Uploaded byDr. Munthear Alqaderi
Plc
The document discusses the development of control systems from manual to PLC control. It provides details on traditional control devices like relays, contactors, and motor starters. It then describes the different types of control systems including PLC, DCS, and PC-based controls. The remainder of the document focuses on PLC systems, their components, functions, advantages, disadvantages and applications in industries like food processing. It also discusses the history and development of PLCs and lists some major PLC brands.
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Plc
- 1. PLC course الدكتورالمهندس محمد منذر القادري munthear@gmail.com
- 2. DEVELOPMENT OF CONTROLSYSTEM Manual control Pneumatic control Hard wired logic control Electronics control PLC control.
- 3. Traditional Devices •Relays •Contactors •Motor Starters •Manually operated switches •Mechanically operated switches •Electrically operated switches
- 4. CR1 CR1-1 Relays • Original control elements • Now used as auxiliary devices • The PLC is not designed to switch high currents or voltages
- 5. Contactors •Used forheavy-duty switching •Provides isolation from high voltages and large currents •Usefully for large inductive currents, such as motor starting
- 6. Motor Starters •Contactors+ Overload Relay •Overload relays were usually heaters and bimetal strips •The bimetal strip separates when heated •Next steps: •PLCs and motor starters •Electronic overloads •Intelligent starters
- 7. Manually Operated Switches •Pushbuttons •Normally open •Normally closed •Break-then-make •Make-then-break •Selector switches •Maintained or spring return
- 8. Mechanically Operated Switches •Limit Switches •Temperature Switches •Pressure Switches •Level Switches
- 9. Electrically Operated Switches •Photoelectric Switches •Proximity Switches
- 10. Control Systems Types Programmable Logic Controllers Distributed Control System PC-Based Controls
- 11. PLC Systems •CPU •Processor •Memory •One Module •Power Supply •Part of the chassis or a separate module •Programming/ Monitoring Device •I/0 Modules
- 12. Programmable Logic Controllers PLC (FUNCTIONS OF CONTROLLERS) Sequential logic solver (sequential control) PID Calculations. Advanced Subroutines (motion control). BIT Operations. Data Transfer. Text Handling. Event Logging Communication Human interface
- 13. Advantages of PLCs •Lessandsimplerwiring. •WiringbetweendevicesandrelaycontactsaredoneinthePLCprogram. •Solid-state-nomovingparts. •Easierandfastertomakechanges.(Flexible). •Fasterresponsetime. •Sophisticatedinstructionsetsavailable. •Troubleshootingaidsmakeprogrammingeasierandreducedowntime. •Reliablecomponentsmaketheselikelytooperateforyearsbeforefailure. •Allowsfordiagnostics”easytotroubleshoot”.Easymaintenance. •Lessexpensive •Awiderangeofcontrolapplication INTRODUCTION TO PLCS
- 14. Disadvantages of PLC: PLC were Designed for Relay Logic Ladder and have Difficulty with some Smart Devices. To maximize PLC performance and Flexibility, a number of Optional Modules must be added
- 15. PLC Origin •-Developedto replace relays in the late 1960s •-Costs dropped and became popular by 1980s •-Now used in many industrial designs
- 16. 16 Historical Background The Hydramatic Divisionof the General Motors Corporationspecified the design criteria for the first programmable controller in 1968 Their primary goal To eliminate the high costs associated with inflexible, relay-controlled systems.
- 17. 17 Historical Background •The controller had to be designed in modular form, so that sub- assemblies could be removed easily for replacement or repair. •The control system needed the capability to pass data collection to a central system. •The system had to be reusable. •The method used to program the controller had to be simple, so that it could be easily understood by plant personnel.
- 18. PLC developments 1968Programmable controller concept developed. 1969Hardware CPU controller, with logic instruction, 1k of memory and 128 I/O points. 1974Use of several processors within a PLC –timers and counters, arithmetic operations, 12k of memory and 1024 I/O points. 1976Remote input/output systems introduced. 1977Microprocessor-based PLC introduced. 1980Intelligent I/O modules developed, Enhanced communications facilities, Enhanced software features, Use of personal microcomputer as programming aids. 1983Low-cost small PLC introduced. 1985Networking of all levels of PLC, computer and Machine under standard specification Distributed, hierarchical control of industrial plants.
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- 20. 20 Programmable LogicControllers ( Definition according to NEMA standard ICS3-1978) A digitally operating electronic apparatus which uses a programming memory for the internal storage of instructions for implementing specific functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analog modules, various types of machines or process.
- 21. 21 Leading BrandsOf PLC AMERICAN1. Allen Bradley 2. Gould Modicon 3. Texas Instruments 4. General Electric 5. Westinghouse 6. Cutter Hammer 7. Square D EUROPEAN1. Siemens 2. Klockner& Mouller 3. Festo 4. Telemechanique JAPANESE1. Toshiba 2. Omron 3. Fanuc 4. Mitsubishi
- 22. Global players Source:ARC Research, 2005-10
- 23. Video:/ 4-siemens –AllenBradly
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- 26. 26 Areas ofApplication Manufacturing /Machine controls Food / Beverage, Packaging, Material handling, Metals Power Mining Petrochemical / Chemical
- 27. In Snack FoodsIndustries ◊Temperature Control ◊Pressure Control ◊Variable Speed Drive Systems Batching Systems ◊Continuous Mixing System Controls ◊Batch Mixing Systems Material Handling ◊Pneumatic Conveying Systems ◊Vacuum Conveying Systems ◊Product Conveying Systems Cooker Systems ◊Temperature Control ◊Level Control ◊PH Control Extrusion & Cutting Systems ◊Speed Control ◊Pressure Control ◊Cutting Control Slurry Mixing and Distribution ◊Pump Control Systems ◊Valve Control Systems
- 29. Kiln Control Systems ◊Temperature Control ◊Humidity Control Material Handling ◊Pneumatic Conveying Systems ◊Vacuum Conveying Systems ◊Product Conveying Systems Cutting Control Systems Forming Systems ◊Variable Speed Drive Systems Gypsum Mixing and Distribution ◊Pump Control Systems ◊Valve Control Systems Batching Systems ◊Continuous Mixing System Controls ◊Inventory Control System
- 30. Tank Used toMix Two Liquids A B C FS MOTOR TIMER FLOAT SWITCH SOLENOIDS SOLENOID 1 -MINUTE
- 31. 31 Tank Usedto Mix Two Liquids A tank is used to mix two liquids. The control circuit operates as follows: 1. When the start button is pressed, solenoids A and B energize. This permits the two liquids to begin filling the tank. 2. When the tank is filled, the float switch trips. This de-energizes solenoids A and B and starts the motor used to mix the liquids together. 3. The motor is permitted to run for one minute. After one minute has elapsed, the motor turns off and solenoid C energizes to drain the tank.
- 32. 4. When thetank is empty, the float switch de-energizes solenoid C. 5. A stop button can be used to stop the process at any point. 6. If the motor becomes overloaded, the action of the entire circuit will stop. 7. Once the circuit has been energized it will continue to operate until it is manually stopped. 32 Tank Used to Mix Two Liquids
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- 34. PLC Size 1.Nano(SMALL)-it covers units with up to 128 I/O’s and memories up to 2 Kbytes. -these PLC’s are capable of providing simple to advance levels or machine controls. 2.Micro (MEDIUM)-have up to 2048 I/O’s and memories up to 32 Kbytes. 3. LARGE-the most sophisticated units of the PLC family. They have up to 8192 I/O’s and memories up to 750 Kbytes. -can control individual production processes or entire plant.
- 35. Kinds of PLC Monolithic construction Monoprocessor Fieldbus connection Fixed casing Fixed number of I/O (most of them binary) No process computer capabilities (no MMC) Typical product: Mitsubishi MELSEC F, ABB AC31, SIMATIC S7 Modular construction (backplane) One-or multiprocessor system Fieldbus and LAN connection 3U or 6U rack, sometimes DIN-rail Large variety of input/output boards Connection to serial bus Small MMC function possible Typical products: SIMATIC S5-115, Hitachi H-Serie, ABB AC110 (2) (1) Compact Modular PLC (3) Soft-PLC Windows NT or CE-based automation products Direct use of CPU or co-processors
- 36. courtesy ABB ModularPLC RS232 CPU CPU Analog I/O Binary I/O backplane parallel bus •housed in a 19" (42 cm) rack (height 6U ( = 233 mm) or 3U (=100mm) •concentration of a large number of I/O Power Supply •high processing power (several CPU) •primitive or no HMI •cost effective if the rack can be filled •tailored to the needs of an application •supply 115-230V~ , 24V= or 48V= (redundant) fieldbus LAN •large choice of I/O boards •interface boards to field busses •requires marshalling of signals fieldbus development environment •cost ~ €10’000 for a filled crate
- 37. Small modular PLC mounted on DIN-rail, 24V supply cheaper (€5000) not water-proof, no ventilator extensible by a parallel bus (flat cable or rail) courtesy ABB courtesy Backmann
- 38. Specific controller (railways) data bus special construction: no fans, large temperature range, vibrations three PLCs networked by a data bus.
- 39. Compact or modular? € # I/O modules Limit of local I/O compact PLC (fixed number of I/Os) modular PLC (variable number of I/Os field bus extension
- 40. Industry-PC Wintel architecture (but also: Motorola, PowerPC), MMI offered (LCD..) Limited modularity through mezzanine boards (PC104, PC-Cards, IndustryPack) Backplane-mounted versions with PCI or Compact-PCI Competes with modular PLC no local I/O, fieldbus connection instead, courtesy INOVA courtesy MPI costs: €2000.-
- 41. Soft-PLC (PC asPLC) • PC as engineering workstation • PC as human interface (Visual Basic, Intellution, Wonderware) • PC as real-time processor (Soft-PLC) • PC assisted by a Co-Processor (ISA-or PC104 board) • PC as field bus gateway to a distributed I/O system 2 12 2 3 3 23 4 I/O modules
- 42. Compact PLC Monolithic(one-piece) construction Fixed casing Fixed number of I/O (most of them binary) No process computer capabilities (no MMC) Can be extended and networked by an extension (field) bus Sometimes LAN connection (Ethernet, Arcnet) Monoprocessor Typical product: Mitsubishi MELSEC F, ABB AC31, SIMATIC S7 costs: €2000 courtesy ABB courtesy ABB courtesy ABB
- 43. Specific Controller (example:Turbine) Thermocouple inputs binary I/Os, CAN field bus RS232 to HMI Relays and fuses Programming port cost: €1000.- tailored for a specific application, produced in large series courtesy Turbec
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- 46. What is aPLC? Inputs Outputs The Basic Block A PROGRAMMABLE LOGIC CONTROLLER is a solid state control system that continuously monitors the status of devices connected as inputs. Based upon a user written program, stored in memory, it controls the status of devices connected as outputs. CPU
- 47. A PLC issimply a block / device use to MANIPULATE input signal by using certain RULES The manipulation process called Control The rules called Program
- 48. Basic criteria forPLC Types Memory Capacity I/O Range Packaging and Cost per Point
- 49. PLC evolution A B P2 P1 I1 Analog World Binary World C continuous processes Regulation, controllers discrete processes combinatorial sequential relay controls, Relay control pneumatic sequencer Pneumatic and electromechanical controllers Programmable Logic Controllers
- 51. PLC: Location inthe control architecture Enterprise Network directly connected I/O Control Bus (e.g. Ethernet) Engineer station I/O I/O I/O I/O CPU Sensor Bus (e.g. ASI) Field Bus gateway Field Stations Control Station with Field Bus direct I/O I/O Field Devices FB gateway gateway I/O I/O I/O I/O CPU COM I/O I/O I/O COM CPU COM COM COM I/O Field Bus CPU COM 2 I/O I/O I/O CPU COM1 COM 2 I/O CPU Operator station large PLCs small PLC PLC PLC COM1 COM1 Supervisor Station data concentrators, not programmable, but configurable
- 52. MAJOR COMPONENTS OFA PLC PROCESSOR POWER SUPPLY I M N O P D U U T L E O M U O T D P U U L T E PROGRAMMING DEVICE From SENSORS Pushbuttons, contacts, limit switches, etc. To OUTPUT Solenoids, contactors, alarms etc.
- 53. GeneralPLC architecture CPU Real-TimeClock flash EPROM ROM buffers signal conditioning power amplifiers relays signalconditioning serial port controller Ethernet parallel bus ethernet controller RS 232 analog- digital converters digital- analog converters Digital Output Digital Input fieldbus controller external I/Os extension bus field bus direct Inputs and Outputs
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- 55. COMPUTERISED CONTROL SYSTEM Reference signal controller Actuator system Output signal COMPUTER Measurement element Block Diagram of Closed Loop System
- 56. The signal chainwithin a PLC analogvariable (e.g. 4..20mA) filtering & scaling analog- digital converter processing digital- analogconverter analogvariable e.g. -10V..10V time y time y(i) sampling binaryvariable (e.g. 0..24V) filtering sampling time y transistororrelay binaryvariable amplifier 011011001111 counter 1 non-volatile memory 0001111 time y(i)
- 57. A/D CPU U/I Trip Digital filter Sample and holdA/D conversion Inputtransformer Anti aliasing filter Protectionalgorithm Outputdriver f = 1 MHz f = 200 kHz f = 100 kHz f = 300 -1200 Hz reaction < 10 ms
- 58. I/O Module DCINPUT MODULE OPTO- ISOLATOR IS NEEDED TO: Prevent voltage transients from damaging the processor. Helps reduce the effects of electrical noise Current Limiting Resistor FROM INPUT DEVICE USE TO DROP THE VOLTAGE TO LOGIC LEVEL Buffer, Filter, hysteresis Circuits TO PROCESSOR
- 59. I/O Module ACINPUT MODULE OPTO- ISOLATOR IS NEEDED TO: Prevent voltage transients from damaging the processor. Helps reduce the effects of electrical noise Rectifier, Resistor Network FROM INPUT DEVICE CONVERTS THE ACINPUT TO DCAND DROPS THE VOLTAGE TO LOGIC LEVEL Buffer, Filter, Hysteresis Circuits TO PROCESSOR
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- 62. I/O Module DC/ AC OUTPUT MODULE OPTO- ISOLATOR IS NEEDED TO: Prevent voltage transients from damaging the processor. Helps reduce the effects of electrical noise FROM PROCESSOR TTL Circuits Amplifier RELAY TRIAC X’SISTOR TO OUTPUT DEVICE
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- 64. I/O Circuits 4.Analog I/O Circuitsofthistypesenseordriveanalogsignals. Analog inputs come from devices, such as thermocouples, strain gages, or pressure sensors, that provide a signal voltage or current that is derived from the process variable. StandardAnalogInputsignals:4-20mA;0-10V Analog outputs can be used to drive devices such as voltmeters, X-Y recorders, servomotor drives, and valves through the use of transducers. Standard Analog Output signals: 4-20mA; 0-5V; 0-10V
- 65. PLC INPUTS OUTPUTS MOTOR LAMP CONTACTOR PUSHBUTTONS
- 66. L1 L2 P.B SWITCH INPUT MODULE WIRING DIAGRAM LADDER PROGRAM I:2 0 I= Input Module slot # in rack Module Terminal # Allen-Bradley 1746-1A16 Address I:2.0/0
- 67. N.O C L2 L1 L1 L2 OUTPUT MODULE WIRING MOTOR CONTACTOR O:4 0 CONTACTOR LADDER PROGRAM L1 L2 FIELD WIRING •SOLENOID •VALVES •LAMP •BUZZER
- 68. Discrete Input Adiscrete input also referred as digital input is an input that is either ON or OFF are connected to the PLC digital input. In the ON condition it is referred to as logic 1 or a logic high and in the OFF condition maybe referred to as logic o or logic low. Normally Open Pushbutton Normally Closed Pushbutton Normally Open switch Normally Closed switch Normally Open contact Normally closed contact
- 69. IN PLC Analog Input Module Tank Level Transmitter An analog input is an input signal that has a continuous signal. Typical inputs may vary from 0 to 20mA, 4 to 20mA or 0 to10V. Below, a level transmitter monitors the level of liquid in the tank. Depending on the level Tx, the signal to the PLC can either increase or decrease as the level increases or decreases. Analog Input
- 70. Memory Map Organization SYSTEM •System memory includes an area called the EXECUTIVE, composed of permanently-stored programs that direct all system activities, such as execution of the users control program, communication with peripheral devices, and other system activities. •The system memory also contains the routines that implement the PLC’s instruction set, which is composed of specific control functions such as logic, sequencing, timing, counting, and arithmetic. •System memory is generally built from read-only memory devices. APPLICATION •The application memory is divided into the data table area and user program area. •The data table stores any data associated with the user’s control program, such as system input and output status data, and any stored constants, variables, or preset values. The data table is where data is monitored, manipulated, and changed for control purposes. •The user program area is where the programmed instructions entered by the user are stored as an application control program. •Data Table •User Program
- 71. Memory Designs VOLATILE. A volatile memory is one that loses its stored information when power is removed. Even momentary losses of power will erase any information stored or programmed on a volatile memory chip. Common Type of Volatile Memory RAM.Random Access Memory(Read/Write) Read/write indicates that the information stored in the memory can be retrieved or read, while write indicates that the user can program or write information into the memory.
- 72. Memory Designs Thewords random accessrefer to the ability of any location (address) in the memory to be accessed or used. Ram memory is used for both the user memory (ladder diagrams) and storage memory in many PLC’s. RAMmemory must have battery backupto retain or protect the stored program.
- 73. Memory Designs SeveralTypes of RAM Memory: 1.MOS 2.HMOS 3.CMOS The CMOS-RAM (Complimentary Metal Oxide Semiconductor) is probably one of the most popular. CMOS- RAM is popular because it has a very low current drain when not being accessed (15microamps.), and the information stored in memory can be retained by as little as 2Vdc.
- 74. Memory Designs NON-VOLATILE Has the ability to retain stored information when power is removed, accidentally or intentionally. These memories do not require battery back-up. Common Type of Non-Volatile Memory ROM, Read Only Memory Read only indicates that the information stored in memory can be read only and cannot be changed. Information in ROM is placed there by the manufacturer for the internal use and operation of the PLC.
- 75. Memory Designs OtherTypes of Non-Volatile Memory PROM,Programmable Read Only Memory Allows initial and/or additional information to be written into the chip. PROM may be written into only once after being received from the PLC manufacturer; programming is accomplish by pulses of current. The current melts the fusible links in the device, preventing it from being reprogrammed. This type of memory is used to prevent unauthorized program changes.
- 76. Memory Designs EPROM,ErasableProgrammable Read Only Memory Ideally suited when program storage is to be semi- permanent or additional security is needed to prevent unauthorized program changes. The EPROM chip has a quartz window over a silicon material that contains the electronic integrated circuits. This window normally is covered by an opaque material, but when the opaque material is removed and the circuitry exposed to ultra violet light, the memory content can be erased. The EPROM chip is also referred to as UVPROM.
- 77. Memory Designs EEPROM,Electrically Erasable Programmable Read Only Memory Also referred to as E2PROM, is a chip that can be programmed using a standard programming device and can be erased by the proper signal being applied to the erase pin. EEPROM is used primarily as a non-volatilebackup for the normal RAM memory. If the program in RAM is lost or erased, a copy of the program stored on an EEPROM chip can be down loaded into the RAM.
- 78. Specifications MEMORY CAPACITY The amount of memory required for a particular application is related to the length of the program and the complexity of the control system. Simple applications having just a few relays do not require significant amount of memory. Program length tend to expand after the system have been used for a while It is advantageous to a acquire a controller that has more memory than is presently needed.
- 79. While the PLCis running, the scanning process includes the following four phases, which are repeated continuously as individual cycles of operation: PHASE 2 Program Execution PHASE 3 Diagnostics/ Comm PHASE 4 Output Scan PHASE 1 Read Inputs Scan
- 80. PHASE 1 –InputStatus scan A PLC scan cycle begins with the CPU reading the status of its inputs. PHASE 2–Logic Solve/Program Execution The application program is executed using the status of the inputs PHASE 3–Logic Solve/Program Execution Once the program is executed, the CPU performs diagnostics and communication tasks PHASE 4 -Output Status Scan •An output status scan is then performed, whereby the stored output values are sent to actuators and other field output devices. The cycle ends by updating the outputs.
- 81. CHECK INPUT STATUS First the PLC takes a look at each I/O to determine if it is on or off. EXECUTE PROGRAM Next the PLC executes the program one instruction at a time. UPDATE OUTPUT STATUS Finally the PLC updates the status of the outputs .It updates the outputs based on which inputs were on during the first step. PLCOPERATION
- 82. PLC Signal Flow Programming Terminal O:0/7 O:0/7 O:1/5 Output Devices Output Modules Processor Memory Input Module Input Devices Ladder Program O:0/7 O:1/5 I:0/6 I:1/4 O:1/5 I:0/6 I:1/4 I:0/6 I:1/4 Data Input Image Table Output Image Table
- 83. PLC Status Indicators •Power On •Run Mode •Programming Mode •Fault
- 84. PLC Programming Standards The open, manufacturer-independent programming standard for automation is IEC 61131-3. You can thus choose what configuration interface you wish to use when writing your application : Ladder Diagram Instruction List Function Block Diagram Sequential Function Chart Structured Text
- 85. 85 Ladder Diagram •Ladder diagrams are specialized schematics commonly used to document industrial control logic systems. •It is a language or a method to create a program. The first PLCs were programmed with a technique that was based on relay logic wiring schematics. •Basic concept of this diagram is similar to the electrical wiring. However in ladder logic, the symbol has changed and been standardized.
- 86. Ladder Diagram cont.. •Type of graphic language automatic control systems. •A drawing program of a switching circuit. •Called "ladder"diagrams because they resemble a ladder, with two vertical linesrepresenting the power trails(supply power) and circuits are connected in horizontal linescalled rungs.Connection between the element in the rungcalled link.
- 87. Ladder logic isa programming language used to develop software for PLC used in industrial control applications. RUNGES RAIL RAIL PLCPROGRAMMING
- 88. Ladder Diagram OperationalPrinciple •Referring to figure below, between these two rails, a horizontal straight line was drawn with two symbols. These two symbols refer to the input and output devices, which are used in the actual process/system. •On the left, we put all kinds of input. While on the right, we place all types of the outputs. •Once we complete one line of the program it seems like a ladder. This horizontal line which places the input and output make one rung. Input Interface Output +24V -0V
- 89. 90 PROGRAMMING NormallyOpen (NO) Normally Closed (NC) Power flows through these contacts when they are closed. The normally open (NO) is true when the input or output status bit controlling the contact is 1. The normally closed (NC) is true when the input or output status bit controlling the contact is 0.
- 90. 91 Coils Coilsrepresent relays that are energized when power flows to them. When a coil is energized it causes a corresponding output to turn on by changing the state of the status bit controlling the output to 1. That same output status bit maybe used to control normally open or normally closed contact anywhere in the program.
- 91. Ladder Diagram Symbols •Ladder diagram uses standard symbols to represent the circuit components and functions found in a control system.
- 92. DEK 3113 94 Normally Open Schematics (NO)-Input Schematics
- 93. DEK 3113 95 Normally Closed Schematics (NC)-Input Schematics
- 94. DEK 3113 96 Output Schematics
- 95. DEK 3113 97 Logic Function •There are 5 logic functions can be developed by combination of switches 1.AND 2.OR 3.NOR 4.NAND 5.EX-OR (XOR)
- 96. Logic Function…cont 1.ANDlogic coils is not energized unless both switch A and B closed. Fig. (b) represent for PLC input.
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- 98. Logic Function…cont 2.ORlogic Coils is not energized until either A or B closed
- 99. Logic Function…cont -OR •DeMorgan's Theorem would predict:
- 100. Logic Function…cont 3.NORlogic Since there has to be an output when neither A nor B have an input, and when there is an input either A or B.
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- 102. Logic Function…cont 4.NANDlogic There is no output when both A and B have an input
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- 105. Logic Function…cont 5.XORlogic There is no output when both input 1 and 2 given.
- 106. DEK 3113 Combinationof AND, OR, and inverter (NOT)gates
- 107. Control Circuit Startstop circuit -PB is pressed, output IR is activated -IR contact will closed -When PB is depressed, the output IR is still activated since current can go through contact IR unless is disturbed by stop button.
- 109. Overload protection device There are several overload protection device: 1) TOR: Thermal Overload Relay -excess heat 2) CB: Circuit Breaker -excess current 3) Fuse -excess current
- 110. DEK 3113 112 Control circuit has Overload Protection Device
- 111. Control circuit inladder diagram. -When PB is pushed(forward/reverse),motor will move according to the command. -But, when there is an overcurrent,CBwill stop the current flow by blow the fuse. -Means, NC of CB will open and stop the current flow to the circuit. -The circuit can be recovered by change the fuse. -If there is thermal overload, TOR will cut the current flow. -Lamp,L3 will turn on and TOR need to be reset.
- 112. 114 Two wirecontrol -only has one contact for switching device either ON or OFF state. -When ON state, M will energize and activate three phase motor. -Heater will heat if there is over current and open the circuit.
- 113. DEK 3113 115 Two-Wire Control Circuit •Used in application of automatic system. •Two wire used to provide voltage to load. •Applications: pump, heater or compressor. •Typically closed a disconnect switch or circuit breaker to energize the circuit. •An overload coils is located to protect the circuit against over current.
- 114. Three wire control -the connection almost the same as two wire circuit except has an extra set of contact connected in parallel as the pilot switch. -this extra contact provide extra third wire. -this auxiliary contact keep coil M energize even after start push button release.
- 116. New folder:/ Video2 video3
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- 120. 10-Siemens PLC Traininglesson-S7 300
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- 143. New folder:/ 4-SiemensStep7 S7-300 PLC Setup
- 144. New folder:/ 5-SiemensS7 300 400 PLC Hardware
- 145. New folder:/ 6-SiemensS7 Project Management