PLC-Based Automatic Liquid Level Controller for Electrical Engineering Project

PLC BASED MULTICHANNEL AUTOMATIC LIQUID LEVEL CONTROLLER ELECTRICAL
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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
RELAYUNIT
AC SUPPLY
230VAC, 50HZ
TRANSFORMER
RECTIFIER
FILTER
12VDC
PROGRAMMABLELOGIC
CONTROLLER
(PLC)
LIQUID LEVEL
SENSORS
SMPS
24VDC
750mA
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.

ENGINEERING
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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.

ENGINEERING
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2
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.

ENGINEERING
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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.

ENGINEERING
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4
PCB DESIGNING

ENGINEERING
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5
 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.

ENGINEERING
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 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.

ENGINEERING
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7
 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

ENGINEERING
Page5
8
PCB LAYOUT OF PROJECT

ENGINEERING
Page5
9

ENGINEERING
Page6
0
PCB LAYOUT FOR RELAY UNIT

ENGINEERING
Page6
1

ENGINEERING
Page6
2
PLC PROGRAMMING

ENGINEERING
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3
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

ENGINEERING
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4
 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 :-


ENGINEERING
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5
ADVANTAGES

ENGINEERING
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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.

ENGINEERING
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7
DISADVANTAGES

ENGINEERING
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8
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.

ENGINEERING
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9
APPLICATIONS

ENGINEERING
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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.

ENGINEERING
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FUTURE SCOPE

ENGINEERING
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2
 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.

ENGINEERING
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3
COST OF PROJECT

ENGINEERING
Page7
4
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

ENGINEERING
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5
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

ENGINEERING
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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.

ENGINEERING
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SPECIFICATIONS

ENGINEERING
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8
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 :-

ENGINEERING
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9
Specifications of transformer
Type Centre-tapped step down transformer
Primary Voltage 230 VAC
Secondary Voltage 12 VAC
Current Rating 1 A
Relays :-

ENGINEERING
Page8
0
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

ENGINEERING
Page8
1
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

ENGINEERING
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2
Diode:-
IN4007
Specifications as per datasheets.
IN4148

ENGINEERING
Page8
3
Capacitors :-

ENGINEERING
Page8
4
IC 4093 :-

ENGINEERING
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5
Transistor :-

ENGINEERING
Page8
6
LED :-

ENGINEERING
Page8
7
PCB Connectors :-
Resistors :-

ENGINEERING
Page8
8

ENGINEERING
Page8
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RESULT AND CONCLUSION

ENGINEERING
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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.

ENGINEERING
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BIBLIOGRAPHY

ENGINEERING
Page9
2
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

ENGINEERING
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DATASHEETS

ENGINEERING
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4
ACKNOWLEDGEMENT

ENGINEERING
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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 Automatic Liquid Level Controller for Electrical Engineering Project

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