SMJ 4222 Instrumentation (02 & 07)Dr Intan Zaurah Mat DarusDr Intan Zaurah Mat Darus

Dr Intan Zaurah Mat Darus

C23-226, Ext. 34693intan@fkm.utm.my

intanmd@yahoo.co.uk016 7616716

Lecture 1

Introduction to measurement and instrumentation

What is measurement?

Measurement Standards and Measurement Standards and UnitsUnits

Measuring system are composed of different elements and condition therefore it needs norms and standards

3 unit systems widely used-International System (SI), CGS System, English System

Basic units - length, time, mass, temperatureDerived units –area, volume, acceleration, force

International System of Units (SI)International System of Units (SI)

The SI is founded on seven SI base units for seven base quantities assumed to be mutually independent, as given in Table 1.

SI base unit

Base quantity Name Symbol

length meter m

mass kilogram       kg

time second s

electric current ampere A

thermodynamic temperature       kelvin K

amount of substance mole mol

luminous intensity candela cd

Derived Units- defined in terms of the seven base quantities via a system of quantity equations. Examples are:

SI base unit

Name Derived units Symbol

area square meter m2

volume cubic meter       m3

velocity meter per second m/s

accelerationMeter per second squared

m/s-2

force m·kg·s-2 N

pressure m-1·kg·s-2 Pa

work m2·kg·s-2 Joule

What is instrumentation?

Automotive Sensors

Oxygen Sensor

Airflow Sensor

Water Temperature

Oil Pressure

Accelerometer

CO Sensor

The need for measurement and instrumentation

In industrial application, it is important for:

1) monitoring and control of a process

2) improving the quality of the product and efficiency of production

3) Safety purposes

Laser Sensor

Laser sensor

Typical Instrumentation System

• Transducer - converts the measured value into another useful value (a sensor)

• Signal conditioner- “conditions” the signal from the sensor

• A/D Converter - changes the signal into a digital format

• Computer - processes, displays, and records the signal

Transducer Signal conditioner

A/D Converter

Display

Sensor• Thermocouple

• Resistance thermometer

Thermocoupleinput output

temperature e.m.f

inputResistance thermometer

output

temperature Resistance change

Signal conditioner• Amplifier

• Wheatstone bridge

input Amplifier

Voltage change

Small e.m.f

Larger voltage

inputWheatstone bridge

output

Amplifier

Resistance change

Larger voltage change

Display• Scale

• Computer

input

current change

scaleoutput

movement of pointer

input

analog signal

DAS VDUdigital signal

output

readings

Temperature Control

The Control System sets the current supplied to the heating elements in the furnace to keep the material temperature at the desired (setpoint) value.

Desired Temperature

Control System

Furnace and

Material

Temperature Sensor

Water level system

h

Assignment

Identify the elements for the pressure measurement system i.e. : transducer, signal conditioner, display

POINTER

SCALE