PLC based Multichannel Automatic Liquid Level Controller

PLC BASED MULTICHANNEL AUTOMATIC LIQUID LEVEL CONTROLLER ELECTRICAL ENGINEERING

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PROJECT REPORT ON PLC BASED MULTICHANNEL

LIQUID LEVEL CONTROL

DESIGN AND FABRICATED BY

NAME ENROLLMENT NO. BADGUJAR VIJAY S. 0900003

WAGHULE SAGAR N. 0900062

SURVASE SACHIN S. 0900056

PATIL MOHIT N. 0900045

NARWADE PRAVIN V. 0910005

OF

THIRD YEAR ELECTRICAL ENGINEERING

AT

GOVERNMENT POLYTECHNIC MUMBAI

BANDRA (E)

MUMBAI-400051

UNDER THE GUIDANCE OF

PROF. C.Y.TOTEWAR.

PROF. M.P.DESHPANDE.

PROF. BHANU BANDI.


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GOVERNMENT POLYTECHNIC MUMBAI (Maharashtra Government Autonomous Institute)

49, Kherwadi, A. Y. Jung Marg, Bandra (East) Mumbai-400051.

. .

CERTIFICATE

DEPARTMENT OF ELECTRICAL ENGINEERING This is to certify that the project entitled “ PLC based Multichannel Automatic

Liquid Level Controller ” is a bonafide work carried out by the students mentioned

below, under my supervision and guidance. It is approved for the fulfillment of

requirement for Diploma in ELECTRICAL ENGINEERING.

Submitted By

Name of the Students Enrollment No . 1. Badgujar Vijay S. 0900003

2. Waghule Sagar N. 0900062

3. Survase Sachin S. 0900056

4. Patil Mohit N. 0900045

5. Narwade Pravin V. 0910005

(Project Guide) (Principal)

(Head of the Department) (External Examiner)


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INDEX


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INDEX

Sr

No. Description Page No.

1 Abstract 6 2 Introduction 8 3 Literature Survey 10 4 Block Diagram 13 5 Block Diagram

Explanation 15

6 Liquid Level Sensor 21 7 Motor Control Circuit 24

7 PLC Introduction 26 8 PLC Advantages 40 9 PLC Disadvantages 46

10 Solenoid Valve 48 11 PCB Design 54

12 PCB Layout of Project

58

13 PCB Layout of Motor Control Circuit

60

14 PLC Programming 62 11 Advantages 65 12 Disadvantages 67 13 Application 69 14 Future Scope 71 15 Cost of Project 73 16 Specifications 77 17 Result and Conclusion 89 17 Bibliography 91 18 Datasheets 93 19 Acknowledgement 130


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ABSTRACT


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ABSTRACT

On our planet earth, 71% of part is occupied by water. Only 2% of water

source is usable and rest of 98% of water is salty water which has no use for human

and all living beings except in sea.

Water, the main source of life. It is the most required, important and

individual part of all living beings. We can not imagine life without water.

Our country India such a populated one is facing such a big problem of water

minimization. If proper precautions are not taken for preserving the most valuable

natural resource then it may lead to an disastrous situation.

This project is based on the theme that water should be controlled to such a level that it

can be utilized with proper use. Due to implementation of this project, water level can

be controlled automatically and hence large amount of water is saved. In future, India

will have not face such problems and there will be a vast progress in the development

of country.

SAVE WATER, SAVE LIFE …..!!!!!!


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INTRODUCTION


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INTRODUCTION

PLC based Multichannel Automatic Liquid Level Controller aims to control

the level of liquid automatically so that water going waste due to overflow of tanks can

be saved easily.

In this project , Two liquid level sensors are provided for overhead tanks and

source tanks. Those liquid level sensors are low level sensors and high sensors. These

sensors sense the level of liquid and operate relays and serves inputs to Programmable

Logic Controller (PLC). Programmable Logic Controller (PLC) is programmed to

control liquid level and maintain it at specific level in overhead tanks automatically.


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LITERATURE SURVEY


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LITERATURE SURVEY

BRIEF HISTORY

DIFFERENT METHODS OF LEVEL MEASUREMENT

The various methods employed for liquid measurement are broadly classified

as shown below.

1)Mechanical Methods.

2) Pneumatic Method.

3) Electrical Method.

4) Ultrasonic Method.

Mechanical System :-

Float Gauge :- This device consist of a float, a counter weight and linkage between them. The

counter weight keeps the linkage i.e. the chain in tension. Depending on the liquid

level, the float rises or falls and this movement of float is displayed on a dial by means

of a pointer and scale.

Electrical Methods for Level Measurement :-

Capacitance Level Indicator :-

The capacitance of parallel plate capacitor is proportional to the dielectric

strength of the insulting medium between the plates. If the area of plates and the

distance between them is kept constant.


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When the liquid level rises and covers more area between the two fixed plates,

the capacitance between the plates increases. When the liquid level falls, the

capacitance decreases. The measurement of the capacitance is the measure or liquid

level in the tank. These types of level indicators are useful for small systems and it is

very sensitive. It is suitable for continuous control or indication of level. The

disadvantages of this type of level indicators are :-

1) The reading is affected by dirt or other contaminants.

2) The sensitivity gets affected by temperature variations.

3) Calibration is often required if the liquid composition or moisture content varies.

Ultrasonic Level Indicator :-

This device consists of an ultrasonic transmitter and receiver. The ultrasonic

wave is transmitted towards the liquid surface, from where it is reflected back. The

receiver detects the signal. The time duration between the transmissions of the signal

up to its reception is a measure of the liquid level in the tank.


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BLOCK DIAGRAM


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BLOCK DIAGRAM

RELAY UNIT

AC SUPPLY230VAC, 50HZ

TRANSFORMERRECTIFIER

FILTER12VDC

PROGRAMMABLE LOGIC CONTROLLER

(PLC)

LIQUID LEVELSENSORS

SMPS24VDC750mA

OUTPUT DEVICES


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BLOCK DIAGRAM EXPLANATION


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BLOCK DIAGRAM EXPLAINATION

RECTIFIER AND FILTER :-

A full wave rectifier circuit produces an output voltage or current which is purely DC or has some specified DC component. Full wave rectifiers have some fundamental advantages over their half wave rectifier counterparts. The average (DC) output voltage is higher than for half wave, the output of the full wave rectifier has much less ripple than that of the half wave rectifier producing a smoother output waveform.

In a Full Wave Rectifier circuit two diodes are now used, one for each half of the cycle. A transformer is used whose secondary winding is split equally into two halves with a common centre tapped connection, (C). This configuration results in each diode conducting in turn when its anode terminal is positive with respect to the transformer centre point C producing an output during both half-cycles, twice that for the half wave rectifier so it is 100% efficient as shown below

RECTIFIER FILTER


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SMPS ( Switch Mode Power Supply ) :-

Electronic Power Supply that incorporates a switching regulator to convert

electrical power efficiently. Like other power supplies, an SMPS transfers power from

a source like the electrical power grid to a load (such as a Personal Computer) while


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converting voltage and current characteristics. An SMPS is usually employed to

efficiently provide a regulated output voltage, typically at a level different from the

input voltage.

Unlike a linear power supply, the past transistor of a switching mode supply

continuously switches between low dissipation, full on and full off states, and spends

early little time in the high dissipation transitions (which minimize wasted energy).

Ideally, a switched mode power supply dissipated no power, voltage regulation is

achieved by varying the ratio of to on to off time. In contrast, a linear power supply

regulates the output voltage by continuously dissipating power in the pass transistor.

This higher power conversion efficiency is an important advantage of a switched mode

power supply. Switched mode power supplies may also be substantially smaller and

lighter than a linear power supply due to the smaller transformer size and weight.

LIQUID LEVEL SENSOR :-

The Liquid Level Sensors are the probe type sensors which senses the level

of liquid in tanks. Whenever the liquid level touches the probes, relay coil is

energized. As working voltage of Liquid level Sensor is 12VDC. 12VDC supply is

provided through step down transformer, full-wave rectifier and filter circuit. This

serves as input to PLC. +24 VDC terminal is connected to the common terminal of

relay hence, it gives +24VDC at output which is further connected to the input ports of

PLC.


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PROGRAMMABLE LOGIC CONTROLLER :-

Programmable Logic Controller (PLC) is a controller for this project. It has

input as well as output ports. All the Liquid Level Sensors serves as input to PLC. As

liquid level sensors senses the liquid level, relay coil is energized and +24VDC

reaches to PLC through input module. As we have already loaded program in PLC, it

gives output according to user program and hence output devices like indicators,

solenoid valves, pump are controlled through output ports. We are using PC (Personal

Computer ) as a programming device for PLC.

RELAY UNIT :-

Due to high prices of PLC, it is very important to protect PLC from various

abnormal conditions. Relay Unit is mainly used for over-current, over-heating and

short-circuit protection so that no damage will occur to PLC.

We are using five 24VDC general purpose relay in this relay unit. Four of them are

use for operating solenoid valves and rest of one is used for operating pump.


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The +24VDC supply from output terminals of PLC is connected to relay coils.

Whenever PLC will give signal to output device, relay coil will be energized and hence

load will be operated.

OUTPUT DEVICES :-

The output devices consists of solenoid valves and pump. The connections

for the output devices are taken from relay unit. All the solenoid valves has operating

voltage of 24VDC and pump is operated by 230VAC, 50Hz supply.


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LIQUID LEVEL SENSOR


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CIRCUIT DIAGRAM

Liquid Level Sensor :

Components of Liquid Level Sensor :-

R1 - 470K Ohm

R2 - 10M Ohm

R3 - 1K Ohm

C1, 2, 3, 4 - 2.2 nF 2.2 kpf/ 222

T1 - BC557 PNP Transistor

D1, 2, 3 - IN4148

LED - 3mm Red.

IC 1 - 4093 Cmos IC

14 Pin IC Socket for IC1

Rly 1 - 12V /1 CO Relay


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Working of Liquid Level Sensor :

The actual circuit of the level sensor is extremely simple. The circuit around

N1 forms an oscillator. If the two sensors are immersed in a conducting solution, C4

will be charged up via the AC coupling capacitors (C2 and C3) and the diodes so that

after a short time the output of N2 is taken low and the relay is pulled in. The relay can

be used to start a pump for example, which in turn controls the level of the liquid.

When a conductive path between the two sensors no longer exists. C4 discharges via

R2 with the result that the output of N2 goes high and the relay drops out. The Relay

turns ON or OFF only when a contact between the two electrodes due to

presence of water.


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MOTOR CONTROL CIRCUIT


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Circuit Diagram of Motor Control Circuit :-

FROM PLC

AC SUPPLY

TO PUMP

P N

N

P

COMPONENT LIST :-

1. General Purpose Relay : 24VDC coil

2. LED 5mm : Red.

3. LED 5mm : Green.

4. Resistors : 2.2 K ohm

WORKING OF MOTOR CONTROL CIRCUIT :-

The working voltage of relay coil is 24VDC. PLC gives 24VDC at it’s

output port. The output port of PLC are further connected to relay coil terminals. 230

VAC supply is required to run 230 VAC operated pump. The common terminal is

provided with phase wire.

When supply is given to relay coil terminals, relay is operated and hence NO

terminal of relay turns into NC. These terminal is further provided to pump and hence

pump is operated

LEDs work as indicators for pump on and pump off condition. Resistors of

2.2 k ohm are provided to drop voltages from 24VDC to 3VDC, because working

voltage of LED is 3VDC. Red LED indicates that motor is OFF and Green LED

indicates that motor is ON.


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INTRODUCTION TO PLC


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Programmable Logic Controller :-


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A programmable logic controller, which is usually called PLC. More

commonly it is known as programmable controller (PC). It is a electronic device operates

on digital signal. It is designed and developed for industrial applications, hence known as

“Industrial Computer”.

PLC was originally designed to replace relay based logic systems and

solid-state hard-wired control panels. PLC has advantages over relay based system, that

they are easily programmed, more reliable, flexible, relatively inexpensive, and

capability to communicate with field computers. Modern PLC’s are powerful and more

complex.

Programmable logic controllers are used for controlling sequences of events.

Hence they are also known as sequential controllers. For example, in the bottle filling

system it senses the empty bottles, place the bottles at proper position for filling, fill

the bottles at desired locations.


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A PLC is defined by National Electrical Manufacturers Association (NEMA,

USA):

“A programmable logic controller is digitally operated electronics

system, designed for use in an industrial environment , which used a

programmable memory for the internal storage of user oriented instructions for

implementing specific functions such as logic, sequencing, timing, counting and

arithmetic to control, through digital or analog inputs and outputs, various types

of machines or processes”.

ELEMENTS OF PLC :-

o The PLC consists of following elements:

Processor (CPU)

Memory

Programming Device

Input Module

Output Module

Power Supply


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Processor ( CPU ) :-

All Programmable Logic Controller contains a Central Processing Unit

(CPU). This is the microprocessor that controls and supervises the entire process. The

CPU solves the users program and updates the status of the outputs. It executes the

various logic and sequencing functions. It is controller of a PLC.

During the program executing the processor reads the inputs, takes these

values and according to control application program, energizes or de-energizes the

outputs, thus solving the ladder network. Once the logic has been solved, the

processor will update the outputs. The process of reading the inputs, executing the

control application program, and updating the output is known as SCAN. PLC’s are

categorized by scan time. Typical scan timer ranges between 1 to 100 milliseconds.

e.g. Z80, 8086, 9900, 286, 386, 486 family are some of the CPUs.


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Memory :-

Which contains the program of logic, sequencing, and other input/output

operations. The memory of PLC may range from 1KB to 64Kb of storage capacity.

PLC memory is divided in two categories: System memory (operating system) and

application memory. System program is stored in ROM. Application program is

stored in RAM.

Programming Device :-

The PLC is programmed by means of a programming device. Through

programming device the programmer or operator can enter or edit program instructions

or data. The basic elements of a programming device are keyboard, visual display,

microprocessor and communication cable.

It is detachable from PLC cabinet so that it can be shared between

controllers. Different PLC manufacturers provide different devices. It can be

handheld programming unit or a personal computer or industrial programming

terminal.

The programming device (terminal) is normally connected only to the

programmable controller system during programming or during troubleshooting of the

control systems. Otherwise the programming device is disconnected from the system.

Functions of programming terminal are :-

Create and transfer the user program to PLCs memory.

Debug the user program and control systems start up

Perform installation diagnostics

The most common programming device are as follows:

Hand held programming unit

Industrial programming terminal

Personal computer


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Hand held programming unit :-

The hand held programmers are inexpensive and portable units, normally

used to program small PLC’s. Most of these units resemble portable calculators, bit

with larger displays and a somewhat different keyword. The displays are generally

LED or matrix LCD and the keyboard consist of alphanumeric keys, Programming

instruction keys, and special function keys. Even through they are mainly used for

inputting and editing the control program, the programmable devices are also used for

testing, changing and monitoring the program.

Hand-Held Programming unit is a ideal service tool and programmer for

PLC that easily and conveniently travels to the controller’s location.

With this device user can :

Monitor and troubleshoot controller operation

Create, enter, and modify application programs

Transfer programs between controllers


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Typical Specifications of hand-held programming unit :-

Operator Power 85 mA @ 24 Vdc

Operating Temperature 0 to 60`C

Operating Humidity 6 to 95%

Display Type 2*16 LCD

Keypad 25 ribbon/carbon based keys

Dimensions in mm Width-96, Height-180, Depth-36

Industrial Programming Terminal :-


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The industrial programming terminal is an intelligent device that not only

displays the control program but also provides program editing functions independent

of the programmable controllers. The industrial programmer normally has cathode ray

tube (CRT) displays, programs, and its own internal memory to create, alter and

monitor programs. The CRT is powerful tool for programming, since the control

program can be edited and viewed being connected to a programmable controller.


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Personal Computer :-

The latest innovations in programming terminals is the personal computer

type. This unit has all features of industrial terminals such as program editing and

storage. But, they also have added features such as automatic, program printouts and

connection to Local Area Networks (LAN’s). LAN gives the programmer or engineer

access to any programmable controllers in the network, so that any device in the

network can be monitored and controlled. Small portable computer, Laptop is also

being used for programming PLC.

Input Module :-

Input modules serve as the link between field input devices and the PLC’s

CPU. Each modules has terminal block for attaching input wiring from each

individual field input device. The main function of an input module is to take the field

device input signal, convert it to a signal level that the CPU can work with, electrically

isolate it, and send the signal by the way of the backplane board, to the Input module is

a electronic circuit, which interface the field input devices to PLC’s CPU.


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Output Module :-

Output module serves the link between the PLC’s CPU and field output

devices. Each module has a terminal block for attaching output wiring to go to each

individual field output device. The main function of an output module is to take the

CPU’s control signal (sent by way of the backplane), electrically isolate it, and

energize or de-energize the modules switching device to turn on or turn off the output

field device. Typical output modules have either 8, 16 or 32 output terminals.

Output module is electronic circuit, which interface field output devices to

PLC’s CPU.

Power Supply :-

The power supply converts AC line voltages, to power the electronic circuit

in a programmable controller systems. These power supplies consists of rectifier, filter

and regulated voltages and currents, to supply the correct amount of voltages and

current to the system. The power supply converts 230VAC line voltage into direct

current voltages such as +5 or +-15 or +24V.


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The power supply for PLC may be integrated with the processor, memory,

and I/O modules into a single housing, or it might be a separate unit connected to the

system through a cable.

The power supply is designed for the higher temperature and humidity as

PLC is used in industrial environment. It is designed to eliminate the electrical noise

present on AC power or signal lines of industrial plants, so that the noise does not

introduce errors in the control system.

PROGRAMMING LANGUAGES FOR PLC :-

The programming languages allows the users to communicate with PLC via

programming device

Ladder Diagram Language :-

The Ladder diagram (LAD) is the most common programmable controller

language.

It consists of instructions that will perform the most basic type of control

functions :

Relay-type logic

Timing and counting

Basic math operations.

However, depending on the programmable controller model,

the instruction set may be extended or enhanced to perform other operations. These

additional functions are used analog control, data manipulation, reporting, complex,

control logic, and other functions.

LAD is a symbolic instruction set that is used to create a

programmable controller program. It is composed of six categories of instructions:

relay type, timer/counter, data manipulation arithmetic, data transfer, and program

control.


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The main function of the LAD program is to control outputs

based on input conditions. This control is accomplished through the use of what is

referred to as ladder rung.

A ladder logic rung consists of a set of inputs conditions that

are represented by relay contact type instructions and, at the end of the rung, an output

instructions, which is represented by the relay coil symbols.

Coil and contacts are the basic symbols of the ladder diagram

instruction set. The contact symbols programmed in a given rung represent conditions

that need to be evaluated to determine how the output should be controlled. All

discrete outputs are represented by coil symbols.

Instruction List Language :- It is the assembly level language of any microprocessor/\computer where

operations mnemonics are used to describe the various operations performed. The

assembly language is used to express the logic of PLC.


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Instruction Mnemonic

Input / Output LD/OUT or OUT NOT/STO

Arithmetic ADD, SUB, MUL, DIV

Timer TIM

Counter CTU, CTD

Compare CMP

LD A

AD B

OUT D

Accept the input from input device A, and perform logical AND operations

with status of input device B and send this output to output device D.

Higher Level Language :- Computer Type Languages (CTL) are languages are languages that employ

English statements and instructions. They are usually similar to BASIC. Several

manufacturers use BASIC as their programming language for PLCs. Most CTLs are

easier than BASIC. They are user friendly and operator-oriented. They are easier for

operator to understand.

The LET, INPUT, READ, DATA instructions are similar to the ladder

contact symbols. The LET instruction is used to assign a number value to a variable.


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ADVANTAGES OF PLC


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ADVANTAGES OF PLC :-

Industries that exist right now, the presence of PLC is necessary especially

to replace the wiring or cabling systems that previously were used in controlling a

system. By using the PLC will get many benefits which are as follows:-

Industries that exist right now, the presence of PLC is necessary especially to

replace the wiring or cabling systems that previously were used in controlling a

system. By using the PLC will get many benefits which are as follows:-

Small size :-

They are usually very compact and do not have large space requirement.

Suitable modular design :

Elements of PLC are in modular form. PLC is designed easily using these modules.

Rugged construction :

It is rugged enough to operate in an industrial environment.

Greater reliability :

According to logic in a program, the operations are performed bu it.

Interfacing easy :

The input and output modules are provided for interfacing the input and

output field devices to it.

Ease of programming :

The powerful instructions are provided for programming the PLC. It is

programmed with a minimum time by using these instructions.


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Reprogrammed easily :-

It is programmed with a minimum time downtime.

Ability to communication with plant computers, another PLC :-

It communicate with data collection system (plant computer) placed in

control room or field. One PLC can communicate to other.

Relatively inexpensive :-

Relatively inexpensive than hardwired relay control.

Maintenance easier :-

It is modular systems, hence maintained easily and it has self diagnostic

facility.

Correcting Errors:-

In old days, with wired relay-type panels, any program alterations required

time for rewiring of panels and devices. With PLC control any change in circuit design

or sequence is as simple as retyping the logic. Correcting errors in PLC is extremely

short and cost effective.

Space Efficient:-

Today's Programmable Logic Control memory is getting bigger and bigger

this means that we can generate more and more contacts, coils, timers, sequencers,

counters and so on. We can have thousands of contact timers and counters in a single

PLC. Imagine what it would be like to have so many things in one panel.

Testing :-

A Programmable Logic Control program can be tested and evaluated in a

lab. The program can be tested, validated and corrected saving very valuable time.


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Visual Observation :-

When running a PLC program a visual operation can be seen on the screen.

Hence troubleshooting a circuit is really quick, easy and simple.

Flexible :-

In the past, each different electronic device controlled by each controller.

Suppose ten machines require ten controllers, but now with only one tenth PLC

machine can be run with each program.

Changes and error correction system easier :- If one system will be modified or corrected, the change is only done on the

programs contained in computers, in a relatively short time, after that it downloaded to

the PLC. If not using a PLC, for example relays the amendments made by altering the

wiring cables. This course takes a long time.

Number of contacts many :-

Number of contacts held by the PLC on each coil is more than the contacts

held by a relay.

Low cost :-

PLC is capable of simplifying a lot of cabling compared to a relay. So the

price of a PLC at a price cheaper than some fruit relay capable of doing the wiring for

the same amount with a PLC. PLC includes relays, timers, counters, sequencers, and

other functions.


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Operating speed :-

PLC operation speed is faster than the relay. Speed PLC scan time is

determined by its in units of milliseconds.

Resistant character test :-

Solid state devices are more resistant than the relay and test mechanical or

electrical timers. PLC is a solid state device that is more resistant test.

Simplifies the control system components :-

The PLC also have counters, relays and other components, so it does not

require components such as additional. Use of relays requires counters, timers or other

components as additional equipment.

Documentation :-

Printout of the PLC can be directly obtained and do not need to see the

blueprint of his circuit. Unlike the printout relay circuit cannot be obtained.

Security

Changing the PLC cannot be done unless the PLC is not locked and

programmed. So there is no unauthorized person can change the PLC program for a

PLC is locked.


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Can make changes by reprogramming :-

Since the PLC can be programmed quickly reset the production process that

mixes can be completed. For example part B will be executed but sections of A is still

in the process, the process in section B can be re-programmed in seconds.

Addition of faster circuits :-

Users can add a circuit controller at any time quickly, without requiring great

effort and cost as in conventional controllers.


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DISADVANTAGES OF PLC


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DISADVANTAGES :-

PLC require modules for interfacing of various input and output device.

PLC is designed for relay logic ladder and have difficulty with some smart devices.

Programming, operation, troubleshooting of PLC, training is required.

The technology is still new :-

Changing the old control system using relay ladder or to a PLC computer concept is difficult for some people

Bad for the application programs that remain :- Some applications are applications with a single function. On application by one function rarely done did not even change at all, so the use of PLC in applications with a single function will be a waste (cost).

Environmental considerations :-

In a process, the environment may experience a high heat, vibration direct contact with electrical appliances within the PLC and this event continuously, thus disrupting the performance of the PLC is not functioning optimally.

Operating with a fixed circuit :-

If the circuit in an operation are not changed then the use of more expensive

PLC compared with other control equipment. PLC will be more effective if the

program on the process to be upgraded periodically.


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SOLENOID VALVE


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SOLENOID VALVE

A solenoid valve is an electromechanical valve for use with liquid or gas.

The valve is controlled by an electric current through a solenoid: in the case of a two-

port valve the flow is switched on or off; in the case of a three-port valve, the outflow


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is switched between the two outlet ports. Multiple solenoid valves can be placed

together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics.

Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in

many application areas. Solenoids offer fast and safe switching, high reliability, long

service life, good medium compatibility of the materials used, low control power and

compact design.

Besides the plunger-type actuator which is used most frequently, pivoted-

armature actuators and rocker actuators are also used.

A solenoid valve has two main parts: the solenoid and the valve. The

solenoid converts electrical energy into mechanical energy which, in turn, opens or

closes the valve mechanically. A direct acting valve has only a small flow circuit,

shown within section E of this diagram (this section is mentioned below as a pilot

valve). This diaphragm piloted valve multiplies this small flow by using it to control

the flow through a much larger orifice.

Solenoid valves may use metal seals or rubber seals, and may also have

electrical interfaces to allow for easy control. A spring may be used to hold the valve

opened or closed while the valve is not activated.


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A- Input side

B- Diaphragm

C- Pressure chamber

D- Pressure relief conduit

E- Solenoid

F- Output side

The diagram to the right shows the design of a basic valve. At the top figure

is the valve in its closed state. The water under pressure enters at A. B is an elastic

diaphragm and above it is a weak spring pushing it down. The function of this spring is

irrelevant for now as the valve would stay closed even without it. The diaphragm has a

pinhole through its center which allows a very small amount of water to flow through

it. This water fills the cavity C on the other side of the diaphragm so that pressure is

equal on both sides of the diaphragm, however the compressed spring supplies a net

downward force. The spring is weak and is only able to close the inlet because water

pressure is equalised on both sides of the diaphram.


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In the previous configuration the small conduit D was blocked by a pin

which is the armature of the solenoid E and which is pushed down by a spring. If the

solenoid is activated by drawing the pin upwards via magnetic force from the solenoid

current, the water in chamber C will flow through this conduit D to the output side of

the valve. The pressure in chamber C will drop and the incoming pressure will lift the

diaphragm thus opening the main valve. Water now flows directly from A to F.

When the solenoid is again deactivated and the conduit D is closed again,

the spring needs very little force to push the diaphragm down again and the main valve

closes. In practice there is often no separate spring, the elastomer diaphragm is

moulded so that it functions as its own spring, preferring to be in the closed shape.

From this explanation it can be seen that this type of valve relies on a

differential of pressure between input and output as the pressure at the input must

always be greater than the pressure at the output for it to work. Should the pressure at

the output, for any reason, rise above that of the input then the valve would open

regardless of the state of the solenoid and pilot valve.

In some solenoid valves the solenoid acts directly on the main valve. Others

use a small, complete solenoid valve, known as a pilot, to actuate a larger valve. While

the second type is actually a solenoid valve combined with a pneumatically actuated

valve, they are sold and packaged as a single unit referred to as a solenoid valve.

Piloted valves require much less power to control, but they are noticeably slower.

Piloted solenoids usually need full power at all times to open and stay open, where a

direct acting solenoid may only need full power for a short period of time to open it,

and only low power to hold it.


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Types

Many variations are possible on the basic, one way, one solenoid valve

described above :

One or Two Solenoid Valves;

Direct Current or Alternating Current powered;

Different number of ways and positions;

Common uses

Solenoid valves are used in fluid power pneumatic and hydraulic systems, to

control cylinders, fluid power motors or larger industrial valves. Automatic irrigation

sprinkler systems also use solenoid valves with an automatic controller. Domestic

washing machines and dishwashers use solenoid valves to control water entry to the

machine. In the paintball industry, solenoid valves are usually referred to simply as

"solenoids." They are commonly used to control a larger valve used to control the

propellant (usually compressed air or CO2).Solenoid valves are used in dental chairs to

control air flow. In the industry solenoid" may also refer to an electromechanical

solenoid commonly used to actuate a sear.

Besides controlling the flow of air and fluids solenoids are used in

pharmacology experiments, especially for patch-clamp, which can control the

application of agonist or antagonist.


Page54

PCB DESIGNING


Page55

PCB DESIGNING

PCB for any given type of equipment’s is very important and so to prepare the

PCB is much more important. To make PCB, the systematic procedure is given below

:-

To design the circuit.

To trace the circuit design on copper board.

To print the tracks.

To give bath of FeCL3 ( Ferric Chloride ) to copper board.

To remove the paint of copper board.

To drill holes for different components.

To mount the components.

The same procedure has been followed by us and PCB dubbing mixture was

prepared.


Page56

Design the circuit :-

For this purpose we have used smart work PCB designing package. This

package is used for designing the whole PCB. It can make, as much pads as per we

want for several component placement. And even this package has facility of joining

any pads to any connection.

So using this package the PCB is designed for the audio dubbing mixture.

Trace this circuit on copper board :-

This procedure can be done using a carbon paper. A carbon paper is placed

between the circuit, design paper and the copper side of PCB. So, any design we make

on the design paper is going to the traced on the copper board. By this we should trace

full circuit on the copper board.

Paint the pads and tracks of the circuit :-

Now, the trace circuit on the copper board should be painted by enamel paint. So

that we can give ferric chloride. So, we have painted all the tracks and pads of

components.

Note :-

These three procedures are known as ARTWORK of the PCB. And below three

procedures is known as ETCHING WORK.

Give a bath of ferric chloride to the copper board :-

This procedure is to be done or not get only the track and pads of the components

of the whole circuit and to dissolve all excess copper from the board. So, we are giving

a both of ferric chloride to the printed board. So that all excess copper should be

dissolved. And after giving bath we should dry the board which contains tracks and

pads.


Page57

Remove paint from the copper board :-

After the board is dried and the excess copper is fully dissolved. Paint on the

tracks and pads should be taken off and the tracks and pads should be visible.

Drill holes on pads :-

The pads for different component should be drilled to place the components

through the holes so the hole is being drilled pads from the copper side.

Mounting of components on PCB :-

This procedure is called as assembling the PCB and this is the last procedure

after preparing the PCB. The component is being fitted to their respective places and it

is soldered properly. So at the end of this procedure we will get the proper

manufactured printed circuit board.

Soldering Techniques :-

To achieve a solder joint, the solder and the base metal must be heated above the

melting point of the solid used. The method, by which the necessary heat is applied,

depends among other things on

Nature and type of the point

Melting temperature of the solder.

Flux


Page58

PCB LAYOUT OF PROJECT


Page59


Page60

PCB LAYOUT FOR RELAY UNIT


Page61


Page62

PLC PROGRAMMING


Page63

LADDER PROGRAMMING Logic :-

1. When the NO push button is pushed , the process starts.

2. When high level of Tank one is sensed, Solenoid 1 gets OFF.

3. When low level of Tank 2 is sensed, Solenoid 2 is ON and whenever high level is

reached, Solenoid 2 gets OFF.

4. When low level of Tank 3 is sensed, Solenoid 3 gets ON and whenever high level is

reached , Solenoid 3 gets OFF.

5. If any solenoid is operated, Pump should be operated.

6. As soon as low level of Source Tank is reached, Pump should get automatically OFF.

7. If already high level of Source Tank is reached, Solenoid 4 (BMC Water Supply)

should get automatically OFF.

8. When NC push button is pushed, the process should stop working.

Input / Output List :- Input List:-

Input Address Description

I:0/0 START push button- NO Contact

I:0/1 STOP push button- NC Contact.

I:0/2 High Level of Tank 1

I:0/3 Low Level of Tank 2


I:0/5 Low Level of Tank 3


I:0/7 Low Level of Source Tank

I:0/8 High Level of Source Tank


Page64

Output List :-

Output Address Description

O:0/0 Solenoid 1 for Tank 1



O:0/3 Pump Operating Relay

O:0/4 Solenoid 4 for Source Tank

Ladder Diagram :-


Page65

ADVANTAGES


Page66

ADVANTAGES :- Low power consumption

Simple construction i.e. compact and elegant design.

High efficiency.

Save Water

Save motor from dry running and increase its life.

System is accurate.

Less Maintenance.

Easily installed.

No man power

It gives fast response.


Page67

DISADVANTAGES


Page68

DISADVANTAGES

Moisture can affect the sensitivity

Cleaning of probes is required due to oxidation problems.

It can not be used for uncovered tanks during rainy season.


Page69

APPLICATIONS


Page70

APPLICATIONS

In house-hold tanks.

In difficult to access over head tanks.

In industries for liquid level sensing and controlling.

In hotels, apartments. hospitals, offices, hotels and all commercial sectors.

In many plants to ensure continuous water supply.

In industries for automation purpose.

In difficult to access over-head tanks.


Page71

FUTURE SCOPE


Page72

FUTURE SCOPE

PLC Based Automatic Liquid level Controller is a very popular project. If

it is used for commercial purpose in various industries so many modifications are

possible in this circuit.

Wireless operation can be provided.

GSM control can also be provided.

For industrial purpose all advanced version of the circuit is required. For this

SCADA based liquid level controller can also be used.

Timing operation can also be provided by using timer circuits.

We can connect alarm and thus we can get audio indication also, which is

more easier.

We can go by simple hardware circuit also by introducing stainless steel

sensors.

This project can be implemented by using PID Controller.


Page73

COST OF PROJECT


Page74

COST OF PROJECT

COST OF PROJECT WITH COMPONENT LIST

SR NO. COMPONENT

QUANTITY

PRICE

TOTAL

1

Resistors

24

0.50

12

2

Capacitors 2.2kpf

32

3

96

3

Capacitor 25v/1000uf

1

4

4

4

Transistor BC557

8

2

16

5

Diode IN4007

2

0.50

1

6

Diode IN4148

32

0.50

16

7

IC 4093

8

6.50

52

8

IC Base

8

1.40

11.20

9

Transformer 12-0-12 1A

1

65

65

10

Relay 12vdc

8

9.50 76

11

Relay 24vdc

5

16

80


Page75

12

LED 5mm

8

1

8

13

Solenoid Valve 24vdc

4

465

1860

14

Pump 230VAC 18W

1

250

250

15

PCB

1

65

65

16

Connecting Wires

5m

18

90

17

Connectors PBT 2

50

3

150

18

Connectors PBT 3

10

5

50

19

PCB Etching Ferrous Chloride

1

20

20

20

Connecting Wire Single Strand

4

35

140

21

Mini Ball Valve

3

75

225

22

T joint 10mm

4

32

128

23

L-joint

2

28

56

24

Teplon Tape

1

10

10

25

Pipe Connectors

12

22

264

26

M-seal

4

5

20


Page76

27

Bucket

1

90

90

28

Tanks

3

80

240

29

Nuts

8

3

24

TOTAL

Rs. 4103.2

In above estimation and costing PLC cost and SMPS costs are not included.


Page77

SPECIFICATIONS


Page78

SPECIFICATIONS OF COMPONENTS

Pump :-

Specifications of pump

Working Voltage 230 VAC

Working Frequency 50 Hz / 60 Hz

Current Rating up to 80 mA

Wattage 18 W

Transformer :-


Page79

Specifications of transformer

Type Centre-tapped step down transformer

Primary Voltage 230 VAC

Secondary Voltage 12 VAC

Current Rating 1 A

Relays :-


Page80

Specifications of 12VDC operated relay

Coil Voltage 12 VDC

Current Rating 60 mA

Power Consumption 0.72 W

Controlling Voltage and Current Rating

A.C. Voltage and Current 250 VAC, 7A


D.C. Voltage and Current 24VDC, 10A

Specifications of 24VDC operated relay

Coil Voltage 24VDC

Current Rating 30 mA



Page81

Controlling Voltage and Current


A.C. Voltage and Current 125 VAC, 1OA

D.C. Voltage and Current 28VDC, 10A

Solenoid Valve :-

Specifications of Solenoid Valves

Working Voltage 24VDC

Current Consumption 60 mA



Page82

Diode:- IN4007

Specifications as per datasheets.

IN4148


Page83

Capacitors :-


Page84

IC 4093 :-


Page85

Transistor :-


Page86

LED :-


Page87

PCB Connectors :-

Resistors :-


Page88


Page89

RESULT AND CONCLUSION


Page90

RESULT :-

When water level of Tank 1 is below high level , Solenoid Valve 1 and pump is

operated.

When water level of Tank 2 is below low level, Solenoid Valve 2 and pump is

operated and when it is reached at high level Solenoid 2 gets OFF.

When water level of Tank 3 is below low level, Solenoid Valve 3 and pump is

operated and when it is reached at high level Solenoid 3 gets OFF.

Whenever any solenoid valve is operated, Pump starts .

When all the solenoids are OFF, Pump gets automatically OFF.

Whenever water level of Source Tank goes below it’s high level Solenoid Valve 4

(BMC Valve ) is operated.

Whenever water of source tank is reached below low level, process goes automatically

OFF.

CONCLUSION :-

Water level is controlled automatically without any manual operations.

Operations are controlled by changing program according to our need and

requirements.


Page91

BIBLIOGRAPHY


Page92

BIBLIOGRAPHY

Books:-

1. Electrical Design by K.B.Raina and Bhattacharya.

2. Electrical Machines by B.L.Theraja.

3. Control of Machines by Bhattacharya.

4. Programmable Logic Controller by V.R.Jadhav.

Websites:-

1. www.wikipedia.com

2. www.circuitstoday.com

3. www.seminarprojects.com

4. www.alibaba.com

5. www.nxp.com

6. www.datasheetarchive.com

7. www.vishay.com


Page93

DATASHEETS


Page94

ACKNOWLEDGEMENT


Page95

ACKNOWLEDGEMENT

We take this opportunity to express our deep gratitude to the respected

principal Prof. D. P. Nathe and head of department (Electrical Engineering) Prof.

C.Y. Totewar for permitting and encouraging us to take up this project work and

complete it successfully.

We also thank to our project guide Prof. C.Y. Totewar, Prof. M.P.

Deshpande, Prof.Shinde, Prof. Bhanu Bandi and Avinash Dabhade who

initialized and set the movement for our project.

We also thank to all our faculty members teaching and non-teaching staff of

Electrical Department as well as Instrumentation Department who offered their

valuable time, guidance, assistance directly or indirectly to carry out the project

successfully.

We also thank our college library for the valuable books issued by them while

preparing this report.

BY

NAME ENROLLMENT NO.

1) Badgujar Vijay S. 0900003

2) Waghule Sagar N. 0900062

3) Survase Sachin S. 0900056

4) Patil Mohit N. 0900045

5) Narwade Pravin 0910005

PLC based Multichannel Automatic Liquid Level Controller

Technology

Transcript of PLC based Multichannel Automatic Liquid Level Controller