MINISTRY OF SCIENCE AND TECHNOLOGY A.G.T.I (Second Year) EP 2012 ELECTRICAL MACHINES AND CONTROL

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MINISTRY OF SCIENCE AND TECHNOLOGY A.G.T.I (Second Year) EP 2012 ELECTRICAL MACHINES AND CONTROL. Presented By Dr. Aung Ze Ya Associate Professor Department of Electrical Power Engineering Yangon Technological University. PART ONE PLC CHAPTER 1 PLC Basics.  PLC Structure
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MINISTRY OF SCIENCE AND TECHNOLOGYA.G.T.I (Second Year)EP 2012 ELECTRICAL MACHINES AND CONTROL Presented By Dr. Aung Ze Ya Associate Professor Department of Electrical Power Engineering Yangon Technological University PART ONEPLCCHAPTER 1PLC Basics  PLC Structure PLC in Comparison with Other Control Systems PLC’s CPU
  • PLC’s Memory
  • PLC Structure Programming Terminal Power Supply CPU Memory Input Module Output Module PLC PROCESS Input Devices Output Devices  PLC Structure
  • Divided into 4 parts, I/O Modules, CPU, Memory and Programming Terminal
  • Operates by examining the input signals from a process and carrying out logic instructions
  • Producing output signals to drive process equipment
  • Standard interfaces built-in to PLC => directly connected to process actuators & transducers without the need for intermediate circuitry or relays
  •  PLC Structure
  • Require short installation & commissioning times
  • Specific features for industrial control:
  • Noise immune equipment
  • Modular plug-in construction
  • Standard I/O connections & signal levels
  • Easily understood programming language
  • Ease of programming & reprogramming in-plant
  • Capable of communicating & reprogramming in-plant
  • Capable of communicating with other PLCs, computers & intelligent devices
  • Competitive in both cost & space occupied with relay & solid-state logic systems
  • PLC in Comparison with Other Control Systems
  • Relay Control System
  • Input & Output contacts in series and/or parallel  desired logic functions
  • Combinations of logic elements  create complex control plans
  • Typical relay system  several hundred or thousand switching contacts
  • Extremely difficult to change control function of panel  complete re-wiring of system
  • Other disadvantages  cost, speed & reliability
  • Replacement of relay control systems by modern alternatives based on electronics & microprocessors
  • Convert small control signals to higher I/ V driving signals  used extensively as output devices
  • PLC in Comparison with Other Control Systems (b) Digital Logic Control System
  • Digital ICs  processing information through various logic gates
  • Operate at much higher speeds & less power than relay circuit
  • Advantage of small size but it cannot switch higher power signal
  •  PLC in Comparison with Other Control Systems (c)Electronic Continuous Control System
  • Op-amp available for computing (mathematical ) operations  quickly adopted in the field of continuous control  provided to much simplified solution to complex control functions than discrete systems
  • But, design & commissioning  difficult task
  •  PLC in Comparison with Other Control Systems (d) Computer Control System
  • Powerful low-cost micro/ mini- computers are used in both sequence & continuous control systems
  • Microprocessor based panels  simple connection requirements
  • Large processes  several micro used instead of single large mainframe computer with resulting benefits
  • Each micro  optimal control, send or receive control data
  • Greater sophistication of control than single computer
  • Distributed control  need not consist exclusively of mini/ micro  include other intelligent devices such as CNC, robots & PLCs.
  • PLC’s CPU
  • Controls & supervises all operations within PLC
  • Carrying out programmed instructions store in memory
  • Communications highway carries information to & from CPU memory & I/O units under control of CPU
  • Modern PLCs microprocessors-based
  • Larger PLCs additional microprocessors to control complex, time consuming functions
  •  PLC’s Memory
  • Executive Memory
  • Operating System  ROM, rarely needs changing
  • Scanning in PLC
  • Helps the microprocessor to interpret programmed symbols & instructions
  • Keeps track of all I/O status
  • Monitors the current status of health of system
  •  PLC’s Memory (b) System Memory
  • System administration  RAM
  • Allotted for use of OS only & not available for programming
  • Stores information which passes between programmer & OS  during / before execution of user program (c) Data Memory
  • Timers, counters, & process parameters  set for data storage
  • Any data manipulation in user program
  • Two sub-memories, (i) fixed data (ii) variable data
  • Fixed data  programmed via programming device
  • Variable data  CPU for data storage
  • CHAPTER 2PLC PROGRAMMING
  • Programming Devices
  •  Programming Languages
  •  Typical Instruction Set
  •  Typical Combinations of Languages
  • 3 Basic Symbols
  •  Elementary Logic Circuit
  •  PLC’s Functions
  •  Programming Devices
  • Programs are input into PLC by programming devices  hand held manual programmer  industrial programming terminal  PC based programmers
  • Hand held  inexpensive, portable, for small PLC
  • Industrial  intelligent device  not only displays control program but also provides edit
  • PC  running on ladder logic software  latest innovation  can be connected to LANs  allows remotely monitored & controlled
  •  Programming Languages 4 most common types
  • Ladder diagrams
  • Boolean mnemonics
  • Function blocks
  • Sequential function chart Basic languages  Ladder & Boolean High languages  Function blocks & Sequential function chart
  •  Typical Instruction Set  Typical Combinations of Languages
  • Ladder diagram only
  • Boolean only
  • Ladder diagrams & function blocks
  • Ladder & sequential function charts
  • Ladder, function blocks, sequential function charts
  • First two  programming simple logic
  • Third for most practical cases
  • Last two  programming using sequential function chart
  •  3 Basic Symbols
  • Normally open contact  input , turn ON
  • Normally closed contact  input , turn OFF
  • Output coil
  •  Elementary Logic Circuit
  • AND gate programming NO contacts in series  All NOmust be ON in order to turn ON the output coil (b) OR gate  programming NO contacts in parallel output coil is turned ON once any of NO contact is ON (c) NOR gate  AND is inversed  NO contacts replaced by NC contacts
  •  Elementary Logic Circuit (d) NAND gate  OR is inversed  All inputs are 1, output is 0 (e) Exclusive OR gate  one make & one break contact in series  either one input or other is ON, output logic is 1  one of the main features of PLC (f) Memory circuits  transform output signal to continuous signal upon activation of initiating contacts  NC contact in series in rung to break logic continuity  PLC’s Functions
  • Timers output instructions provide same function as hardware timers  used to activate or deactivate device after expired interval  specifying time and inputs that are start/ stop timer  most timers are decrementing type  reach 0  associated contact will turn ON  cascading of timers  provide longer time interval
  •  PLC’s Functions (b) Counters to store number of process actions or events  provide same function as hardware counters  most counters are decrementing type  reach 0  counter contact will turn ON  used to activate or deactivate output device  two control paths  count & reset  can reset in the middle of operation by activating reset input  PLC’s Functions (c) Shift Register provide data storage area for sequence of individual data bits  3 control paths  Data input line offers data bit in series to register  Shift line moves data through register  Reset input line resets all data within register  stored data will be shifted one bit into register  certain size, last bit will be shifted out & lost  should be cascaded to ensure shifted of first register is moved into next CHAPTER 3PLC APPLICATION Industrial Programming Example Pneumatic Ram Feed Belt LS 2 LS 3 Assembly Jig Drive F LS 4 Industrial Programming Example
  • Feed belt moves components in succession towards assembly machine
  • Component in position  LS 1 stops feed belt
  • Pneumatic Ram is extended to push component firmly into Assembly Machine
  • LS 2 is activated  Ram to retract
  • LS 3 activates the press
  • After pressing raw into desired shape  ejected
  • Light Sensor LS 4 detects ejection, signal for next cycle
  • CHAPTER 4PLC PRACTICE
  • Selection of PLC
  • Must be remembered that controller is tool to perform necessary task
  • Implementation of actual automation is paramount
  • Specifications are established
  • Basic considerations for suitable PLC:
  • Necessary I/O capacity
  • Types of I/O required
  • Size of memory required
  • Speed & Power required of CPU & instruction set
  • Manufacturer’s support & backup
  • (b) Types of I/O & Capacity Needed
  • Basic specifications with regard to:
  • Voltage levels & current loadings
  • Number & Type of I/O points required / module
  • Isolation required between controller & target process
  • Need for High Speed I/O or Remote I/O or other special facility
  • Future need of plant in terms of both expansion potential & installed spare I/O points
  • Power Supply requirements of I/O points
  • (c) Manufacturer’s Support & Backup
  • Considerations:
  • Can the engineer obtains assistant with the design work?
  • What proportion of the market does the potential supplier/ manufacturer hold & do they have a track record in the necessary area of application?
  • Does the manufacturer offer training course on the type of PLC likely to meet the user’s needs?
  • Are all relevant handbooks & manuals available in the required language, to a good standard?
  • What compatibility exists between any likely system and other types of PLC from the same of different manufacturers?
  • Does the programming method used suit the outline control plan for the application?
  • PART TWOSEQUENCE CONTROLCHAPTER 1Control System Basic  Sequence Control Automatic Control  Terms of Sequence Control Basic Knowledge on Contacts  Sequence Control
  • Each state of control is progressed by predetermined order
  • Conditional control or programmed control
  • Controlling is based on output signals determined by combination of input signals
  • For E.g., in elevator  Device provided on each floor giving signal to call a cage  Cage has signal device which instructs the cage is supported to stop  2 kinds of signals, upward/downward movement of elevator
  • Preferred on the basis of these signals
  • Others  Water Heater  An Electric Pot  An Electric Cooker  A Refrigerator  Electric Foot Warmer
  • Automatic Control
  • Control which is automatically carried on by control device
  • Methods  Feedback Control  Conditional Control  Program Control  Numerical Control  Calculator Control…
  • Large-Scaled Control System by combining of controlling methods
  • Feedback System is main system of Automatic Control, measure the established on end and convert it to analog quality, satisfying these established conditions ( Reference Input )
  • Recently, higher automation by combinations of calculator controls employing many computers
  •  Terms of Sequence Control
  • Controlled System
  • Objects to be controlled
  • Whole or part of machines, processors, etc. (b) Controlled Variable
  • Quantity belonging to controlled system whose sole object is to be controlled (c) Detecting Means
  • Part of controlling device which detects the controlled quantity
  • Compare with standards & give binary signals
  • Examples  thermal switches for controlling temperatures
  •  float switches for controlling quantity of water
  •  pressure switches for compressors
  •  Terms of Sequence Control (d) Input Signal
  • Signals fed to control system & its elements (e) Input Signal Treatment
  • Memorized signals or take out the controlled from detected signals (f) Final Control Element
  • Converts signals from regulator into operating quantity
  • Directly acts on the controlled objects
  • To amplify controlled signals & take safety measure
  •  Terms of Sequence Control (g) Indicator & Alarm
  • Indicates controlling conditions & gives the alarm in abnormal state or emergency in the system (h) Fundamental Variable
  • Serves to give binary signals
  • Functions as monitor to check the upper & lower limits
  • Basic Knowledge on Contacts
  • “a” contact
  •  Make Contact or ON/Closed Contact
  •  Closed when movable armature is activated or by manual
  •  Open by force on spring as soon as finger is released on press button
  • Basic Knowledge on Contacts
  • “b” contact
  •  Break Contact or OFF/Open Contact
  •  Opened when movable armature is activated or by manual
  •  Opposite of “a” contact
  • Basic Knowledge on Contacts
  • “c” contact
  •  Switching Contact
  •  Combination of “a” contact & “b” contact
  •  Lightings in stairs & corridors, turn on & off at 2 places, 2 way switch having function of “c” contact is used
  • CHAPTER 2SEQUENCE CONTROL Representation of Sequence Control
  • Connection Diagram
  • (i) Block Diagram
  • shows the construction of control system
  • by means of blocks
  • blocks are joined each other by lines denoting the flow of signals
  • (ii) Single-line Diagram
  • used for representing connection of electrical power supply
  • line is used to denote a circuit which is actually to be connected by double lines
  • each apparatus is shown in simple way
  • helps the circuit become more understandable in terms of its overall construction
  • (iii) Distribution Diagram
  • represent the construction of system
  • from a power station to sub-station, distribution lines and then to users (b) Diagram of Functional Performance
  • Real Connection D
  • reproduce the actual objects
  • represent the components and their connections in the circuit as near the reality as possible
  • fairly complex circuit
  • expanded Connection Diagram
  • shows operation of sequence control
  • drawn according to the order of operation of apparatus and contacts
  • easy to understand
  • 2 ways, vertical and horizontal diagrams
  • Flow Chart
  • shows the state of operation of circuit in the form of flow
  • (iv) Time Chart
  • fairly difficult to explain the order of operation of sequence control by sentences
  • in order to overcome this difficulty, time chart has been developed. (v) Diagram of Logic Circuit and Truth Table
  • logic circuit denotes the relationship between input and output signals.
  • Truth table has same meaning as the time chart for contact relays
  • Laws of Logic Equations
  • Law of Power (i) X . X = X (ii) X + X = X (b) Complementary Law (i) X . X = 0 (ii) X + X = 1
  • Law on 0 and 1 (i) X + 0 = X (ii) X . 1 = X (iii) X + 1 = 1 (iv) X . 0 = 0
  • (d) Commutative Law (i) X + Y = Y + X (ii) X . Y = Y . X (e) Associative Law (i) X + X . Y = X (ii) X . (X + Y) = X (f) Distributive Law (i) X . (Y + X) = X . Y + X . Z (ii) X + Y . Z = (X + Y) . (X + Z) (iii) (X + Y) . Y = X . Y (g) Law of Self-Duality (X + Y) . (Y + Z) . (Z + X) = X . Y + Y . Z + Z . X (h) de Morgan’s Law (X . Y) = X + Y CHAPTER 3INDUSTRIAL MACHINE CONTROLS
  • Control of Operating and Stopping a Three-phase Induction Motor
  • Control of Forward and Reverse Movement of Three-phase Induction Motor
  • Control of Driving Three-phase Induction Motor at Intervals
  • Control of Star and Delta Starting of Three-phase Induction motor
  • Control of Forward and Reverse Movement of Single-phase Induction Motor
  • Control of Automatic Return Operation of Three-phase Induction Motor
  • Control of Automatic Repetitive Operation of Three-phase Induction Motor
  • Automatic Repetitive Order Operation Control System
  • THANK U VERY MUCH Induction Motor
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