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Contents
Practical activity 1
3
Practical activity 2
4
Practical Activity 3
6
Practical activity 4
7
Practical activity 5
8
Practical activity 6
11
Practical activity 7
13
Practical activity 8
15
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
1
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EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
Practical activity 1
Equipment required

Graph paper, ruler, pencil
Procedure
The voltage supply to most domestic dwellings within dwellings within Australia is
specified by the supply authorities as being 240V, 50Hz.
1
On your graph paper using a scale of 1 cm = 2 ms and 1 cm = 50 V, draw one cycle of
the waveform.
2
On your drawing sketch dotted lines at the rms and average values of the voltage.
3
On your drawing sketch vertical double ended arrows to indicate peak and peak-topeak values of the voltage.
For this waveform complete the following table:
Quantity
Value (don’t forget units)
rms value
peak value
peak-to-peak value
average value
crest factor
form factor
period
instantaneous value at 3 ms
instantaneous value at 12 ms
At your practical session your teacher will discuss your results with you.
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
3
Practical activity 2
Equipment required

2 pulleys

string

two identical weights (A and B), say 0.5 kg each

weight C, say 0.3 kg

large protractor
Procedure
1
Set up pulley system on a vertical surface as shown in Figure 21.
2
Attach two identical weights at A and B.
3
Attach weight C.
4
Measure angles a and b.
angle a = ____
angle b = ____
Figure 21
4
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
5
Using the angles you have just measured and the known weights A and B draw a
vector (phasor) diagram to scale
6
Complete the parallelogram and measure the resultant.
What weight does this measurement represent to your scale?
___________________________________________________________________
Does this correspond to the weight C?
___________________________________________________________________
Explain why this is so.
___________________________________________________________________
At your practical session your teacher will discuss your results with you.
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
5
Practical Activity 3
Equipment required

12 V AC supply capable of delivering at least 1 A

1 × 100 ohm 5 watt resistor

2 × multimeters
Procedure
1
Set one of the multimeters to an appropriate ac current range and the other to an ac
voltage range to measure supply voltage.
2
Connect the resistor to the power supply via the multimeter set to read current.
3
Connect the multimeter set to volts across the power supply.
4
If the power supply is adjustable set it to minimum.
5
Switch on and adjust power supply until 12 volts is showing on your voltage reading
multimeter. If the power supply is not adjustable take a note of the actual voltage
reading.
6
Read the current and note it.
7
Draw a wave diagram of voltage and current using the following scales:
1 cm = 5 ms
1 cm = 5 V
1 cm = 50 mA
8
Draw a phasor diagram using the voltage as a reference and a scale of 1 cm = 50 mA
9
Calculate the power being absorbed by the resistor.
At your practical session your teacher will discuss your results with you.
6
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
Practical activity 4
Equipment required

12 V ac supply capable of delivering at least 1 A

12 V dc supply capable of delivering at least 1 A

1 × 18W fluorescent lamp ballast

1 × 100 ohm 5 watt resistor

2 × multimeters
Procedure
Figure 8
1
Set instruments to suitable dc range and connect circuit as shown in Figure 8.
2
Connect 12 V dc power supply and take ammeter and voltmeter readings.
3
From these readings predict the dc resistance of the choke.
4
Re-set instruments to suitable ac range and connect circuit as shown above.
5
Connect 12 V ac power supply and take ammeter and voltmeter readings.
From these readings predict the inductance of the choke.
At your practical session your teacher will discuss your results with you.
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
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Practical activity 5
Equipment required

12 V ac supply capable of delivering at least 1 A

12 V dc supply capable of delivering at least 1 A

1 × 22 microfarad 50 V dc non polarised electrolytic capacitor

1 × 100 ohm 5 watt resistor

2 × multimeters
Procedure
Figure 7
1
Set instruments to suitable dc range and connect circuit as shown in Figure 7.
2
Connect 12 V dc power supply and take ammeter and voltmeter readings.
Total current IT
Supply voltage
Can you explain the current reading?
_________________________________________________________________
_________________________________________________________________
8
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
3
Re-set instruments to suitable ac range and connect circuit as shown in Figure 7.
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
9
4
Connect 12 V ac power supply and take ammeter and voltmeter readings.
Total current IT
5
Supply voltage
From these readings verify the value of capacitance.
At your practical session your teacher will discuss your results with you.
10
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
Practical activity 6
Equipment required

12 V ac supply capable of delivering at least 1 A

1 × 18 W fluorescent lamp ballast

2 × multimeters
Procedure
A fluorescent lamp choke can be modelled by an inductor in series with a resistor as shown
in Figure 41.
The aim of this exercise is to construct a phasor diagram of the choke and use this to
calculate the inductance of the choke.
Figure 41
Construct the phasor diagram as shown in Figure 42.
Figure 42
1
Construct a horizontal line as the current reference Iref.
2
Measure the dc resistance of the choke R.___________________________________
3
Measure the supply voltage V._____________________________________________
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
11
4
Connect the choke directly across the ac power supply via an ammeter and note the
reading I. ____________________________________________________________
5
Calculate the theoretical voltage drop VR across the resistive component of the choke
VR = I × R.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
6
On your phasor diagram using a suitable scale draw in the phasor VR.
7
From the tip of the phasor VR drop a vertical construction line.
8
Take a compass and adjust its radius to correspond to the supply voltage V.
9
Place the point of the compass at O and scribe an arc to cross the vertical construction line.
10 From this point draw a vertical construction line to the left.
11 Draw a vertical line from point O to an intersection with the horizontal construction
line. This is the phasor VL.
12 Calculate the inductive reactance XL = VL/I.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
13 Calculate the inductance of the choke L = 1/2fXL.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
14 Is this different to the value you calculated in Section 4? If so, why?
______________________________________________________________________
______________________________________________________________________
At your practical session your teacher will discuss your results with you.
12
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
Practical activity 7
Equipment required

12 V ac supply capable of delivering at least 1 A

1 × 18 W fluorescent lamp ballast

2 multimeters

1 × 50 V dc non polarised electrolytic capacitor approximate value to be determined as
detailed in following procedure.

1 × 100 Ω, 5 W resistor
Procedure
1
Accurately determine the inductance of the ballast you are using (either from previous
activities or from manufacturers data sheets).
______________________________________________________________________
2
Calculate the inductive reactance of the choke.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
3
Calculate the capacitance of a capacitor with the same reactance—use the expression:
(it should be somewhere near 10F).
C
1
2fX L
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
13
4
Connect inductor and resistor in series to the power supply through an ammeter and
note the reading.
______________________________________________________________________
5
Re-connect capacitor and resistor in series to the power supply through an ammeter
and note the reading.
______________________________________________________________________
6
Re-connect capacitor, inductor and resistor in series to the power supply through an
ammeter and note the reading.
______________________________________________________________________
7
From the results what is the effect on current when all 3 components are connected
and why?
______________________________________________________________________
______________________________________________________________________
At your practical session your teacher will discuss your results with you
14
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
Practical activity 8
Procedure
Look around your workplace and home and identify 3 or 4 or more transformers if you
can,.
From the nameplate of each transformer or from your knowledge of its characteristics
complete the following table.
Transformer
(identify by
number or
location)
VA rating
Primary volts
Secondary
volts
Turns ratio
(you may need
to calculate
this)
At your practical session your teacher will discuss your results with you.
EGG202A: Appendix 3 Practicals for single phase ac circuits
 NSW DET 2017 2006/060/04/2017 LRR 3822
15