Transcript electronic instrumentation

ELECTRONIC
INSTRUMENTATION
EKT 314/4
WEEK 2 : CHAPTER 1
INTRODUCTION TO EI
Chapter 1 Contents
 Definition
 Measurement
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Week 1 Review: Direct Analysis
 Absolute Error
 Percentage of Error
 Relative Accuracy
 Percentage of Accuracy
Week 1 Review: Direct Analysis
 Absolute Error
e  Yn  X n
 Percentage of Error
 Relative Accuracy
 Percentage of Accuracy
Week 1 Review: Direct Analysis
 Absolute Error
 Percentage of Error
Yn  X n
e
% E  x100 
x100
Yn
Yn
 Relative Accuracy
 Percentage of Accuracy
Week 1 Review: Direct Analysis
 Absolute Error
 Percentage of Error
 Relative Accuracy
Yn  X n
e
A  1
 1
Yn
Yn
 Percentage of Accuracy
Week 1 Review: Direct Analysis
 Absolute Error
 Percentage of Error
 Relative Accuracy
 Percentage of Accuracy


 Yn  Xn 
e


a  Ax100  1 
x100  1 
 x100

Yn 

 Yn 
Week 1 Review: Statistical Analysis
 Arithmetic Mean
n
x
x
n 1
n
n
 Deviation from Mean
 Average Deviation
 Standard Deviation
Week 1 Review: Statistical Analysis
 Arithmetic Mean
 Deviation from Mean
d n  xn  x
 Average Deviation
 Standard Deviation
Week 1 Review: Statistical Analysis
 Arithmetic Mean
 Deviation from Mean
 Average Deviation
Dav
d


n
n
 Standard Deviation
Week 1 Review: Statistical Analysis
 Arithmetic Mean
 Deviation from Mean
 Average Deviation
 Standard Deviation

2
d
 n
n
Week 1 Review
 Assignment Discussion and Cross Check
Chapter 1 Contents
 Definition
 Measurement
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Session Contents
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Session Contents
 Source of Error
 Gross
 Systematic
 Random
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Source of Error
 Errors in measurement can be broadly defined in three
categories:
 Gross errors
 Systematic errors
 Random errors
Gross Errors
 Because of the human mistakes.
 Improper or incorrect installation or use of measurement
instrument.
 Failure to eliminate parallax during reading or recording the
measurement.
 Cannot be remedied mathematically.
Systematic Errors
 Because of the instrument.
 Three types of systematic errors:
 Instrumental errors
 Environmental errors
 Observational errors
 Produce constant uniform deviation.
Random Errors
 Occur when different results in magnitude or sign obtained
on repeated measurement of one or the same quantity.
 The effect can be minimized by taking the measurement
many times.
 This error can be handled mathematically.
Statistical Analysis (Repeat)
n
x
x
n 1
n
n
 Arithmetic Mean
 xn is nth data taken and n is the total of data or measurement.
Statistical Analysis (Repeat)
d n  xn  x
 Deviation from mean
 dn is the deviation of the nth data with the arithmetic mean.
Statistical Analysis (Repeat)
Dav
d


n
n
 Average deviations
 Indicate the precision of the instrument used, lower value of
average deviation specify a highly precise instruments.
Statistical Analysis (Repeat)

d
2
n
n
 Standard deviation
 Small value of standard deviation means that the measurement
is improved.
Session Contents
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Classification of Instrument
Absolute
Secondary
 Provide magnitude of the
 Provide magnitude of the
quantity under
measurement in terms of
physical constant of the
instrument.
quantity under
measurement only from
the observation of the
output from instrument.
 Most instrument used in
practice are secondary.
Session Contents
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Operation Mode
 Grouped by Operation Type
 Deflection
 Null
 Grouped by Signal Type
 Digital
 Analog
Operation Mode: Operation Type
deflection
null
 Only one source of input
 Require two input –
required.
 Output reading is based on
the deflection from the
initial condition of the
instrument.
 The measured value of the
quantity depends on the
calibration of the
instrument.
measurand and balance
input.
 Must have feedback
operation that compare the
measurand with standard
value.
 More accurate and
sensitive compared to
deflection type instrument.
Operation Mode: Signal Type
Analog
digital
 Produce the signal that
 Produce the signal that
vary in continuous way.
 Infinite range of value in
any given range.
vary in discrete steps.
 Finite different values in a
given range.
Session Contents
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Instrument Elements
 Instruments Elements
 Model
 Block Diagram
 Subsystems
Instrument Elements
 Instruments Elements
 Model
 Block Diagram
 Subsystems
Model
 Model

Important element is sensor which can convert
the physical variable into signal variable.
Model
 Model
• Signal variable can be displayed, recorded or
integrated into secondary instrument system.
Model
 Model
• Signal variable may also be used as an input signal
of a control system.
Instrument Elements
 Instruments Elements
 Model
 Block Diagram
 Subsystems
Block Diagram
Block Diagram (Simplified)
Subsystems
 Transducers
Subsystems
 Power Supply
Subsystems
 Signal Conditioning Circuits
Subsystems
 Filter / Amplifier
Subsystems
 Data Processors
 Process Controllers
 Command Generator
Subsystems
 Recorder
Elements of Electronic Instrumentation
 Transducers
 Device that converts a change in physical quantity into a change
of electrical signal magnitude.
 Power Supply
 Provide energy to drive the transducers.
 Signal Conditioning Circuits
 Electronic circuits that manipulate, convert the output from
transducers into more usable electrical signal.
Elements of Electronic Instrumentation
(cont.)
 Amplifiers
 Amplify low voltage signal from transducers or signal
conditional circuit.
 Recorders
 Used to display the measurement for easy reading and
interpretation.
 Data Processors
 Can be a microprocessor or microcontroller.
Elements of Electronic Instrumentation
(cont.)
 Process Controllers
 Used to monitor and adjust any quantity of the specified level or
value.
 Command Generator
 Provide control voltage that represents the difference of the
parameter in a given process.
Session Contents
 Source of Error
 Classification of Instrument
 Operation Mode
 Instrument Elements
 Application Area
Application Area: Engineering
Analysis
 Engineering Analysis
 Process Control
 Monitoring
 Automation
Application Area: Engineering
Analysis
 Engineering Analysis
 To validate new design of structure, component or system by
theoritical and experimental approach
Application Area: Process Control
 Process Control
 Monitoring process: provide real-time data that allow operator
to respond.
 Automatic process: provide real-time feedback data to the
control system.
ELECTRONIC INSTRUMENTATION
EKT 314/4
WEEK 2 : CHAPTER 1
END