 Module number and title Airplane Airplane Airplane Helicopter Avionics Turbine Turbine Piston Turbine 1 Mathematics X X X X X 2 Physics X X X X X 3 Electrical Fundamentals X X X X X 4 Electronic Fundamentals X X X X 5 Digital Techniques / Electronic Instrument Systems X X X X X 6 Materials and Hardware X X X X X 7A Maintenance Practices X X X X X 8 Basic Aerodynamics X X X X X 9A Human Factors X X X X X 10 Aviation Legislation X X X X X 11A Turbine Aeroplane Aerodynamics, Structures and Systems X X 11B Piston Aeroplane Aerodynamics, Structures and Systems X 12 Helicopter Aerodynamics, Structures and Systems X 13 Aircraft Aerodynamics, Structures and Systems X 14 Propulsion X 15 Gas Turbine Engine X X X 16 Piston Engine X 17A Propeller X X X MODULE 03 SYLLABUS AS OUTLINED IN PART-66, APPENDIX 1. LEVELS CERTIFICATION CATEGORY ¦ B1 B2 Sub-Module 01 - Electron Theory Structure and distribution of electrical charges within: atoms, molecules, ions, compounds; 1 1 Molecular structure of conductors, semiconductors and insulators. Sub-Module 02 - Static Electricity and Conduction Static electricity and distribution of electrostatic charges; 2 2 Electrostatic laws of attraction and repulsion; Units of charge, Coulomb's Law; Conduction of electricity in solids, liquids, gases and a vacuum. Sub-Module 03 - Electrical Terminology The following terms, their units and factors affecting them: potential difference, electromotive 2 2 force, voltage, current, resistance, conductance, charge, conventional current flow, electron flow. Sub-Module 04 - Generation of Electricity Production of electricity by the following methods: light, heat, friction, pressure, chemical 1 1 action, magnetism and motion. Module 03 - Electrical Fundamentals v  LEVELS CERTIFICATION CATEGORY ¦ B1 B2 Sub-Module 05 - DC Sources of Electricity Construction and basic chemical action of: primary cells, secondary cells, lead acid cells, nickel 2 2 cadmium cells, other alkaline cells; Cells connected in series and parallel; Internal resistance and its effect on a battery; Construction, materials and operation of thermocouples; Operation of photo-cells. Sub-Module 06 - DC Circuits Ohms Law, Kirchoff's Voltage and Current Laws; 2 2 Calculations using the above laws to find resistance, voltage and current; Significance of the internal resistance of a supply. Sub-Module 07 - Restistance/Resistor (a) Resistance and affecting factors; 2 2 Specific resistance; Resistor colour code, values and tolerances, preferred values, wattage ratings; Resistors in series and parallel; Calculation of total resistance using series, parallel and series parallel combinations; Operation and use of potentiometers and rheostats; Operation of Wheatstone Bridge; (b) Positive and negative temperature coefficient conductance; 1 1 Fixed resistors, stability, tolerance and limitations, methods of construction; Variable resistors, thermistors, voltage dependent resistors; Construction of potentiometers and rheostats; Construction of Wheatstone Bridge. Sub-Module 08 - Power Power, work and energy (kinetic and potential); 2 2 Dissipation of power by a resistor; Power formula; Calculations involving power, work and energy. Sub-Module 09 - Capacitance/Capacitor Operation and function of a capacitor; 2 2 Factors affecting capacitance area of plates, distance between plates, number of plates, dielectric and dielectric constant, working voltage, voltage rating; Capacitor types, construction and function; Capacitor colour coding; Calculations of capacitance and voltage in series and parallel circuits; Exponential charge and discharge of a capacitor, time constants; Testing of capacitors. vi Module 03 - Electrical Fundamentals  LEVELS CERTIFICATION CATEGORY ¦ B1 B2 Sub-Module 10 - Magnetism (a) Theory of magnetism; 2 2 Properties of a magnet; Action of a magnet suspended in the Earth's magnetic field; Magnetisation and demagnetisation; Magnetic shielding; Various types of magnetic material; Electromagnets construction and principles of operation; Hand clasp rules to determine: magnetic field around current carrying conductor; (b) Magnetomotive force, field strength, magnetic flux density, permeability, hysteresis loop, 2 2 retentivity, coercive force reluctance, saturation point, eddy currents; Precautions for care and storage of magnets. Sub-Module 11 - Inductance/Inductor Faraday's Law; 2 2 Action of inducing a voltage in a conductor moving in a magnetic field; Induction principles; Effects of the following on the magnitude of an induced voltage: Magnetic field strength, rate of change of flux, number of conductor turns; Mutual induction; The effect the rate of change of primary current and mutual inductance has on induced voltage; Factors affecting mutual inductance: number of turns in coil, physical size of coil, permeability of coil, position of coils with respect to each other; Lenz's Law and polarity determining rules; Back emf, self induction; Saturation point; Principle uses of inductors. Sub-Module 12 - DC Motor/Generator Theory Basic motor and generator theory; 2 2 Construction and purpose of components in DC generator; Operation of, and factors affecting output and direction of current flow in DC generators; Operation of, and factors affecting output power, torque, speed and direction of rotation of DC motors; Series wound, shunt wound and compound motors; Starter Generator construction. Sub-Module 13 - AC Theory Sinusoidal waveform: phase, period, frequency, cycle; 2 2 Instantaneous, average, root mean square, peak, peak to peak current values and calculations of these values, in relation to voltage, current and power; Triangular/Square waves; Single/3 phase principles. Module 03 - Electrical Fundamentals vii  LEVELS CERTIFICATION CATEGORY ¦ B1 B2 Sub-Module 14 - Resistive (R), Capacitive (C) and Inductive (L) Circuits Phase relationship of voltage and current in L, C and R circuits, parallel, series and series parallel; 2 2 Power dissipation in L, C and R circuits; Impedance, phase angle, power factor and current calculations; True power, apparent power and reactive power calculations. Sub-Module 15 - Transformers Transformer construction principles and operation; 2 2 Transformer losses and methods for overcoming them; Transformer action under load and no-load conditions; Power transfer, efficiency, polarity markings; Calculation of line and phase voltages and currents, calculation of power in a three phase system; Primary and Secondary current, voltage, turns ratio, power, efficiency; Auto transformers. Sub-Module 16 - Filters Operation, application and uses of the following filters: low pass, high pass, band pass, band stop. 1 1 Sub-Module 17 - AC Generators Rotation of loop in a magnetic field and waveform produced; 2 2 Operation and construction of revolving armature and revolving field type AC generators; Single phase, two phase and three phase alternators; Three phase star and delta connections advantages and uses; Permanent Magnet Generators. Sub-Module 18 - AC Motors Construction, principles of operation and characteristics of: 2 2 AC synchronous and induction motors both single and polyphase; Methods of speed control and direction of rotation; Methods of producing a rotating field: capacitor, inductor, shaded or split pole. viii Module 03 - Electrical Fundamentals  CONTENTS ELECTRICAL FUNDAMENTALS Current‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.4 Welcome‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ iii Resistance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.5 Revision Log‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ iii Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.7 Forward‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ iv Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.8 Contents‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ix SUB-MODULE 04 SUB-MODULE 01 GENERATION OF ELECTRICITY ELECTRON THEORY Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.1 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.1 Sources of Electricity‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 Electricity And Electronics‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Pressure Source‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 General Composition Of Matter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Chemical Source‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 Matter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Thermal Sources‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 Elements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Light Sources‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 Compounds‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Friction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 Molecules‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Magnetism and Motion‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.2 Atoms‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.2 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.3 Electrons, Protons, And Neutrons‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.3 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.4 Electron Shells And‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.3 Energy Levels‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.3 SUB-MODULE 05 Ions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.4 DC SOURCES OF ELECTRICITY Free Electrons‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.4 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.1 Electron Movement‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.4 Batteries‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.2 Conductors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.4 Primary Cell‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.2 Insulators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.4 Secondary Cell‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.2 Semiconductors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.4 Battery Ratings‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.4 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.5 Life Cycle Of A Battery‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.4 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.6 Lead-Acid Battery Testing Methods‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.4 Lead-Acid Battery Charging Methods‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.5 SUB-MODULE 02 Nickel-Cadmium Batteries‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.6 STATIC ELECTRICITY AND CONDUCTION Chemistry and Construction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.6 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.1 Operation of Nickel-Cadmium Cells‥‥‥‥‥‥‥‥‥‥‥‥ 5.7 Static Electricity‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.2 General Maintenance and Safety Precautions‥‥‥‥‥ 5.7 Attractive And Repulsive Forces‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.2 Sealed Lead Acid Batteries‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.7 Units Of Charge‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.3 Thermocouples‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.8 Electrostatic Field‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.4 Photo-Cells‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.8 ESD Considerations‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.5 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.9 Conduction Of Electricity‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.5 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5.10 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.7 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2.8 SUB-MODULE 06 DC CIRCUITS SUB-MODULE 03 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.1 ELECTRICAL TERMINOLOGY Series DC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.2 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.1 Introduction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.2 SI Prefixes Used For Electrical Calculations‥‥‥‥‥‥‥‥‥ 3.2 Voltage Drops and Further Application of Ohm's Law‥ 6.3 Conventional Flow And Electron Flow‥‥‥‥‥‥‥‥‥‥‥‥ 3.2 Voltage Sources in Series‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.3 Conventional Flow‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.2 Kirchhoff's Voltage Law‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.4 Electromotive Force (Voltage)‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3.3 Voltage Dividers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.5 Module 03 - Electrical Fundamentals ix  CONTENTS Determining the Voltage Divider Formula‥‥‥‥‥‥‥‥ 6.7 SUB-MODULE 08 Parallel DC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.8 POWER Overview‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.8 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8.1 Voltage Drops‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.8 Power and Energy‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8.2 Total Parallel Resistance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.8 Power in an Electrical Circuit‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8.2 Resistors in Parallel‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.8 Power Formulas Used in the Study of Electricity‥‥‥‥‥ 8.2 Two Resistors in Parallel‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.8 Power in a Series and Parallel Circuit‥‥‥‥‥‥‥‥‥‥‥‥ 8.3 Current Source‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.9 Energy in an Electrical Circuit‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8.4 Kirchhoff's Current Law‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.9 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8.5 Current Dividers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.10 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8.6 Series-Parallel DC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.10 Overview‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.10 SUB-MODULE 09 Determining the Total Resistance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.11 CAPACITANCE/CAPACITOR Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.13 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.1 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 6.14 Capacitance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.2 Capacitors in Direct Current‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.2 SUB-MODULE 07 The RC Time Constant‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.2 RESISTANCE/RESISTOR Units of Capacitance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.3 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.1 Voltage Rating of a Capacitor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.3 Ohm's Law (Resistance)‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.2 Factors Affecting Capacitance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.3 Resistance of a Conductor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.3 Types of Capacitors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.4 Factors Affecting Resistance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.4 Fixed Capacitors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.4 Resistance and Its Relation to Wire Sizing‥‥‥‥‥‥‥‥‥‥ 7.5 Mica Capacitors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.4 Circular Conductors Ceramic‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.4 (Wires/Cables)‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.5 Electrolytic‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.4 Rectangular Conductors Tantalum‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.5 (Bus Bars)‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.6 Polyester Film‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.5 Types of Resistors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.6 Oil Capacitors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.5 Fixed Resistor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.6 Variable Capacitors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.5 Carbon Composition‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.6 Trimmers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.5 Resistor Ratings‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.7 Varactors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.6 Wire Wound‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.9 Capacitors in Series‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.6 Variable Resistors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.9 Capacitors in Parallel‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.6 Rheostat‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.9 Capacitors in Alternating Current‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.7 Potentiometer‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.9 Capacitive Reactance Xc‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.7 Linear Potentiometers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.10 Capacitive Reactances in Series and in Parallel‥‥‥‥‥‥‥ 9.8 Tapered Potentiometers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.10 Phase of Current and Voltage in Reactive Circuits‥‥‥‥ 9.9 Thermistors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.10 Testing Capacitors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.9 PhotoConductive Cells‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.11 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.11 Wheatstone Bridge‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.11 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 9.12 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.13 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7.14 SUB-MODULE 10 MAGNETISM Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.1 Magnetism‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.2 Magnetic Properties and the Hysteresis Loop‥‥‥‥‥‥‥ 10.6 Eddy Currents‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.7 x Module 03 - Electrical Fundamentals  CONTENTS Types of Magnets‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.7 Basic DC Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.13 Care and Storage of Magnets‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.8 DC Motor Construction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.15 Electromagnetism‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.8 Armature Assembly‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.15 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.13 Field Assembly‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.15 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 10.14 Brush Assembly‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.16 End Frame‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.16 SUB-MODULE 11 Types of DC Motors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.16 INDUCTANCE/INDUCTOR Series DC Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.16 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.1 Shunt DC Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.17 Inductance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.2 Compound DC Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.18 Characteristics of Inductance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.2 Counter Electromotive Force (EMF)‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.18 The RL Time Constant‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.3 Types of Duty‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.19 Physical Parameters‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.3 Reversing Motor Direction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.19 Self-Inductance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.3 Motor Speed‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.20 Mutual Induction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.4 Energy Losses in DC Motors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.21 Types of Inductors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.4 Inspection And Maintenance Of DC Motors‥‥‥‥‥‥‥‥ 12.22 Units of Inductance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.4 Electric Starting Systems And Starter Generator Inductors in Series‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.4 Starting System‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.23 Inductors in Parallel‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.5 Troubleshooting a Starter Generator Starting System‥ 12.25 Inductive Reactance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.5 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.27 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.7 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.28 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 11.8 SUB-MODULE 13 SUB-MODULE 12 AC THEORY DC MOTOR/GENERATOR THEORY Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.1 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.1 Alternating Current and Voltage‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.2 DC Generators and Controls‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.2 Generator Principles‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.2 Generators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.2 Generators of Alternating Current‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.4 Armature Reaction‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.5 Cycle Defined‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.6 Compensating Windings‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.5 Frequency Defined‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.6 Interpoles‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.5 Period Defined‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.7 Armature Resistance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.5 Wavelength Defined‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.7 Construction Features of DC Generators‥‥‥‥‥‥‥‥‥‥‥ 12.6 Phase Relationships‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.7 Field Frame‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.6 In Phase Condition‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.7 Armature‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.6 Out of Phase Condition‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.7 Gramme-Ring Armature‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.7 Values of Alternating Current‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.8 Drum-Type Armature‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.7 Instantaneous Value‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.8 Commutators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.7 Peak Value‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.8 Types of DC generators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.8 Effective Value‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.8 Series Wound DC Generators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.8 Triangular/Square Waves‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.9 Parallel (Shunt) Wound DC Generators‥‥‥‥‥‥‥‥‥‥ 12.8 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.11 Compound Wound DC Generators‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.9 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 13.12 Generator Ratings‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.10 DC Generator Maintenance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.10 DC Motors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.11 Force between Parallel Conductors‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.12 Developing Torque‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12.12 Module 03 - Electrical Fundamentals xi  CONTENTS SUB-MODULE 14 SUB-MODULE 17 RESISTIVE (R), CAPACITIVE (C) AND AC GENERATORS INDUCTIVE (L) CIRCUITS Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.1 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.1 Alternators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.2 AC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.2 Alternators & Classifications‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.2 Ohm's Law for AC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.2 Method of Excitation‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.2 Series AC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.2 Number of Phases‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.2 Parallel AC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.4 Armature or Field Rotation‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.2 Resonance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.6 Single Phase Alternator‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.3 Power in AC Circuits‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.7 Two Phase Alternator‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.3 True Power Defined‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.7 Three Phase Alternator‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.3 Apparent Power Defined‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.7 Wye Connection (Three Phase)‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.4 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.9 Delta Connection (Three Phase)‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.4 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14.10 Alternator Rectifier Unit‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.4 Brushless Alternator‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.5 SUB-MODULE 15 Alternator Rating‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.7 TRANSFORMERS Alternator Frequency‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.7 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.1 Alternator Maintenance‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.7 Transformers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.2 Regulation of Generator Voltage‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.9 Current Transformers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.5 Voltage Regulation with a Vibrating-Type Regulator‥ 17.9 Transformer Losses‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.5 Three Unit Regulators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.10 Core Losses‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.5 Differential Relay Switch‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.11 Copper Losses‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.5 Overvoltage and Field Control Relays‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.12 Transformer Action‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.5 Generator Control Units (GCU)‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.12 Power in Transformers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.6 Voltage Regulation‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.12 Power Calculations‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.6 Overvoltage Protection‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.13 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.9 Parallel Generator Operations‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.13 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15.10 Over-Excitation Protection‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.13 Differential Voltage‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.13 SUB-MODULE 16 Reverse Current Sensing‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.13 FILTERS Alternator Constant Speed Drive System‥‥‥‥‥‥‥‥‥‥‥ 17.13 Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.1 Hydraulic Transmission‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.14 Filtering‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.2 Voltage Regulation of Alternators‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.20 Filtering Characteristics of Capacitors‥‥‥‥‥‥‥‥‥‥‥ 16.2 Alternator Transistorized Regulators‥‥‥‥‥‥‥‥‥‥‥‥ 17.21 Filtering Characteristics of Inductors‥‥‥‥‥‥‥‥‥‥‥‥ 16.2 Inverters‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.22 Common Filter Configurations‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.3 Rotary Inverters‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.22 Basic LC Filters‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.4 Permanent Magnet Rotary Inverter‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.23 Low-Pass Filter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.4 Inductor-Type Rotary Inverter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.25 High-Pass Filter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.4 Static Inverters‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.25 Band-Pass Filter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.5 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.29 Band-Stop Filter‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.6 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17.30 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.7 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16.8 xii Module 03 - Electrical Fundamentals  CONTENTS SUB-MODULE 18 AC MOTORS Knowledge Requirements‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.1 AC Motors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.2 Types of AC Motors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.2 Three Phase Induction Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.2 Rotating Magnetic Field‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.2 Construction of Induction Motor‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.3 Induction Motor Slip‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.4 Single Phase Induction Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.4 Shaded Pole Induction Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.4 Split Phase Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.5 Capacitor Start Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.5 Direction of Rotation of Induction Motors‥‥‥‥‥ 18.6 Synchronous Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.6 AC Series Motor‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.8 Maintenance of AC Motors‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.9 Questions‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.11 Answers‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18.12 Acronym Index‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ A.1 Index‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ I.1 Module 03 - Electrical Fundamentals xiii xiv Module 03 - Electrical Fundamentals  ELECTRON THEORY PART-66 SYLLABUS LEVELS CERTIFICATION CATEGORY ¦ B1 B2 Sub-Module 01 ELECTRON THEORY Knowledge Requirements 3.1 - Electron Theory Structure and distribution of electrical charges within: atoms, molecules, ions, compounds; 1 1 Molecular structure of conductors, semiconductors and insulators. Level 1 A familiarization with the principal elements of the subject. Objectives: (a) The applicant should be familiar with the basic elements of the subject. (b) The applicant should be able to give a simple description of the whole subject, using common words and examples. (c) The applicant should be able to use typical terms. Module 03 - Electrical Fundamentals 1.1 ELECTRICITY AND ELECTRONICS This chapter addresses the fundamental concepts that are Each of these questions requires an understanding of the building blocks for advanced electrical knowledge many basic principles. By developing a solid knowledge and practical troubleshooting. Some of the questions of electrical fundamentals it becomes possible to answer addressed are: How does energy travel through a copper these practical questions and more. Understanding wire and through space? What is electric current, electrical current must begin with the nature of matter. electromotive force, and what makes a landing light turn All matter is composed of molecules. All molecules are on or a hydraulic pump motor run? made up of atoms, which are themselves made up of electrons, protons, and neutrons. GENERAL COMPOSITION OF MATTER MATTER Oxygen Atom Matter can be defined as anything that has mass and has volume and is the substance of which physical objects are composed. Essentially, it is anything that can be Nucleus Electrons touched. Mass is the amount of matter in a given object. Typically, the more matter there is in an object the more mass it will have. Weight is an indirect method of determining mass but not the same. The difference between mass and weight is that weight is determined by how much something or the fixed mass is pulled by gravity. Categories of matter are ordered by molecular activity. The four categories or states are: solids, liquids, Hydrogen Atom gases, and plasma. For the purposes of the aircraft Figure 1-1. A water molecule. technician, only solids, liquids, and gases are considered. and two atoms of oxygen. If a drop of water is divided in ELEMENTS two and then divided again and again until it cannot be An element is a substance that cannot be reduced to divided any longer, it will still be water. a simpler form by chemical means. Iron, gold, silver, copper, and oxygen are examples of elements. Beyond ATOMS this point of reduction, the element ceases to be what it is. The atom is considered to be the most basic building block of all matter. Atoms are composed of three COMPOUNDS subatomic particles. These three sub-atomic particles A compound is a chemical combination of two or more are: protons, neutrons, and electrons. These three elements. Water is one of the most common compounds particles will determine the properties of the specific and is made up of two hydrogen atoms and one oxygen atoms. Elements are substances composed of the same atom. atoms with specific properties. Oxygen is an example of this. MOLECULES The smallest particle of matter that can exist and still The main property that defines each element is the retain its identity, such as water (H₂O), is called a number of neutrons, protons, and electrons. Hydrogen molecule. A molecule of water is illustrated in Figure and helium are examples of elements. Both of these 1-1. Substances composed of only one type of atom are elements have neutrons, protons, and electrons but differ called elements. But most substances occur in nature as in the number of those items. This difference alone compounds, that is, combinations of two or more types accounts for the variations in chemical and physical of atoms. It would no longer retain the characteristics of properties of these two different elements. There are water if it were compounded of one atom of hydrogen over a 100 known elements in the periodic table, and 1.2 Module 03 - Electrical Fundamentals  Electron they are categorized according to their properties on Nucleus that table. The kinetic theory of matter also states that ELECTRON THEORY (1 Proton) the particles that make up the matter are always moving. Thermal expansion is considered in the kinetic theory and explains why matter contracts when it is cool and expands when it is hot, with the exception of water/ice. Figure 1-2. Hydrogen atom. ELECTRONS, PROTONS, AND NEUTRONS At the center of the atom is the nucleus, which contains the protons and neutrons. The protons are positively 8 Protons charged particles, and the neutrons are a neutrally 8 Neutrons charged particle. The neutron has approximately the same mass as the proton. The third particle of the atom is the electron that is a negatively charged particle with a very small mass compared to the proton. The proton's mass is approximately 1 837 times greater than the electron. Due to the proton and the neutron location in the central portion of the atom (nucleus) and the electron's position at the distant periphery of the atom, it is the electron that undergoes the change during chemical reactions. Since a proton weighs approximately Figure 1-3. Oxygen atom. 1 845 times as much as an electron, the number of protons and neutrons in its nucleus determines the overall weight of an atom. determines its potential energy. The total energy of an electron is the main factor that determines the radius of The weight of an electron is not considered in determining the electron's orbit. the weight of an atom. Indeed, the nature of electricity cannot be def ined clearly because it is not certain Electrons of an atom will appear only at certain definite whether the electron is a negative charge with no mass energy levels (shells). The spacing between energy levels (weight) or a particle of matter with a negative charge. is such that when the chemical properties of the various elements are cataloged it is convenient to group several Hydrogen represents the simplest form of an atom, as closely spaced permissible energy levels together into shown in Figure 1-2. At the nucleus of the hydrogen electron shells. The maximum number of electrons atom is one proton and at the outer shell is one orbiting that can be contained in any shell or sub-shell is the electron. At a more complex level is the oxygen atom, as same for all atoms and is defined as Electron Capacity shown in Figure 1-3, which has eight electrons in two = 2n2. In this equation n represents the energy level in shells orbiting the nucleus with eight protons and eight question. The first shell can only contain two electrons; neutrons. When the total positive charge of the protons the second shell can only contain eight electrons; the in the nucleus equals the total negative charge of the third, 18 and so on until we reach the seventh shell for electrons in orbit around the nucleus, the atom is said to the heaviest atoms, which have six energy levels. Because have a neutral charge. the innermost shell is the lowest energy level, the shell begins to fill up from the shell closest to the nucleus ELECTRON SHELLS AND and fill outward as the atomic number of the element ENERGY LEVELS increases. However, an energy level does not need to be Electrons require a certain amount of energy to stay in completely filled before electrons begin to fill the next an orbit. This particular quantity is called the electron's level. The Periodic Table of Elements should be checked energy level. By its motion alone, the electron possesses to determine an element's electron configuration. kinetic energy, while the electron's position in orbit Module 03 - Electrical Fundamentals 1.3 VALENCE ELECTRONS CONDUCTORS Valence is the number of chemical bonds an atom can Elements such as gold, copper and silver possess many form. Valence electrons are electrons that can participate free electrons and make good conductors. The atoms in in chemical bonds with other atoms. The number of these materials have a few loosely bound electrons in electrons in the outermost shell of the atom is the their outer orbits. Energy in the form of heat can cause determining factor in its valence. Therefore, the electrons these electrons in the outer orbit to break loose and drift contained in this shell are called valence electrons. throughout the material. Copper and silver have one electron in their outer orbits. At room temperature, a IONS piece of silver wire will have billions of free electrons. Ionization is the process by which an atom loses or gains electrons. Dislodging an electron from an atom INSULATORS will cause the atom to become positively charged. This These are materials that do not conduct electrical current net positively charged atom is called a positive ion or very well or not at all. Good examples of these are: a cation. An atom that has gained an extra number of glass, ceramic, and plastic. Under normal conditions, electrons is negatively charged and is called a negative atoms in these materials do not produce free electrons. ion or an anion. When atoms are neutral, the positively The absence of the free electrons means that electrical charged proton and the negatively charged electrons are current cannot be conducted through the material. Only equal in number. when the material is in an extremely strong electrical field will the outer electrons be dislodged. This action is FREE ELECTRONS called breakdown and usually causes physical damage to Valence electrons are found drifting midway between the insulator. two nuclei. Some electrons are more tightly bound to the nucleus of their atom than others and are positioned in SEMICONDUCTORS a shell or sphere closer to the nucleus, while others are This material falls in between the characteristics of more loosely bound and orbit at a greater distance from conductors and insulators, in that they are not good at the nucleus. These outermost electrons are called "free" conducting or insulating. Silicon and germanium are the electrons because they can be easily dislodged from the most widely used semiconductor materials. For a more positive attraction of the protons in the nucleus. Once detailed explanation on this topic, refer to Module 04 freed from the atom, the electron can then travel from Electronic Fundamentals in this series. atom to atom, becoming the flow of electrons commonly called current in a practical electrical circuit. ELECTRON MOVEMENT The valence of an atom determines its ability to gain or lose an electron, which ultimately determines the chemical and electrical properties of the atom. These properties can be categorized as being a conductor, semiconductor or insulator, depending on the ability of the material to produce free electrons. When a material has a large number of free electrons available, a greater current can be conducted in the material. 1.4 Module 03 - Electrical Fundamentals  QUESTIONS Question: 1-1 Question: 1-3 __________________ of an atom hold electrons at A material that is neither a good conductor or insulator different energy levels. is known as a __________________. Question: 1-2 A material that has a large number of free electrons available is known as a __________________. Module 03 - Electrical Fundamentals 1.5  ANSWERS Answer: 1-1 Answer: 1-3 Electron shells. semiconductor. Answer: 1-2 a conductor. 1.6 Module 03 - Electrical Fundamentals  STATIC ELECTRICITY AND CONDUCTION PART-66 SYLLABUS LEVELS CERTIFICATION CATEGORY ¦ B1 B2 Sub-Module 02 STATIC ELECTRICITY AND CONDUCTION Knowledge Requirements 3.2 - Static Electricity and Conduction Static electricity and distribution of electrostatic charges; 2 2 Electrostatic laws of attraction and repulsion; Units of charge, Coulomb's Law; Conduction of electricity in solids, liquids, gases and a vacuum. Level 2 A general knowledge of the theoretical and practical aspects of the subject and an ability to apply that knowledge. Objectives: (a) The applicant should be able to understand the theoretical fundamentals of the subject. (b) The applicant should be able to give a general description of the subject using, as appropriate, typical examples. (c) The applicant should be able to use mathematical formula in conjunction with physical laws describing the subject. (d) The applicant should be able to read and understand sketches, drawings and schematics describing the subject. (e) The applicant should be able to apply his knowledge in a practical manner using detailed procedures. Module 03 - Electrical Fundamentals 2.1 STATIC ELECTRICITY Electricity is often described as being either static or usually caused when non-conductive materials such as dynamic. The difference between the two is based rubber, plastic or glass are rubbed together, causing a simply on whether the electrons are at rest (static) or transfer of electrons, which then results in an imbalance in motion (dynamic). Static electricity is a build up of of charges between the two materials. The fact that there an electrical charge on the surface of an object. It is is an imbalance of charges between the two materials considered "static" due to the fact that there is no current means that the objects will exhibit an attractive or flowing as in AC or DC electricity. Static electricity is repulsive force. ATTRACTIVE AND REPULSIVE FORCES One of the most fundamental laws of static electricity, Charge Rod as well as magnetics, deals with attraction and repulsion. Like charges repel each other and unlike charges attract each other. All electrons possess a negative charge and as such will repel each other. Similarly, all protons possess a positive charge and as such will repel each other. Electrons (negative) and protons (positive) are Pithballs opposite in their charge and will attract each other. For example, if two pith balls are suspended, as shown in Figure 2-1, and each ball is touched with the charged (A) A glass rod, some of the charge from the rod is transferred to the balls. The balls now have similar charges and, consequently, repel each other as shown in part B of Figure 2-1. If a plastic rod is rubbed with fur, it becomes negatively charged and the fur is positively charged. By touching each ball with these differently charged sources, the balls obtain opposite charges and attract each other as shown in part C of Figure 2-1. B Repulsion Coulomb's law further defines the relationship between charges. It states that like charges repel and opposite charges attract with a force proportional to the product of the charges and inversely proportional to the square of the distance between them. This means that objects with greater charge repel similar charges and attract opposite charges with greater force. Also, as the distance between charges becomes greater, the repulsion or attraction between the charges decreases. C Attraction Figure 2-1. Reaction of like and unlike charges. 2.2 Module 03 - Electrical Fundamentals UNITS OF CHARGE A single elementary charge (e) is the charge that a single proton (or electron) possesses. The coulomb (C) is an SI Electrons are attracted Positively charged by positive charge derived unit of electrical charge. One coulomb is equal rod almost touching to the charge carried by one ampere in one second. An uncharged bar STATIC ELECTRICITY AND CONDUCTION ampere represents the flow of 6.241 × 101⁸ electrons. Although most objects become charged with static electricity by means of friction, a charged substance When rod touches bar, can also inf luence objects near it by contact. This is electrons enter rod illustrated in Figure 2-2. If a positively charged rod touches an uncharged metal bar, it will draw electrons from the uncharged bar to the point of contact. Some electrons will enter the rod, leaving the metal bar with a deficiency of electrons (positively charged) and making the rod less positive than it was or, perhaps, even Metal bar now has positive charge neutralizing its charge completely. The rod is now less positively charged A method of charging a metal bar by induction is demonstrated in Figure 2-3. A positively charged rod is brought near, but does not touch, an uncharged metal bar. Figure 2-2. Charging by contact. Electrons in the metal bar are attracted to the end of the bar nearest the positively charged rod, leaving a deficiency of electrons at the opposite end of the bar. If this positively charged end is touched by a neutral object, electrons will Electrons are attracted toward charged rod. flow into the metal bar and neutralize the charge. The metal bar is left with an overall excess of electrons. Electrons are attracted of fnger and enter bar. Finger is removed. Positive and negative charges are mostly neutralized. Rod is removed and excess electrons remain. Figure 2-3. Charging a bar by induction. Module 03 - Electrical Fundamentals 2.3 ELECTROSTATIC FIELD A field of force exists around a charged body. This field is an electrostatic field (sometimes called a dielectric field) and is represented by lines extending in all directions from the charged body and terminating where there is an equal and opposite charge. To explain the action of an electrostatic field, lines are used to represent the direction and intensity of the Figure 2-4. Direction of electric field around electric field of force. As illustrated in Figure 2-4, the positive and negative charges. intensity of the field is indicated by the number of lines per unit area, and the direction is shown by arrowheads on the lines pointing in the direction in which a small test charge would move or tend to move if acted upon by the field of force. Either a positive or negative test charge can be used, but it has been arbitrarily agreed that a small positive charge will always be used in determining the direction of the field. Thus, the direction of the field around a positive charge is always away from the charge, as shown in Figure 2-4, because a positive test charge would be repelled. On the other hand, the direction of the lines about a negative charge is toward the charge, since a positive test charge is attracted toward it. Figure 2-5. Field around two positively charged bodies. Figure 2-5 illustrates the field around bodies having like charges. Positive charges are shown, but regardless of the type of charge, the lines of force would repel each other if the charges were alike. The lines terminate on material objects and always extend from a positive charge to a negative charge. These lines are imaginary lines used to show the direction a real force takes. It is important to know how a charge is distributed on an object. Figure 2-6 shows a small metal disk on which a concentrated negative charge has been placed. By using Figure 2-6. Even distribution of charge on metal disk. an electrostatic detector, it can be shown that the charge is spread evenly over the entire surface of the disk. Since the metal disk provides uniform resistance everywhere on its surface, the mutual repulsion of electrons will result in an even distribution over the entire surface. Inside Another example, shown in Figure 2-7, is the charge Surface Neutral on a hollow sphere. Although the sphere is made of conducting material, the charge is evenly distributed over the outside surface. The inner surface is completely neutral. This phenomenon is used to safeguard operating Figure 2-7. Charge on a hollow sphere. 2.4 Module 03 - Electrical Fundamentals personnel of the large Van de Graaff static generators used for atom smashing. The safest area for the operators is inside the large sphere, where millions of volts are being generated. Greatest Charge The distribution of the charge on an irregularly shaped STATIC ELECTRICITY AND CONDUCTION object differs from that on a regularly shaped object. Figure 2-8 shows that the charge on such objects is not evenly distributed. The greatest charge is at the points, or areas of sharpest curvature, of the objects. Figure 2-8. Charge on irregularly shaped objects. ESD CONSIDERATIONS One of the most frequent causes of damage to a solid- Other precautions that should be taken with working state component or integrated circuits is the electro- with electronic components are: static discharge (ESD) from the human body when one 1. Always connect a ground between test equipment of these devices is handled. Careless handling of line and circuit before attempting to inject or monitor a replaceable units (LRUs), circuit cards, and discrete signal. components can cause unnecessarily time consuming 2. Ensure test voltages do not exceed maximum and expensive repairs. This damage can occur if a allowable voltage for the circuit components and technician touches the mating pins for a card or box. transistors. Other sources for ESD can be the top of a toolbox 3. Ohmmeter ranges that require a current of more that is covered with a carpet. Damage can be avoided than one milliampere in the test circuit should not by discharging the static electricity from your body by be used for testing transistors. touching the chassis of the removed box, by wearing a 4. The heat applied to a diode or transistor, when grounding wrist strap, and exercising good professional soldering is required, should be kept to a minimum handling of the components in the aircraft. This can by using low-wattage soldering irons and heat- include placing protective caps over open connectors sinks. and not placing an ESD sensitive component in an 5. Do not pry components off of a circuit board. environment that will cause damage. Parts that are ESD 6. Power must be removed from a circuit before sensitive are typically shipped in bags specially designed replacing a component. to protect components from electrostatic damage. 7. When using test probes on equipment and the space between the test points is very close, keep the exposed portion of the leads as short as possible to prevent shorting. CONDUCTION OF ELECTRICITY Electricity can be conducted through solids, liquids, Water, for example, ionizes when electricity is applied and gases. It can even pass through a vacuum. Electric and the ions carry the electric current. Gases are typically current is the movement of valence electrons. Solids, good insulators but some gases also ionize and carry particularly metals, that have valence electrons with current, especially in the presence of a large electromotive weak covalent bonds are excellent conductors. Liquid force such as lightening. There are no electrons to carry metals possess the same characteristics. Some non- current in a vacuum, however, should electrons be metallic liquids also conduct electricity by ionization of injected into a vacuum, there is nothing to inhibit their their molecules. movement. As such a vacuum is an ideal conductor. Module 03 - Electrical Fundamentals 2.5 2.6 Module 03 - Electrical Fundamentals  QUESTIONS Question: 2-1 Question: 2-3 The buildup of an electrical charge on the surface of an To prevent damage to electronic equipment when object is known as __________________. handling, the technician must take precautions to prevent EDS which stands for __________________. Question: 2-2 A sphere made of conductive material has electric charge on the outer surface. The charge on the inside is __________________. Module 03 - Electrical Fundamentals 2.7  ANSWERS Answer: 2-1 Answer: 2-3 static electricity. electrostatic discharge. Answer: 2-2 neutral. 2.8 Module 03 - Electrical Fundamentals  PART-66 SYLLABUS LEVELS TERMINOLOGY B1 B2 ELECTRICAL CERTIFICATION CATEGORY ¦ Sub-Module 03 ELECTRICAL TERMINOLOGY Knowledge Requirements 3.3 - Electrical Terminology The following terms, their units and factors affecting them: potential difference, electromotive force, 2 2 voltage, current, resistance, conductance, charge, conventional current flow, electron flow. Level 2 A general knowledge of the theoretical and practical aspects of the subject and an ability to apply that knowledge. Objectives: (a) The applicant should be able to understand the theoretical fundamentals of the subject. (b) The applicant should be able to give a general description of the subject using, as appropriate, typical examples. (c) The applicant should be able to use mathematical formula in conjunction with physical laws describing the subject. (d) The applicant should be able to read and understand sketches, drawings and schematics describing the subject. (e) The applicant should be able to apply his knowledge in a practical manner using detailed procedures. Module 03 - Electrical Fundamentals 3.1 SI PREFIXES USED FOR ELECTRICAL CALCULATIONS In any system of measurements, a single set of units is The symbol for kilo is the letter "k". Thus, 1 000 volts usually not sufficient for all the computations involved is one kilovolt or 1kV. Conversely, one volt would equal in electrical repair and maintenance. Small distances, for one-thousandth of a kV, or 1⁄1 000 kV. This could also be example, can usually be measured in inches, but larger written 0.001 kV. distances are more meaningfully expressed in feet, yards, or miles. Since electrical values often vary from numbers Similarly, the word "milli" means one-thousandth, and that are a millionth part of a basic unit of measurement thus, 1 millivolt equals one-thousandth (1⁄1 000) of a volt. to very large values, it is often necessary to use a wide Figure 3-1 contains a complete list of the multiples range of numbers to represent the values of such units used to express electrical quantities, together with the as volts, amperes, or ohms. A series of prefixes which prefixes and symbols used to represent each number. appear with the name of the unit have been devised for the various multiples or sub multiples of the basic units. Number Prefix Symbol There are 12 of these prefixes, which are also known as conversion factors. 1 000 000 000 000 tera t 1 000 000 000 giga g Four of the most commonly used pref ixes used in 1 000 000 mega M electrical work with a short definition of each are as 1 000 kilo k follows: 100 hecto h Mega (M) means one million (1 000 000) 10 deka dk Kilo (k) means one thousand (1 000) 0.1 deci d Milli (m) means one-thousandth (1⁄1 000) 0.01 centi c Micro (μ) means one-millionth (1⁄1 000 000) 0.001 milli m 0.000 001 micro μ One of the most extensively used conversion factors, 0.000 000 001 nano n kilo, can be used to explain the use of prefixes with basic 0.000 000 000 001 pico p units of measurement. Kilo means 1 000, and when used Figure 3-1. Prefixes and symbols for multiples of basic quantities. with volts, is expressed as kilovolt, meaning 1 000 volts. CONVENTIONAL FLOW AND ELECTRON FLOW Today's technician will find that there are two competing ELECTRON FLOW schools of thought and analytical practices regarding the Later discoveries were made that proved that just flow of electricity. The two are called the conventional the opposite is true. Electron f low is what actually current theory and the electron theory. happens where an abundance of electrons flow out of the negative (−) source to an area that lacks electrons CONVENTIONAL FLOW or the positive (+) source. Both conventional flow and Of the two, the conventional current theory was the first electron flow are used in industry. Many textbooks in to be developed and, through many years of use, this current use employ both electron flow and conventional method has become ingrained in electrical texts. The f low methods. From the practical standpoint of the theory was initially advanced by Benjamin Franklin who technician, troubleshooting a system, it makes little to reasoned that current flowed out of a positive source into no difference which way current is flowing as long as it is a negative source or an area that lacked an abundance of used consistently in the analysis. charge. The notation assigned to the electric charges was positive (+) for the abundance of charge and negative (−) for a lack of charge. It then seemed natural to visualize the flow of current as being from the positive (+) to the negative (−). 3.2 Module 03 - Electrical Fundamentals ELECTROMOTIVE FORCE (VOLTAGE) Unlike current, which is easy to visualize as a f low, Figure 3-2 illustrates the flow of electrons of electric voltage is a variable that is determined between two current. Two interconnected water tanks demonstrate points. Often we refer to voltage as a value across two that when a difference of pressure exists between the points. It is the electromotive force (emf) or the push two tanks, water will f low until the two tanks are or pressure felt in a conductor that ultimately moves equalized. The illustration shows the level of water in the electrons in a flow. The symbol for emf is the capital tank A to be at a higher level, reading 10 psi (higher letter "E." potential energy) than the water level in tank B, reading 2 psi (lower potential energy). Between the two tanks, Across the terminals of the typical aircraft battery, there is 8-psi potential difference. If the valve in the TERMINOLOGY voltage can be measured as the potential difference of interconnecting line between the tanks is opened, water ELECTRICAL 12 volts or 24 volts. That is to say that between the two will flow from tank A into tank B until the level of water terminal posts of the battery, there is an electromotive (potential energy) of both tanks is equalized. force of 12 or 24 volts available to push current through a circuit. Relatively free electrons in the negative It is important to note that it was not the pressure in terminal will move toward the excessive number of tank A that caused the water to flow; rather, it was the positive charges in the positive terminal. Recall from difference in pressure between tank A and tank B that the discussion on static electricity that like charges repel caused the flow. each other but opposite charges attract each other. The net result is a flow or current through a conductor. There This comparison illustrates the principle that electrons cannot be a flow in a conductor unless there is an applied move, when a path is available, from a point of excess voltage from a battery, generator, or ground power unit. electrons (higher potential energy) to a point deficient in The potential difference, or the voltage across any two electrons (lower potential energy). The force that causes points in an electrical system, can be determined by: this movement is the potential difference in electrical energy between the two points. This force is called the electrical pressure or the potential difference or the electromotive force (electron moving force). Where: E = potential difference in volts E = energy expanded or absorbed in joules (J) Q = Charge measured in coulombs A B Figure 3-2. Difference of