for new student of engineering

1. DEE10013
MEASUREMENT
DEVICES
POLITEKNIK SEBERANG PERAI
JABATAN KEJURUTERAAN ELEKTRIK

2. COURSE LEARNING OUTCOME
CLO1
• Apply the concept of
measurement principles
and measuring equipment
in electrical and electronic
measurement.
• Solve problems of electrical
and electronic circuit using
appropriate measuring
operations and theorems.
(C3,PLO1)
CLO2
(C3,PLO2)

3. MEASUREMENT PROCESS
01 You can understand
measurement process
ELEMENT MEASUREMENT
02 You can understand the element
in measurement system
ERROR
03 You can describe error in
measurement
CHARACTERISTICS
04 You can understand the
characteristics of measurement
LEARNING OUTCOME
TERMINOLOGIES
05 You can understand the
measurement terminologies
STANDARDS
06 You can understand standards
used in measurement

4. The process of determining the amount,
degree, or capacity by comparison (direct or
indirect) with the accepted standards of the
system units being used.
(Electronic measurement, H.s Kalsi)
DEFINITION MEASUREMENT
The process by which physical parameters
can be converted to meaningful numbers.
(Bhavani and Vasantha)

5. MEASUREMENT PROCESS
Measurement is an estimation of a physical
parameter (quantity) by a measurement device
(instrument)
INPUT SIGNAL
(PHYSICAL
PARAMATER)
MEASUREMENT
INSTRUMENT
OUTPUT SIGNAL
(ELECTRICAL
PARAMATER)

6. PRIMARY SENSING
Sense and converts the input
signal to a more convenient and
practicable form
(example: electrical signal)
VARIABLE MANIPULATION
Processthe transducer signal
(electricalsignal) to makeitsuitable
for applicationtodata presentation
element
DATA PRESENTATION
An indication of the value of the
measurement (readout device /
display / recording etc )
3 ELEMENT IN MEASUREMENT SYSTEM

7. EXAMPLE :
MEASUREMENT
SYSTEM IN ANALOG
METER

8. SCALE
A series of marks at regular intervals on an
instrument that is used for measuring.
The scale is depending on the range.
RANGE
The minimum and maximum values of a
quantity for which an instrument is
designed to measure is called its range .
Ex. ammeter range : 0mA to 5 mA
MEASUREMENT TERMINOLOGIES

9. SCALE RANGE
Range Selected = 1V Use Scale = 0 -
10V
Voltage reading pointed by the pointer
= 4.4𝑉 ×
1𝑉
10𝑉
= 0.44𝑉
READING ANALOGUE SCALES
Range Selected =25V
Use Scale = 0 - 250V
Voltage reading pointed by the pointer
= 110𝑉 ×
25𝑉
250𝑉
= 11𝑉

10. SCALE RANGE SELECTOR
Figure 3.0 shows the scale panel of analog multimeter.
When the range selector is set at DC 2.5V, what is
1. The maximum range of the meter = 2.5V
2. The reading value of one scale = 0.05V
3. The voltage reading pointed by the pointer = 1.85V
READING ANALOGUE SCALES

11. DEFINITION OF ERROR
Error is defined as the deviation of the
measured value from the true value.
ERROR IN MEASUREMENT

12. TYPE OF ERROR
1. Gross Error
2. Systematic Error
3. Random Error
4. Absolute Error
5. Relative Error

13. GROSS ERROR
• Error occurs due to the human factors
involved in the measurement of the
parameter.
Can be reduced
• by proper meter reading and connection,
avoid careless etc.

14. GROSS ERROR
Examples :
• Error due to carelessness of user while
noting down the reading
• Errors due to selection of instrument with
improper range

15. SYSTEMATIC ERROR
Due to problems with
instruments,
environmentaleffects,
or observational error

16. SYSTEMATIC ERROR
• INSTRUMENT ERRORS may be due to friction in
bearing of the meter, incorrect spring tension,
improper calibration or faulty instruments.
• ENVIRONMENTAL ERRORS is Environmental
conditions in which instruments are used may
cause errors. (Example : high temperature/
pressure / humidity/strong electrostatic or
electromagnetic field.

17. SYSTEMATIC ERROR
• Observable errors are those errors introduced
by the observer. Probably the parallax error in
reading a meter scale and the error of
estimation.
Can be reduced :
• proper maintenance, use and handling of
instruments and minimized those effect
magnetic shield

18. RANDOM ERROR
• These are errors that remain after gross and
systematic errors have been substantially
reduced.
• These errors are due to unknown causes.
Can Be Minimized (Reduced)
by taking many reading of each instrument and
analyzed statistically (determining mean value).

19. • Absolute (Actual ) Error is the differences
between the expected value and the measured
value , or
ABSOLUTE ERROR
e=|Yn- Xn|
where,
e =Absoluteerror
Yn =ExpectedValue, True Value
Xn =Measuredvalue

20. RELATIVE ERROR
Relative error is how much error you had
compared to the real measurement
𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒𝐸𝑟𝑟𝑜𝑟, 𝑅𝐸 =
𝐴𝑏𝑠𝑜𝑙𝑢𝑡𝑒
𝐸𝑥𝑝𝑒𝑐𝑡𝑒𝑑 𝑉𝑎𝑙𝑢𝑒
=
𝑌𝑛 − 𝑋𝑛
𝑌𝑛
=
𝑒
𝑌𝑛
% 𝐸𝑟𝑟𝑜𝑟 =
𝑒
𝑌𝑛
× 100

21. EXAMPLE
Question :
The measured value of a resistance is 10.25Ω,where as its
value is 10.22Ω.Determine the absolute error of
measurement.
Solution:
Given: Measured value, Xn= 10.25Ω
True Value, Yn= 10.22Ω
Absolute Error, 𝑒 = 𝑌𝑛 − 𝑋𝑛
= 10.22Ω − 10.25Ω
= 𝟎. 𝟎𝟑Ω

22. 1. Accuracy
• How close to indicating the the actual value
𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦, 𝐴 = 1 −
𝑌𝑛 − 𝑋𝑛
𝑌𝑛
% 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦, 𝐴 = 1 −
𝑌𝑛 − 𝑋𝑛
𝑌𝑛
× 100
CHARACTERISTIC OF MEASUREMENT
2. Precision
• Is a measure of the consistency or repeatability of
measurements

23. ACCURACY AND PRECISION

24. 3. Resolution
• The smallest change in a measured variable to which
an instrument will respond.
• It is very near to sensitivity
CHARACTERISTIC OF MEASUREMENT
4. Significant Figure
• A number are those digits that carry meaning
contributing to its precision
• Example : 68Ω, 69Ω - two significant figures.
68.0Ω, 67.9Ω - three significant figures

25. STANDARD USED IN MEASUREMENT
1. International Standards
2. The Primary Standards
3. Secondary Standards
4. Working Standards

26. 1. International System Of Units (Si)
• Define by international agreement.
• They represent certain units of measurement to the closest
possibly accuracy that production and measurement
technology allow.
• Maintained at the International Bureau of Weight and
Measures in Paris
• Example BSI(British Standard Institution), IEC(international
Electro technical commission) and ISO (International
Organization for Standard)

27. 1. International System Of Units (Si)

28. SI PREFIXES

29. • Maintained at national standard laboratories in
different countries.
• Not available for use outside the national laboratories.
• Function - calibration and verification of secondary
standards.
• EXAMPLE : SI : KG, POUND. (L , GELEN)
2. The Primary Standards

30. 3. Secondary Standards
• It is basic reference standards used in industrial
measurement laboratories.
• Each industry has its own secondary standard. Example:
SIRIM, Timbang & Sukat kem. Perdagangan &
perindustrian, Pusat penyelidikan pertahanan, local
universiti and industries

31. 3. Working standards
• The principle tools of a measurements laboratory.
• They are used to check and calibrate the instruments
used in laboratory or to make comparison
measurements in industrial application.
• Example : Instrumentation laboratory (The resistor
manufacturing industry maintains a standard resistor in
the laboratory for checking the values of the
manufactured resistors)

32. Tutorial
1) Describe the meaning of:
i. Error.
ii. Accuracy.
iii.Measurement.
iv.Precision.
2) Explain three of the types of error below:
i. Gross error
ii. Systematic error
iii.Random error