Submitted by:
Ramneek Singh

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Automation
• It’s the process of making the machine self acting or self moving.
• PLC-Programmable Logic Controller
What is plc???
• A plc is a computer type device used to control equipment in an industrial facility.
• The kinds of equipments that PLC’s can control are as varied as industrial facilities themselves.
How PLC helps in removing complexity?
• In a traditional control system , all the control devices are wired directly to each other according to how the system is supposed to operate.
• But in a plc system, however, the PLC replaces the wiring between the devices. Thus, instead of being wired directly to each other, all the equipments are wired to PLC. Then the control program inside the PLC provides the wiring connections between the devices.
Have a look at an example…
– Lets say that a push button is supposed to control the operation of a motor. In a traditional control system, the push button would be wired directly to the motor. In a PLC system, however, both the push button & the motor would be wired to the PLC instead. Then, the PLC’s control program would complete the electrical circuit between the two, allowing the button to control the motor.
Control program…
• The control program is the computer program stored in the PLC’s memory that tells the PLC what to do.
• Its similar to d any other programming…
• E.g- the programming in C Language, programming in microcontrollers etc.
Advantages of PLC
• High reliability
• Small space requirements
• Computing capabilities
• Reduced costs
• Ability to withstand harsh environments
• expandability
Difference between the old techniques and the PLC’s.. old techniques
 Huge, costly & inflexible
 Trouble shooting by running the actual system
 Less speed
 Low quality & less productivity plc’s
 Small, inexpensive, flexible
 Trouble shooting through software
 Fast speed
 Improved quality and productivity
Manufacturers of plc
1 Rockwell automation
2 AB- Allen Bradley
3 Siemens
4 Schneider electric
5 Mitsubishi electric
6 Honey well
7 Emerson
Need for PLC
• Due to the disadvantages of the hardwired control panels industry saw the need to replace them with PLC’s.
• Increased competition to manufacturers to improve both quality and productivity.
• Flexibility, rapid changeover and reduced time became important.
Inputs and outputs of PLC
* I/O modules are the devices with connection terminals to which the field devices are wired. Together, the rack and the I/O modules form the interface between the field devices and the PLC. This creates the physical connection between the field equipment and PLC.
• All the field devices connected to a PLC can b classified into two categories:
• Inputs- these are the devices that supply a signal to a PLC.
• e.g. push buttons, switches etc
• Outputs are the devices that await a signal from a PLC to perform their control functions.
• E.g. :- lights, horns, motors , valves etc.
• Ram
• Random access memory
• Volatile memory
• User can read or write to the memory
• Timers
• On delay
• Off delay
Counter
 Up counter
 Down counter
• Flags
 Bits , bytes and words used for temporary data storage.
PII
 Process Image Input-stores status of all the inputs
• PIO
 Process Image Output-stores status of all the outputs.
ALU
 Arithmetic and logic unit
 It performs all the calculations and logic functions of the PLC
• Input section
 It takes input from the outside world & also protects CPU from the outside world.
 Input devices are often called field devices.
• Output section
* The output section of PLC provides connections to the real world output devices.
* The output devices might be motor, lights, valves etc.
• Power supply
* The power supply is used to supply the power for the central processing unit.
* Most of the PLC’s operate on 115V AC.
Programming in PLC
About ladder logic :
origin of ladder diagram:-
The ladder diagram (LD) programming originated from the graphical representation used to design an electrical control system.
Advantages of LD
 LD was developed to make program creation and maintenance easier.
 Computer based graphical representation of wiring diagrams was easy to understand.
 Reduced training and support cost.
• Contacts
Normally open contact -| |-
Normally closed contact -|/|-
Output –( )-
Negative output-(/)-
4 WAY TRAFFIC LIGHTS
• RUN PROGRAM
• THANKS
AC Drives
• Ac are also known as Inverters, Variable speed Drives (VSD’s), Variable Frequency Drives (VFD’s) & frequency Converters.
• Ac drives are used to used to control induction motors & in some applications fixed speed is required.. Ac drives provides the solution by modifying the voltage and frequency of the AC supply to the motor. Control is achieved either by estimating the motor speed known as OPEN LOOP CONTROL, or by measuring the speed, known as CLOSED LOOP CONTROL.
Open Loop Control
• Open loop control provides the simplest means of controlling AC induction motors, as the speed of the supply, a basic means of control is simply to vary the voltage & frequency to achieve the desired motor speed.
• Open Loop Drives are used where the Motor is never required to hold a load at zero or low speed and where the torque and speed accuracy are not important.
Applications
Typical applications includes;
 Pumps
 Fans
 Conveyors
 Mixers
 centrifuges
Closed Loop Control
• Closed Loop Control is achieved by using a speed and position sensors connected to the motor shaft. The result is stable, accurate, dynamic speed & torque control from standstill through to max speed.
Applications
o cranes & hoists
o Lifts
o Material handling
o Automotive testing