Content # Module 3. Electrical fundamentals (Part-66)

## Module 3. Electrical fundamentals (Part-66)

### Duration

100 hours training

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## Content: Part-66 Module 3. Electrical fundamentals

### 1. Electron Theory

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

### 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 a vacuum.

### 3. Electrical Terminology

• The following terms, their units and factors affecting them: potentialdifference, electromotive force, voltage, current, resistance, conductance,charge, conventional current flow, electron flow.

### 4. Generation of Electricity

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

### 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.

### 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.

### 7.1 Resistance and affecting factors;

• Specific resistance;
• Resistor colour code, values and tolerances, preferred values, wattageratings;
• Resistors in series and parallel;
• Calculation of total resistance using series, parallel and seriesparallel combinations;
• Operation and use of potentiometers and rheostats;
• Operation of Wheatstone Bridge.

### 7.2 Positive and negative temperature coefficientconductance;

• Fixed resistors, stability, tolerance and limitations,methods of construction;
• Variable resistors, thermistors, voltage dependentresistors;
• Construction of potentiometers and rheostats;
• Construction of Wheatstone Bridge;

### 8. Power

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

### 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.

### 10.1 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;
• Hand clasp rules to determine: magnetic field around current carryingconductor.

### 10.2 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.

### 11. Inductance/Inductor

• 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: magneticfield strength, rate of change of flux, number of conductor turns;
• Mutual induction;
• The effect the rate of change of primary current and mutual inductancehas on induced voltage;
• Factors affecting mutual inductance: number of turns in coil, physical sizeof 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;

### 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 anddirection of rotation of DC motors;
• Series wound, shunt wound and compound motors;S
• tarter Generator construction.

### 13. AC Theory

• Sinusoidal waveform: phase, period, frequency, cycle;
• Instantaneous, average, root mean square, peak, peak to peak currentvalues and calculations of these values, in relation to voltage, current andpower Triangular / Square waves;
• Single / 3 phase principles.

### 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.

### 15. Transformers

• Transformer construction principles and operation;
• Transformer losses and methods for overcoming them;
• 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.

### 16. Filters

• Operation, application and uses of the following filters: low pass, highpass, band pass, band stop.

### 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.

### 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 splitpole.

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