1. Electrical Fundamentals
Module 1

2. Grading policy Participation 10 marks HWs 10 marks Quizzes 10 marks
Preparation, Promptness, Level of Engagement, Behavior
HWs marks
2 HWs
Quizzes marks
2 quizzes & SWQ
Practical marks
Lab activities and Practical exam
IAT competency exams (practical and knowledge ) 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. Application: Widely used
Power Supply
constant current
power supply
the same current level regardless
of the demand placed on it by the load. However, the voltage varies
according to the size of the load.
Application: Limited
constant voltage power supplies
They maintain a constant voltage output, regardless of the load.
Here, the current varies instead of the voltage.
Application: Widely used

9. Constant voltage power supply
DC Voltage
AC voltage
Function Generator

10. The T7017 power supply

11. 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.

12. 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.

14. Closed circuit
Open circuit

15. 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.)

16. 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

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

18. What is the difference ?

19. Pushbutton Switch

20. Selector Switch

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

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

23. 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

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

25. Activity 2-Part 1

26. Activity 2-Part 2

27. Activity 2-Part 3

28. Output Devices
Lamp
Resistor
Buzzer
Solenoid
Motor

29. 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

30. 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.

31. 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.

32. 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

33. 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

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

35. Activity 3
motor of a fan

36. Recap
What are the output devices

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

39. 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.

40. Short Circuit

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

42. 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

43. What is the current ratings for the following fuses ?
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 ?

44. 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).

45. 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.

46. Say it in a simple words…
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…

47. 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.

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

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

50. 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

51. Circuit breakers can have different types of reset switches
Some have lever type resets, while some have pushbutton resets.
Most newer homes and businesses use circuit breakers in their electrical control pannel
control panels electrical control panels.

52. Is it lever type or push button type?
When this circuit breaker will trip?

53. Activity 4
I=24/25 = 0.96 A
I= 1.25 A
Wait for about 30 seconds to see if the circuit breaker “trips” off.
Repeat step 2 and observe the circuit breaker’s operation.
I=24/10 = 2.4 A

54. Activity 4 Measure continuity of the circuit breaker
Replace the 10 ohm resistor with a 25 ohm resistor.

55. Recap High current Short circuit
Circuit protection: Fuse and circuit breaker
Fuse rating
Fuse operation
Testing the continuity of the fuse
Circuit breaker