fyp. automation of box filling machine using plc 2
TRANSCRIPT
AUTOMATION OF BOX FILLING MACHINE USING
PROGRAMMABLE LOGIC CONTROLLER
Supervisor
Dr. Inamul Hasan Shaikh
Assistant Professor
Submitted By
Hanan Bin Ahmed 10-EE-47
Muhammad Jawad Kareem 10-EE-27
H. M. Atif Imtiaz 10R/09-EE-62
DEPARTMENT OF ELECTRICAL ENGINEERING
FACULTY OF ELECTRONICS & ELECTRICAL ENGINEERING
UNIVERSITY OF ENGINEERING AND TECHNOLOGY
TAXILA.
JUNE 2014
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AUTOMATION OF BOX FILLING MACHINE USING
PROGRAMMABLE LOGIC CONTROLLER
Supervisor
Dr. Inamul Hasan Shaikh
Assistant Professor
Submitted By
Hanan Bin Ahmed 10-EE-47
Muhammad Jawad Kareem 10-EE-27
H. M. Atif Imtiaz 10R/09-EE-62
A Project Report Submitted in Partial Fulfillment of the Requirements
for the Award of Bachelor’s Degree in
Electrical Engineering
DEPARTMENT OF ELECTRICAL ENGINEERING FACULTY OF ELECTRONICS & ELECTRICAL ENGINEERING
UNIVERSITY OF ENGINEERING AND TECHNOLOGY
TAXILA.
JUNE 2014
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Undertaking
We certify that project work titled “Automation of Box Filling Machine Using PLC” is our own
work. No portion of the work presented in this project has been submitted in support of another
award or qualification either at this institution or elsewhere. Where material has been used from
other sources it has been properly acknowledged / referred.
a) Hanan Bin Ahmed
Regd. # 10-EE-47
b) M. Jawad Kareem
Regd. # 10-EE-27
c) H.M. Atif Imtiaz
Regd. #10R/09-EE-62
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DEDICATION
A bird learns flying from his parents, a child learns walking from his parents and teacher is guide
to success. So,
“All from us is dedicated to our parents.”
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ACKNOWLEDGEMENT
Success and achievement is possible only through hard work, determination and strong will.
We are grateful to ALLMIGHTY ALLAH who gave me the strength to think, plan and act
accordingly which make us possible to complete our visit. Through it is a literary tradition to
acknowledge the contribution and help by different people and organization in the completion of
our Project. But as a matter of fact some words cannot express our gratitude to the various
helping hands. It is very difficult to appreciate each person for his contribution, but there is a
standing contribution of our advisor Dr. Inamul Hasan Shaikh, who was there with us at the
time we needed him and without his guidelines, it would be difficult for us to complete this
project successfully.
We would like to thank all our teachers especially “Sayd Aftab Ali Shah” and “Eng. Adil
Usman” guiding us in solving our problems.
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Abstract
In the last era, before 1892 it was a very difficult task to carry heavy load from one place to
another especially in industries. A man can carry a very small load and tired very soon. So, a
very big labor was required for this. In 1892 a concept of a Mechanical Structure named
conveyor Belt System was introduced. It was operated through big motors.it can carry the big
loads.
So, we as a group members of final year project, arise this point of view and make a small but
latest carrying equipment. This equipment resembles to a small industrial part. It has two
conveyor belts, one is for manufactured products and second is for boxes to be filled. The
carrying and transferring of products and boxes is controlled by Programmable logic controller
without any man interference. PLC is a small, simple, latest and accurate electronic device used
to control small as well as big machinery systems. By performing this automated controlled
industrial conveyor belt system, we have given to industries a new point of view to control their
heavy machinery systems and other industrial parts through PLCs. These PLCs will make their
works easy, simple and more accurate.
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Contents List of Figures .............................................................................................................................................. 10
List of Tables ............................................................................................................................................... 11
Chapter 1 .................................................................................................................................................. 12
1.1 Introduction to Automation ........................................................................................................... 12
1.2 Automation ...................................................................................................................................... 12
1.3 Industrial Automation .................................................................................................................... 13
1.4 Advantages of Automation ........................................................................................................... 13
1.5 Disadvantages of Automation ...................................................................................................... 14
1.6 Applications .................................................................................................................................... 14
1.7 Industrial Automation Tools ......................................................................................................... 14
1.8 Devices used for Automation ....................................................................................................... 14
1.8.1 Sensors ................................................................................................................................... 14
1.8.2 Controllers ............................................................................................................................. 15
1.8.3 Motion Devices ..................................................................................................................... 15
1.8.4 Indicator Lights ..................................................................................................................... 15
1.9 Programmable Logic Controller ................................................................................................... 15
1.9.1 History ..................................................................................................................................... 15
1.9.2 Introduction to Programmable Logic Controller ......................................................... 16
1.9.3 Development ......................................................................................................................... 16
1.9.4 Programming ......................................................................................................................... 16
1.9.5 PLC Configurations and Types ........................................................................................ 16
1.9.6 Single Frame PLCs .............................................................................................................. 17
1.9.7 Shoe Box PLCs ..................................................................................................................... 17
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1.9.8 Modularized PLCs ................................................................................................................ 18
1.10 Typical Components of a PLC Based System ........................................................................ 18
1.10.1 Processor or Main Case ................................................................................................... 18
1.10.2 Input and Output Modules ............................................................................................... 19
1.10.3 Digital Input/output Modules .......................................................................................... 19
1.10.4 Analog Input/output Modules ......................................................................................... 19
1.10.5 High Speed Counters ........................................................................................................ 19
1.10.6 Register Input and Output Modules .............................................................................. 19
1.10.7 Mounting Rack .................................................................................................................... 19
1.11 Programming Unit ....................................................................................................................... 20
1.12 Power Supply ............................................................................................................................... 20
1.13 Block Diagram of PLC ................................................................................................................ 20
1.14 PLC Ladder Logic Programming ............................................................................................... 21
1.15 An Example Program .................................................................................................................. 23
Chapter 2 ................................................................................................................................................... 24
2.1 Problem Statement ........................................................................................................................ 24
2.2 List of Main Components .............................................................................................................. 24
2.2.1 Conveyor Belt System ........................................................................................................ 24
2.2.2 DC Series Motor ................................................................................................................... 27
This can lead to damage of some internal components. ...................................................................... 30
Chapter #3 ................................................................................................................................................ 33
3.1 Implementation of Project............................................................................................................. 33
3.1.1 Implementation of Electric circuitry ................................................................................ 34
FEATURES ........................................................................................................................................... 35
Connection Diagrams .......................................................................................................................... 36
SCHEMATIC DIAGRAM ..................................................................................................................... 36
We are using two types of DC relays .......................................................................................................... 37
24 V DC Relay for Actuator Circuit ................................................................................................... 37
12 V DC Relay for Sensor Circuit ...................................................................................................... 37
Definition .................................................................................................................................................. 37
Connection Diagram ............................................................................................................................ 37
What is a relay? .................................................................................................................................... 37
Why is a relay used? ..................................................................................................................... 38
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NPN Relay Switch Circuit ................................................................................................................... 38
NPN Relay Switch Circuit ............................................................................................................. 39
Features ................................................................................................................................................. 39
Specifications ........................................................................................................................................ 39
COIL SPECIFICATION AT 20 ........................................................................................................ 40
Advantages ........................................................................................................................................... 45
Disadvantages ...................................................................................................................................... 45
Individual devices in the series .......................................................................................................... 46
Features ............................................................................................................................................ 47
Project hardware ........................................................................................................................................ 48
Chapter 4 .................................................................................................................................................. 50
Simulation Results ................................................................................................................................... 50
Ladder Logic programming ..................................................................................................................... 50
Explanation ................................................................................................................................................ 51
Inputs: ........................................................................................................................................................ 51
Outputs: ..................................................................................................................................................... 51
Other instructions: .................................................................................................................................... 51
Simulation Results: .................................................................................................................................. 52
Basic commands used in PLC ladder logic .......................................................................................... 52
Counter: ..................................................................................................................................................... 55
Function .................................................................................................................................................. 57
Conclusion ............................................................................................................................................... 58
Recommendations ................................................................................................................................. 59
APPENDIX ................................................................................................................................................ 60
References ............................................................................................................................................... 61
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List of Figures
Figure 1.1 industrial automation ................................................................................................................ 13
Figure 2 PLC module ................................................................................................................................... 17
Figure 3 Omron PLC Kit ............................................................................................................................... 18
Figure 4 modular PLC .................................................................................................................................. 18
Figure 5 ladder parts ................................................................................................................................... 22
Figure 6 IEC 1131-3 symbles ....................................................................................................................... 23
Figure 7 old conveyor belt .......................................................................................................................... 25
Figure 8 dc series motor ............................................................................................................................. 29
Figure 9 Motor Gear System ....................................................................................................................... 30
Figure 10 rotation of motor ........................................................................................................................ 30
Figure 11 Efficiency graph ........................................................................................................................... 32
Figure 12 DC Series Motor .......................................................................................................................... 33
Figure 13 Block Diagram ............................................................................................................................. 34
Figure 14 LM 741 IC .................................................................................................................................... 35
Figure 15 Connection Diagram of LM 741 .................................................................................................. 36
Figure 16 Schematic Diagram LM 741 ........................................................................................................ 36
Figure 17 12V DC Relay ............................................................................................................................... 37
Figure 18 Connection Diagram of Relay ..................................................................................................... 37
Figure 19 C945 ............................................................................................................................................ 41
Figure 20 Collector Current vs Vce.............................................................................................................. 42
Figure 21 Dimension of LDR ........................................................................................................................ 44
Figure 22 Voltage Regulator 7812.............................................................................................................. 45
Figure 23 Assembly of conveyors ............................................................................................................... 48
Figure 24 Assembly 2 .................................................................................................................................. 48
Figure 25 Omron PLC .................................................................................................................................. 49
Figure 26 Interfacing Circuit ........................................................................................................................ 49
Figure 27 Ladder logic code ........................................................................................................................ 50
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List of Tables Table 1 Coil Specification of Relay .............................................................................................................. 40
Table 2 Electrical Characteristics of Transistor ........................................................................................... 42
Table 3 Electrical Characteristics of LDR ..................................................................................................... 43
Table 4 Instructions used in code ............................................................................................................... 51
Table 5 Timer .............................................................................................................................................. 54
Table 6 Counter ........................................................................................................................................... 55
Table 7 Interlock instruction ....................................................................................................................... 57
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Chapter 1
1.1 Introduction to Automation
This chapter will gives you a brief introduction about the automation, history of automation and
recent advancements made in this field. This chapter will also through the light on the
advantages and disadvantages of the automation. Further, detailed information about the
applications of automation, devices employed for automation is also given in this chapter.
Automation is the back bone of industry and it is involved in each kind of process that is being
running in industry. With the invention of programmable logic controller the field of automation
has totally changed. Prior to programmable logic controllers, a large number of relays were used
for automation and this method is very costly. In addition to cost, if you want to change the
control scheme you have to rewire all the circuitry that is very time consuming and a tough job.
But programmable logic controller has changed the whole world of automation. In our final year
project we are focusing on the automation of a box filling machine using programmable logic
controller. We have tried our best to make an efficient and fully automated machine that can
place the objects of different type accurately in the box according to the user’s desire.
1.2 Automation
1.2.1 Definition
Automation may be defined as” the technique, method, or system of operating or
controlling a process by highly automatic means, as by electronic devices, reducing human
intervention to a minimum.” The term automation refers to devices such as automated machinery
or other intelligent devices that are used to control and execute some required task. The devices
used for automation ranges from small sensors like IR sensors, Proximity sensors, thermocouples
to large robots and highly efficient computers.
1.2.2 Introduction to Automation
Automation employs modern control systems and algorithms to make a process fully
automated and reduce the human interference. Automation has greatly reduced the need of
human operator and mental exercise. Everything to be performed is downloaded in the intelligent
systems in the form of program and no more human monitoring and controlling is required.
Automated machines have made the life of human easy. Automation plays an increasingly
important role in the world economy and in daily experience.
1.2.3 Why is Automation Vital?
The question is that why to employ automation, its answer is as given below. There are several
factors that force to employ automation. This first one is productivity. This is the major reason of
using automated machines in industry. By using such automated machines productivity increases
and industry get more profit for same labor hours. Second factor is the high cost of out dated
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relay automation system that employs hundreds of switches, fuses and contactors. To make a
small change you need to rewire the whole system and operators are also required. The need of
operators further increases the labor cost. Hence to make the system flexible, durable, and
productive and to eliminate human error automation is preferred. Decisions associated with
automation are usually concerned with some or all of these economic and social considerations.
1.3 Industrial Automation “The control of industrial machines and process with the help of computer by replacing human
operators is known as Industrial Automation. “
Automation is used in almost every field on earth. It is used in industry; homes; offices; schools;
military applications and in transportation system. The devices employed for automation include
different king of sensors, programmable logic controllers, actuating systems, intelligent control
systems, modern control algorithms, robotics, electronic systems and many other devices.
Figure 1.1 industrial automation
1.4 Advantages of Automation Automation has several advantages over older relay system. Automation increases productivity,
reliability, durability and safety. Automation brings many advantages when incorporated
properly. The main advantages are listed below:
1. Low production cost
2. Decrease in service cycle time
3. Better quality and reliability
4. Better utilization of floor space
5. Less by products
6. Stay competitive
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1.5 Disadvantages of Automation There are several disadvantages associated with automation. Some of them are listed below:
1. High starting cost
2. Skilled operator is required
3. Not always produce the required result
4. Difficult to maintain
1.6 Applications Automation finds its applications in every discipline. It is found in offices, homes, schools and
industry. Some of its applications are listed below:
1. Automated video surveillance
2. Automated highway airway systems
3. Automated military applications
4. Automated manufacturing and production
5. Home and office automation
1.7 Industrial Automation Tools There is a list of tools used for the industrial automation. These tools ranges from HMI by mean
on which operator controls the process, to SACDA, used for data acquisition. Different types of
industrial automation tools are listed below:
1. Simulator
2. Distributed Control System (DCS)
3. Programmable Logic Controller (PLC)
4. Human Machine Interface (HMI)
5. Supervisory Control and Data Acquisition (SCADA)
6. Batch Management System (BMS)
7. Manufacturing Execution System (MES)
8. Laboratory Information Management System (LIMS)
1.8 Devices used for Automation Some of the devices employed for the automation are given below:
1. Sensors
2. Controllers
3. Motion Devices
4. Indicator Lights
1.8.1 Sensors Sensors used for automation falls into different categories. Some of them are listed below:
1. Proximity sensors
2. Photoelectric sensors
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3. Area sensors
4. Door sensors
5. Fiber optic sensors
6. Rotary encoders
7. Pressure sensors
1.8.2 Controllers Different controllers used for automation are:
1. Temperature controllers
2. Counters
3. Timers
4. Panel meters
5. Pulse rate meters
6. Display units
1.8.3 Motion Devices Motion devices used for automation are:
1. Stepping motors
2. Stepping motor drivers
3. Motion controllers
1.8.4 Indicator Lights Different types of indicators used for automation are:
1. Indicator lights
2. Push buttons
3. Control switches
1.9 Programmable Logic Controller Programmable Logic controller is just a digital computer that is designed for
specific applications mostly for the control of industrial processes. Its applications include
conveyor belt control, control of different valves in industrial processes like bottle filling,
temperature control of boilers etc. Programmable logic controller is designed in such a way
that it can bear the harsh environment of industry. It should be able to with stand high
temperatures, vibrations and electromagnetic interferences.
1.9.1 History
The programmable logic controller was invented in response to the need of
automation industry to control various manufacturing, production and packaging processes.
In the early days to control the industrial processes a large number of relays, timers, hand
driven switches, fuses and different bulky and large components ware used. It is very
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difficult to control and manage these bulky circuits and it is too difficult to make changes in
the control scheme as whole the system is needed to be rewired and in addition to time
consuming it is also expensive. Electricians or technicians were required to do this.
1.9.2 Introduction to Programmable Logic Controller Stand harsh environment and they also lacks in the availability of a number
of discrete input/output ports. Further a computer’s response time should be fast enough to
perfectly control a process. Response time requirements vary from process to process. The
first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was
the result. Bedford Associates started a new company dedicated to developing,
manufacturing, selling, and servicing this new product: Modicon, which stood for Modular
Digital Controller. One of the people who worked on that project was Dick Morley, who is
considered to be the "father" of the PLC.
1.9.3 Development The Programmable Logic controller was invented to replace the relay logic and
hard wired circuitry. In early days the commonly used programming languages for
programmable logic controller are ladder logic and instruction list programming. Ladder
logic programming resembles the relay logic and is easy. Other modern languages used for
programmable logic controller are BASIC and C.With the invention of remote programming
terminals that graphically displays the states of different relays, contacts, timers and counters
the use of ladder logic programming gain popularity.
1.9.4 Programming In early days programmable logic controller was programmed using special
programming terminals provided by the manufacturer of the controller, which often had
dedicated function keys representing the various logical elements of programmable logic
controller programs. The facility for printing and storing program on non-volatile memory
was minimal. Now a day, programmable logic controller is programmed using application
software on personal computers. The computer is connected to the programmable logic
controller through Ethernet, RS-232, RS-485 or RS-422 communication ports using a variety
of communication protocols. User can edit the program; perform debugging using graphical
display and troubleshooting very easily using the software. The software has the functionality
of upload and downloads the program for backup and restoration purposes. In some models
of programmable logic controller, the program is transferred from a personal computer to the
PLC though a programming board which writes the program into a removable chip such as
an EEPROM or EPROM.
1.9.5 PLC Configurations and Types Programmable logic controller is much like a typical personal computer with a vast variety of
functions and options available. It is available in a number of different configurations and
specifications. The best model or configuration to be used depends on a particular situation
that how many input/output ports you need, how much memory is required etc. One can learn
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Fig. 1.1 Figure 2 PLC module
all such things only through experience and that’s why during installing a new system a
professional experienced person is required. The most basic configuration is available to a
single printed circuit board as shown in
1.9.6 Single Frame PLCs
This type of programmable logic controllers are often called single frame or open frame
programmable logic controller. This controller is totally a self-contained unit and to put it to
use it has to be installed on a control cabinet. Screws are used to make input/output
connections with the printed board. Most of the time, power supply is also external to the unit
and is provided externally through a pair of wires. This type of configuration or card can’t be
upgraded and has a limited number of input/output ports. Hence while designing the system
the user should consider the number of ports and memory required, then choose a proper
card. Single board PLC is not expensive, small easy to program and consume little power.
But on the other hand it has less number of input/output ports.
1.9.7 Shoe Box PLCs PLC is also available in another configuration named as shoe box. This type of
PLC consist of a single case in which all the input/output ports and power supply is housed.
This type of configuration is chosen depending upon the number of ports, memory and voltage
level required. Such type of PLC often has an extension port to extend the number of
input/output ports, memory or to attach external modules like analog input/output module, high
speed counter module, touch pad and addition digital ports. To connect these modules a cable is
used or sometimes these modules are directly plugged with the PLC. Figure 2.2 shows a shoe
box PLC.
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Figure 3 Omron PLC Kit
1.9.8 Modularized PLCs Finally the most recent and widely used form of PLC is modularized PLC. It has a
large number of options and you can make addition of different modules easily and its
maintenance is also easy. A modularized PLC is shown in figure 1.4
Figure 4 modular PLC
1.10 Typical Components of a PLC Based System A Programmable logic controller based system consists of a number of modules
connected to a main case or processor. Below is given the description of some of the normally
used module.
1.10.1 Processor or Main Case Processor is generally specified according to the memory required for the program to be
implemented. In modular system capability can also be a factor. This includes the features
such as PID control loops, math functions and addition commands. A self-contained processor
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usually consists of a microprocessor, program memory, communication ports, and input/output
modules and in some cases power supply.
1.10.2 Input and Output Modules Input and output modules are of different types depending on the type on the input signal and
particular application. There are digital input/output modules, analog input/output modules, high
speed counters and registers etc.
1.10.3 Digital Input/output Modules This type of input/output modules deals with digital input/output signals. These modules usually
have 8 or 16 points but some special modules may also have 32 points. These modules also have
two categories depending on the type of signal it deals with AC or DC along with the voltage
levels it is designed for.
1.10.4 Analog Input/output Modules These modules deal with the analog signals and are categorized depending on their
resolution and current or voltage range. These modules can deal with analog current as well as
analog voltage signal. Analog modules are also available that can be directly interfaced with
temperature measuring devices such as thermocouples.
1.10.5 High Speed Counters
These modules are used for the pulse type input to the PLC. These modules are
capable of measuring the frequency of input signal or can be used to count the high frequency
input signal pulses.
1.10.6 Register Input and Output Modules These types of modules are used to transfer 8 or 16 bit of data to and from the PLC.
This type of module is generally used with encoders to receive the information and with display
unit to give it the data to display. In addition to these modules there are also other modules for
specific purposes like communication modules to make serial communication between PLC and
other remote devices.
1.10.7 Mounting Rack Mounting rack is made up of metal and everything including processor, input/output
modules and power supply is mounted on it. It is normally used with modularized systems. It consist
of a printed board attached at the back and is used to attach all the devices to module. It consists of
the communication busses that connect different modules to gather and power rails that provide the
power to each module. Sometime cables are also used in addition to printed board. These mounting
racks can be mounted directly in a cabinet. Mounting racks are cascaded to interconnect several to
increase the number of input/output modules that can be accommodated.
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1.11 Programming Unit The programming unit is a hand held device that is used to download and edit the program with
the help of keypad and has a display unit to monitor the status of different coil and timers etc.
Recent advance systems employ the proprietary software that can be installed on a personal computer
and can be used to edit, debug and download the program into the PLC. Devices such as inter relays,
coil, registers that are not visible internally can be monitored through these software and help a
person in debugging a program or making a program more efficient by analyzing the values of
different registers, counters and timers. A typical programming unit is shown in figure. There is
special port on PLC that is used to connect these units to PLC.
1.12 Power Supply These units are used to supply power to PLC. As stated earlier some PLC contains their own
supply in the same case while other requires external power supplies. There are certain cases
when the internal supply of the PLC is not enough to provide the required current or voltage in
that case a separate external supply is necessary. A power supply should be chosen such that it is
capable of providing enough current required to fulfill the need of all the modules connected to
PLC.
1.13 Block Diagram of PLC Typically a PLC system has the basic functional components of processor unit, memory, power
supply unit, input/output interface section, communications interface, and the programming
device. Figure 2.5 shows the basic arrangement. The processor unit or central processing unit
(CPU) is the unit containing the microprocessor. This unit interprets the input signals and
carries out the control actions according to the program stored in its memory, communicating
the decisions as action signals to the output.
The power supply unit is needed to convert the mains AC voltage to the low DC voltage (5 V) necessary for the processor and the circuits in the input and output interface modules. The programming device is used to enter the required program into the memory of the processor. The program is developed in the device and then transferred to the memory unit of the PLC. The memory unit is where the program containing the control actions to be exercised by the microprocessor is stored and where the data is stored from the input for processing and for the output. The input and output sections are where the processor receives information from external
devices and communicates information to external devices. The inputs might thus be from
switches with the automatic drill, or other sensors such as photoelectric cells, temperature
sensors, flow sensors, or the like. The outputs might be to motor starter coils, solenoid valves, or
similar things. Input and output devices can be classified as giving signals that are discrete,
digital or analog (Figure 2.7). Devices giving discrete or digital signals are ones where the
signals are either off or on.Thus a switch is a device giving a discrete signal, either no voltage or
a voltage. Digital devices can be considered essentially as discrete devices that give a sequence
of on/off signals. Analog devices give signals of
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Which the size is proportional to the size of the variable being monitored. For example, a
temperature sensor may give a voltage proportional to the temperature.
Figure 1.5: Signals: (a) Discrete, (b) Digital, and (c) Analog
1.14 PLC Ladder Logic Programming
A very commonly used method of programming PLCs is based on the use of
ladder diagrams. Writing a program is then equivalent to drawing a switching circuit. The ladder
diagram consists of two vertical lines representing the power rails. Circuits are connected as
horizontal lines, that is, the rungs of the ladder, between these two verticals.
In drawing a ladder diagram, certain conventions are adopted:
1. The vertical lines of the diagram represent the power rails between which circuits are
connected. The power flow is taken to be from the left-hand vertical across a rung.
2. Each rung on the ladder defines one operation in the control process.
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3. A ladder diagram is read from left to right and from top to bottom. Figure 2.7 shows the
scanning motion employed by the PLC. The top rung is read from left to right. Then the
second rung down is read from left to right and so on. When the PLC is in its run mode, it
goes through the entire ladder program to the end, the end rung of the program being
clearly denoted, and then promptly resumes at the start. This procedure of going through
all the rungs of the program is termed a cycle. The end rung might be indicated by a
block with the word END or RET, for return, since the program promptly returns to its
beginning. The scan time depends on the number of runs in the program, taking about
1ms per 1000 bytes of program and so typically ranging from about 10ms up to 50ms.
4. Each rung must start with an input or inputs and must end with at least one output. The term
input is used for a control action, such as closing the contacts of a switch. The term output
is used for a device connected to the output of a PLC, such as a motor. As the program is
scanned, the outputs are not updated instantly, but the results stored in memory and all
the outputs are updated simultaneously at the end of the program scan.
5. Electrical devices are shown in their normal condition. Thus a switch that is normally
open until some object closes it is shown as open on the ladder diagram. A switch that is
normally closed is shown closed.
6. A particular device can appear in more than one rung of a ladder. For example, we might
have a relay that switches on one or more devices. The same letters and/or numbers are
used to label the device in each situation.
7. The inputs and outputs are all identified by their addresses; the notation used depends
8. On the PLC manufacturer. This is the address of the input or output in the memory of
the PLC.
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Figure 6 IEC 1131-3 symbles
1.15 An Example Program To illustrate the drawing of the rung of a ladder diagram, consider a situation where
energizing an output device, such as a motor, depends on a normally open start switch
being activated by being closed. The input is thus the switch and the output the motor.
Figure 2.9a shows the ladder diagram. Starting with the input, we have the normally open
symbol | | for the input contacts. There are no other input devices and the line terminates
with the output, denoted by the symbol ( ). When the switch is closed, that is, there is an
input; the output of the motor is activated. Only while there is an input to the contacts is
there an output. If there had been a normally closed switch |/| with the output (Figure
2.9b), there would have been an output until that switch was opened. Only while there
was no input to the contacts would there has been an o
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Chapter 2
2.1 Problem Statement Before 1892 the heavy and low load was carried from one place to another through men
labor. So, it was a difficult task to transfer heavy loads especially in industries. By
considering this point we choose such small industry project which carries some
manufactured products to their final destination using conveyor belts. In it transferring is
performed without any men labor. The whole system is automated controlled.
In our Project “Automation of Box Filling Machine Using PLC” There are different
Objects which join to each other and make a complete apparatus these are two conveyor
belt systems, two DC Series gear Motors to move conveyors, two Sensor circuits to
control the motion of motors, Actuator Circuit and The Brain of our project
Programmable Logic Controllers.
2.2 List of Main Components Conveyor Belt System
DC Series Motor
Sensor Circuit(Light Dependent Resistor and 12V DC Relays)
Actuator Circuit(24V DC Relays)
Programmable Logic Controller(PLCs)
2.2.1 Conveyor Belt System
What is Conveyor Belts?
A conveyor belt consists of two or more pulleys, with a continuous loop of material - the
conveyor belt - that rotates about them. One or both of the pulleys are powered, moving
the belt and the material on the belt forward. The powered pulley is called the drive
pulley while the unpowered pulley is called the idler. There are two main industrial
classes of belt conveyors:
a) Those in general material handling such as those moving boxes along inside a
factory and bulk material handling such as those used to transport industrial and
agricultural materials, such as grain, coal, ores, etc. generally in outdoor
locations. Generally companies providing general material handling type belt
conveyors do not provide the conveyors for bulk material handling.
b) In addition there are a number of commercial applications of belt conveyors such
as those in grocery stores.
Construction Material
The belt consists of one or more layers of material. They can be made out of rubber.
Many belts in general material handling have two layers. An under layer of material to
provide linear strength and shape called a carcass and an over layer called the cover. The
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carcass is often a cotton or plastic web or mesh. The cover is often various rubber or
plastic compounds specified by use of the belt. Covers can be made from more exotic
materials for unusual applications such as silicone for heat or gum rubber when traction is
essential.
A wide variety of related conveying machines are available, different as regards principle
of operation, means and direction of conveyance, including screw conveyors, vibrating
conveyors, pneumatic conveyors, the moving floor system, which uses reciprocating slats
to move cargo, and roller conveyor system, which uses a series of powered rollers to
convey boxes or pallets
History of Conveyor Belt System
In 1892, Thomas Robins developed a conveyor belt for carrying coal, ore and
other raw materials. Some years later, in 1901, the Swedish firm Sandvik started
with the production of conveyor belts made out of steel. In 1905, the British
mining engineer Richard Suttcliffe, designed the world’s first conveyor belt for
underground mining (to be used in coal mines). His invention revolutionized the
whole mining industry.
Figure 7 old conveyor belt
From 1907 on, conveyor belts were also used in Germany, more precisely in a
coffee company in Bremen. In 1913 famous Henry Ford became the first car
manufacturer using assembly lines with conveyor belts. In 1957, the B.F.
Goodrich Company filed a patent for the so-called Turnover Conveyor Belt
System. This system had an integrated half-twist that extended a belts lifetime
significantly, because it allowed the belt to wear and tear off on both sides.
A French society created in 1972 a straight conveyor belt with a length of 13.8
km, at the time it was the longest conveyor belt in the world. Today, the longest
conveyor belt has a length of 100 km and transports phosphate from the mines in
the Western Sahara to the coast. Nowadays such heavy belts for outdoor
transporting of bulk materials like stone, coal or boulder, are rugged rubber belt
with a steel cord traction member.
The light, fully synthetic fabric conveyor belt goes back to the 1960s, when the
industrial production of consumer goods started. These belts are mainly used for
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indoor transportation of unit loads – such as food, boxes, cans, and luggage and so
on. Constant effort on research and innovation – steady amelioration of materials
and production techniques – turned light conveyor belts gradually to versatile and
indispensable machine elements for uncountable applications in almost every
industry range.
Types of conveyor Belt System
1. Long belt conveyors
i. The longest belt conveyor system in the world is in Western Sahara. It is 98 km
(61 mi) long, from the phosphate mines of Bu Craa to the coast south of El-Aaiun.
ii. The longest conveyor system in an airport is the Dubai International
Airport baggage handling system at 63 km (39 mi). It was installed
by Siemens and commissioned in 2008, and has a combination of traditional belt
conveyors and tray conveyors.
iii. Paddington Bauxite Mine in Western Australian is officially recognized as having
the world's longest and second-longest single belts with a 31-kilometre-long
(19 mi) belt feeding a 20 km (12.5 miles) long belt.
iv. The longest single-belt international conveyor runs from Meghalaya in India to a
cement factory at Chhatak Bangladesh. It is about 17 km long and
conveys limestone and shale at 960 tons/hour, from the quarry in India to the
cement factory (7 km long in India and 10 km long in Bangladesh). The conveyor
was engineered by AUMUND France and Larsen & Toubro. The conveyor is
actuated by three synchronized drive units for a total power of about 1.8 MW
supplied by ABB (two drives at the head end in Bangladesh and one drive at the
tail end in India). The conveyor belt was manufactured in 300-meter lengths on
the Indian side and 500-meter lengths on the Bangladesh side, and was installed
on-site by NILOS India. The idlers, or rollers, of the system are unique in that
they are designed to accommodate both horizontal and vertical curves along the
terrain. Dedicated vehicles were designed for the maintenance of the conveyor,
which is always at a minimum height of 5 meters (16 ft) above the ground to
avoid being flooded during monsoon periods.
Belt conveyor safety system
Conveyors used in industrial settings include tripping mechanisms such as
trip cords along the length of the conveyor. This allows for workers to immediately shut
down the conveyor when a problem arises. Warning alarms are included to notify
employees that a conveyor is about to turn on. In the United States, the Occupational
Safety and Health Administration has issued regulations for conveyor safety and some
are below:
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Food Grade Conveyor Belts
Agriculture Belts
General Purpose Conveyor Belts
Health and Fitness Belts
Packages and Baggage Handling
Recycling Belts
Underground Mining Belts
Wood Product Conveying Belts
2.2.2 DC Series Motor A DC series motor converts electrical energy to mechanical energy. Its principle of
operation is based on a simple electromagnetic law that states that when a magnetic field
is created around current carrying conductor and interacts with an external field,
DC Series Motor Fig 2.2
The key components of a DC series motor are the armature (rotor), stator, commutator,
field windings, axle, and brushes.
The stationary part of the motor, the stator is made up of two or more electromagnet pole
pieces, and the rotor is comprised of the armature, with windings on the core connected
to the commutator. The output power source is connected to the armature windings
through a brush arrangement connected to the commutator. The rotor has a central axle
about which the rotor rotates.
The field winding should be able to support high current because the greater the amount
of current through the winding, the greater will be the torque generated by the motor. So
the winding of the motor is made up of thick heavy gauge wire. Heavy gauge wire does
not allow a large number of turns. The winding is made up of thick copper bars as it helps
in easy and efficient dissipation of heat generated as a result of flow of large amount of
current through winding.
Principle of Operation
An external voltage source is applied across the series configuration of field winding and
armature. So one end of the voltage source is connected to the winding and the other end
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is connected to the armature through the brushes. Initially at the motor start up, with the
voltage source connected to the motor, it draws a huge amount of current because both
the winding and the armature of the motor, both made up of large conductors, offer
minimum resistance to the current path. The large current through the winding yields a
strong magnetic field.
This strong magnetic field provides high torque to the armature shaft, thus invoking the
spinning action of the armature. Thus the motor starts rotating at its maximum speed in
the beginning. The rotating armature in the presence of the magnetic field results in
counter EMF, which limits the current build up in the series combination of armature and
winding.
Thus series motors once started will offer maximum speed and torque but gradually, with
an increase in speed, its torque will come down because of its reduced current. Practically
this is what required from the motors. Due to the high torque provided by the armature,
the load on the shaft is set to rotate initially. Subsequently lesser torque will keep the load
on the move. This further helps in increasing the heat dissipation of the motor. However,
the amount of torque generated by motor is directly proportional to the winding current.
The higher current demands a higher power supply, too
Motor Speed
In DC series motors, a linear relationship exists between the amount of torque produced
and the current flowing through the field windings. The speed of the motor can be
controlled by varying the voltage across the motor, which further controls the torque of
motor.
To increase the speed of the motor, decrease the field current by placing a small
resistance in parallel to the winding and armature. The decrease in current will result in
lowering of magnetic flux and counter EMF, which further hastens the motor’s speed.
To decrease the speed, use an external series resistance along with the field winding and
armature. This will reduce the voltage across the armature with the same counter EMF,
thus resulting in a lower speed of motor.
Unlike DC shunt motors, series motor does not operate at the constant speed. The speed
of the motor varies with change in the shaft load, so speed control of the motor is not
easy to put into practice.
Applications, Advantages and Precautions
Series motors can produce large turning effect, or torque, from a stand still.
These motors have found application in small electrical appliances where high
torque is necessary at start up.
DC series motors are used mainly for industrial applications, e.g. elevator and
pulley and winches systems for carrying heavy loads.
Heavy and magnificent cranes drawing thousands of amperes are driven by this
motor.
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An automobile engine can be started by this motor which draws around 500A of
current.
However, these motors are not suitable where constant speed is required as the
speed of series motors is dependent (varies with load) on load unlike DC shunt
motors whose speed is independent of load.
The construction, designing, and maintenance of these motors is very easy.
Series motors are cost effective as well.
A final advantage of series motors is that they can be used by providing either an
Alternating Current (AC) or Direct Current (DC) power source.
Precautions
Proper care should be taken that a series motor is not operated without any load as
they are totally dependent on shaft loads.
As the armature speed increases, the current through the winding decreases which
further helps in reducing the counter EMF. This reduction fastens the speed of the
armature. As this process continues, the motor speed increases beyond the limit
thus causing devastation to the motor.
Figure 8 dc series motor
What is A GEARBOX?
A gearbox uses mechanical advantage to increase output torque and reduce RPM.
The motor's shaft is feed into the gearbox and through a series of internal gearing
provides the torque and speed conversion. Our gearboxes are available in a variety of
sizes and gear ratios to meet a wide range of torque requirements. The basic design is a
spur gearbox with gear wheels in metal, plastic and combinations of the two materials. A
particular feature is the availability of freewheels and slipping clutches. The gearboxes
are turned by the motor, energy flow is from input to output shaft.
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Figure 9 Motor Gear System
That means, they are not allowed to be driven by the output shaft (for instance turning
manually)
This can lead to damage of some internal components.
Direction of rotation
As a function of the number of stages, the direction of rotation can be either clockwise or
counte clockwise. The direction of rotation of motor gearbox units is generally specified
by the gearbox output shaft.
Figure 10 rotation of motor
Ratio
A gearbox is characterized by its gear ratio i or its time T. Gear ratio i is the ratio of input
speed ne and output speed na. T is the time for one revolution of the output shaft
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Permissible Torque
The lifetime of a gearbox is determined by the load on the gear teeth and the number of
revolutions of the gear wheels. The maximum permissible torque Mn is defined by the
load on the final stage of the gearbox and the stability of the housing. Some gearboxes
have lifetime graphs. It shows the relationship between ratios i and the associated torque
for a fixed period of time, e.g. 1000 or 10000 hours. A conditional parameter is the input
speed (equivalent to motor speed) corresponding to the total number of revolutions of all
gear wheels. In the catalogue we show therefore two curves - for a motor having 250/300
rpm and 500/600 rpm.
For example: Maximum output torque Mx1 is permissible at a ratio of ix1.With smaller
ratios the max. Permissible torque has to be reduced, because otherwise the first stages of
the gearbox would be overloaded.
Example1: The application of motor 1 combined with a gearbox of ratio ix1 leads to an
output torque Mx1 at point A.
The gearbox can transmit this torque, meeting its lifetime.
Fig 2.6
If a ratio of i >ix1 is selected, actual torque would be M > Mx1. However lifetime cannot
be guaranteed, as the operating point now lies above of the lifetime curve.
Efficiency
The number of stages in the gearbox determines the efficiency. With high ratios of i this
factor will decrease below 10%, as the graph below show:
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Figure 11 Efficiency graph
Fig 2.7
Condition for Maximum Mechanical Power
The back emf is equal to half of the applied voltage for maximum gross mechanical
power. It is impossible to achieve this condition practically. Since half of the power input
is wasted as heat in the armature, efficiency will be less than 50 per cent taking account
of other mechanical losses also.
Back EMF
During rotation of the armature, its conductors cut the magnetic flux and emf is induced
in the conductors according to the laws of electromagnetic induction. The direction of
this induced emf can be found by Fleming's right-hand rule and have the direction
opposite to the applied voltage. Therefore, this induced emf is called back emf (Eb)
Rotational Losses of Dc Machines
DC motors have the following rotational losses:
i. Loss due to friction of bearings
ii. The winding loss due to consumption of power by the circulation of air or other
cooling gas in the machine and
iii. Losses in the magnetic core of the machine known as core losses or iron losses.
iv. Core losses are divided into hysteresis loss and eddy current loss.
Let Pr be the rotational loss, Pb be bearing friction loss, Pw be windage loss, Ph be
hysteresis loss, Pe be eddy current loss and Pi be iron or core loss = Ph + Pe.
Let Ta be average torque or internal torque at which the conversion of electromechanical
power takes place, Tsh be useful torque or shaft torque developed at the shaft of an
electric motor and TP be prime mover torque applied at the shaft of a generator.
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Figure 12 DC Series Motor
Chapter #3
3.1 Implementation of Project 1. Block Diagram
2. Electric Circuitry
3. Fabrication of Hardware
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Figure 13 Block Diagram
3.1.1 Implementation of Electric circuitry To drive the complete mechanism of line packaging control system and to interface with
Programmable Logic Controller (PLC) we use the electric circuitry to meet fulfill the required
conditions. Some explanation of devices used in circuit is given below one by one:
Electric Circuits Used For the Project
1) Input Sensor circuit
2) Output Actuator circuit
Basic components of sensor circuit
a) LM-741 (OP-amp)
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b) 24V DC relay
c) LDR (Light dependent resistor)
d) Resistor having various values
e) Diode
f) Transistor(c945)
g) Voltage regulator (7812)
Details and working procedure of Electrical components
3.1.1.1 Operational Amplifier (LM 741)
An operational amplifier (op-amp) is a DC-coupled high-gain electronic
voltage amplifier with a differential input and, usually, a single-ended output.
Figure 14 LM 741 IC
FEATURES Overload Protection on the Input and Output
No Latch-Up When the Common Mode Range is exceeded
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Figure 16 Schematic Diagram LM 741
Connection Diagrams
Figure 15 Connection Diagram of LM 741
SCHEMATIC DIAGRAM
3.1.1.2 Relay
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We are using two types of DC relays
24 V DC Relay for Actuator Circuit
12 V DC Relay for Sensor Circuit
Definition An electrical device, typically incorporating an electromagnet, which is activated by a
current or signal in one circuit to open or close another circuit.
Figure 17 12V DC Relay
Connection Diagram
Figure 18 Connection Diagram of Relay
What is a relay?
We know that most of the high end industrial application devices have relays for their
effective working. Relays are simple switches which are operated both electrically and
mechanically. Relays consist of a n electromagnet and also a set of contacts. The
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switching mechanism is carried out with the help of the electromagnet. There are also
other operating principles for its working. But they differ according to their applications.
Most of the devices have the application of relays.
Why is a relay used?
The main operation of a relay comes in places where only a low-power signal can be used
to control a circuit. It is also used in places where only one signal can be used to control a
lot of circuits. The application of relays started during the invention of telephones. They
played an important role in switching calls in telephone exchanges. They were also used
in long distance telegraphy. They were used to switch the signal coming from one source
to another destination. After the invention of computers they were also used to perform
Boolean and other logical operations. The high end applications of relays require high
power to be driven by electric motors and so on. Such relays are called contactors.
Main Types of DC Relays
NPN Relay Switch Circuit A typical relay switch circuit has the coil driven by a NPN transistor switch, TR1 as
shown depending on the input voltage level. When the Base voltage of the transistor is
zero (or negative), the transistor is cut-off and acts as an open switch. In this condition no
Collector current flows and the relay coil is de-energized because being current devices,
if no current flows into the Base, then no current will flow through the relay coil.
If a large enough positive current is now driven into the Base to saturate the NPN
transistor, the current flowing from Base to Emitter (B to E) controls the larger relay coil
current flowing through the transistor from the Collector to Emitter.
For most bipolar switching transistors, the amount of relay coil current flowing into the
Collector would be somewhere between 50 to 800 times that of the required Base current
to drive the transistor into saturation. The current gain, or beta value ( β ) of the general
purpose BC109 shown is typically about 290 at 2mA (Datasheet).
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NPN Relay Switch Circuit
Figure 3.6
Note that the relay coil is not only an electromagnet but it is also an inductor.
When power is applied to the coil due to the switching action of the transistor, a
maximum current will flow as a result of the DC resistance of the coil as defined
by Ohms Law, (I = V/R). Some of this electrical energy is stored within the relay
coil’s magnetic field.
When the transistor switches “OFF”, the current flowing through the relay coil decreases
and the magnetic field collapses. However the stored energy within the magnetic field has
to go some where and a reverse voltage is developed across the coil as it tries to maintain
the current in the relay coil. This action produces a high voltage spike across the relays
coil that can damage the switching NPN transistor if allowed to build up.
So in order to prevent damage to the semiconductor transistor, a “flywheel diode”, also
known as a freewheeling diode, is connected across the relay coil. This flywheel diode
clamps the reverse voltage across the coil to about 0.7V dissipating the stored energy and
protecting the switching transistor. Flywheel diodes are only applicable when the supply
is a polarized DC voltage. An AC coil requires a different protection method, and for this
an RC snubber circuit is used.
Features Very small size with light weight. Various coil sensitivity types are available.
Plastic sealed type is available for washing protective.
Wide operation coil voltage range.
Specifications
Max. 100mΩ at initial value.
Contact Resistance Test Current: 1A, Open Circuit Test Voltage: 6VDC.
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By using Voltage Drop Method.
Contact Capacity 2 Amps at 120VAC Cosφ=1.
2 Amps at 24VDC L/R=0.
Operate Time 5m Sec. Max.
Release Time 3m Sec. Max.
COIL SPECIFICATION AT 20 Table 1 Coil Specification of Relay
Nominal Nominal Coil Power Pull-In Drop-Out
Max.
Coil Allowable
Voltage Current Resistance Consumption Voltage Voltage
Sensitivity Voltage
(VDC) (mA) (Ω±10%) (W) (VDC) (VDC)
(VDC)
3 120 25
5 71.4 70
ST-D
6 60 100 Abt. 0.36
75% 5% 130%
9 40 225 Max. Min.
12 30 400
24 15 1,600
3 66.7 45
5 40 125
ST-T
6 33.3 180 Abt. 0.20
75% 5% 130%
9 22.5 400 Max. Min.
12 16.7 720
24 8.3 2,880
3 50.0 60
5 29.9 167 80% 5%
ST-L 6 25.0 240 Abt. 0.15 130%
Max. Max.
9 16.7 540
12 12.5 960
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3.1.1.3 Transistor C945
A C945 transistor is a type of negative-positive-negative (NPN) bipolar junction transistor.
Typically, circuits where a low-current, high-speed transistor is required will employ a
transistor such as the C945 transistor. Circuits such as a small-signal amplifier or a high-
speed switching circuit might employ one or more C945 transistors. A C945 transistor can be
used in several types of electronic circuits, but it is best suited for use in low-power
applications.
Figure 19 C945
Bipolar junction transistors contain three semiconductor regions: the collector, the base and
the emitter. An NPN bipolar junction transistor — such as the C945 — contains a base
region that is doped with positive, or P-type, semiconductor material, along with collector and
emitter regions that are doped with negative, or N-type, semiconductor material. This
configuration allows the C945 transistor to conduct electric current between the collector and
emitter regions when voltage is applied to the transistor’s base region.
Configuration of pins
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Table 3.2
Table 2 Electrical Characteristics of Transistor
Figure 20 Collector Current vs Vce
Figure 3.8
Total Power Dissipation vs Ambient Temperature Collector Current vs
Collector to Emitter Voltage
3.1.1.4 LDR (Light dependent resistor)
A photo resistor or light dependent resistor or Cadmium Sulfide (CdS) is a resistor whose
value resistance decreases with increasing incident light intensity. It can also referred to a
Photoconductor.
A photo resistor is made of a light resistance semiconductor. If light falling on the device
is of high enough frequency. Photons absorbed by the semiconductor give bound
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electrons enough energy to jump into the conduction band. The resulting free electron
and it hole partner conduct electricity thereby lowering resistance.
Applications
Auto flash for cameras
Industrial control
Photoelectric control
Photo switch
Room light control
Photo lamp
Photo musical I.C.
Electronic toys
Circuit Diagram
Electrical characteristics TA = 25°C. 2854°K tungsten light source
Table 3 Electrical Characteristics of LDR
Parameter Conditions Min. Typ. Max. Units
Cell resistance 1000 lux - 400 - Ω
10 lux - 9 - kΩ
Dark resistance - 1.0 - - MΩ
Dark capacitance - - 3.5 - pF
Rise time 1 1000 lux - 2.8 - Ms
10 lux - 18 - Ms
Fall time 2 1000 lux - 48 - Ms
10 lux - 120 - Ms
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Figure 3.9 Figure 21 Dimension of LDR
Features Wide spectral response Low cost Wide ambient temperature range.
Dimensions
Light memory characteristics Light dependent resistors have a particular property in that they remember the lighting conditions in which they have been stored. This memory effect can be minimised by storing the LDRs in light prior to use. Light storage reduces equilibrium time to reach steady resistance values.
Spectral Reponse
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3.1.1.5 Voltage Regulator (7812)
We are using a 7812 voltage regulator which converts input 24V to output 12V. We are
using 12v DC relay to operate our sensor circuit.
Figure 22 Voltage Regulator 7812
Advantages
78xx series ICs do not require additional components to provide a constant,
regulated source of power, making them easy to use, as well as economical and
efficient uses of space. Other voltage regulators may require additional
components to set the output voltage level, or to assist in the regulation process.
Some other designs (such as a switched-mode power supply) may need
substantial engineering expertise to implement.
78xx series ICs have built-in protection against a circuit drawing too much power.
They have protection against overheating and short-circuits, making them quite
robust in most applications. In some cases, the current-limiting features of the
78xx devices can provide protection not only for the 78xx itself, but also for other
parts of the circuit.
Disadvantages
The input voltage must always be higher than the output voltage by some
minimum amount (typically 2.5 volts). This can make these devices unsuitable for
powering some devices from certain types of power sources (for example,
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powering a circuit that requires 5 volts using 6-volt batteries will not work using a
7805).
As they are based on a linear regulator design, the input current required is always
the same as the output current. As the input voltage must always be higher than
the output voltage, this means that the total power (voltage multiplied by current)
going into the 78xx will be more than the output power provided. The extra input
power is dissipated as heat. This means both that for some applications an
adequate heat sink must be provided, and also that a (often substantial) portion of
the input power is wasted during the process, rendering them less efficient than
some other types of power supplies. When the input voltage is significantly higher
than the regulated output voltage (for example, powering a 7805 using a 24 volt
power source), this inefficiency can be a significant issue
Individual devices in the series TS7805 linear voltage regulator in a TO-220 variant package with electrically isolated
tab.
There are common configurations for 78xx ICs, including 7805 (5 volt), 7806 (6 volt),
7808 (8 volt), 7809 (9 volt), 7810 (10 volt), 7812 (12 volt), 7815 (15 volt), 7818
(18 volt), and 7824 (24 volt) versions. The 7805 is common, as its regulated 5 volt supply
provides a convenient power source for most TTL components. Each device in this series
has minimum input voltage to be maintained to get regulated output.
Less
comm
on are
lower
-
power
versions such as the LM78Mxx series (500 mA) and LM78Lxx series (100 mA) from
Part Number Output Voltage (V) Minimum Input Voltage (V)
7805 +5 7.3
7806 +6 8.3
7808 +8 10.5
7810 +10 12.5
7812 +12 14.6
7815 +15 17.7
7818 +18 21.0
7824 +24 27.1
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National Semiconductor. Some devices provide slightly different voltages than usual,
such as the LM78L62 (6.2 volts) and LM78L82 (8.2 volts) as well as STMicroelectronics
L78L33ACZ (3.3 volts)
Features
Output Current up to 1A
Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24
Thermal Overload Protection
Short Circuit Protection
Output Transistor Safe Operating Area Protection
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Project hardware
Figure 23 Assembly of conveyors
Figure 24 Assembly 2
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Figure 25 Omron PLC
Figure 26 Interfacing Circuit
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Chapter 4
Simulation Results
Ladder Logic programming
Figure 27 Ladder logic code
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Explanation
In above ladder logic:
Inputs:
1. Box detector sensor
2. Counter input
3. Emergency switch
Outputs:
1. Stop the box conveyor
2. Stop the product conveyor
3. Counter output
Other instructions:
1. Timer
2. Counter
3. Interlock
Name of
instruction
Input/output Status Address of I/O
Box detector
sensor Input N/C 0.02
Counter input Input N/O 0.03 Emergency switch Input N/O 0.04 Stop the box
conveyor Output N/C 1.00
stop the product
conveyor Output N/O 1.01
Counter output Output N/O 1.02 Timer Input/output N/O T0001 Counter Input/output N/O C0000
Table 4 Instructions used in code
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Simulation Results:
In normal operation status box detection sensor (0.02) is ON (normally close N/C). And
stop the box conveyor (1.00) is in OFF status (N/C). When 0.02 turns ON the 1.00 also
turns ON and PLC sends a signal and turns OFF the box conveyor motor. At same while
0.02 turns ON the product conveyor (1.01). The sensor on the edge of product conveyor
acts as counter input (0.03) and sends signal to PLC and counts the products falling from
product conveyor. When counter reaches its preset value then it stops the product
conveyor (1.01) again and same time it starts the box conveyor (1.00) and same process
occurs when next box reaches in front of box detection sensor. The emergency switch
(0.04) is actually interlocking instruction. So when 0.04(N/C) is at logic 1 all ladder logic
stops and retain its condition. When 0.04 is at logic on then all ladder logic is operated
normally. Timer (T1) is for security gap.
Basic commands used in PLC ladder logic
AND
AND is used for a normally open bit connected in series. AND cannot be directly connected to the bus
bar, and cannot be used at the beginning of a logic block. If there is no immediate refreshing
specification, the specified bit in I/O memory is read. If there is an immediate refreshing specification,
the status of the Basic Input Unit's input terminal is read.
AND NOT
AND NOT is used for a normally closed bit connected in series. AND NOT cannot be directly
connected to the bus bar, and cannot be used at the beginning of a logic block. If there is no immediate
refreshing specification, the specified bit in I/O memory is read. If there is an immediate refreshing
specification, the status the Basic Input Unit's input terminals is read.
Instruction mnemonic function
AND AND Takes a logical AND of
status of the specified
operand bit and the current
execution condition.
AND NOT AND NOT Reverses the status of the
specified operand bit and
takes a logical AND with
the current execution
condition
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OR/OR NOT
OR
OR is used for a normally open bit connected in parallel. A normally open bit is configured to form a
logical OR with a logic block beginning with a LOAD or LOAD NOT instruction (connected to the
bus bar or at the beginning of the logic block). If there is no immediate refreshing specification, the
specified bit in I/O memory is read. If there is an immediate refreshing specification, the status of the
Basic Input Unit's input terminal is read.
l OR NOT
OR NOT is used for a normally closed bit connected in parallel. A normally closed bit is configured to
form a logical OR with a logic block beginning with a LOAD or LOAD NOT instruction (connected
to the bus bar or at the beginning of the logic block). If there is no immediate refreshing specification,
the specified bit in I/O memory is read. If there is an immediate refreshing specification, the status of
the Basic Input Unit's input terminal is read.
Instruction Mnemonic Function
OR OR Takes a logical OR of
ON/OFF status of specified
operand and the current
execution condition.
OR NOT OR NOT Reverses the status of the
specified bit and takes a
logical OR with the current
execution condition.
Table 4.3(OR/OR NOT)
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TIM/TIMX
Instruction Mnemonic Function code Function
Hundred-MS Timer TIM/TIMX 550 TIM or
TIMX(550)
operates a
decrementing timer
with units of 0.1-s. Table 5 Timer
Function
When the timer input is OFF, the timer specified by N is reset, i.e., the timer's PV is reset
to the SV and its Completion Flag is turned OFF.
• When the timer input goes from OFF to ON, TIM/TIMX (550) starts decrementing the
PV. The PV will continue timing down as long as the timer input remains ON and the
timer's Completion Flag will be turned ON when the PV reaches 0.
• The status of the timer's PV and Completion Flag will be maintained after the timer
times out. To restart the timer, the timer input must be turned OFF and then ON again or
the timer's PV must be changed to a non-zero value (by MOV (021), for example).
• The setting range for the set value (SV) is 0 to 999.9 s for TIM and 0 to 6,553.5 s for
TIMX (550).
• The timer accuracy is -0.01 to 0 s.
Note The timer accuracy for CS1D CPU Units is 10 ms + the cycle time. The timer
accuracy for unit version 4.1 of the CJ1-H-R is -0.1 to 0 s.
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CNT/CNTX
Instruction Mnemonic Function code function
COUNTER CNT/CNTX 546 CNT/CNTX(546)
operates a
decrementing
counter Table 6 Counter
Table 4.5(Counter)
Counter:
N: Counter Number
The counter number must be between 0000 and 4095 (decimal).
S: Set Value
BCD: #0000 to #9999
Binary: &0 to &65535 (decimal) or #0000 to #FFFF (hex
Function
• The counter PV is decremented by 1 every time that the count input goes from OFF to ON. The
Completion Flag is turned ON when the PV reaches 0.
• Once the Completion Flag is turned ON, reset the counter by turning the reset input ON or by using
the CNR (545)/CNRX (547) instruction. Otherwise, the counter cannot be restarted.
• The counter is reset and the count input is ignored when the reset input is ON. (When a counter is
reset, its PV is reset to the SV and the Completion Flag is turned OFF.)
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OUT/OUT NOT
Instruction Mnemonic Function code Function
OUTPUT OUT ---- Output the
result(execution
condition) of the
logical processing
and output it to the
specified bit
OUTPUT NOT OUT NOT ---- Reverses the result
(execution condition)
of the logical
processing, and
outputs it to the
specified bit.
Table 4.6(OUT/OUT NOT)
OUT
If there is no immediate refreshing specification, the status of the execution condition (power flow) is
written to the specified bit in I/O memory. If there is an immediate refreshing specification, the status
of the execution condition (power flow) is also written to the Basic Output Unit's output terminal in
addition to the output bit in I/O memory.
OUT NOT
If there is no immediate refreshing specification, the status of the execution condition (power flow) is
reversed and written to a specified bit in I/O memory. If there is an immediate refreshing specification,
the status of the execution condition (power flow) is reversed and also written to the Basic Output
Unit's output terminal in addition to the output bit in I/O memory.Table 4.7(SET/RESET)
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IL/ILC
Instruction Mnemonic Function code Function
INTERLOCK IL 002 Interlocks all
outputs between
IL(002) and
ILC(003) when the
execution condition
for IL(002) is OFF.
INTERLOCK
CLEAR
ILC 003 Indicates the end of
the interlock range. Table 7 Interlock instruction
Function
When the execution condition for IL (002) is OFF, the outputs for all instructions
between IL (002) and ILC (003) are interlocked. When the execution condition for IL
(002) is ON, the instructions between IL (002) and ILC (003) are executed normally.
Instruction Mnemonic Function
SET SET SET turns the operand bit
ON when the execution
condition is ON. After this,
the specified contact will
remain ON regardless of
ON/OFF of the input
condition.
RESET RSET RSET turns the operand bit
OFF when the
execution condition is ON.
After this, the specified
contact will remain OFF
regardless of ON/OFF of
the input condition.
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Conclusion We started the project with the objectives mentioned in the project statement and
achieved all of them. We have implemented the interfacing of DC Series Motors with
Programmable Logic Controller. After doing work on this project and having hand
experience of PLC, we have become a good familiar with the use of PLC.
It is concluded that PLC is a simple and useful machine in the industry because of its
easy languages.
In industries many types of processes are being controlled through PLCs, DCS and
SCADA systems. Packaging processes, bottle filling, packets filling etc. are some
examples which are controlled by PLCs.
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Recommendations After all experience and interaction with PLC we recommend some steps for the future
team who wants to proceed in this field
1. Soft start and soft stop concepts of motor should be used for vanishing inertia if
load (boxes or products) are heavy.
2. HMI and SCADA system can be used for monitoring of all processes at distance.
3. An extra sensor at the product conveyor that prevent the product conveyor from
moving without load i.e. when products shortage occurs after some seconds
product conveyor should stop automatically for prevention of energy loss.
4. Pressure sensor or weight sensor may also be used for box so we can also detect
products on the basis of pressure/weight.
5. Manual placement of objects may be replaced with robotic arm for automatic
boxes and products placement.
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APPENDIX
PLC: Programmable Logic Controller
SCADA: Supervisory Control and Data Acquisition
IL: Inter lock
ILC: Inter lock Clear
TIM: Timer
CNT: Counter
IC: Integrated Chip
N/O: Normally Open
N/C: Normally Close
DCS: Distributed Control System
HMI: Human Machine Interface
BMS: Batch Management System
MES: Manufacturing Execution System
LIMS: Laboratory Information Management System
EMF: Electromagnetic Force
Op-Am: Operational Amplifier
LDR: Light Dependent Resistance
LED: Light Emitting Diode
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References
[1]Image Courtesy, Awn Muhammad
[2]DC Series Motors, http://zone.ni.com/devzone/cda/ph/p/id/53
[3]Series Motors, http://www.tpub.com/content/neets/14177/css/14177_58.htm
[4]Bright Hub: Understanding Shunt-Wound DC Motors
[5]Series DC Motor, http://www.lmphotonics.com/DCSpeed/series_dc.htm
[6]Bright Hub: Build a DC Motor Speed Controller Circuit
[7]LM78XX Series Voltage Regulator:www.DatasheetCatalog.com
[8]C945 Transistor(NPN):http://www.HZ-DZ.NET
[9] C945 Transistor(NPN):http://www.weitron.com.tw
[10] http://www.ece.com.tw/product-list.php?uID=6&cID=11 (relay)
[11]http://www.oxforddictionaries.com/definition/english/relay
[12]http://electronics.howstuffworks.com/relay.htm (working of relay)
[13]http://www.ti.com/lit/ds/symlink/lm741.pdf (LM-741 OP-AMP)