EUROPEAN TRADESMAN PROJECT
NOTES ON ELECTRICAL TESTS OF ELECTRICAL INSTALLATIONS
¨EUROPEAN TRADESMAN PROJECT¨
NOTES ON ELECTRICAL TESTS OF ELECTRICAL INSTALLATIONS
The students to learn how to carry out measurements of Voltage ,
current and Resistance in a circuit and document the results
The European Tradesman - Using measuring instruments - Practical - Cyprus
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Students shall be split in work groups for this experiment
Materials
Analog multimeter and a circuit as
shown on the previous slide
Procedure
The teacher carries out demonstration of measuring
the voltage, and students carry out the same in groups
The European Tradesman - Using measuring instruments - Practical - Cyprus
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Write down in your practical books the available settings on the multimeter for
measuring.
Note the test leads and note the color, position and markings. The black lead is
always connected in the position marked as Common. The red lead can be
connected in different points when measuring A, mA, V, and Ω.
Adjust the meter for measuring DC V
When the multimeter positions is confirmed by the teacher connect the leads
at the points as shown below on the circuit on test:
Take proper care when connecting an analog multimeter
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a) At the ends of the battery
V = ……
b) At the two ends of the lamp with the switch in the OFF position
V = ……
c) At the two ends of the lamp with the switch in the
ON position
V = ……
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Repeat the same exercise as before in Activity 1 using this time a digital
multimeter.
Complete in your practical books all
particulars of the digital multimeter
Complete worksheet 1b taking
measurements with the digital multimeter
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A0 At the two ends of the battery
V = ……
b) At the two ends of the lamp with the switch in the ON position
V = ……
c) At the two ends of the lamp with the switch in the
OFF position
V = ……
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Adjust the meter to the position of DC Α
When the multimeter positions is confirmed by the teacher connect the
multimeter at the points as shown below on the circuit on test, measure the
current.
I = ….
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Procedure
The teacher carries out demonstration of measuring the resistance, and
students carry out the same in groups.
The setting (0) in the scales of resistance in the analog multimeters can be used
to zero the leads resistance.
To do so we connect the two leads together and make the adjustment so the
needle shows zero ohms. This should be carried out in all scales of resistance on
the meter.
Normally the following scales can be found: R x 1, R x 10, R x 100, R x 1K, R x
10K, R x 1 M, R x 10 M
The European Tradesman - Using measuring instruments - Practical - Cyprus
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Remove the battery from the circuit and prepare the meter to measure the
resistance of the lamp. Measure also the resistance of other resistors given.
Rbulb =..........
R1 =.........
R2 =........
R3 =.........
Questions.
What is the measured resistance in the following positions:
α) Needle stops on ‘33’, meter is set on scale R x 100 …….
b) Needle stops on ‘7’, meter is set on scale R x 1K ……..
c) Needle stops on ‘44’, meter is set on scale R x 10 …….
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Procedure
The teacher carries out demonstration of measuring the resistance, and students
carry out the same in groups.
Normally the following scales can be found:
20 ΜΩ, 2 ΜΩ, 200 ΚΩ, 2 ΚΩ, 200 Ω.
If the meter is set to 200 Ω, and the resistor to be measured is larger then the
meter will not show a value but will show 1. If a larger scale is set and we still get
the same then probably there is an open circuit. In this circuit probably it means
that the bulb is burnt.
If we need to check continuity using a digital multimeter normally there is a
setting giving us a sound indication when connected on a close circuit without a
resistor in the circuit.
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Repeat the same using a digital multimeter. Complete the measurements as
before.
Rbulb =..........
R1 =.........
R2 =........
R3 =.........
Questions
1) When we use the sound scale on a digital multimeter?
2) What means an indication 1. on a digital multimeter?
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Complete the measured values on the
circuit
Compare the measurements of the
digital and analogue multimeters.
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