Grade 10: Robotics Electrical Measurements Grade 10: Robotics Electrical Measurements

electrical

1. ELECTRICAL
MEASUREMENTS

2. Before the start
of lecture:
•Ready your Tinkercad on
your laptops for a short
activity later
•Make a simple circuit in the
breadboard (Source, Resistor,
LED)
!

3. MUltimeters
ANALOG MULTIMETER
3
DIGITAL MULTIMETER
“Multi-purpose meters” are measurement tools that
can function as a voltmeter, an ammeter, or
ohmmeter

4. anALOG
mULTIMETE
R
⊹Also called Analog VOM or Analog
Volt-Ohm-Milliammeter
⊹The construction consists of a coil of
fine wire wound on a drum mounted
⊹the many scales on the face of the
meter movement for the different
ranges and functions selectable by the
rotary switch
⊹The advantage of using an analog
multimeter is when checking a diode
the analog is usually more accurate.
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5. 5
Analog
multimeter
parts
For Calibration
Probes
Ammeter
Ohmmeter
AC Voltmeter
DC Voltmeter

6. 6

7. “
When direct current flows in the
coil, the magnetic field of the
current reacts with the magnetic
field of the permanent magnet.
The resultant force turns the drum
with its pointer, winding up the
restoring spring. When the current
is removed, the pointer returns to
zero. The amount of deflection
indicates the amount of current in
the coil.
When the polarity is connected
correctly, the pointer will read up-
scale, to the right; the incorrect
polarity forces the pointer off-scale,
to the left. (D’Arsonal Movement)
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8. DIGITAL
mULTIMETE
R
DMM or Digital Multimeter has become a
very popular test instrument because the
digital value of the measurement is
displayed automatically with decimal
point, polarity, and the unit for V, A, or Ω.
The basis of the DMM operation is an
analog-to-digital (A/D) converter circuit. It
converts analog voltage values at the input
to an equivalent binary form. These values
are processed by digital circuits to be
shown on a liquid-crystal display (LCD) as
decimal values.
Provides more accurate data
8

9. 9
DIGITAL
multimeter
parts
Display
Probes
Ohmeter
DC Voltmeter
AC Voltmeter
DC Ammeter
AC Ammeter
Frequency
meter

10. Measuring
Voltage, current
and resistance
using multimeters

11. Measuring voltage Measuring Current

12. Measuring voltage
⊹The multimeter must be connected in
parallel in a circuit in order to
measure voltage.
⊹the two test probes should be
connected in parallel with the voltage
source, load or any other two points
across which voltage needs to be
measured.
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13. Measuring Current
⊹A multimeter must be inserted
in series in a circuit in order to
measure current.
⊹This implies that an ammeter
must be connected in the path
of the current flow where the
current is being measured.
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Cautions
⊹Never leave the multimeter in ammeter position once the current
measurement is taken.
⊹Don’t test higher currents than that of highest current measured by the
multimeter in their respective ranges, i.e., mA as well as A range.

14. If the circuit cannot be broken or
opened, we use a
clamp meter (especially for ac
circuits)
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15. Measuring REsistance
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⊹The multimeter measure the
resistor or component separately
and not connected with any
other components
⊹Remove the component from the
circuit or test it before you install
it. Testing the component while
still in the circuit can cause
inaccurate readings from other
components..

16. 16
Assessment Activity
Prepare your Tinkercad and let’s try to use the
multimeters!

17. Let’s try
1.Measure the voltage drop for resistor in your simple breadboard
circuit following the right way of voltage measurement. Discuss
your observation.
2.Try connecting the voltmeter in series with the circuit. What
happens?
3.Measure the current following the right procedure. Tell us what
you observe.
4.Connect ammeter in parallel with your resistor. Was the LED
affected?
5.Compare the results when the resistor is measured individually
and when it is connected with other components
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18. Circuit faults and
troubleshooting

19. Open Circuit

20. SHORT
CIRCUIT

21. Reverse
Polarity

22. What
have you
learned
today?
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