Module 03. Electrical Fundamentals
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This course is currently closed
Free
This course is currently closed
Module Details
Module 03. Electrical Fundamentals
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1 month
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Module
Materials
3.1 Electron Theory
- Structure and distribution of electrical charges within: atoms, molecules, ions, compounds;
- Molecular structure of conductors, semiconductors and insulators.
3.2 Static Electricity and Conduction
- Static electricity and distribution of electrostatic charges;
- Electrostatic laws of attraction and repulsion;
- Units of charge, Coulomb's Law;
- Conduction of electricity in solids, liquids, gases and vacuum.
3.3 Electrical Terminology
- The following terms, their units and factors affecting them: potential
- difference, electromotive force, voltage, current, resistance, conductance, charge, conventional current flow, electron flow.
3.4 Generation of Electricity
- Production of electricity by the following methods: light, heat, friction, pressure, chemical action, magnetism and motion.
3.5 DC Sources of Electricity
- Construction and basic chemical action of primary cells, secondary cells, lead acid cells, nickel 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.
3.6 DC Circuits
- Ohms Law, Kirchoff's Voltage and Current Laws;
- Calculations using the above laws to find resistance, voltage and current;
- Significance of the internal resistance of a supply.
- 3.7 Resistance/Resistor
(a)
- Resistance and affecting factors;
- 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;
- Fixed resistors, stability, tolerance and limitations, methods of construction;
- Variable resistors, thermistors, voltage dependent resistors;
- Construction of potentiometers and rheostats;
- Construction of Wheatstone Bridge;
3.8 Power
- Power, work and energy (kinetic and potential);
- Dissipation of power by a resistor; Power formula;
- Calculations involving power, work and energy;
3.9 Capacitance/Capacitor
- Operation and function of a capacitor;
- 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;
3.10 Magnetism
(a)
- Theory of magnetism;
- 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;
- Handclasp rules to determine: magnetic field around current carrying conductor.
(b)
- Magnetomotive force, field strength, magnetic flux density,
- permeability, hysteresis loop, retentivity, coercive force reluctance,
- saturation point, eddy currents;
- Precautions for care and storage of magnets.
3.11 Inductance/Inductor
- Faraday's Law;
- 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;
3.12 DC Motor/Generator Theory
- Basic motor and generator theory;
- 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
3.13 AC Theory
- Sinusoidal waveform: phase, period, frequency, cycle;
- 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.
3.14 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;
- Power dissipation in L, C and R circuits;
- Impedance, phase angle, power factor and current calculations;
- True power, apparent power and reactive power calculations.
3.15 Transformers
- Transformer construction principles and operation;
- 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;
- Autotransformers.
3.16 Filters
- Operation, application and uses of the following filters:
- Low pass, high pass, band pass, band stop.
3.17 AC Generators
- Rotation of loop in a magnetic field and waveform produced;
- 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.
3.18 AC Motors
- Construction, principles of operation and characteristics of: 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.
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