project report on electrical engineering

7/28/2019 project report on electrical engineering

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1.1. INTRODUTIONINTRODUTION

In three phase application, if low voltage is available in any one or two phase,

and you want your equipment to work on normal voltage, this circuit will solved

your problem. However a proper-rating fuse needs to be used in the input lines of

each phase. The circuit provides correct voltage in the same power supply lines

through relays from the other phase where correct voltage is available. Using it

you can operate all your equipment even when correct voltage is available on a

single phase in the building.

VALIA INSTITUTE OF TECHNOLOGY, VALIA. Page 1


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2. BLOCK DIAGRAM



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3. COMPONANT LIST WITH RATING

NO Component List Range Quantity

1 TRANSFORMER 230/12-12 V 3

2 OP-AMP IC LM741 8 PIN 3

3 RELAY 12V, 6 Amp 3

4 TRANSISTOR BC557 3

5 ZENER DIODE 5.1V 3

6 DIODE 1N4007 9

7 RESISTOR 3.3K

10K

6

3

8 VARIABLERESISTOR 10K 3

9 CAPACITOR 1000F,5V

470F,35 V

4

3

10 LED 5 mA 3

11 WOODEN BOARD 30 x 30 1

12 BREAD BOARD 10 x 10 1

13 WIRES - -

14 SWITCH 230V/10 Amp 4

15 FUSE 230V/10 Amp 3

4. DESCRIPTION OF COMPONANT



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4.1 TRANSFORMER :-

(Figure Transformer)

Basic principle :-

The transformer is based on two principles: firstly that an electric current can

produce a magnetic field within a coil of wire induces a voltage across the ends

of the coil (electromagnetic induction).changing the current in the primary coil

changes the magnetic flux that is developed. The changing magnetic flux induces

a voltage in the secondary coil.

An ideal transformer. An ideal transformer is shown in the adjacent figure.

Current passing through the primary coil creates a magnetic field. The primary

and secondary coils are wrapped around a core of very high magnetic

permeability such as iron, so that most of magnetic flux passes through both

primary and secondary coils.

The use of transformer in project, to step down the voltage in each phase to

230/12V, 500 mA.



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Induction law :-

The voltage induced across the secondary coil may be calculated from faradays

law of induction, which state that:-

Where VS is the instantaneous voltage, NS is the number of turns in the

secondary coil and equals the magnetic flux through one turns of the coil. If the

turns of the coil are product of the magnetic field strength B and the area A

through sectional area of the transformer core, whereas the magnetic field varies

with time according to the excitation of the primary and secondary coils in an

ideal transformer, the instantaneous voltage across the primary winding equals.

Taking the ratio of two equations for VS and VP gives the basics equation for

stepping up or down the voltage.



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4.2 OPAMP I.C.-741:-

(Figure Operational Amplifier IC)

(Symbol)



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Here IC-741 is used as a comparator and not an amplifier. The difference

between the two is small but significant. Even if used as a comparator the 741

still detects weak signals so that they can be recognized more easily.

A comparator is a circuit that compares two input voltages. One voltage is

called the reference voltage (Vref) and the other is called the input voltage (Vin).

(Pin Diagram of OP-Amp IC LM 741))

Power Supply for Integrated Circuit :-

Most linear ICs use one or more differential stages, and differential amplifier

require both a positive and negative power supply for proper operations of a

circuit. Amplifier this means that most liner ICs need both a positive and a

negative power supply. A few liner ICs need both a positive and a use unequal

power supplies, and some ICs supply. For example, the 702 op-amp requires

unequal power supplies, whereas the 342 requires only a positive supply. When a

circuits to the IC some dual-supply op-amp ICs can also be operated from a

single supply voltage, provided that a special external require only one positive

supply voltage.

The two power supplies required for a linear IC are usually equal in magnitude,

+15V For example. These power supply voltages must be referenced to a

common point or ground. Unfortunately, as in the case of ordering information,

manufactures, do not agree on power supply labeling, for example, Fairchild uses



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V+ to indicate the positive and negatives voltages. On the other hand, Motorola

uses the symbol of +Vcc and Vee to represent positive and negative voltages,

respectively. We will follow Motorolas notation for the power supplies.

Fig. show power supply connections for the 741 or 351 op-amp. The numerals

adjacent to the terminal are pin numbers. Thus, for the 741 or 351 op-amp, pin 7

is a positive supply pin and pin 4 is negative supply pin. The remaining pins on

the 741 or 351 are omitted for the sake of simplicity.

The use of op-amp IC 741in project for comparator to compare the output signal

and reference signal and produced high gain output.

4.3 Relay:-

(Figure- Construction of relay)



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(Contact Arrangement & Outer look of Relay)

Simple electromechanical relay :-

Small relay as used in electronics. A simple electromagnetic relay, such as the

one taken from a car in the first picture, is an adoption of an electromagnet. It

consists of a coil of wire surrounding a soft iron core, an iron yoke, which

provides a low reluctance path for magnetic flux, a moveable iron armature, and

a set or sets, of contacts; two in the relay pictured. The armature is hinged to the

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

in the magnetic circuit. In this condition, one of the two sets of contacts in the

relay .Pictured is closed, and the other set is open.

Other relays may have more of fewer sets of contacts depending on their

functions the relay in the picture also have a wire connecting the armature to the

yoke. This ensures continuity of the circuits between the moving contacts on the



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armatures, and the circuits track on the printed circuit board (PCB) via the yoke,

which is soldered on the PCB.

When an electric current is passed through the coil, the resulting magnetic field

attracts the armature and the consequent movement of the movable contact or

contacts either males or breaks a connection with a fixed contact. If the set of

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

opens the contacts and breaks the connection , and vice versa if the contacts

are returned by a force, approximately half as strong as the magnetic force, to its

relaxed position. Usually this force is provided by a spring, but gravity is also

commonly in industrial motor starters. Most relays are manufactured to operate

quickly. In a low voltage application, this is to reduce noise. In a high voltage or

high current application, this is to reduce arcing.

In this project relay is used for when the fault obtain in any one phase voltage or

low voltage so relay is operate and normally close contact is open. And give

supply from to another phase

4.4 Transistor (BC 557):-



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(Figure Transistor)

(Types of transistor and symbol)

There are two types of standard Transistors, NPN or PNP, with different circuits

symbols, the letters refer to the layers of semiconductor material used to make

the Transistor. Most Transistors used today are NPN because this is the easiest

type to make from silicon.

The leads are labeled base (B), collector(C) and emitter (E).

In this project transistor is used for the to give the signal to operate the relay in

faulty condition.

4.5 Zener diode:-



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(Figure Zener Diode)

(Characteristic of Zener Diode)

A zener diode is a type of diode that permits current to flow in the forward

direction like a normal diode, but also in reverse direction if the voltage is larger

than the rated breakdown voltage or Zener voltage. The device was named of

Clarence zener, who discovered the electrical property.



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A conventional solid-state diode will not let significant current flow if reverse-

biased below its reverse bias breakdown voltage, a conventional diode is subject

to high current is limit by external circuitry, the diode will be permanentlydamaged.

In case of large forward bias (current flow in the direction of the arrow), the

diode exhibits a voltage drop depends on the design of the diode.

A zener diode exhibits almost the same properties, accepts the device is

especially designed so as to have a greatly reduced breakdown voltage, that so-

called zener voltage. A zener diode contains a heavily doped p-n junction

allowing electrons to tunnel from the valance band of the p-type material to the

conduction band of n-type material. A reverse-biased zener diode will exhibit a

controlled breakdown and let the current flow keep the voltage across the zener

diode at the Zener voltage.

In this project zener diode is produced to fixed reference at the non inverting pinnumber 3.

4.6 DIODE:-



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(Figure Diode)

In electronics diode is two terminal electronic component which conducts electric

current asymmetrically or unidirectional that is it conducts current more easily in

one direction than in the opposite direction. The term usually refers to a

semiconductor diode, the most common type today, which is a two terminal

semiconductor P-N junction.

In this project diode is used as a rectifier and to dissipate energy from relay coil.



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4.7Resistor:-

(Figure- Resistance and Variable resistance)

It is used to adjust the condition of the circuits by the technician. The rotationangle of the variable resistor is usually about 300 degrees.

Some variable resistors must be turned many times to use whole range of

resistance they offer. This allows for very precise adjustments of their value,

these are called potentiometers.

In this project the variable resister is used for to set the reference voltage



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4.8 Capacitor :-

(Figure Capacitor)

A capacitor consists of two conductors separated by a non-conductive region

called the dielectric medium though it may be avacuum or

a semiconductordepletion region chemically identical to the conductors. The

conductors thus hold equal and opposite charges on their facing surfaces, and the

dielectric develops an electric field.

The capacitor is a reasonably general model for electric fields within electric

circuits. An ideal capacitor is wholly characterized by a constant capacitance C,

defined as the ratio of charge Q on each conductor to the voltage Vbetween

them.

Sometimes charge build-up affects the capacitor mechanically, causing its

capacitance to vary. In this case, capacitance is defined in terms of incremental

changes:

http://en.wikipedia.org/wiki/Electrical_conductorhttp://en.wikipedia.org/wiki/Dielectric_mediumhttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Depletion_regionhttp://en.wikipedia.org/wiki/Depletion_regionhttp://en.wikipedia.org/wiki/Dielectric_mediumhttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Depletion_regionhttp://en.wikipedia.org/wiki/Electrical_conductor


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Structure of capacitor:-

(Figure Construction of Capacitor)

The arrangement of plates and dielectric has many variations depending on the

desired ratings of the capacitor. For small values of capacitance (microfarads and

less), ceramic disks use metallic coatings, with wire leads bonded to the coating.

Larger values can be made by multiple stacks of plates and disks. Larger value

capacitors usually use a metal foil or metal film layer deposited on the surface of

a dielectric film to make the plates, and a dielectric film of impregnatedpaperor

plastic these are rolled up to save space. To reduce the series resistance andinductance for long plates, the plates and dielectric are staggered so that

connection is made at the common edge of the rolled-up plates, not at the ends of

the foil or metalized film strips that comprise the plates.

The assembly is encased to prevent moisture entering the dielectric early radio

equipment used a cardboard tube sealed with wax. Modern paper or film

http://en.wikipedia.org/wiki/Electrical_insulation_paperhttp://en.wikipedia.org/wiki/Electrical_insulation_paper


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dielectric capacitors are dipped in a hard thermoplastic. Large capacitors for

high-voltage use may have the roll form compressed to fit into a rectangular

metal case, with bolted terminals and bushings for connections. The dielectric in

larger capacitors is often impregnated with a liquid to improve its properties.

Capacitors may have their connecting leads arranged in many configurations, for

example axially or radially. "Axial" means that the leads are on a common axis,

typically the axis of the capacitor's cylindrical body the leads extend from

opposite ends. Radial leads might more accurately be referred to as tandem; they

are rarely actually aligned along radii of the body's circle, so the term is inexact,

although universal. The leads (until bent) are usually in planes parallel to that of

the flat body of the capacitor, and extend in the same direction; they are often

parallel as manufactured.

In this project capacitor is used for filtration purposes.



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5. CIRCUIT DIAGRAM



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WORKING:-

The circuit is built around a transformer, comparator, transistor and relay. Three

identical sets of this circuit, one each for three are used. Working of the circuit

connecting red cable(R phase).The main power supply phase R is stepped down

by transformer X1 to deliver 12V, 300mA, which is rectified by diode D1 and

filtered by capacitor C1 to produce the operating voltage for the operational

amplifier (IC1).

Voltage divider circuit of resistor R1 and preset resistor VR1.VR1 is used to set

the reference voltage according to the requirement. The reference voltage at non-

inverting pin 3 is fixed to 5.1V through zener diode ZD1.Till the supply voltageavailable in phase R is in the range of 200V-230V, the voltage at inverting pin 2

of ICI remains high, i.e. more than reference voltage of 5.1V, and its output pin 6

also remain high, as a result transistor T1 does not conduct, relay RL1 remains

de-energized and phase R supplies power to load L1 via normally closed (N/C)

contact of relay RL1.As soon as phase R voltage goes below 200V the voltage at

inverting pin 2 of IC1 goes below reference voltage of 5.1 V and its output goes

low.

As a result transistors T1 conducts and relay RL1 energizes and load L1 is

disconnected from phase R and connected to phase Y through relay RL2.Similarly the auto phase changer of the remaining two phases, viz phase Y and

phase B can be explained. Switch S1 is mains power on/ off switch. Use relay

contacts of proper rating and fuses should be able to take on the load when

transferred from other Phases.

Three identical sets of this circuit, one each for three phases, are used. Let us now

consider the working of the circuit connecting red cable (call it R phase). The

mains power supply phase R is stepped down by transformer X1 to deliver 12V,

300 mA, which is rectified by diode D1 and filtered by capacitor C1 to produce

the operating voltage for the operational amplifier (IC1).



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The voltage at inverting pin 2 of operational amplifier IC1 is taken from the

voltage divider circuit of resistor R1 and preset resistor VR1. VR1 is used to set

the reference voltage according to the requirement. The reference voltage at non-

inverting pin 3 is fixed to 5.1V through zener diode ZD1. Till the supply voltage

available in phase R is in the range of 200V-230V, the voltage at inverting pin 2of IC1 remains high, i.e., more than reference voltage of 5.1V, and its output pin

6 also remains high.

As a result, transistor T1 does not conduct; relay RL1 remains de-energized and

phase R supplies power to load L1 via normally closed (N/C) contact of relay

RL1. As soon as phase-R voltage goes below 200V, the voltage at inverting pin 2

of IC1 goes below reference voltage of 5.1V, and its output goes low.

As a result, transistor T1 conducts and relay RL1 energizes and load L1 is

disconnected from phase R and connected to phase Y through relay RL2.Similarly, the auto phase-change of the remaining two phases, viz, phase Y and

phase B, can be explained. Switch S1 is mains power on/off switch. Use

relay contacts of proper rating and fuses should be able to take-on the load when

transferred from other phases. While wiring, assembly and installation of the

circuit, make sure that you.



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6. OBSERVATION TABLE

I. If any1 phase given

Protection R phase Y phase B phase

Under voltage 113v 100v 138v

Over voltage 246v 238v 236v

II. If any 2 phase given

Protection Y - B phase R -B phase R -Y phase

Under voltage 159v 142v 127v

Over voltage 238v 236v 236v

7. SOLDERING TECHNOLOGY



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Soldering is the process of joining together two metallic conductor at a conductor

are to be joined is heated with a device called a soldering iron and an alloy of tin

and lead called solder is applied which metallic and covers the joint the solder

cools and solidifiers and quickly to ensure a good and durable connection

between the components tie and solder iron the electric soldering iron and

normally means of operated soldering iron are also available soldering iron are

rated in watts for TV and radio or electric work 25w to 30w soldering iron is

commonly used solder material used for electronic work is graded of 60% tin and

40% lead this folder is melts easily and makes soldering easy and safe without

any damage. A solder flux is one type of material of paste. This melts easily and

cleans the surface of any oxide films to ensure a smooth and clean soldered joint.

7.1 Conditions essential for perfect soldering:-

Certain condition necessary for perfect soldering are

i. The surface of to be soldered must be free from dust partials oil etc. it a PCB is

used it must be cleaned with petrol or sprit.

ii. The tip of the soldering iron must be sinning clean and smooth.

iii. The soldering rod tip should be operated at the spiffed temperature.

iv. The component lead must be warned sufficiently so that solder can flow easily.

Care should be taken while the leads of heat sensitive semiconductor like ICs

v. Soldering core is basically and alloy of tin and lead. The two soldering allowed

most commonly used contain tin lead in a ratio of 60:40 respectively. These two

soldered alloys have low melting points and are sufficient for most electronic

work.

7.2Soldering processing:-



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i. Remove the dust partials or chemicals from the PCB.

ii. Apply small amount of flux on the surface to be soldered.iii. Heat of surface slightly and apply the solder directly and not to tip of the

soldering iron.

iv. Avoid overheating the component printed circuit board overheating may

damaged the component or PCB.v. Do not use too much soldering to avoid short circuit between conducting path on

PCB.

7.3 Disordering:-

This technique is to remove the component from circuit board. To remove the

component properly disordering pump is used to extract the component fromcircuit board. It care is not taken then tracks on circuit board might be destroyed

while doing disordering.

8. Approximate Cost



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NO COMPONENT Quantity Cost

1 TRANSFORMER 3 240

2 OP-AMP IC LM741 3 195

3 RELAY 3 240

4 TRANSISTOR 3 125

5 ZENER DIODE 3 105

6 DIODE 9 180

7 RESISTOR 6

3

60

30

8 VARIABLERESISTOR 3 120

9 CAPACITOR 4

3

140

105

10 LED 3 45

11 WOODEN BOARD 1 175

12 BREAD BOARD 1 225

13 WIRES - 150

14 SWITCH 4 750

15 FUSE 3 105

16 Total cost 2885

9. MERITS & DEMERITS



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MERITS

i. Over and under voltage protection with help of relay and op-amp IC

ii. If one phase is give a low voltage that the voltage provide by another two phase,

so we receive continuous 3 supply

DEMERITS

i. The phase angle of 3-phase can not be maintain in this method

10. APPLICATION



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When we require constant voltage we use this circuit without stabilizer.

For Example:-

i. Home appliances (1 phase & 3 phase)

ii. Industries

iii. Computer LAB application (schools, colleges, laboratories, R&D side

etc.)



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11. FUTURE SCOPE

After successfully completion of project we will use in distribution system like

pole mounted substation, multistoried building, hospitals, colleges, commercial

buildings of incoming lines.



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12. CONCLUSION

After studying this project we can conclude that project maintain the three phase

supply and if any one or two phase fail or becomes low so this project give the

constant output. Also study about how to give the constant voltage at output

terminal with the help of different power electronic based component.



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13. REFERENCES

Sr. No References

1 ELECTRONICS FOR YOU, JULY 2007 [93, 94]

2 Pulse & Linear circuit - Ramakant Gayakwad

Basic Electronics- R.P.Ajawaliya

PRINCIPLE OF ELECTRONICS BY V.K.MEHTA

3 www.google.com

www.efymag.com

www.allboutdatasheet.com

http://www.google.com/http://www.efymag.com/http://www.allboutdatasheet.com/http://www.google.com/http://www.efymag.com/http://www.allboutdatasheet.com/


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VALIA INSTITUTE OF TECHNOLOGY VALIA

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