Upload
chandan-mandal
View
223
Download
0
Embed Size (px)
Citation preview
CONTENT:
1. ACNOWLEDGEMENT
Write your own Text
2. INTRODUCTION
Write your own TextINDEX:
SECTION A:1. GENERAL OVERVIEW OF PLC – Given below, edit if you like
A. ROCKWELL
Write your own text
(Hardware platform – FlexLogix 5434, Software platform – RSLogix 5000, HMI – RSView32)
2. FACTORY VISIT
Write your own text(PLC Panel – Visual observation, system info, continuity check, Control Desk/Post)
SECTION B: AUTOMATION PROJECT ON AIR POLLUTION CONTROL
A. PROJECT OBJECTIVEB. LOGIC WRITE UPC. LADDER PROGRAME. HMI SCREEN SHOTS
SECTION A
1. WHAT IS INDUSTRIAL AUTOMATION
Industrial Automation is the use of Control Systems to control Industrial Machinery and Processes, reducing the need for human intervention.
If we compare a job being done by human and by Automation, the physical part of the job is replaced by use of a Machine, whereas the mental capabilities of the human are replaced with the Automation.
The human sensory organs are replaced with electrical, mechanical or electronic Sensors to enable the Automation systems to perform the job.
For example, a grinding wheel driven by a human can be replaced by a motor (which is a machine). But starting and stopping the grinding, which were done by the human by ‘looking at’ the output, will be replaced by the control of the motor by Automation.
Higher level of human intelligence like planning, analysis, prediction and intuitive decision making is not done by this Level of Automation.
Automation compared to human activity
HUMAN BRAIN
SENSORY ORGANSLIMBS TO DO
THE WORK
AUTOMATION
SENSORS
IN FIELD
CONTROL OF MACHINES & DEVICES
CONTROL SYSTEMS USED IN INDUSTRIAL AUTOMATION
• Micro-controllers
• Programmable (Logic) Controllers or PLC• Distributed Control System or DCS
• Computers, etc.
WHAT IS PROGRAMMABLE (LOGIC) CONTROLLER
Programmable (Logic) Controller or PLC is a type of computer commonly used in commercial and industrial control applications.
The prominent manufacturers of PLC are Allen-Bradley (Rockwell), Siemens, GE Fanuc, Schneider Electric, Mitsubishi, etc.
HOW IS PLC DIFFERENT FROM COMMON COMPUTERS
The PLC and computers are different in their hardware and software as their target application and solution areas are different. While the computer is required to do many activities simultaneously or compute and handle huge amount of data, the PLC is required to interact with the process and focus on controlling a physical process reliably, which means, common PC syndromes like hang, crash or reboot can not be tolerated for a PLC.
Hence, the difference can be summarized as follows:
The number of simultaneous processes handled by PC is more than PLC
PC is faster in terms of processor speed and data handling capacity
PLC has higher capability of handling external input output signals, specially discreet input and outputs
The PLC is more reliable, repetitive and precise for a particular job
PLCs are very rugged and designed to work under harsh ambient conditions
PLC hardware is generally modular and expandable
PLC is essentially a Real Time System
REAL TIME SYSTEM
A system is a Real Time System when it can respond to an external event within a specified window of time.
Responses can be periodic, time-initiated, input driven or interrupt driven. The time is determined by the time constant of the dynamic process.
Example of time constants for external processes:
• Milliseconds for machining or electric power systems
• Seconds for flow / pressure processes
• Minutes for temperature controlled processes
• Weeks/months/years for social / economic processes
LEVELS OF AUTOMATION
Automation can be categorized in various levels based on the required intelligence level. In relation to the human capabilities, both physical and mental, each level relates to a particular capability.
The definition of levels is not unique and is available in 3 Level, 4 Level, 5 level models. One of the commonly used models is described below.
Process Automation
MES
ERP Level 4
Level 3
PLC, DCS,
HMI, SCADA
FOCUS ON PROCESS & CONTROL
Level 2
Level 1
Level 0Sensors
Drives
FOCUS ON MANAGEMENT
COMPONENTS OF PLC
A PLC consists of minimum the following components:
Central Processing Unit (CPU)
Memory
Power Supply
Rail / Rack
Input Modules
Output Modules
Components of PLC
Power Supply
CPUMEMORY
INPUT OUTPUT
PROGRAMMING TERMINAL RAIL / RACK
CPU
The CPU is the “Brain” of the PLC. It essentially performs the following functions:
Updating the Input / Output status
Scanning the application program
Perform all binary (logical) and arithmetic functions as per the inputs and the application program and generate output
Communicate with Memory and Programming Terminal to read or write program or data
The CPUs are categorized primarily based on their Input/Output handling, special functions and communication capabilities.
The operating system of the CPU is permanently written in the same. Unlike personal computers, the hardware and the OS, as well as the programming software, are always from the same manufacturer.
Memory
The Memory stores the operating system, the application program and sometimes user data. Depending on the type of data to be stored, memory can be Read-Only type or ROM. Operating systems of the CPU are stored in such memory areas. The user program is generally stored in a Read-Write memory or RAM.
Memory can be built in the CPU or can be external. External memory is normally of Flash EPROM type. The RAM is normally backed up by the Battery provided in the PLC in case of power failure.
Power Supply
The Power Supply provides power to the CPU, Memory and the Input / Output modules. This is the power required by the electronics of the modules to function and NOT the field power required for the input / outputs.
Rail / Rack
The modules of a PLC are either mounted on a Rail or a Rack. While the Rail serves only as a mechanical support for the modules, the Rack serves both as a mounting support as well as a backplane. The backplane is the PCB board, similar to the motherboard of a PC, on which modules are connected.
Input / Output Modules
If CPU is the “Brain” of the PLC, Inputs are the “Sensors”. The information acquired by the inputs is used by the CPU to generate outputs. Input / Outputs are of two types:
Digital
Analog
Digital Modules
Though the digital input and output modules vary through a wide range in terms of size and type, the following are their characteristics.
Digital input modules are used to read signals from selector switches, push buttons, limit switches, proximity switches, etc
Digital output modules switch on/off relays, contactors, lamps, etc.
Digital inputs and outputs can accept 24V DC, 48V DC, 120V AC or 240V AC. The entire module is for a particular voltage.
The number of inputs / outputs or channels available on a single module can be 8, 16, 32 or 64.
The most commonly used signal voltage level is 24V DC.
Types of Digital Inputs and Outputs
DIGITAL OUTPUTS
DIGITAL INPUTS
PLC
CPU
Analog Modules The Analog Input modules are used to read signals from analog transducers, potentiometers,
etc
Analog Output modules are used to give setpoints to drives or other processes or for displaying values on meters
Types of Analog Inputs and Outputs
The principle of operation of an analog module is based on the analog to digital converters or vice versa.
For analog input modules, the analog value connected to the terminals of the analog channel is converted into digital value by means of Analog to Digital Converter (ADC). The digital value is further processed for diagnostic data like overflow, wire breakage, etc. before being sent to the CPU via the backplane bus.
For analog output modules, the digital value generated by the CPU is sent to the analog module via the backplane bus for conversion into analog value by means of Digital to Analog Converter (DAC). The digital value is processed for diagnostic data like overflow, etc. before being sent to the DAC.
Analog Input Types
Analog Inputs are available in four types –
Voltage – 0-10V, +/-10V
ANALOGOUTPUTS
ANALOG INPUTS
PLC
CPU
Current – 0-20mA, 4-20mA
Resistance – Pt100, standard resistance (linear)
Thermocouple – J, K, N, L, etc.
CONFIGURATION OF PLC
PLC is a modular system can be configured in different ways:
Centralized
In Centralized configuration, the I/Os are located near the CPU or within a short distance from it. The input/outputs, irrespective of their physical location, are wired up to the PLC panel. This type of configuration is useful when the process is compact and concentrated and not spread across a long distance.
Centralized configuration of PLC
Remote I/O
In the Remote I/O configuration, the I/Os are distributed in smaller groups and located near the devices the signals are connected to. The communication between the CPU and the I/Os are established with the help of BUS system. The protocol of the communication is specific to the manufacturer of the PLC.
The advantages of the Remote I/O systems are as follows:
Savings in wiring cost as the I/Os are wired near the field devices and the major length of the cable is one single twisted pair cable.
Troubleshooting in field cable problems become easier.
Remote I/O stations are rugged and can be housed in control desks, control posts, MCC or other similar enclosures
Remote I/O configuration of PLC
PROGRAMMING BASICS
The user develops the Application Program on a Programmer and transfers the program to the CPU for execution.
Programming is done through a Programming Software Package, which is dependant on the manufacturer and the type of PLC used.
Almost all prominent PLC vendors have PLCs in Small, Medium and Large category. The categorization is done on the I/O handling and communication capacity.
Some of the CPUs come with a mode switch on it. At PROG position, only programming can be done, but outputs are not transferred. At REM position, both programming and execution is done. At RUN position, only program execution is done, no program transfer to the CPU is allowed.
The way of execution of the program in the CPU is based on the Type of Program it is written into.
Types of Programs
The application program running in a CPU can be categorized as per their type of execution –
Cyclic Program
Time Interrupt Program
Event Interrupt Program
Startup Program
The Cyclic Program is the main program of the PLC and is executed cyclically. The status of inputs from the field and the status of outputs by the PLC is updated once every cycle.
Cyclic Program Execution
The Time Interrupt Program is a section of the program which is triggered based on a time value. E.g., this part of the program is executed every 100 mS.
The Event Interrupt Program is triggered by an event, which can be either internal or external. It can be triggered by a hardwired signal or a fault or other internal event.
Startup Programs are executed during startup only and are not processed during normal running.
A. ROCKWELL
Write your own text
(Hardware platform – FlexLogix 5434, Software platform – RSLogix 5000, HMI – RSView32)
2. FACTORY VISIT
Write your own text(PLC Panel – Visual observation, system info, continuity check, Control Desk/Post)
SECTION B – AUTOMATION PROJECT
PROJECT OBJECTIVE
To use a Programmable Logic Controller (PLC) to control Air pollution develops the PLC software and HMI Screens for the system.
LOGIC WRITE UP
The process is following:
Bag filters are used in industry for pollution control and recycling material which would normally be wasted. Take the case of a cement plant where the raw material is limestone pollution is created by flying dust at every transit point that is from conveyor to conveyor or conveyor to crusher. The flying dust is collected by suction by a fan and passing through bag filters. The dust is collected by the bag filters and clean air is sent to the atmosphere. The dust collecting on the bag is sent to the line below
Giving a high pressure pulse in the reverse direction from where it is recycled and sent back to the process.
At startup the fan is started, after closing the damper fully, and then the pulsing is started. Solenoid valves 1 to 4 are energized one at a time with a time delay in between.
LADDER PROGRAM
HMI SCREEN SHOTS