Table Of ContentPlant and Process Engineering 360(cid:2)
Note from the Publisher
This book has been compiled using extracts from the The extracts have been taken directly from the above
following books within the range of Plant and Process source books, with some small editorial changes.
Engineeringbooks in theElseviercollection: These changes have entailed the re-numbering of
Sections and Figures. In view of the breadth of con-
Crowder, (2005) Electric Drives and Electromechanical tent and style of the source books, there is some
Systems, 9780750667401 overlap and repetition of material between chapters
Laughton and Warne, (2002) Electrical Engineer’s Ref- and significant differences in style, but these features
erence Book, 9780750646376 have been left in order to retain the flavour and
Parr,(2006)HydraulicsandPneumatics,9780750644198 readability of the individual chapters.
Zhang, (2008) Industrial Control Technology,
9780815515715 Endof chapter questions
Warne, (2005) Newnes Electrical Power Engineer’s Within the book, several chapters end with a set of
Handbook,9780750662680 questions; please note that these questions are for ref-
Mobley, (2001) Plant Engineer’s Handbook, erence only. Solutions are not always provided for these
9780750673280 questions.
Girdhar,MonizandMackay,(2004)PracticalCentrifugal
Pumps: Design, Operation and Maintenance, Unitsofmeasure
9780750662734 Units are provided in either SI or IP units. A conver-
Barnes, (2003) Practical Variable Speed Drives and sion table for these units is provided at the end of the
Power Electronics,9780750658089 book.
Plant and Process
(cid:2)
Engineering 360
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10 10 9 8 7 6 5 4 3 2 1
Contents
Section1 INTRODUCTION ................................................................ 1
1.1 Instrumentation and transducers .... .... .... ..... .... .... .... ..... .... .... .... .3
1.2 Controlsystems .... .... ..... .... .... .... ..... .... .... .... ..... .... .... ....43
1.3 Programmable controllers ..... .... .... .... ..... .... .... .... ..... .... .... ...109
1.4 Controlsystems interfacing .... .... .... .... ..... .... .... .... ..... .... .... ...165
Section2 MOTORSANDDRIVES ......................................................... 255
2.1 Electromechanical systems .... .... .... .... ..... .... .... .... ..... .... .... ...257
2.2 Analysing a drive system . ..... .... .... .... ..... .... .... .... ..... .... .... ...277
2.3 Motors, motor controland drives ... .... .... ..... .... .... .... ..... .... .... ...295
2.4 Variablespeed drives .... ..... .... .... .... ..... .... .... .... ..... .... .... ...317
2.5 Induction motors ... .... ..... .... .... .... ..... .... .... .... ..... .... .... ...341
Section3 ELECTRONICDRIVECONTROL .................................................. 363
3.1 Electronic circuitsand devices . .... .... .... ..... .... .... .... ..... .... .... ...365
3.2 Electronic converters .... ..... .... .... .... ..... .... .... .... ..... .... .... ...381
Section4 POWERTRANSMISSION ....................................................... 411
4.1 Powertransmission . .... ..... .... .... .... ..... .... .... .... ..... .... .... ...413
4.2 Gearsand gearboxes .... ..... .... .... .... ..... .... .... .... ..... .... .... ...431
Section5 HYDRAULICANDPNEUMATICSYSTEMS ........................................... 439
5.1 Hydraulic fundamentals .. ..... .... .... .... ..... .... .... .... ..... .... .... ...441
5.2 Pneumaticfundamentals . ..... .... .... .... ..... .... .... .... ..... .... .... ...489
5.3 Pump types andcharacteristics .... .... .... ..... .... .... .... ..... .... .... ...509
5.4 Centrifugal pumpdesign . ..... .... .... .... ..... .... .... .... ..... .... .... ...519
5.5 Pump hydraulics ... .... ..... .... .... .... ..... .... .... .... ..... .... .... ...537
5.6 Hydraulic pumpsand pressureregulation . .... ..... .... .... .... ..... .... .... ...555
5.7 Actuators . .... .... .... ..... .... .... .... ..... .... .... .... ..... .... .... ...579
Index ........................................................................... 597
v
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Section One Section One Section One Section One Section One
Section One
Introduction
1
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1.1
Chapter 1.1
Instrumentation
and transducers
Parr
1.1.1 Introduction
specified accuracy can be obtained. Assuming the accu-
racy is maintained across the range, the pressure trans-
1.1.1.1 Definition of terms mitter above has a turndown of 4:1. Orifice plates and
otherdifferentialflowmeterslose accuracyatlowflows,
Accuratemeasurementofprocessvariablessuchasflow, andtheirturndownislessthanthetheoreticalmeasuring
pressure and temperature is an essential part of any in- range wouldimply.
dustrial process. This chapter describes methods of Theerrorisameasurementofthedifferencebetween
measuring common process variables. the measured value and the true value. The accuracy is
Likemosttechnologies,instrumentationhasarangeof the maximum error which can occur between the pro-
common terms with precisemeanings. cess variable and the measured value when the trans-
Measuredvariableandprocessvariablearebothterms ducer is operating under specified conditions. Error can
forthephysicalquantitythatistobemeasuredontheplant beexpressedinmanyways.Thecommonestareabsolute
(e.g.thelevelintank15).Themeasuredvalueistheactual value (e.g. (cid:2)2 (cid:3)C for a temperature measurement), as
valueinengineeringunits(e.g.thelevelis1252mm). apercentageoftheactualvalue,orasapercentageoffull
A primary element or sensor is the device which con- scale. Errors can occur for several reasons; calibration
vertsthemeasuredvalueintoaformsuitableforfurther error, manufacturing tolerances and environmental
conversion into an instrumentation signal, i.e. a sensor effects are common.
connectsdirectlytotheplant.Anorificeplateisatypical Many devices have an inherent coarseness in their
sensor. A transducer is a device which converts a signal measuringcapabilities.Awirewoundpotentiometer,for
fromonequantitytoanother(e.g.aPT100temperature example,canonlychangeitsresistanceinsmallstepsand
transducer converts a temperature to a resistance). A digital devices such as encoders inherently measure in
transmitter is a transducer which gives a standard in- discrete steps. The term resolution is used to define the
strumentationsignal (e.g. 4–20mA) asanoutput signal, smallest steps in which a readingcan be made.
i.e. it converts from the process measured value to Inmanyapplicationstheaccuracyofameasurementis
a signal which can beused elsewhere. less important than its consistency. The consistency of
ameasurementisdefinedbythetermsrepeatabilityand
1.1.1.2 Range, accuracy and error hysteresis.
Repeatability is defined as the difference in readings
The measuring span, measuring interval and range are obtained when the same measuring point is approached
terms which describe the difference between the lower several times from thesamedirection.
and upper limits that can be measured (e.g. a pressure Hysteresis occurs when the measured value de-
transducer which can measure from 30 to 120 bar has pends on the direction of approach as Figure 1.1.1.
a range of 90 bar). The rangeability or turndown is the Mechanical backlash or stiction are common causes of
ratiobetweentheupperlimitandlowerlimitswherethe hysteresis.
ElectricalEngineer’sReferenceBook;ISBN:9780750646376
Copyright(cid:2)2002ElsevierLtd.Allrightsofreproduction,inanyform,reserved.
