CONTROL SYSTEM COMPONENTS M.D. Desai Professor of Instrumentation and Control Engineering Institute of Technology Nirma University Ahmedabad New Delhi-110001 2008
CONTROL SYSTEM COMPONENTS M.D. Desai 2008 by PHI Learning Private Limited, New Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN-978-81-203-3605-6 The export rights of this book are vested solely with the publisher. Published by Asoke K. Ghosh, PHI Learning Private Limited, M-97, Connaught Circus, New Delhi-110001 and Printed by Mudrak, 30-A, Patparganj, Delhi-110091.
Contents Preface xiii 1. Control System Parameters 1 4 1.1 Introduction 1 1.2 Accuracy and Mode of Control 1 1.3 Closed-loop Control System 2 1.4 Components of Control System 3 Questions 3 2. Cams 5 17 2.1 Introduction 5 2.2 Components of Cam 6 2.3 Types of Cams 6 2.4 Types of Follower 9 2.5 Classification of Cams According to Constraints 10 2.6 Cam Motions 10 2.7 Cam Terminology 10 2.8 Drawing a Cam Profile 12 2.9 Cam as a Mechanical Function Generator 13 2.10 3-D Cam 16 Questions 17 3. Gears 18 37 3.1 Introduction 18 3.2 Types of Gears 19 3.2.1 Spur Gear and Pinion 19 3.2.2 Rack and Pinion 21 3.2.3 Helical Gear 22 3.2.4 Herringbone Gear 22 iii
iv Contents 3.2.5 Bevel Gear 22 3.2.6 Worm Gear 23 3.3 Gears for Load Matching 26 3.4 Design of a Gear Train 26 3.5 Backlash in Gears 31 3.6 Design of a Multi-mesh Gear Train 33 3.7 Manufacture of Gears 36 Questions 36 4. Gyroscope 38 59 4.1 Introduction 38 4.2 Gyroscopic Effect 38 4.3 Positional References 39 4.4 Construction of the Gyroscope 40 4.5 Construction of a Horizontal Gyroscope 42 4.6 Working and Application of Horizontal Gyroscope 43 4.7 Construction and use of a Vertical Gyroscope 44 4.8 Precession and Velocity of Precession 45 4.9 Generalized Equations of Gyroscope 47 4.10 Restrained Gyroscope 51 4.11 Applications of Gyroscope 55 Questions 58 5. Potentiometer 60 78 5.1 Introduction 60 5.2 Types of Potentiometers 61 5.3 Applications of Potentiometers 72 5.4 Selection of Potentiometers 77 Questions 78 6. Synchros 79 102 6.1 Introduction 79 6.2 Synchro Construction and Operation 80 6.3 Synchro Characteristic 83 6.4 Synchro Application 84 6.5 Synchro Pair as an Error Detector 86 Questions 101 7. Servomotors 103 132 7.1 Introduction 103 7.2 DC Servomotors 104 7.2.1 Transfer Function of dc Servomotor 111 7.2.2 Transfer Function of Field Controlled dc Servomotor 112 7.2.3 Armature-controlled dc Servomotor 114
7.3 AC Servomotors 116 7.3.1 Construction of ac Servomotors 117 7.3.2 Theory of Operation of Induction Motor 120 7.3.3 Theory of Operation of ac Servomotor 121 7.3.4 Shaded Pole ac Servomotor 130 Questions 132 Contents v 8. Stepper Motors 133 155 8.1 Introduction 133 8.2 Permanent Magnet Stepper Motor 134 8.3 Variable Reluctance Type Stepper Motors 136 8.3.1 Modified Variable Reluctance Motor 139 8.4 Hybrid Stepper Motor 140 8.5 Disc Magnet Stepper Motor 142 8.6 Applications of Stepper Motors 145 8.6.1 Instrumentation Applications 145 8.7 Drive Circuits for Stepper Motors 149 8.7.1 Stepper Motor Controller 149 8.7.2 Logic Sequencer 150 Questions 154 9. Tachometers 156 173 9.1 Introduction 156 9.2 Characteristic Requirements of Tachogenerator 157 9.3 DC Tachogenerator 158 9.3.1 Construction of dc Tachogenerator 158 9.3.2 Advantages and Disadvantages 161 9.3.3 EMF Equation of dc Tachogenerator 161 9.3.4 Commutation Problem 162 9.3.5 Armature Reaction Problem 163 9.3.6 Compensating Winding 164 9.3.7 Optimum Design of Tachogenerators 164 9.4 AC Tachogenerators 165 9.4.1 AC Induction Tachogenerator 165 9.4.2 Working of ac Induction Tachogenerator 167 9.4.3 Sources of Error for ac Tachogenerator 168 9.5 Tachometer Applications 169 9.5.1 Position Control with Velocity Damping 169 9.5.2 Tachometer as an Integrator 170 9.6 Characteristics of Tachogenerator 172 Questions 172
vi Contents 10. Rotating Amplifiers 174 192 10.1 Introduction 174 10.2 Rototrol Generator 174 10.3 Regulex Generator 177 10.4 Metadyne Generator 177 10.5 Rosenberg Generator 179 10.6 Amplidyne Generator 179 10.6.1 Principle of Amplidyne Generator 179 10.6.2 Amplidyne as Modified dc Machine 183 10.6.3 Armature Reaction of Second Stage 185 10.6.4 Commutation 187 10.6.5 Multiple Windings of Amplidyne 188 10.6.6 Transfer Function of Amplidyne 189 Questions 192 11. Magnetic Amplifiers 193 221 11.1 Introduction 193 11.2 Series Connected Magnetic Amplifier 195 11.2.1 Series Connected Magnetic Amplifier Waveforms 200 11.2.2 Analysis of Series Connected Magnetic Amplifier 202 11.2.3 Time Constant of Series Connected Magnetic Amplifier 204 11.3 Parallel Connected Magnetic Amplifiers 207 11.3.1 Time Constant of Parallel Connected Magnetic Amplifier 212 11.4 Magnetic Amplifiers with Feedback 216 11.4.1 Series Connected Magnetic Amplifier with Feedback 216 11.4.2 Time Constant of Parallel Connected Magnetic Amplifier with Feedback 219 Questions 221 12. Servo Amplifiers 222 233 12.1 Introduction 222 12.2 Features of Servo Amplifiers 222 12.3 DC Servo Amplifiers 223 12.4 AC Amplifiers 226 12.5 Performance Characteristics of Electronic Amplifiers 226 12.6 Classification of Amplifiers 227 Questions 232 13. Modulators and Demodulators 234 254 13.1 Introduction 234 13.2 Amplitude Modulation Theory 237 13.2.1 Sinusoidal Amplitude Modulation 238 13.2.2 Frequency Spectrum of Sinusoidal AM 240
13.3 Double-side Band Suppressed Carrier (DSBSC) Amplitude Modulation 240 13.3.1 Half Wave Balanced Switching Modulator 240 13.3.2 Full Wave Balanced Modulator 242 13.4 Amplitude Modulator Circuit 244 13.4.1 Amplitude Demodulator Circuit 245 13.4.2 Single Balanced Modulator Circuit 247 13.4.3 Ring Modulator 248 13.4.4 Transistorized Chopper Modulator 250 13.5 Diode Discriminators 251 Questions 253 Contents vii 14. Relays 255 286 14.1 Introduction 255 14.2 Classification of Relays 256 14.2.1 AC and dc Relays 256 14.2.2 Electromechanical and Solid State Relays 257 14.2.3 General Purpose Relays 258 14.2.4 High Speed Relays 258 14.2.5 High Voltage Relays 258 14.2.6 Power Relays 259 14.2.7 Overload Relays 259 14.2.8 Power System Protection 259 14.2.9 Frequency Sensitive Relays 259 14.2.10 Latching Relays 260 14.2.11 Mercury Operated Relay 260 14.2.12 Plunger Relays 260 14.2.13 Miniature Relays 261 14.2.14 Polarized Relays 261 14.2.15 Rotary Relays 262 14.2.16 Radio Frequency Relays 263 14.2.17 Sensitive Relays 263 14.2.18 Snap Action Relays 263 14.2.19 Telephone Relays 263 14.2.20 Time Delay Relays 264 14.2.21 Optoelectronic Relays 264 14.2.22 Vacuum Relays 264 14.3 Relay Circuits 265 14.4 Construction of the Relay 270 14.4.1 Electromechanical Relay 270 14.4.2 Reed Relays 273 14.4.3 Reed Relay Types 274 14.5 Logic Relays 274 14.6 Optoelectronic Relay 275
viii Contents 14.7 Relay Problems and Remedies 276 14.8 Relay Race 277 14.9 Actuation and Release Time 278 14.10 Characteristics of Electromechanical Relays 281 14.11 Dynamic Characteristics of Reed Relays 283 14.12 Merits and Design Features of Reed Relays 285 Questions 286 15. Hydraulic Systems 287 316 15.1 Introduction 287 15.2 Advantages and Disadvantages of Hydraulic Systems 287 15.3 Operating Pressure for Hydraulic System 288 15.4 Components of Hydraulic System 289 15.4.1 Hydraulic Tank 289 15.4.2 Filter 290 15.4.3 Pumps 290 15.4.4 Accumulators 290 15.4.5 Relief Valves 291 15.4.6 Check-valve 292 15.4.7 Needle Valve 292 15.5 Classification of Hydraulic Systems 293 15.5.1 Pump-controlled Hydraulic System 293 15.5.2 Valve-controlled Hydraulic System 294 15.6 Hydraulic Pumps 295 15.6.1 Axial Piston Pump 295 15.6.2 Radial Piston Pump 296 15.6.3 Ball Pump 297 15.6.4 Gear Pump 298 15.6.5 Vane Pump 300 15.7 Control with Pump-controlled Hydraulic System 301 15.8 Pump-controlled Hydraulic Motor 303 15.9 Performance Characteristics of Hydraulic Pumps 304 15.10 Hydraulic Transmission Lines 305 15.11 Hydraulic Power Supply 305 15.11.1 Hydraulic Supply Using Relief Valve 305 15.11.2 Hydraulic Relief Valve 306 15.11.3 Hydraulic Supply Using Accumulator and Unloading Valve 307 15.11.4 Constant Pressure Power Supply with Variable Flow Pump 309 15.11.5 Differential Pressure Regulator 309 15.11.6 Pressure Regulator 312 15.11.7 Analysis of Pump-controlled Hydraulic System 313 15.11.8 Transfer Function of Pump-controlled Hydraulic System 315 Questions 315
Contents ix 16. Hydraulic Valves 317 339 16.1 Spool Type Valve 317 16.1.1 Two-way Spool Valve 317 16.1.2 Four-way Spool Valve 319 16.1.3 Four-land Four-way Spool Valve 320 16.1.4 Three-land Four-way Spool Valve and Actuator 320 16.2 Valve-controlled Hydraulic Feedback Control System 321 16.3 Three-way Hydraulic Valve Amplifier 324 16.3.1 Spring Loaded Piston 325 16.4 Four-way Hydraulic Valve Amplifiers 326 16.4.1 Underlap and Overlap Problem 328 16.5 Nozzle Valve 329 16.6 Slide Valve 330 16.7 Multistage Valves 331 16.8 Flapper Valves 332 16.8.1 Flapper Valve with Bellows 335 16.8.2 Flapper Valve and Spring Loaded Cylinder 337 16.9 Pulsed Operation of Control Valves 338 Questions 339 17. Pneumatic Systems 340 360 17.1 Introduction 340 17.2 Pneumatic Power Supply 341 17.2.1 Centrifugal Compressor 341 17.2.2 Axial Flow Compressor 342 17.2.3 Reciprocating Piston Compressor 342 17.2.4 Multistage Compressor 344 17.3 Compressor Efficiency 345 17.3.1 Diaphragm Compressor 346 17.3.2 Vane Compressor 347 17.3.3 Helical Compressor 347 17.4 Accessories for Air Compressor 348 17.4.1 Intake Filter 348 17.4.2 After Cooler 349 17.4.3 Receiver Tank 350 17.4.4 Pressure Switch 350 17.4.5 Safety Relief Valve 351 17.4.6 Dryers 352 17.5 Air Compressor Installation 355 17.6 Air Supply System 355 17.7 Flow Control 356 Questions 360
Control System Components Publisher : PHI Learning ISBN : 9788120336056 Author : M D Desai Type the URL : http://www.kopykitab.com/product/6184 Get this ebook