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Electrical Fundamentals

Electrical Fundamentals. Module 1 . Grading policy . Participation 10 marks Preparation, Promptness, Level of Engagement, Behavior HWs 10 marks 2 HWs Quizzes 10 marks 2 quizzes & SWQ Practical 30 marks Lab activities and Practical exam

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Electrical Fundamentals

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  1. Electrical Fundamentals Module 1

  2. Grading policy • Participation 10 marks • Preparation, Promptness, Level of Engagement, Behavior • HWs 10 marks • 2 HWs • Quizzes 10 marks • 2 quizzes & SWQ • Practical 30 marks • Lab activities and Practical exam • IAT competency exams (practical and knowledge ) 40 marks

  3. Preparation marks • Print the modules and cover it and bring it to every class with you • Calculator • Stationary • Lab cout

  4. Participation Marks • Promptness: On time or Late • Level of Engagement • Behavior

  5. Objectives • Electrical Circuit Components • Power supplies • Types of power supplies • Functions of power supplies • Close circuit / open circuit • Switches • Parts • Manually operated switches: Knife Switch, push button and selector switch

  6. Electrical Circuit Components How many elements do you see ? Input device, what do you think it do? Output device / Load. Give example of other loads How the elements are connected ? What does generate the electric current ? Which device allow the current to flow ?

  7. Power supplies • Power supply are used in electrical systems to modify the power supplied from the power company (e.g. from the wall socket) to a form that is needed for the application. • One feature power supplies are usually designed to do, is provide a constant current or constant voltage output. This is called regulation.

  8. The T7017 power supply

  9. DC Power Supply, Battery • A battery depends on chemical reaction to produce electricity. It does not require an external source of power. • However, most constant voltage supplies, require an external AC power source.

  10. Functions of Power supplies • Regulating voltage or current (providing constant voltage or constant current) • Reducing voltage levels • Changing AC to DC • Providing over current protection.

  11. Switches • The two main components of a manual switch • Operator (lever) • Contacts • Switches use two types of contacts: • Normally Open (N.O.) • Normally Closed (N.C.)

  12. Switches • Switch operators are: • Manually-operated - The operator is activated by a person. • Knife switch • Pushbutton switch • Selector switch • Automatically-operated - The operator is activated by a machine

  13. Knife Switch • Single-pole double-throw (SPDT) :one set of contacts • Double-pole double-throw (DPDT) knife switch: two sets of contacts.

  14. What is the difference ?

  15. Pushbutton Switch

  16. Selector Switch

  17. Recap • Electrical Circuit Components • Power supplies • Types of power supplies • Functions of power supplies • Close circuit / open circuit • Switches

  18. Just a minute! Yesterday you said x equals two

  19. Class warm up • Electrical Circuit Components • Power supplies • Types of power supplies • Functions of power supplies • Close circuit / open circuit • Switches • Parts • Manually operated switches: Knife Switch, push button and selector switch

  20. Objectives • Lab activity 2, testing different kinds of switches • Output devices

  21. Activity2-Part 1

  22. Activity2-Part 2

  23. Activity2-Part 3

  24. Output Devices • Lamp • Resistor • Buzzer • Solenoid • Motor

  25. Lamp • A lamp contains a resistive element inside a glass bulb. The bulb is filled with a gas. When current flows through the element, the element heats up and excites the gas. This produces the light that we see

  26. Resistor • A resistor limits the flow of electrical current. • It is one of the most commonly used components in an electrical circuit. • Resistors are often used with motors to suppress the surge of current and allow the current to the motor to be gradually increased. • A resistor is made of a material that does not allow current to easily flow through ex. carbon.

  27. Buzzer • When electricity is applied to a buzzer, it causes a vibration to occur inside the buzzer’s housing. This vibration is what causes the buzzing noise.

  28. Solenoid • A solenoid produces linear mechanical motion from electrical energy. • Solenoids are used to • operate flippers in pinball machines • operate fluid power valves • turn motors on and off

  29. Solenoid • Solenoid consist of • armature (plunger) • C Frame (coil) • The solenoid has an armature or plunger that moves in a linear motion when electrical current is applied to its electrical coil

  30. Motor • A motor is the output device that produces rotary mechanical motion, ex. a fan

  31. Activity 3 motor of a fan

  32. Recap • What are the output devices

  33. High current • High current can damage electrical components. • High current occur for two reasons: • many loads are connected to the circuit 2. A short circuit

  34. Short circuit • A short circuit is a direct path with little or no resistance created between the positive and negative terminals of the power supply • Since current flows through the path with least resistance, it will take this path.

  35. Short Circuit

  36. Circuit protection • Devices used to protect electrical components from high current: • Fuse • Circuit Breaker

  37. The Fuse Operation • A fuse is used to protect the circuit components from high current. • The fuse must be replaced each time an overload or short circuit condition occurs. • Fuses are used in applications where a problem rarely occurs, ex. car’s light

  38. Fuses are rated for a maximum current value. • If the maximum current value is exceeded, the fuse blows to protect the components of the circuit. What is the current ratings for the following fuses ?

  39. Fuse rating • When the current flow exceeds the rated value of the fuse, the wire or foil strip melts and opens the circuit (the fuse is blown).

  40. Testing the continuity of the fuse • If the fuse is good, it has continuity (like a wire) • If a fuse is blown, it has no continuity. Continuity

  41. Fuses • Many electrical devices have fuses. • Fuses are easy to replace. • Fuse are low cost. One fuse cost 0.25 DHS per fuse. • Special care needs to be taken to make sure that the properly rated fuse is installed to provide the needed protection. Say it in a simple words…

  42. Circuit Breakers • Circuit breaker is used to protect the circuit components from high current. • Just as a fuse blows, a circuit breaker opens or trips when an excessive current is present. • The circuit breaker can be reset and used again.

  43. Circuit breakers are used where overloads commonly occur • Ex. power supply and your house wiring

  44. Testing the continuity of the circuit breaker • If the breaker is tripped, it has no continuity • if the breaker is reset, it has continuity

  45. Circuit breaker • Circuit breakers are either • thermally-triggered tripped due to heat caused by excessive current • magnetically-triggered tripped due to the strength of the magnetic field created by excessive current. • In some cases a circuit breaker is combination of both

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