Download BTEC National Diploma in Engineering Unit 6 Electrical and

BTEC National Diploma in Engineering
Unit 6
Electrical and Electronic Principles
Unit Name and Number
Student
Assessor
Task book issue date
Completion date (pass outcomes)
Learner Signature
Outcomes included in this task book
Tasks are ordered in accordance with the outcomes listed
P1
Use DC circuit theory to calculate current, voltage and resistance in DC
Networks
P2
Use a multimeter to carry out circuit measurements in a DC circuit
P3
Compare the forward and reverse characteristics of two different semi
conductor diode
P4
Describe the function of different types of capacitors
P5
Carry out and experiment to determine the relationship between
voltage and current for a charging and discharging capacitor
P6
Calculate the charge, voltage and energy values in a DC network for
both three capacitors in series and three capacitors in parallel
P7
Describe the characteristics of a magnetic field
P8
Describe the relationship between flux density (B) and field strength
(H)
P9
Describe the principles and applications of electromagnetic induction
Achieved?
Assessor
Signature
P10
Use single phase AC circuit theory to determine the characteristics of a
sinusoidal waveform
P11
Use an oscilloscope to measure and determine the inputs and outputs
of a single phase AC circuit
M1
Use Kirchoff’s laws to determine the current in various parts of a
network having four nodes and the power dissipated in a load resistor
containing two voltages sources
M2
Evaluate capacitance, charge, voltage and energy in a network
containing a series-parallel combination of three capacitors
D1
Analyse the operation and the effects of varying component
parameters of a power supply circuit that includes a transformer,
diodes and capacitors
D2
Evaluate the performance of a motor and a generator by reference to
electronic theory
Learner Declaration
I confirm that the work submitted to complete the given tasks is my own. I have indicated where
research and other resources have been used to confirm the conclusions reached within the submission
and listed those resources in a bibliography
Sign and date for each task
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
M1
M2
M3
D1
D2
Task 1 Covering P1
Before you submit your work to be marked for this task please check the following, if you omit any of
the items listed in the table you may have to repeat the submission.
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you properly introduced the task, explaining what you are
trying to achieve?
Are your calculations clearly laid out with answers double
underlined?
Have you put your name on the submitted work?
Have you produced drawings to back up your calculations?
Especially drawings showing how the circuit is broken down to
calculate resistance.
Have you used a simulator to check your calculated results?
Have you provided screen dumps with this submission to prove
the accuracy of your calculations?
Task 1 P1
For the circuit shown below:
Circuit 1
Choose 5 different value resistors from the following table for resistors R1 – R5
Choose a value of supply voltage from the table for V1
Resistor values for R1 – R5
Voltage values for V1
10 Ω
3 volts
22 Ω
5 volts
33 Ω
6 volts
47 Ω
9 volts
100 Ω
10 volts
220 Ω
12 volts
330 Ω
15 volts
470 Ω
24 volts
1k Ω
Calculate:
The total circuit resistance Rt
The total circuit current It
The current flowing through R3
The voltage dropped across R2
The power dissipated by R1
Confirm the results of your calculation using the laboratory simulator (Multisim)
Care should be taken by each student to ensure that the combination of components and supply voltage
are unique for each assessment.
Task 2 P2
Evidence requirements
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you made sure you have the performance evidence
statement signed?
Have you evaluated the differences between the calculated,
measured and simulated results? What could cause the
difference in the results for example
Have you provided a plan of the circuit you made along with the
correct test points to make the required measurements?
Once again have you properly introduced the task to your
reader and informed them of what you are attempting to
accomplish?
You are required to construct the circuit used for P1 above. You are to use test equipment to carry out
the following measurements as listed in the table below. You need to have the witness statement.
Parameter
Calculated values
Measured values
Simulated values
Total circuit resistance
Total circuit current
Current flowing through R3
Voltage dropped across R2
Power dissipated in R1
For this observation the learner:
Safely constructed a DC network comprising of 5 resistors
Connected the network to a DC source (5 volts)
Correctly demonstrated the safe use of a multimeter
Used a multimeter to measure voltage, current and resistance in accordance with the set tasks
Was able to contrast and compare the readings taken by a multimeter with calculated and
simulated results
Signed Observer ………………………………..
Date …………………………….
Task 3 P3
Evidence requirements
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you introduced the task to your reader?
Are your drawings neatly completed in pencil?
Are all of your drawings and graphs completed in pencil and
neatly labeled or given headings where appropriate?
Have you provided a table for all of the results you measured
both in the simulator and using the laboratory test equipment?
Have you properly read all of the tasks below to make sure you
are providing all of the evidence required?
You are required to use test equipment to measure the forward and reverse characteristics of two semiconductor diodes. In order to carry out this experiment you will need to read through the instructions
on www.mindfyre.co.uk.
Tasks
Draw and label a diagram of a general purpose diode connected in forward bias and reverse bias
mode
Measure the forward and reverse characteristics of the 1N4001 diode using Multisim, record
your results in a suitable table and use them to plot a graph.
Measure the forward and reverse characteristics of a zener diode of your choice using test and
measuring equipment, record your results in a suitable table and use them to plot a graph
Compare the two graphs showing the conduction characteristics of both diodes, consult the
data sheets and evaluate your findings in terms of forward and reverse voltages, power
dissipation and maximum operating current
Task 4 P4
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you introduced the task to your reader?
Have you drawn and labeled a simple diagram explaining how a
capacitor is constructed?
Have you given a typical application for each of the types of
capacitor listed? For example electrolytic capacitors are used in
power supplies because of their high capacitance and energy
storage.
Have you attempted to explain in your own words how a
capacitor works?
Describe the function and type of capacitors
This is best completed using a table of values, consult www.mindfyre.co.uk for more information on this
task
Tasks
Describe the following list of capacitors in terms of their construction, working voltages, dielectric, flux
density, permittivity and energy storage:
Electrolytic
Mica
Plastic
Paper
Ceramic
Fixed and variable
Task 5 P5
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you introduced the task to your reader?
Have you checked your measured results and your calculated
results?
Have you provided a photograph of the oscilloscope trace
showing the capacitor charging and discharging?
Have you evaluated this task?
Did you use the formula below to plot a basic graph of showing
how the voltage changes across a charging capacitor?
Did you use the formula below to show how the current
decreases through a discharging capacitor
Construct the circuit shown below, if you need further guidance you can consult www.mindfyre.co.uk
Tasks
Connect the circuit to the power supply as shown
Calculate the time constant of the circuit
Set up an oscilloscope to measure the voltage across the capacitor using suitable time and
amplitude settings
Switch on the circuit and measure the rise in capacitor voltage for 5 time constants. Save your
results as a screen dump
Switch off the circuit and measure the decay in capacitor voltage for 5 time constants. Save your
results as a screen dump
Show how the rise in capacitor voltage is related to v =Vmax (1 – e –t/cr)
Show how the decay in current is related to i = Imaxe-t/cr
Task 6 P6 (Evidence requirements should be apparent by this stage)
Calculate the charge, voltage, capacitor and energy values stored by each capacitor for the following
networks. Check www.mindfyre.co.uk for further details and support.
Task 7 P7
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Where you are asked to describe something, it should be your
description in your own words. You can use other information
sources to confirm your explanation
It’s fine to use information sources to define the properties of a
magnetic field. However make sure you confirm your
understanding in your own words
Have you provided labeled sketches to back up your
descriptions of the items listed below?
1) Draw the magnetic field associated with a permanent bar magnet and use the diagram to carry out
the following tasks.
a.
b.
c.
d.
e.
Give 5 general properties of a magnetic field.
Define flux, flux density and magnetic field strength
Describe the effects of reluctance and hysteresis with respect to magnetic circuits.
Define the term ferromagnetic and give three examples of a ferromagnetic material
Describe the process and advantages of magnetic screening
Task 8 P8
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you provided two graphs? One for relative permeability
and the other for flux density?
Have you briefly explained what you deduce is happening to
both materials as the magnetizing force is increased?
Have you provided a table showing how you calculated the
relative permeability of each material for the 5 given stages?
Plot the B/H curve on a suitable graph for the materials shown on the table from the given data
and determine the relative permeability (µr) of the material for each stage. Given that µo = 4 x
10-7 H/m find the range of relative permeability for each material.
Use the data plotted on the graph to analyse and explain the relationship between the two
given materials in terms of flux density (B) and magnetizing force (H)
Remember relative permeability µr = B/(H x µo)
Plot the graph that shows relative permeability against the magnetizing force
Describe what happens to a material as the magnetizing force is increased in terms of flux
density and relative permeability
Magnetizing
Mild steel
Cast Iron
Force (H) At/m
Flux density (B) Tesla’s
Flux density (B)
Tesla’s
1000
0.7
0.3
2000
1.24
0.48
3000
1.45
0.6
4000
1.55
0.67
5000
1.6
0.72
Task 9 P9
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you explained the laws using your own words?
Have you used sketches to show how the laws listed below
operate, and are the provided sketches completed in pencil and
neatly labeled?
Have you included any of the simple transformer calculations
which help to show how a transformer operates?
In both the case of the 3 phase motor and the transformer, how
does your description of how both machines operate relate to
Faraday’s laws?
Use the following tasks to describe the principles and applications of electromagnetic induction.
a. Define Faraday’ laws in your own words using diagrams where appropriate.
b. Define Lenz’s law in your own words using diagrams where appropriate.
c. Draw a diagram of a simple AC generator and use Fleming’s right hand rule to demonstrate the
direction of the current in the rotating conductor when it is perpendicular to the North Pole.
d. Explain the principle of operation of a simple transformer
e. Explain the principle operation of a 3 phase AC induction motor.
Task 10 P10 & P11
Check the following
Tick to confirm you have fulfilled the
requirements for this outcome
Have you included a sketch of a sine wave showing the major
characteristics listed below e.g. periodic time?
Have you included a screen dump from Multisim to confirm
your results showing circuit operation?
Have fully described and evaluated the experiment using
calculations, sketches and photographs as appropriate to the
tasks listed below?
Have you suggested where and when this time of circuit might
come in useful?
V1 is a function generator. You can use it to vary the frequency and amplitude of an ac voltage (for
further details see the handbook). You can carry this experiment out either using a real oscilloscope, a
virtual oscilloscope or by using Multisim (simulation software).
Remember the equation for a sine wave VInstantaneous = VSupply x sin(ωt +/- φ)
Set up the function generator to generate a sinusoidal waveform with an amplitude of 5 volts
and a frequency of 1000 Hz
Set up an oscilloscope to measure the input signal(applied across both the resistor and
capacitor) and the output signal applied just across the capacitor.
Apply an input signal and measure the input and output using the oscilloscope
With reference to your measurements define frequency, amplitude, periodic time, phase shift
and the RMS value of the input and output waveforms.
With reference to theory at what time (after t = 0) should the positive peak of the input signal
occur?
From your measurements, at what time does the first positive peak (after t = 0) of the output
signal occur
With this information can you find the phase shift introduced by this circuit at 1000 Hz?
Task 11 M1
For the circuit shown below:
Use the same table as for P1 in order to choose component values.
Circuit 2
From the attached table choose different values for R1 – R3
From the attached table choose different voltages for V1 –V2
Use Kirchoff’s laws to determine the current flowing through R1, R2 and R3
Determine the power dissipation in R1
Use Multisim to confirm the results of your calculations and attach to the assignment as a screen dump.
Task 12 M2
Calculate the total capacitance, total charge, the voltage dropped across each capacitor and the total
energy stored for the following network.
Task 13 D1
Tasks
Use an oscilloscope to measure the output voltage of this circuit at the point shown
Compare the output voltage with the input voltage V1 (Screen dump)
From you initial measurements use the graphing function in Multisim to measure the ripple
voltage of this circuit
Adjust R1 until the ripple voltage of the circuit reads 200 mV
From your results calculate the time constant for this circuit
If R1 = 100Ω what value of capacitance would be required to produce a ripple voltage of 200
mV?
If the instantaneous current conducted by the capacitor on its charge phase is I = C x dv/dt, find
the repetitive forward current conducted by the circuit on each charge phase (use the grapher
function)
Explain the importance of the Vrrm rating when designing power supply circuits
Explain why the voltage rating of the capacitor and the diodes should be at least twice the Vrrm
rating given
Task 14 D2
1) Draw and label the component parts of a basic DC machine.
2)
Describe the action of a two segment commutator using appropriate diagrams.
3)
Define:
a. Wave windings
b. Lap Windings
4) Briefly describe the operation of DC machines that are wound in:
a. Shunt
b. Series
c. Compound
5) Briefly describe armature reaction and show one way in which it can be overcome.
6)
A 4 pole generator has a lap-wound armature with 50 slots with 16 conductors per slot. The
useful flux per pole is 30 mWb. Determine the speed at which the machine must be driven to
generate an e.m.f. of 240 V.
7) A d.c. shunt-wound generator running at constant speed generates a voltage of 150 V at a
certain value of field current. Determine the change in the generated voltage when the field
current is reduced by 20%, assuming the flux is proportional to the field current.
8) With reference to the basic construction of a d.c. machine state the principle difference
between a d.c. generator and a d.c. motor.
9) The armature of a d.c. machine has a resistance of 0.25 Ω and is connected to a 300 V supply.
Calculate the e.m.f. generated when it is running:
a. as a generator giving 100 A
b. as a motor taking 80 A