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ELECTRICAL TECHNOLOGY SENIOR FOUR TOPIC AND SUB -TPOICS 1. 1.1 1.2 1.3 Safety (Identify risks of accidents) Risks of accidents; Before starting work, ask the tutor; Keep your work station clean; Use tools appropriately. Names & uses of tools; Report any injury, Don’t leave controls of a machine in motion, Be attentive at your work, ask permission before using electrical tools , comply with instructions, use proper methods for lefting or moving objects 1.4 -Protect environment -Think before acting -Know the location of fire extinguishers and learn how to use them 1.5 -Ensure that equipment is in good order before use -When you use a piece of equipment for the first time, ask for information even if you believe you know how to use it, lack of knowledge can be dangerous and repairs of equipment are expensive 1.6 2. 2.1 First aid and First aid treatment ( at least four methods.) Electrical Circuits Conductors and Insulators 2.2 Cables and joints 2.3 Circuits and sub-circuits (Lighting and power circuits). EXPECTED NUMBER OF QUESTIONS FROM @ TOPIC 3 5 2.4 Conduits, trunkings and Ducting. SECOND TERM: 3 3.1 3.2 3.3 4. 4.1 4.2 4.3 5 5.1 5.2 5.3 5.4 Illumination Definitions, lighting laws and related calculations Types of lighting fittings Determination of lighting points Signalling systems Different types of bells Fire alarm systems Burglary alarm systems Circuit protection Fuses Circuit breakers Earthing systems RCDs 3 3 4 THIRD TERM 6. 7. 7.1 7.2 7.3 7.4 Electrical standard definitions Electrical systems TT systems, IT systems TN-C systems TN-C-S systems ELECTRICAL TECHNOLOGY SENIOR FIVE 2 1 FIRST TERM 1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 COMTACTORS Definition of terms used General construction Different types Different categories Operation principles Special features: Arcing, Interlocks and labeling Special contactors Standard symbols Name plate Faults, Causes and remedies Relays Definition of terms used General construction Different types Different categories Operation principles Interlocks Special relays: ON delayed, OFF delayed, etc Standard symbols Factors affecting their choices Faults, Causes and remedies 4 3 TERM TWO 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 D.C GENERATORS Construction and constructional parts Generator action of commutator Types of D.C armature windings E.M.F equation of a D.C Generator Types of D.C Generators Losses in D.C Machines Power stages Efficiency and Maximum efficiency Related calculations ARMATURE REACTION Geometrical and Magnetic neutral axes 4 2 4.2 4.3 4.4 5 5.1 5.2 5.3 5.4 5.5 Explanation on armature reaction Commutator and commutation Methods of improving commutation D.C Generator characteristics Voltage build up Critical field resistance Voltage regulation Parallel operation of D.C Generators Shunt down of generators 2 TERM THREE 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 D.C MOTORS The motor & working principle Back E.M.F and its significancy Voltage equation of a D.C Motor Power equation and maximum power Types of D.C motors Armature torque Shaft torque Speed of D.C Motor Related calculations Armature reaction in D.C Motor Commutation in D.C Motor Losses in D.C Motor Efficiency Power stages D.C Motor characteristics Application Faults, Causes and remedies 6 7 7.1 7.2 7.3 7.4 SPEED CONTROL Speed control and speed control methods Electric braking Motor starters Testing of D.C Machines 2 ELECTRICAL TECHNOLOGY SENIOR SIX FIRST TERM 8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 9 9.1 9.2 9.3 Transformers Introduction, Ideal and No load transformer E.M.F Equation and Voltage transformation ratio Practical loaded transformer Phasor diagrams and related calculations Shifting impedances and related calculations Equivalent circuit of transformer Transformer tests Transformer ratings and losses Types of transformers Cooling of transformers Auto transformers Advantages and disadvantages of Auto transformers Application of auto transformers Parallel operation of transformers Three phase transformers Three phase transformer connections Applications of transformers Instrument transformers SECOND TERM 10 Three phase Induction motors (Asynchronous Motors) 10.1 Introduction to three phase induction motors 10.2 Advantages and disadvantages 10.3 Construction 10.4 Operation 10.5 Rotor constants 10.6 Starting torque 10.7 Maximum torque 10.8 Motor conditions under load 10.9 Comparison between Induction motors and transformers 10.10 Speed regulation 10.11 Speed control 6 3 5 10.12 10.13 10.14 10.15 10.6 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11.10 11.11 11.12 11.13 Power stages and losses of induction motors Equivalent circuit Methods of starting a motor Squirrel cage motors versus Slip ring motors Motor nameplate Single phase motors TERM 3 SYCHRONOUS MOTORS Introduction Construction Principle of operation Making synchronous motors self starting Equivalent circuit Terms used Phasor diagram Motor on load Power stages and losses Motor torue Power factor of synchronous motors Application Comparison between Synchronous and Asynchronous motors 3 4