lecture about industrial instrumentation

1. Industrial Instrumentation
Systems
1

2. IE476:INDUSTRIAL INSTRUMENTATION SYSTEMS
[ Cr. Hrs = 1] [ Marks: 50 ]
OBJECTIVES: To foster knowledge about the standards and
current techniques of industrial instrumentation systems. The
course will also nurture basic working principles and interfacing
techniques of common field elements. An overview of Classical
Industrial Control Instrumentation with an imperative knowledge
of Modern Industrial Control Instrumentation would also be
provided.
COURSE OUTLINE:
 Introduction of Industrial Instrumentation:IEEE standards
& Industrial data acquisition protocols
 Industrial Instrumentation Technology: Interfacing of
common field elements with PLCs, Thermocouple, Pressure
transmitter, RTD, special signal conditioning techniques for
temperature sensors (RTD & Thermocouple), operation and
interfacing of motor drives in industry.

3.  HMI (Human Machine Interface) and MMI (Machine-
Machine interface): Concepts of Virtual
Instrumentation in modern industrial monitoring
systems. Hardware and software, Interfacing and
Configuration, Creation of Tags, Alarms, Trends, Data
entry.
 Classical Industrial Control Instrumentation:
Overview
 Modern Industrial Control Instrumentation
Systems: DCS architecture, SCADA Interfaces,
Fieldbus technology, I/O bus technology, Types & I/O
Bus networks, Local Area Network, Network
Technologies, communication media, Network access
method, Network protocols, Fuzzy Logic system,
Artificial Intelligence and PLC systems.

4. TEXT BOOK:
 Industrial Instrumentation: Principles and Design, by
Tattamangalam R. Padmanabhan.
RECOMMENDED BOOKS:
 Lessons in Industrial Instrumentation Systems by Tony
R. Kuphaldt
 Principles and Practice of Automation Process
Control, C.A.Smith & A.B.Corripio
 Field buses for Process Control: Engineering &
Maintenance, Jonas Berge
 Plant wide Process control by K.T. Erickson, J.L.
Hedrick
 Hardware and Programming Manuals of available
PLC and HMI trainers in IIEE

5. Introduction
 Instrumentation is the science of
measurement and control.

6. Industrial measurement and control systems
have their own unique terms and standards.
 Process
 Process Variable (PV)
 Setpoint (SP)
 Primary Sensing Element (PSE)
 Transducer
 Lower and upper range
 Controller
 Final controlling element

7. Process: The physical system we are attempting to
control or measure. Examples: water filtration system,
molten metal casting system, steam boiler, oil refinery
unit, power generation unit.
Process Variable: The specific quantity we are
measuring in a process. Examples: pressure, level,
temperature, flow, electrical conductivity, pH, position,
speed, vibration.
Setpoint, or SP: The value at which we desire the
process variable to be maintained at. In other words, the
“target” value for the process variable.
Primary Sensing Element: A device directly sensing the
process variable and translating that sensed quantity
into an analog representation (electrical voltage,
current, resistance; mechanical force, motion, etc.).

8.  Examples: thermocouple, thermistor, bourdon tube,
microphone, potentiometer, electrochemical cell,
accelerometer.
 Transducer: A device converting one
standardized instrumentation signal into another
standardized instrumentation signal, and/or
performing some sort of processing on that
signal.
Often referred to as a converter. Examples: I/P
converter (converts 4-20 mA electric signal into
3-15 PSI pneumatic signal), P/I converter
(converts 3-15 PSI pneumatic signal into 4-20
mA electric signal), square-root extractor
(calculates the square root of the input signal).

9. Transmitter: A device translating the signal produced by
a primary sensing element (PSE) into a standardized
instrumentation signal such as 3-15 PSI air pressure, 4-
20 mA DC electric current, Fieldbus digital signal
packet, etc., which may then be conveyed to an
indicating device, a controlling device, or both.
Controller: A device receiving a process variable (PV)
signal from a primary sensing element
PSE or transmitter, comparing that signal to the desired
value (called the setpoint) for that
process variable, and calculating an appropriate output
signal value to be sent to a final control
element (FCE) such as an electric motor or control
valve.

10.  Final Control Element: A device receiving the
signal output by a controller to directly influence
the process. Examples: variable-speed electric
motor, control valve, electric heater.
 Manipulated Variable: The quantity in a process
we adjust or otherwise manipulate in
order to influence the process variable (PV).
Also used to describe the output signal
generated by a controller; i.e. the signal
commanding (“manipulating”) the final control
element to influence the process.

11. Industrial Instrumentation
Systems
 The term “system” refers to a set of components
that are connected to form and act as an entire
unit.
 An industrial instrumentation system is collection
of instruments used to measure, monitor, and
control an Industrial process.
 Developing and building instrumentation systems
involves numerous scientific and technical
disciplines, such as electronic, electrical, control,
mechanical, chemical, metallurgical, and industrial
engineering.

12.  In recent years many factors such as the
development of advanced mathematical theories,
improvements in information and communication
systems, and developments in sensors,
measurement technology, computers, digital
systems, Internet technology, and human–machine
interactions have contributed to Industrial
Instrumentation Systems.
 Modern instruments and instrumentation systems
are largely based on digital
technology.

14.  The digital data communication needs to follow
protocols to ensure effective and efficient data flow.
The protocols are managed by international standard
organizations, such as IEEE and ISO.
 The Open System Interconnection (OSI) model,
developed by the International Organization for
Standardization, is rapidly gaining industry support.
The OSI model reduces every design and
communication problem into a number of layers.

15. OSI Model

17.  Application layer is the top layer of the OSI model
responsible for providing services to the user.
 Presentation layer manages data-format information
for networked communications (the network’s
translator). For outgoing messages, it converts data
into a generic format for network transmission; for
incoming messages, it converts data from the
generic network format to a format that the receiving
application can understand. It is also responsible for
certain protocol conversions, data encryption/
decryption, or data compression/ decompression.
 Session Layer enables networked resources to hold
ongoing communications (called a session) across
a network. Responsible for initiating, maintaining
and terminating sessions.
 The transport layer is responsible for the delivery
of a message from one process to another. It
manages the flow of data between nodes by
segmenting long data streams into smaller data

18. chunks (based on allowed “packet” size for a given
transmission medium) and reassembles chunks into
their original sequence at the receiving end. Also
provides acknowledgements of successful
transmissions and requests resends for packets which
arrive with errors.
 Network layer handles addressing messages for
delivery, as well as translating logical network
addresses. It is responsible for deciding transmissions
routes between computers. This layer also handles
packet switching and network congestion control.
 Data link layer at the receiving end packages raw data
from the physical layer into data frames for delivery to
the Network layer. At the sending end this layer
handles conversion of data into raw formats that can
be handled by the Physical layer. Its sub layer MAC
controls medium access control.

19.  This layer manages the interface between the
computer and the network medium (coax, twisted
pair, etc.). It converts bits into electronic signals for
outgoing messages and converts electronic signals
into bits for incoming messages.