INTELLIGENT SINGLE PHASE SUPPLY

Government College of Engineering, Amravati

Chapter 1. INTRODUCTION

A. Need and Necessity:

Indian agriculture is dependent on the monsoons which is not a reliable source of water, so

there is a need for an automatic irrigation system in the country which can provide water to

the farms according to their water availability and moisture of soils. Modern Irrigation is

today’s need because water resources are very limited, diminishing day by day and most of

them depend upon monsoons. The one and only one solution to this problem is automated

Irrigation system. In the conventional irrigation system, the farmer has to follow a schedule

for turning ON and OFF of pumps. Also during the unavailability of water there will be

wastage of electricity due to running of pumps in dry conditions resulting into damage of

pumps further causing economical losses to the farmer. Excessive irrigation which causes the

soil to deteriorate can be prevented by the use of this project. A variety of irrigation methods

have been proposed, but most of them have been found to be very expensive and complicated

to use. In future each and every farmer, whether poor or uneducated might wake up in need

of such a system, therefore the proposed applications targeting an automatic irrigation system

with minimal cost, time and human interaction.

B. Objectives

To overcome the above mentioned problems we propose the “AUTOMATIC PLANT

IRRIGATION. In this project we are trying to explain few of the agricultural process such

as Water pumping with a precise level as required by the crop. In our system we have

automated the water pump to turn On and OFF according to water availability and to pump

the water whenever the prescribed water level or humidity of the soil goes down .For this

ca0se we use a water level sensor & Humidity sensor.


Chapter 2. IMAGE OF PROJECT

Fig.2.1 Image of project


Chapter 3. COMPONENT USED IN CIRCUIT

1. Transformer- 230/12-0-12 volts,1 A

2. Diode

3. Capacitor- 1000 microfarad, 25 V & 100 microfarad,25 V,0.1 microfarad

4. IC-555

5. LED

6. Variable resistance-220 K, 10 K

7. Transistor- CL 100, BC 457

8. Comparator IC (LM 324)

9. Relay- Double port (DPDT), single pole (SPST)

10. Pump- 18 w, 230 V a.c


DESCRIPTION OF COMPONENTS USED:

1. Transformer- 230/12-0-12 volts,1 A

Fig.3.1 Transformer

A transformer is generally a four-terminal device that is capable of transforming

an alternating current (AC) input voltage into a relatively higher or lowers AC output voltage.

A transformer usually consists of two closely coupled coils that are designed to transfer

energy between its winding circuits. A typical transformer has two or more coils that share a

common laminated iron core. In this 230 V supply coming from AC mains is provided to the

step down transformer which lowers the voltage from 230V AC to 12V AC. Step down

transformers convert electrical voltage from one level or phase configuration usually down to

a lower level. They can include features for electrical isolation, power distribution, and

control and instrumentation applications. Step down transformers typically rely on the

principle of magnetic induction between coils to convert voltage and/or current levels.


2. Diode

Fig.3.2.Diode

In electronics, a diode is a two terminal device with asymmetric conductance; it has low

(ideally zero) resistance to current in one direction, and high (ideally infinite) resistance in

the other. A semiconductor diode, the most common type today, is a crystalline piece of

semiconductor material with a p–n junction connected to two electrical terminals. A diode is

a unidirectional device permitting the easy flow of current in direction but restraining the

flow in other direction. This is a simple, very common rectifier diode. Often used for reverse

voltage protection


3. Capacitor- (1000 microfarad, 25 V & 100 microfarad, 25 V, 0.1 microfarad)

A capacitor is a passive electronic component consisting of a pair of conductors separated by

a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a

static electric field develops in the dielectric that stores energy and produces a mechanical

force between the conductors. An ideal capacitor is characterized by a single constant value,

capacitance, measured infrareds. This is the ratio of the electric on each conductor to the

potential difference between them.

Fig.3.3.Capacitor

http://en.wikipedia.org/wiki/Passivity_(engineering)

http://en.wikipedia.org/wiki/Electronic_component

http://en.wikipedia.org/wiki/Electrical_conductor

http://en.wikipedia.org/wiki/Dielectric

http://en.wikipedia.org/wiki/Potential_difference

http://en.wikipedia.org/wiki/Electric_field

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Capacitance


4. IC-555

Fig.3.4.(a).Internal Structure of IC555 Fig.3.4.(b).IC555

The 555 Timer IC is available as an 8-pin metal can, an 8-pin mini DIP (dual-in-package) or

a 14-pin DIP. The pin configuration is shown in the figures.

This IC consists of 23 transistors, 2 diodes and 16 resistors. The use of each pin in the IC is

explained below. The pin numbers used below refers to the 8-pin DIP and 8-pin metal can

packages. These pins are explained in detail, and you will get a better idea after going

through the entire post.

The internal resistors act as a voltage divider network, providing (2/3)Vcc at the non-

inverting terminal of the upper comparator and (1/3)Vcc at the inverting terminal of the lower

comparator. In most applications, the control input is not used, so that the control voltage

equals +(2/3) VCC. Upper comparator has a threshold input (pin 6) and a control input (pin 5).

Output of the upper comparator is applied to set (S) input of the flip-flop. Whenever the

threshold voltage exceeds the control voltage, the upper comparator will set the flip-flop and

its output is high. A high output from the flip-flop when given to the base of the discharge

transistor saturates it and thus discharges the transistor that is connected externally to the

discharge pin 7. The complementary signal out of the flip-flop goes to pin 3, the output. The

output available at pin 3 is low. These conditions will prevail until lower comparator triggers

the flip-flop. Even if the voltage at the threshold input falls below (2/3) VCC, that is upper

comparator cannot cause the flip-flop to change again. It means that the upper comparator

can only force the flip-flop’s output high.To change the output of flip-flop to low, the voltage

at the trigger input must fall below + (1/3) Vcc. When this occurs, lower comparator triggers

the flip-flop, forcing its output low. The low output from the flip-flop turns the discharge

1

2

3

4

8

7

6

5

555

GND

TRIGGER

O/P

VCC

THRESHOLD

CONTOLED VOLTAGE

DISCHARGE

RESET


transistor off and forces the power amplifier to output a high. These conditions will continue

independent of the voltage on the trigger input. Lower comparator can only cause the flip-

flop to output low. From the above discussion it is concluded that for the having low output

from the timer 555, the voltage on the threshold input must exceed the control voltage or +

(2/3) VCC. This also turns the discharge transistor on. To force the output from the timer high,

the voltage on the trigger input must drop below +(1/3) VCC. This turns the discharge

transistor off. A voltage may be applied to the control input to change the levels at which the

switching occurs. When not in use, a 0.01 nano Farad capacitor should be connected between

pin 5 and ground to prevent noise coupled onto this pin from causing false triggering.

Connecting the reset (pin 4) to a logic low will place a high on the output of flip-flop. The

discharge transistor will go on and the power amplifier will output a low. This condition will

continue until reset is taken high. This allows synchronization or resetting of the circuit’s

operation. When not in use, reset should be tied to +VCC.


5.LED

Fig.3.5.LED

A light-emitting diode (LED) is a semiconductor device that emits visible light when an

electric current passes through it. The light is not particularly bright, but inmost LEDs it is

monochromatic, occurring at a single wavelength. The output of an LED can range from red

(at a wavelength of approximately 700 nanometers) to blue-violet (about 400 nanometers).

An LED consists of two elements of processed material called P-type semiconductors and N-

type semiconductors. These two in these elements are placed in direct contact, forming a

region called the P-N junction. In this respect, the LED resembles the most other type diode

types, but there are Important other differences between the light emitting diode and the

normal diodes


6.Variable resistance-220 K, 10 K

Fig3.6.Variable Resister

A variable resistor is a three terminal passive electronic component which implements

electrical resistance as a circuit element. When a voltage V is applied across the terminals of

a resistor, a current I will flow through the resistor in proportion to that voltage. The reciprocal

of the constant of proportionality is known as the resistor R, since, with a given voltage V, a

larger value of R further "resists" the flow of current I . Resistors are common elements of

electrical and electronic circuits .Avariable resistance can used from 0 to it’s maximum value.

http://en.wikipedia.org/wiki/Terminal_(electronics)

http://en.wikipedia.org/wiki/Passivity_(engineering)

http://en.wikipedia.org/wiki/Electronic_component

http://en.wikipedia.org/wiki/Electrical_resistance


7. Transistor- CL 100, BC 457

Fig.3.7. Transistor

Transistor is a semiconductor device used to amplify and switch electronic signals. It is made

of a solid piece of semiconductor material, with at least three terminals for connection to an

external circuit. Transistors are commonly used as electronic switches, for both high power

applications including switched-mode power supplies and low power applications such as

logic gates. A voltage or current applied to one pair of the transistor's terminals changes the

current flowing through another pair of terminals. Because the controlled (output) power can

be much more than the controlling (input) power, the transistor provides amplification of a

signal. When used operates within its "Active" region and the linear part of the output

characteristics curves are used. However, both the NPN & PNP type bipolar transistors can

be made to operate as an "ON/OFF" type solid state switch for controlling high power

devices.


8. Comparator IC (LM324)

Fig.3.8.Comparator

These devices consist of four independent high-gain frequency-compensated operational

amplifiers that are designed specifically to operate from a single supply over a wide range of

voltages .Operation from split supplies also is possible when the difference between the two

supplies is 3 V to 30 V (for the LM2902, 3 V to 26 V) and VCC is at least 1.5 V more

positive than the input common-mode voltage. The low supply-current drain is independent

of the magnitude of the supply voltage. Applications include transducer amplifiers, dc

amplification blocks, and all the conventional operational-amplifier circuits that now can be

more easily implemented in single-supply-voltage systems.

1

2

3

4

5

6

7

14

13

12

11

10

9

8

LM324

OUTPUT

OUTPUT OUTPUT

+INPUT

+INPUT+INPUT

+INPUT

-INPUT -INPUT

-INPUT -INPUT

+VCC -VCC

OUTPUT


9. Relay- Double port (DPDT), single pole (SPST)

Fig.3.9. DPDT Relay

A relay is an electrically operated switch Many relays use an electromagnet to mechanically

operate a switch, but other operating principles are also used, such as solid-state relays.

Relays are used where it is necessary to control a circuit by a low-power signal (with

complete electrical isolation between control and controlled circuits), or where several

circuits must be controlled by one signal.

Basic design and operation

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core an

iron yoke which provides a low reluctance path for magnetic flux, a movable iron armature

and one or more sets of contacts (there are two in the relay pictured). The armature is hinged

to the yoke and mechanically linked to one or more sets of moving contacts. It is held in

place by a spring so that when the relay is de-energized there is an air gap in the magnetic

circuit.When an electric current is passed through the coil it generates a magnetic field that

activates the armature and the consequent movement of the movable contact either makes or

breaks (depending upon construction) a connection with a fixed contact. If the set of contacts

was closed when the relay was de-energized, then the movement opens the contacts and

breaks the connection, and vice versa if the contacts were open. When the current to the coil

is switched off, the armature is returned by a force, approximately half as strong as the

magnetic force, to its relaxed position.


Pole and throw

Since relays are switches the terminology applied to switches is also applied to relays; a relay

switches one or more poles, each of whose contacts can be thrown by energizing the coil in

one of three ways

• Normally-open (NO) contacts connect the circuit when the relay is activated; the circuit is

disconnected when the relay is inactive. It is also called aForm A contact or "make"

contact. NO contacts may also be distinguished as "early-make" or NOEM, which means that

the contacts close before the button or switch is fully engaged.

• Normally-closed (NC) contacts disconnect the circuit when the relay is activated; the circuit

is connected when the relay is inactive. It is also called a Form B contact or "break"

contact. NC contacts may also be distinguished as "late-break" or NCLB, which means that

the contacts stay closed until the button or switch is fully disengaged.

• Change-over (CO), or double-throw (DT), contacts control two circuits: one normally-open

contact and one normally-closed contact with a common terminal. It is also called a Form

C contact or "transfer" contact ("break before make"). If this type of contact utilizes “make

before break" functionality, then it is called a Form D contact.

The following designations are commonly encountered:

• SPST – Single Pole Single Throw. These have two terminals which can be connected or

disconnected. Including two for the coil, such a relay has four terminals in total. It is

ambiguous whether the pole is normally open or normally closed. The terminology "SPNO"

and "SPNC" is sometimes used to resolve the ambiguity

• SPDT – Single Pole Double Throw. A common terminal connects to either of two others.

Including two for the coil, such a relay has five terminals in total.

• DPST – Double Pole Single Throw. These have two pairs of terminals. Equivalent to two

SPST switches or relays actuated by a single coil. Including two for the coil, such a relay has

six terminals in total. The poles may be Form A or Form B (or one of each).

• DPDT – Double Pole Double Throw. These have two rows of change-over terminals.

Equivalent to two SPDT switches or relays actuated by a single coil. Such a relay has eight

terminals, including the coil.


Applications

Relays are used for:

• Logic functions. For example, the boolean AND function is realised by connecting normally

open relay contacts in series, the OR function by connecting normally open contacts in

parallel. The change-over or Form C contacts perform the XOR (exclusive or) function.

Similar functions for NAND and NOR are accomplished using normally closed contacts.

The Ladder programming language is often used for designing relay logic networks.

• Switching to a standby power supply.


10. Pump- 18 W, 230 V a.c

A submersible motor (or sub pump, electric submersible pump (ESP)) is adevice which has

a hermetically sealed motor close-coupled to the pump body. The whole assembly is

submerged in the fluid to be pumped. The main advantage of this type of pump is that it

prevents pump cavitation, a problem associated with a high elevation difference between

pump and the fluid surface. Submersible pumps push fluid to the surface as opposed to jet

pumps having to pull fluids. Submersibles are more efficient than jet pumps.

Submersible motor are used in application including sewage

treatment plants, seawater handling, groundwater pumping, fire fighting (since it is flame

retardant cable), borehole drilling and pumping, water well and deep well drilling,

offshore drilling rigs, artificial lifts, mine dewatering, irrigation systems, and water supply

systems. Pumps used for combustible liquids or for water that may be contaminated with

combustible liquids must be designed not to ignite the liquid or vapors.

Fig.3.10. Submersible Motor Specifications:

Power: 19 W

Voltage: 165-220 V / 50Hz


Chapter 4. DESCRIPTION OF CIRCUIT

Power Supply

Water Level Indicator

Controlling Circuit

Soil Moisture Detector (Humidity Sensor)

POWER SUPPLY:

A. Circuit Diagram:

Fig.4.1.(a).Rectifier circuit

Fig.4.1.(b).Rectifier circuit waveform

B. Working:

In a rectifier, centre tapped transformer and two diodes forms a full wave rectifier

that allows both half cycles of AC waveform to contribute direct current(DC) making it

smoother than half wave rectifier. Output from diodes gives pulsating DC. To make it into

pure DC form we use capacitor filter across the output.LED used in circuit indicate that

power supply is in good condition.


WATER LEVEL INDICATOR:

A. Circuit Diagram:

Fig.4.2.Water level indicator

B. Working:

IC 555 is used in the monostable mode for making water level indicator. Circuit is made

as shown in figure. In the circuit, the value of R and C decide the time constant. As we require

instant response to input, values of R and C are taken small. i.e. 10 K-ohm and 100 microfarad.

To trigger, pin Vcc is connected through a variable resistor and to the same pin we connect the

water (as a resistor) and give it to ground.

As we know the value of water resistor is from 80 K to 100 K. We set the pot having more

resistor than 100 K-ohm. When the terminal which is used for indication is in the air, it acts as

infinite resistance between ground terminal and pin 2. So, current flowing through the circuit is

due to Vcc as it follows low resistance path and pin is triggered by Vcc i.e. logic1 and the output

of circuit is logic 0. When the indicating terminal is in the water, resistance between indicating

terminal and ground is about 80K-ohm to 100 K-ohm. It follows the low resistance path as

resistance between trigger pin and Vcc is greater than resistance between trigger pin and ground.

Ground appears at trigger pin. Hence, input to the pin 2 is logic 0 and the output of circuit is logic

1.

As IC 555 is used in monostable mode it acts as inverter. When it is triggered by logic 0,circuit

gives output as one i.e.,when indicating signal is in contact with water, output is logic 1.

i/p from water

vcc

GND

1

2

3

4

8

7

6

5

555

0.01µF

220Kohm

100µF25V


CONTROLLING CIRCUIT:

A. Circuit Diagram:

Fig.4.3.Controlling Circuit

B. Working:

It consist of four NPN power transistors (CL 100), diodes and DPDT relay. The components

are connected as per the circuit diagram.

When the signal to the base of transistor Q1 is logic 1, then transistor Q1 will get ON and

Vcc occurs at base of transistor Q3 which make Q3 ON and Vcc is applied through transistor

which occur at collector of Q4.

When input to the base of Q2 is also logic 1 then it gets turned ON and Vcc is applied at the

collector of Q2 and it occurs at base of Q4 so that it also gets turned ON. As transistor Q3

and Q4 get turned ON because the inputs given to base of Q1 and Q2 is at logic 1 and

current flows through the coil of DPDT relay which is sufficient to turn it ON. As relay gets

turned ON, none of the terminal is closed and hence the controlled output is logic 1.

As relay gets turnedON holding circuit starts and it provides input to the transistor Q3.Now it

is in ON state. So its output is independent of the input to the base of Q1.

If input to the Q1 is zero then transistor Q3 is in ON state. But when input to the Q2 is logic

0, Q2 becomes OFF and input to Q4 is logic 0 which makes it OFF. No current flows through

DPDT relay and relay becomes ON which disconnects the holding circuit. Now turning ON

the relay depends on input to the transistor Q1.

When both inputs to transistors Q1 and Q2 becomes one rely turns ON and operates as above.

i/p from waterlevel indicator

i/p from waterlevel indicator

vcc

Q1

Q2

Q3

Q4


SOIL MOISTURE DETECTOR (HUMIDITY SENSOR)

A. Circuit Diagram:

Fig.4.4.Soil Moisture Detector circuit

B. Working:

It is comparator IC. It has four operational amplifier. When we apply positive voltage with

respect to ground then it gives output as Vcc. If difference between positive & negative is

negative, it gives -Vcc.

When positive input is in wet soil then it is connected to ground. Ground and no o/p gives

negative voltage difference and hence o/p is at logic negative i.e. at logic0. When it is in dry

soil, the difference is positive and output is at logic1 i.e., we get output as Vcc. All the four

outputs are connected to OR gate(constructed with help of transistors). When all input is in

wet soil resultant output is at logic 0 and if any of input is in dry soil output is at logic 1.

1

2

3

4

5

6

7

14

13

12

11

10

9

8

LM324

vcc

O/P

i/pfromsoil

vcci/p

fromsoil

i/pfromsoil

i/pfromsoil


COMBINED CIRCUIT:

Fig.4.5.Combined circuit

A. Working: According to the water available we set the position of our water level indicator. When we

extract water from well by pump, the rate of extraction of water is greater than rise of water in well.

When we turn ON thepump, after some time water level gets lowered and reaches to the bottom

of well but pump is still running. As no any arrangement is made for cooling of pump, it gets heated

and it may burn out and continuous losses occurs.

In this system, two sensors are used. One at upper level and other at lower level. When both

indicators are in water, water indicator gives output out of which one is the input to controller circuit.

When both inputs to the controller are logic 1 then one transistor turns on and it means output of

circuit is logic 1.


After some time water level gets lowered which means upper indicator is in the air. But due to

the holding circuit used output will remain one when bottom indicator will be in air.When bottom

indicator is in air, it means there is no water in the well and output of controller is zero which turns off

the pump automatically.

When again the water level in the well rises bottom indicator will be in water so it will recognise

and gives output as one. So air relay becomes off and output of controller is zero. When water reaches

to level of upper indicator both the inputs to controller becomes one which gives its output also as

one. This turns ON the pump and operation of circuit by indicator is done sequentially.

Due to the continuous operation of pump soil becomes wet so there will be no meaning of

providing water to field because it leads to salinity of soil, wasting of electricity also. In order to

overcome this issue we use soil moisture indicator circuit to control the operation of pump. When all

terminals of indicator are in soil then output of each indicator is one. These all inputs are connected

through OR gate hence so there combined output will be one. When any of the terminals is in the dry

soil then its output will be one and pump will provide water to that part of the plant.

When all terminals are in wet soil then output of each cell is zero & combined output will also be

zero which results in stopping the operation of pump. So when there is no need then pump will get

turn OFF.

If both conditions are satisfying i.e. availability of water in well and necessity of water to field

input to and gate becomes one pump will get turn on. If any of the condition doesn’t get satisfied

motor will be in OFF state. It means either there is no water available or no need of water so pump

gets turn OFF.


Chapter 5. COST AND ACTUAL IMPLEMENTATION

To implement this project only some replacement should be taken out and we can implement the

project as it is. Only we have to replace SPST relay by contactor (relay) of higher rating (which is

used in star-delta starter).The cost of contactor is near about 900/- only.

As we keep terminals of indicator in soil and water due to corrosion and chemical reaction the contact

resistance is increase. To avoid this problem we can use stainless steel spoon at the indicator terminal,

as stainless steel is free from corrosion. Only there is need to wash it after specific interval of time.

Sr.

No.

Component Price

1 Transformer

45

2 Diodes

2

3 Capacitor

20

4 IC-555

10

5 IC LM 324

8

6

LED 5

7 Pot

15

8

Transistor 60

9

Relay 35

10 Contactor

900

11 Dot matrix PCB

50

12 Stainless steel spoon

50

13 Other 100

Total

1300

Therefore, for actual implementation of project estimated cost is 1300/- rupees only


Chapter 6. ADVANTAGES AND LIMITATIONS

Advantages

1. There is no need of operator for irrigation as all things are done automatically so labour cost

is reduced.

2. Installation cost is reduced.

3. There is no need of network like in GSM based auto irrigation.

4. Dry running of pump is avoided so there is rare chance of damage to pump.

5. As the pump runs according to the requirement and availability only, electricity is saved.

6. Wastage of water avoided.

7. As use of water is optimum, it avoids soil from become infertile.

8. If any problem arises then pump can operate manually by simply turning ON the ICTP .

Limitations

As the contact resistance of indicator lead is increased by keeping it in soil and water, the accuracy

may be reduced after a long time. So there is need to wash the lead after specific interval of time.


Chapter 7. FUTURE SCOPE

In this project we have dealt with the problems of automatic turning ON and OFF of the

pumps according to the availability of water supply and supply of appropriate water to the

soil. In future we can expand this project to solve the further irrigation problems like single

phasing and heating of pump by the use of single phasing preventing circuit and heat sensors.

In the above circuit, we have used transistor logic for turning processes and since transistors

are unreliable, we can replace it by the use of relay logic.


Chapter 8. CONCLUSION

By the use of this project, the farmer now does not follow a schedule for turning ON and OFF

of pumps. Also no electricity will be wasted due to running of pumps in dry conditions

resulting into damage of pumps. Excessive irrigation which causes the soil to deteriorate can

be prevented by the use of this project. In future each and every farmer might wake up in

need of such a system, therefore the proposed applications which targeted an automatic

irrigation system with minimal cost, time and human interaction was studied.


Chapter 9. REFERENCE

1. Digital Electronics –R.P.Jain

2. Power Electronics –P.S.Bhimbhra

3. www.circuitstoday.com

INTELLIGENT SINGLE PHASE SUPPLY

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