Controls & Instrumentation Powerpoint - Familiarizing with I&C Engineering.

1. CONTROL AND
INSTRUMENTATION

2. Reference:
ELECTRONIC INSTRUMENTS
AND MEASUREMENTS
Second Edition
LARRY D. JONES
A. FOSTER CHIN

3. INSTRUMENT
A device of mechanism used to
determine the percent value of a
quantity under observations.

4. Two kinds of Instruments
Analog Instruments
It was coined to identify deflection-type
instrument.
Digital Instruments
It display in digital form the value of the
quantity being measured.

5. Three basic functions of Instrument
INDICATING
Providing a visual indication of the
quantity being measured.
RECORDING
Furnishes a permanent record.
CONTROLLING
Used to control a quantity.

6. ELECTRONIC INSTRUMENTS
Contain amplifying circuits to increase the
amplitude of the quantity being measured.
ADVANTAGES:
1. High sensitivity rating.
2. Capable of measuring very small signals.
3. Ability to monitor remote signals

7. Fundamental and Some Derived Quantities of the SI System
QUANTITY UNIT
Fundamental:
Length, l meter, m
Mass, m kilogram, kg
time, t second, s
Temperature,T Kelvin, K
Electric Current I ampere,A
Derived:
Electromotive force,Vvolt,V
Quantity of charge, Q coulomb, C
Electrical resistance, Rohm, Ω
Capacitance, C farad, F
Inductance, L henry, H

8. SCIENTIFIC NOTATION AND METRIC
PREFIXES
Scientific Notation Prefix Symbol
tera T
giga G
mega M
kilo K
deka da
deci d
centi c
milli m
micro µ
nano n
pico p

9. Standard Classifications
1. International Standards
2. Primary Standards
3. Secondary Standards
4. Working Standards

10. International Standards
are defined by international agreements,
and are maintained at the International
Bureau of Weights and Measures in
France and are periodically evaluated
and checked by absolute measurements in
terms of the fundamental units of Physics.

11. Primary Standards
are maintained at national standards
laboratories in different countries such as
National Bureau of Standards in
Washington DC.

12. Secondary Standards
are employed in industry as references
for calibrating high-accuracy equipment
and components, and for verifying the
accuracy of working standards.

13. Working Standards
are used as measurement references on a
day-to-day basis in virtually all electronic
laboratories.

14. Error in measurement
The degree to which a measurement
conforms to the expected value.

15. Gross Errors and Systematic Errors
Gross Errors
 Fault of the person using the instrument
Example:
 Incorrect reading of instrument.
 Incorrect reading of experimental data
 Incorrect use of Instrument
Systematic Errors
 Due to problems with instruments, environmental effects or
observational error.

16. Absolute Error
may be defined as the difference between
the expected value of the variable and the
measured value of the variable, or
e =Yn – Xn
where:
e = absolute error
Yn = expected value
Xn = measured value

17. Percentage of Error
Relative Accuracy
Percent Accuracy
a = 100% - Percent Error
a = A x 100

18. Example:
The expected value of the voltage
across a resistor is 50V; however,
measurement yields a value of 49V.
Calculate
a. The absolute error
b. The percent error
c. The relative accuracy
d. The percent accuracy

19. PRECISION
The precision of measurement is a
quantitative or numerical indication of the
closeness with which a repeated set of
measurements of the same variable agrees
with the average of the set of
measurements.
⃒
Xn = the value of the nth measurement
Xn = the average of the set of n
measurement

20. Example:
The following set of ten measurements was recorded in
the laboratory. Calculate the precision of the fourth
measurement.
Measurement Number MeasurementValue, Xn
1 98
2 102
3 101
4 97
5 100
6 103
7 98
8 106
9 107
10 99

21. Seatwork:
1. The current through a resistor is 1.5A,
but measurement yields a value of 1.46
A. Compute the absolute error and the
percentage of error of the
measurement.

22. 2.The output voltage of an amplifier was
measured by six different students using
the same oscilloscope with the following
results.
a. 20.20V
b. 19.90V
c. 20.05V
d. 20.10V
e. 19.85V
f. 20.00V
Which is the most precise measurement?