DJJ 2022 – ELECTRICAL TECHNOLOGY [Document subtitle]
[DATE] GRIZLI777 [Company address]
i
TABLE OF CONTENT
PAGE
TABLE OF CONTENT ................................................................................................................................. i 1
EXPERIMENT 1 : UNIT CONVERSION AND MEASUREMENT............................................................ 1 1.1
AIM.......................................................................................................................................... 1
1.2
OUTCOMES ............................................................................................................................. 1
1.3
EQUIPMENTS/MATERIALS NEEDED ........................................................................................ 1
1.4
THEORY ................................................................................................................................... 1
1.5
ELECTRIC AND MAGNETIC QUANTITIES.................................................................................. 2
1.6
INTRODUCTION TO ANALOGUE MULTIMETER ....................................................................... 3
1.7
LABEL OF EACH INDICATOR ON THE ANALOGUE MULTI METER............................................ 3
1.7.1
Resistance Measurement................................................................................................ 4
1.7.2
DC Voltage Measurement............................................................................................... 5
1.7.3
DC Current Measurement............................................................................................... 5
Taking accurate readings ....................................................................................................................... 6 Precautions............................................................................................................................................. 6 Multi meters are easily damaged by careless use so please take these steps: ................................... 6 1.7.4
EXAMPLE MEASUREMENT METHOD OF ANALOGUE MULTI METER.............................. 6
1.7.4.1
DC Voltage Measurement ( unit volt) ......................................................................... 6
1.7.4.2
Resistor value measurement (unit тДж) ......................................................................... 7
1.7.4.3
DC Ampere measurement (unit mA) .......................................................................... 7
1.7.4.4
AC volt measurement (unit volt)................................................................................. 8
1.8
INTRODUCTION TO RESISTOR ................................................................................................. 9
1.9
INTRODUCTION TO BREAD BOARD.......................................................................................11
1.9.1
How it work...................................................................................................................11
1.9.1.1
Series Connection .....................................................................................................12
1.9.1.2
Parellel Connection ...................................................................................................13
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1.10
CALCULATION........................................................................................................................14
1.11
EXPERIMENTAL PROCEDURES............................................................................................1-15
1.12
QUESTIONS ...........................................................................................................................16
1.13
DISCUSSIONS.........................................................................................................................17
1.14
CONCLUSION.........................................................................................................................19
1.15
REFERENCES ..........................................................................................................................19
EXPERIMENT 2: ELECTRICAL CIRCUITS: SERIES AND PARALLEL CIRCUITS.....................................20 2.1
AIM........................................................................................................................................20
2.2
OUTCOMES ...........................................................................................................................20
2.3
EQUIPMENTS/MATERIALS NEEDED ......................................................................................20
2.4
THEORY .................................................................................................................................21
2.4.1
2.5
2.4.1.1
Series Circuit..............................................................................................................21
2.4.1.2
Parallel Circuit ...........................................................................................................22
EXPERIMENTAL 2A: SERIES PROCEDURES.............................................................................23
2.5.1 2.6
3
INTRODUCTION TO SERIES, PARALLEL AND SERIES PARALLEL CIRCUIT........................21
DATA AND RESULT 2A : .................................................................................................26
EXPERIMENTAL 2B: PARALELL PROCEDURES........................................................................28
2.6.1
DATA AND RESULT EXPERIMENT 2B: ............................................................................32
2.6.2
Draw THE PARALLEL circuit connection ON THE PROTOBOARD:.................................33
2.7
DISCUSSIONS.........................................................................................................................34
2.8
CONCLUSION.........................................................................................................................37
2.9
REFERENCES ..........................................................................................................................37
EXPERIMENT 3 : TRANSFORMER...................................................................................................38 3.1
AIM........................................................................................................................................38
3.2
OUTCOMES ...........................................................................................................................38
3.3
EQUIPMENTS/MATERIALS NEEDED ......................................................................................38
3.4
THEORY .................................................................................................................................38
iii 3.4.1
4
Energy losses in a transformer......................................................................................40
3.5
PROCEDURE ..........................................................................................................................41
3.6
QUESTION/DISSCUSSIONS ....................................................................................................42
3.7
CONCLUSIONS.......................................................................................................................44
3.8
REFERENCES ..........................................................................................................................44
EXPERIMENT 4: BASIC MOTOR DC ................................................................................................ 45 4.1
AIM........................................................................................................................................45
4.2
OUTCOMES ...........................................................................................................................45
4.3
EQUIPMENTS/MATERIALS NEEDED ......................................................................................45
4.4
THEORY .................................................................................................................................45
4.5
EXPERIMENTAL PROCEDURES...............................................................................................47
4.6
DISCUSSIONS.........................................................................................................................49
4.7
CONCLUSION.........................................................................................................................50
4.8
REFERENCES ..........................................................................................................................50
DJJ2022 – ELECTRICAL TECHNOLOGY (LABORATORY RUBRIC) .............................................................51 DJJ2022 – ELECTRICAL TECHNOLOGY (GENERIC SKILLS RUBRIC)..........................................................53
Unit Conversion & Measurement
DJJ 2022 – ELECTRICAL TECHNOLOGY
1
EXPERIMENT 1 : UNIT CONVERSION AND MEASUREMENT
1.1
AIM 1. To understand how to use unit conversion 2. To introduce analogue multimeter 3. To learn using the correct meter scale
1.2
OUTCOMES 1. At the end of the session the students will able to : 2. Determine the unit conversion 3. Apply in generic skill for analogue multimeter 4. Determine the correct meter scale
1.3
EQUIPMENTS/MATERIALS NEEDED 1. Analogue Multimeter 2. Resistor 3. Breadboard
1.4
THEORY
UNIT CONVERSION
I. Name tera giga mega kilo hecto deca
DECIMAL MULTIPLES AND SUB-MULTIPLES Symbol T G M k h −
Equivalent 1012 109 106 103 102 10
Name deci centi milli micro nano pico
Symbol d c m μ n p
Equivalent 10-1 10-2 10-3 10-6 10-9 10-12
Table 1 :Decimal Multiples Table
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1.5
ELECTRIC AND MAGNETIC QUANTITIES
Table 2 Electrical Quantities Table
Practice Exercise: 1.
Complete the unit equation for each of the following resistance quantity: a. 1KΩ = …… Ω b. 10KΩ = …… Ω
2.
Complete the unit equation for each of the following capacitance quantity: equivalents: a. 1000µF = ……… F = ………mF b.
3. a. b.
0.07F
= ……..F
= ……..mF
Complete the unit equation for each of the following inductance quantity : 100mF = ……… H = ………µF 0.01H
= ……..mH
= ……..µF
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1.6
INTRODUCTION TO ANALOGUE MULTIMETER
By operating a multi-position switch on the meter they can be quickly and easily set to be a voltmeter, an ammeter or an ohmmeter. In other words, this instrument is used to measure resistance, current and voltage in electric circuit. It is also used to test electronic component such as resistor, capacitor, inductor, diode, transistor and etc. Besides, we can check the condition of these components whether good or not. If we looked at the analogue multi meter, this equipment is classified into 4 basic divisions:
1.7
A.
Control Unit Control unit can be set followed by measurement unit as we need. For example, if we want to measure alternating voltage and current (AU/AC), we must set the control unit to AVC (alternating current voltage) and so on.
B.
Reading Scale Reading scale has several curve line with certain unit such as DCV.A, AVC, and so on. Electric quantity is measured in this meter by the reading scale.
C.
Pointer The pointer is moving on the reading scale to show you the value of the electric quantity being measured.
D.
Terminal Meter There are two terminal meter named positive terminal and negative terminal. Both of terminal are joint to test lead where as the red colour for positive terminal (+) and black colour for negative terminal (-).
LABEL OF EACH INDICATOR ON THE ANALOGUE MULTI METER
POINTER READING RESISTOR SCALE READING DCV SCALE READING
POINTER ADJUSTMENT AT 0 Volt OFF MULTI METER SELECTOR RESISTOR SCALE ADJUSTMENT TO 0Ω
DCV SELECTOR
ACV SELECTOR
NEGATIVE TERMINAL (-VE) CONNECTOR DC mA SELECTOR
TRANSISTOR TESTING
BUZZER
POSITIVE TERMINAL (+VE) CONNECTOR
Figure 1.1
RESISTOR SELECTOR
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Unit Conversion & Measurement
DJJ 2022 – ELECTRICAL TECHNOLOGY
Analogue meters take a little power from the circuit under test to operate their pointer. They must have a high sensitivity of at least 20k /V or they may upset the circuit under test and give an incorrect reading. Batteries inside the meter provide power for the resistance ranges, they will last several years but you should avoid leaving the meter set to a resistance range in case the leads touch accidentally and run the battery flat. Typical ranges for analogue multi meters like the one illustrated in Figure: 1.1 (the voltage and current values given are the maximum reading on each range)
DC Voltage: 0.5V, 2.5V, 10V, 50V, 250V, 1000V. AC Voltage: 10V, 50V, 250V, 1000V. DC Current: 50µA, 2.5mA, 25mA, 250mA. A high current range is often missing from this type of meter. AC Current: None. (You are unlikely to need to measure this). Resistance: 20 , 200 , 2k , 20k , 200k . These resistance values are in the middle of the scale for each range.
If we looked at the reading scale of multi meter, we will see many colourful curve lines. Every line is used for certain unit such as resistance (), direct voltage and current (DCV.A), alternating voltage current (ACV) and so on (see Figure 1.2).
Figure
1.7.1
Resistance Measurement The resistance scale on an analogue meter is normally at the top, it is an unusual scale because it reads backwards and is not linear (evenly spaced). This is unfortunate, but it is due to the way the meter works. 1. Set the meter to a suitable resistance range. Choose a range so that the resistance you expect will be near the middle of the scale. For example: with the scale shown below and an expected resistance of about 50k choose the × 1k range. 2. Hold the meter probes together and adjust the control on the front of the meter which is usually labelled "0 ADJ" until the pointer reads zero (on the RIGHT remember!). If you can't adjust it to read zero, the battery inside the meter needs replacing. 3. Put the probes across the component. Avoid touching more than one contact at a time or your resistance will upset the reading!
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DJJ 2022 – ELECTRICAL TECHNOLOGY
Choose scale range at x1. When the pointer shows at 20 scale reading, therefore the total of resistance is 20 x 1 = 20.
1.7.2
DC Voltage Measurement
There are 3 ranges in this scale reading: 0 to 10, 0 to 50 and 0 to 250. When you want to measure a voltage not more than 50V, the suitable scale Range is 0 to 50V. For example, if the pointer shows at 20, the total of Voltage measured is 20V. If the voltage is around 0.1V, so suitable scale reading is 0 to 10V (10/100=0.1V). For example, if the pointer shows at 4.4, the total of voltage measured is 4.4/100=0.044V.
1.7.3
DC Current Measurement Scale range has been choosing is 25mA. The suitable scale reading is 0 to 250 (250/10=25mA). If pointer at 150, the total of current measured is 150/10=15mA.
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Taking accurate readings To take an accurate reading from an analogue scale you must have your eye in line with the pointer.
rrect
Wrong
lection hidden
Avoid looking at an angle from the left or right because you will see a reading which is a little too high or too low. Many analogue meters have a small strip of mirror along the scale to help you. When your eye is in the correct position the reflection of the pointer is hidden behind the pointer itself. If you can see the reflection you are looking at an angle.
reflection visible
Figure: 1.3
Precautions Multi meters are easily damaged by careless use so please take these steps:
Always disconnect the multi meter before adjusting the range switch. Always check the setting of the range switch before you connect to a circuit. Never leave a multi meter set to a current range (except when actually taking a reading). The greatest risk of damage is on the current ranges because the meter has a low resistance.
1.7.4 1.7.4.1
EXAMPLE MEASUREMENT METHOD OF ANALOGUE MULTI METER DC Voltage Measurement ( unit volt)
Point 2
Point 1
Answer : 100 Volt
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1.7.4.2
Resistor value measurement (unit Ω) Point 1
Answer : 1KΩ
1.7.4.3
DC Ampere measurement (unit mA) Point 2
Point 1
Answer : 150 mA
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1.7.4.4
AC volt measurement (unit volt)
Point 2
Point 1
Answer : 41 V
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1.8
INTRODUCTION TO RESISTOR
Resistor values can be determined using the Resistor Colour Code. For the 4-band type, the first two bands are numerical values the third is the multiplier or number of noughts. The fourth band indicates tolerance. Resistor values are also available as 5-band types. Example: 1st stripe: Brown = 1 2nd stripe: Black = 0 3rd stripe: Orange = x1,000 4th stripe: silver Resistor value
= 10% tolerance = 10 x 1000 = 10,000 Ω =
10kΩ Tolerance
= 10% x 10,000 = 1000
Minimum Value = Resistor Value – Tolerance = 10,000 – 1000 = 9,000Ω Maximum Value = Resistor Value + Tolerance = 10,000 +1000 = 11,000Ω
Table 1 – Resistor Colour Code
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Unit Conversion & Measurement
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1.9
Unit Conversion & Measurement
INTRODUCTION TO BREAD BOARD
A breadboard also known as protoboard is a type of solder less electronic circuit building.You can build an electronic circuit on a breadboard without any soldering! Best of all it is reusable. It was designed by Ronald J Portugal of EI Instruments Inc. in 1971.
1.9.1
How it work
Basically, a bread board is an array of conductive metal clips encased in a box made of white ABS plastic, where each clip is insulated with another clips. There are a number of holes on the plastic box, arranged in a particular fashion. A typical bread board layout consists of two types of region also called strips. Bus strips and socket strips. Bus strips are usually used to provide power supply to the circuit. It consists of two columns, one for power voltage and other for ground. Socket strips are used to hold most of the components in a circuit. Generally it consists of two sections each with 5 rows and 64 columns. Every column is electrically connected from inside.
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1.9.1.1 Series Connection
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1.9.1.2
Unit Conversion & Measurement
Parellel Connection
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1.10 CALCULATION
Resistor
1.
2.
3.
4.
5.
Third Band
First Band
Second Band
(Colour&digit)
(Colour&digit)
Brown
Black
Red
Yellow
Violet
Brown
Brown
Black
Orange
Brown
Green
Brown
Orange
White
Red
(multiplier) (Colour&digit)
Resistor Value
Tolerance
Min Value
Max Value
Table 3 – Calculation result
(20 marks) Lecturer signature: ___________________________________
Date : ____________________
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1.11 EXPERIMENTAL PROCEDURES 1.
By using Bread Board and resistor, connect a multimeter a shown below.
2.
Choose ohm scale at the maximum range then reduce the range until you get the correct answer. Point
3.
Write the answer in Table 4, experiments result.
4.
Repeat the procedure 1 until 3 to complete the Table 4.
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Resistor
Calculation Value
Experiment Value
R1 R2 R3 R4 R5 Table 4 – Experiments result (5 marks)
1.12 QUESTIONS 1.
Complete the unit equation for each of the following resistance quantity: a.
100Ω = ……..K Ω
b.
1500 Ω = ……. K Ω (2 marks)
2.
Complete the unit equation for each of the following capacitance quantity: equivalents: a.
600µF = ……..F
= ……..mF
b.
150mF = ……..F
= ……..µF (2 marks)
3.
Complete the unit equation for each of the following inductance quantity : a.
6.5mH = ……..H
= ……..µF
b.
750µF = ……..H
= ……..Mf (2 marks)
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Unit Conversion & Measurement
1.13 DISCUSSIONS a) How to change the unit conversion.
(2marks) b) How to choose the correct meter scale.
(6marks)
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Unit Conversion & Measurement
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c) How to know the value of resistor using calculation.
(3 marks)
1.14 CONCLUSION ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ (6marks)
1.15 REFERENCES Book: _______________________________________________________________________ _______________________________________________________________________ Internet Address: _______________________________________________________________________ _______________________________________________________________________ (2 marks)
Total :
50
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Electrical Circuits
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2
2.1
EXPERIMENT 2: ELECTRICAL CIRCUITS: SERIES AND PARALLEL CIRCUITS AIM 1. To learn using the correct meter scale 2. To analyse the series and parallel connection using breadboard 3. To study the measurement method of voltage and current in series and parallel circuit connection
2.2
OUTCOMES
At the end of the session the students will able to: 1. Determine the correct meter scale 2. Explain the operation of the circuit 3. Explain the measurement method of voltage and current in series and parallel circuit
2.3
EQUIPMENTS/MATERIALS NEEDED 1. Analogue Multimeter 2. Resistor (150Ω, 120Ω, 160Ω) 3. Breadboard 4. 9V Battery 5. Jumper Wire
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2.4
THEORY
2.4.1 2.4.1.1
INTRODUCTION TO SERIES, PARALLEL AND SERIES PARALLEL CIRCUIT Series Circuit
In a practical circuit consisting of just three resistors, connected in series across a battery, four circuit parameters can be measured using a simple multi-meter. Firstly the current I flowing which is determined by inserting an ammeter in series with the resistors and then the three voltage drops across the individual resistors. The current is a result of the applied voltage divided by the total series circuit resistance. Apply the formula for series resistance to determine the total resistance R. Formula :
RT R1 R
VT V1 V IT I1 I
2
2
2
R
V3 I3
3
V1 IT R1 V V
2
IT R
2
3
IT R
3
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Electrical Circuits
DJJ 2022 – ELECTRICAL TECHNOLOGY
Individual resistor voltage drops are each found by applying Ohm's Law. Resistance R1, R2 or R3 multiplied by the series circuit current. Adding the individual voltage drops together will always equal the applied battery voltage. Series circuits are commonly used in on-board computer sensor and actuator circuits. A series circuit has several unique characteristics: There is only one path for electric current. The amount of electric current is the same at all points in the circuit. The source voltage will be dropped across all of the electrical loads in the circuit. An open anywhere in a series circuit will stop the current and shut off the circuit. The total circuit resistance is the sum (add them together) of all the resistive loads in the circuit.
2.4.1.2
Parallel Circuit
The first principle to understand about parallel circuits is that the voltage is equal across all components in the circuit. This is because there are only two sets of electrically common points in a parallel circuit, and voltage measured between sets of common points must always be the same at any given time. Therefore, in the above circuit, the voltage across R1 is equal to the voltage across R2 which is equal to the voltage across R3 which is equal to the voltage across the battery. I1 I
2
I3
VT R1 VT R V2 T V 1 V VT I R3
T
I1 I
2
2
V I
3
3
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2.5
EXPERIMENTAL 2A: SERIES PROCEDURES 1.
Calculate the total resistance, current and voltage for each resistance in series circuit as shown in figure 1 using the related formula. Measure the battery given.
Given equipment: 1. Battery =_________v 2. R1
= 150 Ω
3. R2
=120 Ω
4. R3
= 160 Ω
Fig. 1: series circuit
2.
Construct the three resistors in series on the protoboard as shown in figure 2 below.
Fig. 2: construction of series circuit on protoboard
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3.
Using the multimeter, measure and record the current and voltage across R1, R2 and R3.
Current measurement:
Disconnect the given series circuit at point between the battery and R1. Connect the multimeter at that point as shown in fig.3. Make sure that the multimeter is in current measurement mode. The measured current value of Itotal =____________ Itotal = I1 So, I1 = ______________ Fig. 3: Measuring Itotal or I1 in series circuit Reconstruct the circuit as shown in fig. 1. Disconnect the given series circuit at point between the R1 and R2. Connect the multimeter at that point as shown in fig. 4. Make sure that the multimeter is in current measurement mode. The measured current value of I2 =____________ Fig. 4: Measuring I2 in series circuit
Reconstruct the circuit as shown in fig. 1. Disconnect the given series circuit at point between the R2 and R3. Connect the multimeter at that point as shown in fig. 5. Make sure that the multimeter is in current measurement mode. Fig. 5: Measuring I3 in series circuit
The measured current value of I3 =____________
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Voltage measurement Reconstruct the circuit as shown in fig. 1. Connect the multimeter at that point as shown in fig. 6. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of Vtotal =____________
Fig. 6: Measuring Vtotal in series circuit
Disconnect the multimeter from the circuit. Connect the multimeter at that point as shown in fig. 7. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of V1 =____________
Fig. 7: Measuring V1 in series circuit
Disconnect the multimeter from the circuit. Connect the multimeter at that point as shown in fig. 8. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of V2 =____________
Fig. 8: Measuring V2 in series circuit
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Disconnect the multimeter from the circuit. Connect the multimeter at that point as shown in fig. 9. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of V3 =____________
Fig. 9: Measuring V3 in series circuit
2.5.1
DATA AND RESULT 2A : Experimental Data: Value indicated by multimeter
Electric Quantities Resistor 1 (R1)
Resistor 2 (R2)
Resistor 3 (R3)
Total
Voltage V1
V2
V3
VT
I1
I2
I3
IT
Current
Table 1 – Measurement value for series circuit (8 marks)
Lecturer’s signature : ____________________________
Date : _________________
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DRAW THE SERIES CIRCUIT CONNECTION ON THE PROTOBOARD:
(5 marks)
Lecturer’s signature: ____________________________
Date: _________________
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2.6
EXPERIMENTAL 2B: PARALELL PROCEDURES 1.
Calculate the total resistance, current and voltage for each resistance in parallel circuit as shown in figure 1 using the related formula. Measure the battery given.
Current measurement
Connect the given parallel circuit on a protoboard. Given equipment: 1. 2. 3. 4.
Battery =_________v R1 = 150 Ω R2 = 120 Ω R3 = 160 Ω
Fig. 10: Parallel circuit 2.
Construct the three resistors in series on the protoboard as shown in figure 2 below.
Fig. 11: construction of parallel circuit on protoboard 3.
Using the multimeter, measure and record the current and voltage across R1, R2 and R3.
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Current measurement:
Disconnect the given parallel circuit at point between the battery and junction of R1, R2 and R3. Connect the multimeter at that point as shown in fig. 12. Make sure that the multimeter is in current measurement mode. The measured current value of Itotal =____________
Fig. 12: Measuring Itotal in parallel circuit
Reconstruct the circuit as shown in fig. 10. Disconnect the given parallel circuit at point between the junction of R1 with junction of R2 and R3. Connect the multimeter at that point as shown in fig. 13. Make sure that the multimeter is in current measurement mode. The measured current value of I1 =____________ Fig. 13: Measuring I1 in parallel circuit
Reconstruct the circuit as shown in fig. 10. Disconnect the given parallel circuit at point between the junction of R2 with junction of R1 and R3. Connect the multimeter at that point as shown in fig. 14. Make sure that the multimeter is in current measurement mode. The measured current value of I2 =____________ Fig. 14: Measuring I2 in parallel circuit
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Reconstruct the circuit as shown in fig. 10. Disconnect the given parallel circuit at point between the junction of R3 with junction of R1 and R2. Connect the multimeter at that point as shown in fig. 15. Make sure that the multimeter is in current measurement mode. Fig. 15: Measuring I3 in parallel circuit
The measured current value of I3 =____________
Voltage measurement Reconstruct the circuit as shown in fig. 10. Connect the multimeter at that point as shown in fig. 16. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of Vtotal =____________
Fig. 16: Measuring Vtotal in parallel circuit
Disconnect the multimeter from the circuit. Connect the multimeter at that point as shown in fig. 17. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of V1 =____________
Fig. 17: Measuring V1 in parallel circuit
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Electrical Circuits
Disconnect the multimeter from the circuit. Connect the multimeter at that point as shown in fig. 18. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of V2 =____________
Fig. 18: Measuring V2 in parallel circuit
Disconnect the multimeter from the circuit. Connect the multimeter at that point as shown in fig. 19. Make sure that the multimeter is in voltage measurement mode. The measured voltage value of V2 =____________
Fig. 19: Measuring V3 in parallel circuit
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2.6.1
DATA AND RESULT EXPERIMENT 2B: Experimental Data: Value indicated by multimeter
Electric Quantities Resistor 1 (R1) Voltage
Resistor 2 (R2)
Resistor 3 (R3)
Total
V1
V2
V3
VT
I1
I2
I3
IT
Current
Table 3 – Measurement value for parallel circuit (8 marks)
Lecturer’s signature : ____________________________
Date : _________________
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DJJ 2022 – ELECTRICAL TECHNOLOGY
2.6.2
Draw THE PARALLEL circuit connection ON THE PROTOBOARD:
(5 marks)
Lecturer’s signature: ____________________________
Date: _________________
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Electrical Circuits
DJJ 2022 – ELECTRICAL TECHNOLOGY
2.7 1.
DISCUSSIONS By referring the series circuit as shows, complete the table below with a calculation:
Fig. 1: series circuit Value calculated
Electric Quantities Resistor 1 (R1)
Resistor 2 (R2)
Resistor 3 (R3)
Total
Voltage
V1
V2
V3
VT
Current
I1
I2
I3
IT
Table 2 –Calculated value for series circuit (12 marks)
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Electrical Circuits
DJJ 2022 – ELECTRICAL TECHNOLOGY
2.
By referring the series circuit as shows, Complete the table below with a calculation :
Fig. 10: Parallel circuit Value calculated
Electric Quantities Resistor 1 (R1)
Resistor 2 (R2)
Resistor 3 (R3)
Total
Voltage
V1
V2
V3
VT
Current
I1
I2
I3
IT
Table 4 –Calculated value for series circuit (12 marks)
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Electrical Circuits
DJJ 2022 – ELECTRICAL TECHNOLOGY
3. State the Ohm’s Law ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ (6 marks) 4. State the use of resistors. ________________________________________________________________________ ________________________________________________________________________ (2 marks) 5. What is the effect of a resistor in a circuit? ________________________________________________________________________ ________________________________________________________________________ (2 marks) 6.
What is the connection between the resistors size and value of current flow? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ (2 marks) ELECTRICAL TECHNOLOGY LABORATORY
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Electrical Circuits
DJJ 2022 – ELECTRICAL TECHNOLOGY
2.8
CONCLUSION ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ (6marks)
2.9
REFERENCES Book : _______________________________________________________________________ _______________________________________________________________________ Internet Address : _______________________________________________________________________ _______________________________________________________________________ (2 marks)
Total :
70
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DJJ 2022 – ELECTRICAL TECHNOLOGY
3
3.1
Transformer
EXPERIMENT 3 : TRANSFORMER
AIM 1. To determine the output voltage of step down transformer 2. To determine the transformer turns ratio
3.2
OUTCOMES
At the end of the session the students will able to : 1. Explain the operation of transformer 2. Apply in generic skill for analogue multimeter 3. Explain the transformer turns ratio
3.3
EQUIPMENTS/MATERIALS NEEDED 1. Analogue Multimeter 2. Transformer 3. Power Supply
3.4
THEORY A transformer is a device used to change voltages and currents of AC electric power. In the simplest version it consists of two windings wrapped around a magnetic core; windings are not electrically connected, but they are coupled by the magnetic field, as it shown in Figure 1. When one winding is connected to the AC electric power, the electric current is generated. This winding is called the primary winding. The primary current produces the magnetic field and the magnetic flux links the second winding, called the secondary winding. The AC flux through the secondary winding produces an AC voltage, so that if some impedance is connected to the terminals, an AC electric current is supplied. Figure 2 shows the schematic symbols of a transformer.
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DJJ 2022 – ELECTRICAL TECHNOLOGY
Transformer
Figure 1: Sketch of an ideal transformer.
Figure 2: Schematic symbols of a transformer.
The simplest model of the transformer is called the ideal transformer and it neglects any power losses and leakage magnetic fluxes. Assuming that the primary winding has Np turns of wire, and the secondary winding has Ns turns, the relationship between the primary voltage and the secondary voltage is
Where a is the turns ratio in the primary and secondary windings
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DJJ 2022 – ELECTRICAL TECHNOLOGY
Transformer
Similarly, for the primary and secondary currents
For AC power the same can be also expressed in the phasor notation
If the secondary voltage is less than the primary voltage, the transformer is known as a STEPDOWN transformer. If the secondary voltage is greater than the primary voltage it is known as a STEP-UP transformer A voltage change from primary to secondary will mean a current change also. If the voltage is increased the current will be decreased and vice versa. So a 20:1 step-down transformer for voltage will be a 20:1 step-up transformer for current. Bigger currents need thicker wire and so step down transformers have primary coils of thin wire and secondary coils of thick wire. Examples of step up and step down transformers: (a) Step down: electric mains clock, stereo, substation, low voltage power supplies, and audio systems in televisions. (b) Step up: power station end of transmission cables, electron gun in a TV, "starter" coils in fluorescent lights.
3.4.1
Energy losses in a transformer These formulae are only correct if the transformer is 100% efficient but of course they never are. Energy is always lost and so the output voltage will be a little smaller than the calculated value. Energy can be lost as: (a) heat in the coils because of the resistance of the wire; (b) incomplete transfer of magnetic field; (c) heating of the core due to induced currents in it. This is reduced by making the core out of insulated soft iron in laminated strips. If this were not done the cores of large transformers would get so hot that they would melt.
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DJJ 2022 – ELECTRICAL TECHNOLOGY
3.5
Transformer
PROCEDURE
1. Make a connection as shown in Figure 3. 2. Set the range selector to 250ACV or higher. 3. Connect the probe of the multimeter to the secondary side of the transformer. 4. Do not turn the power on before your circuit has been checked by your lecturer. 5. When the layout has been completed, have your lecturer to check your circuit connections. 6. Adjust the ACV range selector to gain a proper reading. 7. Show the measured value.
Figure 3: Experimental transformer measurement
Measured output voltage at the secondary windings=_______________V
Measured output voltage at the secondary windings=_______________V
ELECTRICAL TECHNOLOGY LABORATORY
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DJJ 2022 – ELECTRICAL TECHNOLOGY
3.6
Transformer
QUESTION/DISSCUSSIONS 1. What is the windings ratio of the transformer? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ (4 marks)
2. Complete the following table as an example 1. Show all the calculation. eNoo
Primary voltage
Secondary voltage
Primary turns
Secondary turns
Primary current
2000
1A
1
12V
240V
100
2
240V
12V
5000
3
100V
2000
100
4
200V
200
10000
secondary current 0.05A
0.1A 2A 1A
(6 marks)
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DJJ 2022 – ELECTRICAL TECHNOLOGY
Transformer
1. Draw the input and output waveform of the transformer.
Input voltage (5 marks)
Output voltage (5 marks)
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DJJ 2022 – ELECTRICAL TECHNOLOGY
3.7
Transformer
CONCLUSIONS ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ (5 marks)
3.8
REFERENCES Book : ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
Internet Address : ___________________________________________________________________________ ___________________________________________________________________________ (5 marks)
(2 marks)
Total :
30
ELECTRICAL TECHNOLOGY LABORATORY
44
Basic DC Motor
DJJ 2022 – ELECTRICAL TECHNOLOGY
4
EXPERIMENT 4: BASIC MOTOR DC
4.1
AIM 3. To design basic motor DC
4.2
OUTCOMES
At the end of the session the students will able to : 1. To determine the direction of the magnetic field. 2. To determine the speed at which the motor turns by; a. Increasing the number of current carrying wires (number of loops in the rotor) b. Increasing the size of the magnetic field by using additional and/or stronger ceramic magnets
4.3
EQUIPMENTS/MATERIALS NEEDED 1. 2. 3. 4. 5. 6. 7.
4.4
Copper Wire Paper Clips Wood (3" 1X2) Neodymium Magnet Battery (AA) Insulated Wire Sand Paper
THEORY Motors convert electrical energy (from a battery or voltage source) into mechanical energy (used to cause rotation). When a wire that carries current is placed in a region of space that has a magnetic field, the wire experiences a force. The size of the force, which determines how fast the motor spins, depends on : a. the amount of current in the wire b. the length of the wire c. the strength of the magnetic field
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DJJ 2022 – ELECTRICAL TECHNOLOGY
Basic DC Motor
The direction of the force, which determines which direction the motor spins, depends on: a. the direction of the current in the wire b. the direction of the magnetic field The Right Hand Rule is used to determine the direction of the force when the direction of the current and the direction of the magnetic field are known.
Thumb = direction of current Fingers = dir. of magnetic field Palm = direction of force
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Basic DC Motor
DJJ 2022 – ELECTRICAL TECHNOLOGY
4.5
EXPERIMENTAL PROCEDURES 1. Cut a length of copper wire (between 2 and 3ft) using a pair of wire cutters.
2. Use a AA Battery as a winding template; begin winding the Copper Wire around the AA Battery (Make sure to leave about two inches of wire trailing off one end of the coil). 3. Continue winding the Copper Wire around the AA Battery; make sure that you wind a nice tight coil.
4.
Leave a length of wire (two inches) trailing from your coil after winding the Copper Wire around the AA Battery 15 times.
5.
Wrap the trailing ends of wire around your coil two or three times. This will hold the coil in place (its important to wrap the ends directly across from each other; balance is key in creating a good motor). ELECTRICAL TECHNOLOGY LABORATORY
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DJJ 2022 – ELECTRICAL TECHNOLOGY
Basic DC Motor
6. The two ends that are trailing off the completed coil need to have the enamel sanded off of the Copper Wire (this is extremely important because the more enamel you remove the better electrical connection you are able to make between the AA Battery and the Motor). 7. (This step is even more important than the first) Start by sanding only ONE SIDE of the trailing ends of Copper Wire. (Only ONE SIDE) 8. The other trailing end of Copper Wire needs to have all of the enamel completely sanded off. (Remember, the more wire you expose the better the connection)
ELECTRICAL TECHNOLOGY LABORATORY
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Basic DC Motor
DJJ 2022 – ELECTRICAL TECHNOLOGY
4.6
DISCUSSIONS Part I. Fill in the blanks.
1. Motors are devices that convert ____________________________ energy into _____________________________ energy.
2. The basic principle behind the simple DC motor is that wires that carry _______________________ experience _________________________when placed in regions of space that have _______________________________. 3. Only sections of wire that carry current in a direction _____________________to a magnetic field experience forces. 4. The speed at which the rotor of a motor spins depends on three important factors: ________________________________, ______________________________, and _________________________________. 5. The direction that the rotor of a motor spins depends on the ______________________________ rule. (10 marks)
Part 2. Illustrate a complete basic motor.
(5 marks) ELECTRICAL TECHNOLOGY LABORATORY
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Basic DC Motor
DJJ 2022 – ELECTRICAL TECHNOLOGY
4.7
CONCLUSION ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ (10 marks)
4.8
REFERENCES Book : ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
Internet Address : ___________________________________________________________________________ ___________________________________________________________________________ (5 marks)
Total :
30
ELECTRICAL TECHNOLOGY LABORATORY
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DJJ2022 – ELECTRICAL TECHNOLOGY (LABORATORY RUBRIC) Student’s Name : _________________________________
Group No :
Date : ______________________
Registration No : Excellent
Average
Weak
4-5
2-3
0-1
A: Understanding the material
Procedures are followed correctly (choosing scale, parts, material)
Some procedures are followed and some procedures are missing (choosing scale, parts, material)
(choosing scale, parts, material)
B:Ability to construct the given circuit
Able to construct a circuit without assistance
Able to construct a circuit with slight assistance
C: Efficiency in taking data.
All data are taken correctly
D: Ability to relate practical result with theories.
Able to relate the practical result with the theories
Marks
Skills / Aspects/ Criteria PRAC 1
PRAC 2
PRAC 3
PRAC 4
/5
/5
/5
/5
Unable to construct circuit without assistance.
/5
/5
/5
/5
Parts of the data are taken correctly.
Most of all the data are taken incorrectly.
/5
/5
/5
/5
Able to relate the practical with some of the theories.
Unable to relate practical result with theories
/5
/5
/5
/5
Total
/20
/20
/20
/20
Percentage %
/100
/100
/100
/100
Major procedures are missing
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DJJ2022 – ELECTRICAL TECHNOLOGY (GENERIC SKILLS RUBRIC) Student’s Name : _________________________________
Group No :
Date : ______________________
Registration No : Excellent
Average
Weak
Marks
4-5
2-3
0-1
PRAC 1
PRAC 2
PRAC 3
PRAC 4
Meet all the criteria
Minor flaws to dress codes or lab regulations
Major flaws to all the criteria
/5
/5
/5
/5
Attend class on time.
Late less than 10 minutes.
Late more than 10 minutes.
/5
/5
/5
/5
Meet all the criteria
Minor flaws to pre-lab, assignment & tools.
Major flaws to all the criteria
/5
/5
/5
/5
Procedures are followed correctly
Some procedures are missing
Major procedures are missing
/5
/5
/5
/5
Total
/20
/20
/20
/20
Percentage %
/100
/100
/100
/100
Skills / Aspects/ Criteria
A : Disciplines
Dress Code Lab Regulations
B : Punctuality C : Pre-lab preparation
Pre-assisgnment Bringing necessary usable tools such as laptop Bringing Lab-sheet
D : Practice Safety
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