Module 03. Electrical Fundamentals

3.1 Electron Theory

1. Structure and distribution of electrical charges within: atoms, molecules, ions, compounds;
2. Molecular structure of conductors, semiconductors and insulators.

3.2 Static Electricity and Conduction

1. Static electricity and distribution of electrostatic charges;
2. Electrostatic laws of attraction and repulsion;
3. Units of charge, Coulomb's Law;
4. Conduction of electricity in solids, liquids, gases and vacuum.

3.3 Electrical Terminology

1. The following terms, their units and factors affecting them: potential
2. difference, electromotive force, voltage, current, resistance, conductance, charge, conventional current flow, electron flow.

3.4 Generation of Electricity

1. Production of electricity by the following methods: light, heat, friction, pressure, chemical action, magnetism and motion.

3.5 DC Sources of Electricity

1. Construction and basic chemical action of primary cells, secondary cells, lead acid cells, nickel cadmium cells, other alkaline cells;
2. Cells connected in series and parallel;
3. Internal resistance and its effect on a battery;
4. Construction, materials and operation of thermocouples;
5. Operation of photo-cells.

3.6 DC Circuits

1. Ohms Law, Kirchoff's Voltage and Current Laws;
2. Calculations using the above laws to find resistance, voltage and current;
3. Significance of the internal resistance of a supply.
4. 3.7 Resistance/Resistor

(a)

1. Resistance and affecting factors;
2. Specific resistance;
3. Resistor colour code, values and tolerances, preferred values, wattage
4. ratings;
5. Resistors in series and parallel;
6. Calculation of total resistance using series, parallel and series parallel combinations;
7. Operation and use of potentiometers and rheostats;
8. Operation of Wheatstone Bridge.

(b)

1. Positive and negative temperature coefficient conductance;
2. Fixed resistors, stability, tolerance and limitations, methods of construction;
3. Variable resistors, thermistors, voltage dependent resistors;
4. Construction of potentiometers and rheostats;
5. Construction of Wheatstone Bridge;

3.8 Power

1. Power, work and energy (kinetic and potential);
2. Dissipation of power by a resistor; Power formula;
3. Calculations involving power, work and energy;

3.9 Capacitance/Capacitor

1. Operation and function of a capacitor;
2. Factors affecting capacitance area of plates, distance between plates, number of plates, dielectric and dielectric constant, working voltage,
3. voltage rating;
4. Capacitor types, construction and function;
5. Capacitor colour coding;
6. Calculations of capacitance and voltage in series and parallel circuits;
7. Exponential charge and discharge of a capacitor, time constants;
8. Testing of capacitors;

3.10 Magnetism

(a)

1. Theory of magnetism;
2. Properties of a magnet;
3. Action of a magnet suspended in the Earth's magnetic field;
4. Magnetisation and demagnetisation;
5. Magnetic shielding;
6. Various types of magnetic material;
7. Electromagnets construction and principles of operation;
8. Handclasp rules to determine: magnetic field around current carrying conductor.

(b)

1. Magnetomotive force, field strength, magnetic flux density,
2. permeability, hysteresis loop, retentivity, coercive force reluctance,
3. saturation point, eddy currents;
4. Precautions for care and storage of magnets.

3.11 Inductance/Inductor

1. Faraday's Law;
2. Action of inducing a voltage in a conductor moving in a magnetic field;
3. Induction principles;
4. Effects of the following on the magnitude of an induced voltage: magnetic field strength, rate of change of flux, number of conductor turns;
5. Mutual induction;
6. The effect the rate of change of primary current and mutual inductance has on induced voltage;
7. Factors affecting mutual inductance: number of turns in coil, physical size of coil, permeability of coil, position of coils with respect to each other;
8. Lenz's Law and polarity determining rules;
9. Back emf, self induction;
10. Saturation point;
11. Principle uses of inductors;

3.12 DC Motor/Generator Theory

1. Basic motor and generator theory;
2. Construction and purpose of components in DC generator;
3. Operation of, and factors affecting output and direction of current flow in DC generators;
4. Operation of, and factors affecting output power, torque, speed and direction of rotation of DC motors;
5. Series wound, shunt wound and compound motors;
6. Starter Generator construction

3.13 AC Theory

1. Sinusoidal waveform: phase, period, frequency, cycle;
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;
3. Single/3 phase principles.

3.14 Resistive (R), Capacitive (C) and Inductive (L) Circuits

1. Phase relationship of voltage and current in L, C and R circuits, parallel, series and series parallel;
2. Power dissipation in L, C and R circuits;
3. Impedance, phase angle, power factor and current calculations;
4. True power, apparent power and reactive power calculations.

3.15 Transformers

1. Transformer construction principles and operation;
2. Transformer losses and methods for overcoming them;
3. Transformer action under load and no-load conditions;
4. Power transfer, efficiency, polarity markings;
5. Calculation of line and phase voltages and currents;
6. Calculation of power in a three phase system;
7. Primary and Secondary current, voltage, turns ratio, power, efficiency;
8. Autotransformers.

3.16 Filters

1. Operation, application and uses of the following filters:
2. Low pass, high pass, band pass, band stop.

3.17 AC Generators

1. Rotation of loop in a magnetic field and waveform produced;
2. Operation and construction of revolving armature and revolving field type
3. AC generators;
4. Single phase, two phase and three phase alternators;
5. Three phase star and delta connections advantages and uses;
6. Permanent Magnet Generators.

3.18 AC Motors

1. Construction, principles of operation and characteristics of: AC synchronous and induction motors both single and polyphase;
2. Methods of speed control and direction of rotation;
3. Methods of producing a rotating field: capacitor, inductor, shaded or split pole.