EKT 314/4 WEEK 1 : CHAPTER 1 INTRODUCTION TO EI ELECTRONIC INSTRUMENTATION

Chapter 1 Problem Statements Not confident what is exactly Electronic Instrument Cannot state all of the Instrument characteristics that need to be taken care of. Not clear whether one instrument is suppose to be called electronic instrument or not.

Chapter 1 Objectives To define electronic instrumentation To do measurement & analysis To characterize instruments To differentiate between instrument and indicators

Chapter 1 Contents Definition Measurement Source of Error Classification of Instrument Operation Mode Instrument Elements Application Area

Session Contents Definition Measurement Source of Error Classification of Instrument Operation Mode Instrument Elements Application Area

Session Contents Definition Instrumentation & Electronic Instrumentation Related Definition Measurement

Definition Instrumentation is a technology of measurement which serves not only science but all branches of engineering, medicine, and almost every human endeavor. Electronic Instrumentation – the application of measurement technology in Electronic-related field.

Session Contents Definition Instrumentation & Electronic Instrumentation Related Definition Measurement

Related Definition Instrument A device or mechanism used to determine the present value of the quantity under measurement. Measurement The process of determining the amount, degree, or capacity by comparison (direct or indirect) with the accepted standards of the system units being used. Accuracy The degree of exactness (closeness) of a measurement compared to the expected (desired) value.

Related Definition Resolution The smallest change in a measured variable to which an instrument will respond. Precision A measure of the consistency or repeatability of measurements, i.e. successive reading do not differ. (Precision is the consistency of the instrument output for a given value of input). Expected value The design value, i.e. the most probable value that calculations indicate one should expect to measure.

Related Definition Error The deviation of the true value from the desired value. Sensitivity The ratio of the change in output (response) of the instrument to a change of input or measured variable.

Session Contents Definition Measurement

The process of comparing an unknown quantity with an accepted standard quantity. The process of determining the amount, degree, or capacity by comparison (direct or indirect) with the accepted standards of the system units being used.

Session Contents Definition Measurement Measurand Unit Analysis

Measurand Displacement Strain Vibration Pressure Flow Temperature Force Torque

Displacement Vector representing a change in position of a body or a point with respect to a reference.

Strain Relative deformation of elastic, plastic, and fluid materials under applied forces.

Vibration Oscillatory motion which can be described in term of amplitude (size), frequency (rate of oscillation) and phase (timing of the oscillation relative to fixed time).

Pressure Ratio of force commonly acting on a surface to the area of the surface.

Flow Stream of molten or liquidified material that can be measured in term of speed and quantity

Temperature Measure of relative warmth or coolness of an object compared to absolute value.

Force Defined as a quantity that changes the motion, size, or shape of a body.

Torque Defined as the tendency of a force to rotate the body to which it is applied.

Session Contents Definition Measurement Measurand Unit Analysis

Unit International System of Units (abbreviated SI from the French le Système international d'unités) It is the world's most widely used system of measurement, both in everyday commerce and in science. The SI was developed in 1960 from the old metre-kilogram- second system.

Session Contents Definition Measurement Measurand Unit Base Unit Derivative Unit Analysis

Base Unit Length – meter (m) Mass – kilogram (kg) Time – second (s) Electric current – ampere (A) Temperature – kelvin (K) Luminous intensity – candela (cd) Amount of substance – mole (mol)

Session Contents Definition Measurement Measurand Unit Base Unit Derivative Unit Analysis

Derivative Unit Electric charge – coulomb (C) Electric potential difference – volt (V) Electric resistance – ohm ( Ω ) Electric capacitance – farad (F) Electric inductance – henry (H) Energy – joule (J) Force – newton (N) Magnetic flux – weber (Wb) Power – watt (W)

Session Contents Definition Measurement Measurand Unit Analysis Direct Term Formula Example Statistical

Direct Analysis - Term Error is the degree to which a measurement nears the expected value. It can be expressed as: Absolute error Percentage of error Accuracy can be calculated based on error.

Session Contents Definition Measurement Measurand Unit Analysis Direct Term Formula Example Statistical

Direct Analysis - Formula e = absolute error Y n = expected value X n = measured value

Direct Analysis - Formula %E = percentage of error e = absolute error Y n = expected value X n = measured value

Direct Analysis - Formula A = relative accuracy e = absolute error Y n = expected value X n = measured value

Direct Analysis - Formula a = percentage of accuracy A = relative accuracy e = absolute error Y n = expected value X n = measured value

Direct Analysis - Example The expected value of the voltage across a resistor is 80V. However the measurement give a value of 79V. Calculate (i) absolute error, (ii) percentage of error, (iii) relative accuracy and (iv) percentage of accuracy.

Direct Analysis - Example i. Absolute error = 1V ii. Percentage of error = 1.25% iii. Relative accuracy = iv. Percentage of accuracy = 98.75%

i. Absolute error ii. Percentage of error Direct Analysis - Example

Session Contents Definition Measurement Measurand Unit Analysis Direct Term Formula Example Statistical

iii. Relative accuracy iv. Percentage of accuracy Direct Analysis - Example

Session Contents Definition Measurement Measurand Unit Analysis Direct Statistical General Formula Example

Statistical Analysis Can be used to determine the uncertainty of the test results. The analysis require a large number of measurement (data) to be taken.

Session Contents Definition Measurement Measurand Unit Analysis Direct Statistical General Formula Example

Statistical Analysis - Formula Arithmetic Mean x n is n th data taken and n is the total of data or measurement.

Statistical Analysis - Formula Deviation from mean d n is the deviation of the n th data with the arithmetic mean.

Statistical Analysis - Formula Average deviations Indicate the precision of the instrument used, lower value of average deviation specify a highly precise instruments.

Statistical Analysis - Formula Standard deviation Small value of standard deviation means that the measurement is improved.

Session Contents Definition Measurement Measurand Unit Analysis Direct Statistical General Formula Example

Statistical Analysis - Example The table value represent readings of one instrument. Calculate: i. Arithmetic Mean ii. Deviation from Mean iii. Average Deviation iv. Standard Deviation Attempt No.Reading Value

Statistical Analysis - Example Answer: i. Arithmetic Mean = ii. Deviation from Mean Put in table iii. Average Deviation = iv. Standard Deviation = 0.22 Attempt No.Deviation

Statistical Analysis - Assignment Suppose that a certain voltage is measured 51 times. The result which might be obtained a shown in the Table. Calculate 1. Average 2. Average Deviation 3. Standard Deviation x, Voltage (V)Occurrence, (n)

EKT 314/4 WEEK 1 : CHAPTER 1 END ELECTRONIC INSTRUMENTATION