Engineering Practices Lab 5d2d2

RAMCO INSTITUTE OF TECHNOLOGY, RAJAPALAYAM - 626117 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING YEAR: I

SEMESTER: I

ENGINEERING PRACTICES LABORATORY

LAB MANUAL [Group – B]

I

RAMCO INSTITUTE OF TECHNOLOGY, RAJAPALAYAM - 626117 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

Class/ Semester

: I/ I

Sub & Code

: GE2116- Engineering Practices Laboratory – [Group – B]

LIST OF EXPERIMENTS

 STUDY OF SYMBOLS  SIMPLE WIRING CONNECTION  STAIRCASE WIRING  FLUORESCENT LAMP WIRING  MEASUREMENT OF POWER USING WATTMETER  MEASUREMENT OF ENERGY USING SINGLE PHASE ENERGY METER  STUDY OF MEASUREMENT OF RESISTANCE USING COLOR CODING  MEASUREMENT OF AC SIGNAL PARAMETERS USING CRO  STUDY OF BASIC LOGIC GATES  HALF WAVE AND FULL WAVE RECTIFIER  MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL EQUIPMENT

II

STUDY OF SYMBOLS AIM: To study the various symbols used in electric circuits. COMPONENT

CIRCUIT SYMBOL

DESCRIPTION

WIRE CONNECTIONS Wire

To current very easily from one part of a circuit to another.

Wires ed

A 'blob' should be drawn where wires are connected (ed), but it is sometimes omitted. Wires connected at 'crossroads' should be staggered slightly to form two Tjunctions, as shown on the right.

Wires not ed

In complex diagrams it is often necessary to draw wires crossing even though they are not connected. I prefer the 'bridge' symbol shown on the right because the simple crossing on the left may be misread as a where you have forgotten to add a 'blob'!

POWER SUPPLIES

Cell

Supplies electrical energy. The larger terminal (on the left) is positive (+). A single cell is often called a battery, but strictly a battery is two or more cells ed together.

Battery

Supplies electrical energy. A battery is more than one cell. The larger terminal (on the left) is positive (+). The smaller terminal (on the right) is negative (-).

DC supply

Supplies electrical energy. DC = Direct Current, always flowing in one direction.

AC supply

Supplies electrical energy. AC = Alternating Current, continually changing direction. A safety device which will 'blow' (melt) if the current flowing through it exceeds a specified value.

Fuse

1

Transformer

Two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core. There is no electrical connection between the coils.

Earth (Ground)

A connection to earth. For many electronic circuits this is the 0V (zero volts) of the power supply, but for mains electricity and some radio circuits it really means the earth. It is also known as ground.

OUTPUT DEVICES: LAMPS, HEATER, MOTOR, etc. Lamp (lighting)

A transducer which converts electrical energy to light. This symbol is used for a lamp providing illumination, for example a car headlamp or torch bulb.

Lamp (indicator)

A transducer which converts electrical energy to light. This symbol is used for a lamp which is an indicator, for example a warning light on a car dashboard.

Heater

A transducer which converts electrical energy to heat.

Motor

A transducer which converts electrical energy to kinetic energy (motion).

Bell

A transducer which converts electrical energy to sound.

Buzzer

A transducer which converts electrical energy to sound.

Inductor (Coil, Solenoid)

A coil of wire which creates a magnetic field when current es through it. It may have an iron core inside the coil. It can be used as a transducer converting electrical energy to mechanical energy by pulling on something.

Switches A push switch allows current to flow only when the button is pressed. This is the switch used to operate a doorbell.

Push Switch (push-to-make) 2

Push-to-Break Switch

This type of push switch is normally closed (on), it is open (off) only when the button is pressed.

On-Off Switch (SPSTS)

SPSTS = Single Pole Single Throw Switch. An on-off switch allows current to flow only when it is in the closed (on) position.

2-way Switch (SPDTS)

SPDTS = Single Pole Double Throw Switch. A 2-way changeover switch directs the flow of current to one of two routes according to its position. Some SPDT switches have a central off position and are described as 'on-off-on'.

Dual On-Off Switch (DPSTS)

DPST = Double Pole, Single Throw Switch. A dual on-off switch which is often used to switch mains electricity because it can isolate both the live and neutral connections.

Reversing Switch (DPDTS)

DPDT = Double Pole, Double Throw Switch. This switch can be wired up as a reversing switch for a motor. Some DPDT switches have a central off position.

Relay

An electrically operated switch, for example a 9V battery circuit connected to the coil can switch a 230V AC mains circuit. NO = Normally Open, COM = Common, NC = Normally Closed.

Resistors A resistor restricts the flow of current, for example to limit the current ing through an LED. A resistor is used with a capacitor in a timing circuit. Some publications still use the old resistor symbol:

Resistor

This type of variable resistor with 2 s (a rheostat) is usually used to control current. Examples include: adjusting lamp brightness, adjusting motor speed, and adjusting the rate of flow of charge into a capacitor in a timing circuit.

Variable Resistor (Rheostat)

3

Variable Resistor (Potentiometer)

This type of variable resistor with 3 s (a potentiometer) is usually used to control voltage. It can be used like this as a transducer converting position (angle of the control spindle) to an electrical signal.

Variable Resistor (Preset)

This type of variable resistor (a preset) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment. Presets are cheaper than normal variable resistors so they are often used in projects to reduce the cost.

CAPACITORS Capacitor

A capacitor stores electric charge. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but AC signals.

Capacitor polarized

A capacitor stores electric charge. This type must be connected the correct way round. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but AC signals.

Variable Capacitor

A variable capacitor is used in a radio tuner.

Trimmer Capacitor

This type of variable capacitor (a trimmer) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment.

DIODES Diode

A device which only allows current to flow in one direction.

LED Light Emitting Diode

A transducer which converts electrical energy to light.

Zener Diode

A special diode which is used to maintain a fixed voltage across its terminals.

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Photodiode

A light-sensitive diode.

TRANSISTORS

Transistor NPN

A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit.

Transistor PNP

A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit.

Phototransistor

A light-sensitive transistor.

AUDIO AND RADIO DEVICES Microphone

A transducer which converts sound to electrical energy.

Earphone

A transducer which converts electrical energy to sound.

Loudspeaker

A transducer which converts electrical energy to sound.

Piezo Transducer

A transducer which converts electrical energy to sound.

Amplifier (general symbol)

An amplifier circuit with one input. Really it is a block diagram symbol because it represents a circuit rather than just one component.

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A device which is designed to receive or transmit radio signals. It is also known as an antenna.

Aerial (Antenna)

METERS AND OSCILLOSCOPE Voltmeter

A voltmeter is used to measure voltage. Voltmeter must be connected across the terminal.

Ammeter

An ammeter is used to measure current. It is always connected in series with the circuit.

Galvanometer

A galvanometer is a very sensitive meter which is used to measure tiny currents, usually 1mA or less.

Ohmmeter

An ohmmeter is used to measure resistance. Most multimeters have an ohmmeter setting.

Oscilloscope

An oscilloscope is used to display the shape of electrical signals and it can be used to measure their voltage and time period.

SENSORS (INPUT DEVICES) LDR

A transducer which converts brightness (light) to resistance (an electrical property). LDR = Light Dependent Resistor

Thermistor

A transducer which converts temperature (heat) to resistance (an electrical property).

LOGIC GATES

NOT

A NOT gate can only have one input. The 'o' on the output means 'not'. The output of a NOT gate is the inverse (opposite) of its input, so the output is true when the input is false. A NOT gate is also called an inverter.

AND

An AND gate can have two or more inputs. The output of an AND gate is true when all its inputs are true.

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NAND

A NAND gate can have two or more inputs. The 'o' on the output means 'not' showing that it is a Not AND gate. The output of a NAND gate is true unless all its inputs are true.

OR

An OR gate can have two or more inputs. The output of an OR gate is true when at least one of its inputs is true.

NOR

A NOR gate can have two or more inputs. The 'o' on the output means 'not' showing that it is a Not OR gate. The output of a NOR gate is true when none of its inputs are true.

EX-OR

An EX-OR gate can only have two inputs. The output of an EX-OR gate is true when its inputs are different (one true, one false).

EX-NOR

An EX-NOR gate can only have two inputs. The 'o' on the output means 'not' showing that it is a Not EX-OR gate. The output of an EX-NOR gate is true when its inputs are the same (both true or both false).

RESULT: Thus the various symbols in electric circuits were studied and drawn.

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CIRCUIT DIAGRAM:

LAYOUT DIAGRAM:

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SIMPLE WIRING CONNECTION AIM: To study and practice the various types of electrical wiring circuit connections. REFERENCE: 1.Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2.Engineering Practice by M.S. Kumar – D D Publications. TOOLS REQUIRED: S.No.

TOOLS

QUANTITY (No.)

1.

Tester

1

2.

Electrician Knife

1

3.

Wire Cutter

1

4.

Screw Driver

1

MATERIAL REQUIRED: 1. Single Pole One Way Switch

-

3 No.s

2. Lamps

-

3 No.s

3. Wires

-

Required

4. Two Pins or Three Pins Wall Socket

-

1 No.

5. Batten Holder

-

3 No.s

THEORY: Any conductor which is composed of a conducting material, and is uniform in diameter and circular in cross section is called wire. A length of single insulated conductor or two or more such conductors each provided with its own insulation which are laid up together is called a cable. A cable consists of the following three main parts: a) Conductor, b) Insulation Covering and c) Protective covering.

9

10

CONDUCTOR: Any pure metal which offers low resistance to the age of electric current is called a conductor. The current is taken from one place to the other by means of a conductor. Copper is used as a conductor in majority of applications. INSULATION CONVERING: It is the covering which bounds the current flow in a definite path. The insulation of the cable must be strong enough because a leakage current will start giving electrical shocks and cause fire. PROTECTIVE COVERING: It protects the insulation covering against any mechanical injury. VARIOUS TYPES OF WIRES: The various types of wires are vulcanized Insulation Rubber(VIR) wires, Cab Type Sheathed(CTS), Poly Vinyl Chloride (PVC) wires,flexible Wires,etc…out of these for house hold applicatios PVC wires are used. PRECAUTIONS:  The circuit should be checked by series test lamp.  Bare portion of the conductor should not come out of the terminal and the insulation of the conductor should keep up to the end of the terminal.  All the connections should be tight.  All the switches should be connected in positive wire.  Always keep the live wires on the right hand side. PROCEDURE:  First the layout diagram of the electrical circuit is made.  The circuit is made with the given material.  The output is verified by switching ON the switches. RESULT: Thus the various electrical circuit connections were made and studied.

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STAIRCASE WIRING CIRCUIT DIAGRAM:

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STAIRCASE WIRING AIM: To construct and control the status of lamp using two way switch by Stair – Case wiring. REFERENCE: 1.Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2.Engineering Practice by M.S. Kumar – D D Publications. TOOLS REQUIRED: S.No.

TOOLS

QUANTITY (No.)

1.

Tester

1

2.

Electrician Knife

1

3.

Wire Cutter

1

4.

Screw Driver

1

5.

Combination Plier

1

MATERIAL REQUIRED: 1. Two Way Switches

-

2 No.s

2. Lamp

-

1 No

3. Wires

-

Required

4. Lamp Holder

-

1 No

PRECAUTIONS:  The circuit should be checked by series test lamp.  Bare portion of the conductor should not come out of the terminal and the insulation of the conductor should keep up to the end of the terminal.  All the connections should be tight.  All the switches should be connected in positive wire.  Always keep the live wires on the right hand side. 13

LAYOUT DIAGRAM:

TABLULATION:

Sl.NO 1

Switch A

Switch B

1

2

2 3 4

14

Output-Lamp OFF

PROCEDURE:  First the layout diagram of the electrical circuit is made.  The connections are made as per the wiring diagram.  The output table is verified by switching ON the switches.

RESULT: Thus the stair – case wiring was constructed and output was verified.

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FLUORESCENT TUBE WIRING CIRCUIT DIAGRAM:

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FLUORESCENT LAMP WIRING AIM: To construct and study the working of a fluorescent lamp circuit. REFERENCE: 1.Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2.Engineering Practice by M.S. Kumar – D D Publications. TOOLS REQUIRED: S.No.

TOOLS

QUANTITY (No.)

1.

Tester

1

2.

Electrician Knife

1

3.

Wire Cutter

1

4.

Screw Driver

1

5.

Combination Plier

1

MATERIAL REQUIRED: 1. Choke

-

1 No.

2. Starter

-

1 No.

3. Tube light holder, frame

-

1 No.

4. Tube light

-

1 No.

5. Connecting wires

-

Required

PRECAUTIONS:  All the connections should be tight.  Twisting of wires should be avoided.  Always keep the live wires on the right hand side. THEORY: The fluorescent tubes are usually available in lengths of 0.61 m and 1.22 m. The various parts of fluorescent tube include.

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18

1. Glass tube 2. Starter 3. Choke 4. Fluorescent materials 5. Filaments The inside surface of the fluorescent tube is coated with a thin layer of fluorescent material in the form of powder. The tube also contains low pressure argon gas and one or two drops of mercury. The two filaments are coated with electron emissive material. The starter (initially in closed position) puts the filaments directly across the supply mains at the time of starting, there by initiating emission of electrons. After 1 or 2 seconds the starter switch gets opened. The interruption of current makes the choke to act like ballast providing a voltage impulse across the filaments. Due to this, ionization of argon takes place. Mercury vapour arc provides a conducting path between the filaments. The starter used may be of thermal starter or glow starter whose function is to complete the circuit initially for preheating the filaments (to initiate emission of electrons) and then to open the circuit for high voltage across choke for initiating ionization. PROCEDURE:  First the layout diagram of the electrical circuit is made.  The connections are made as per the wiring diagram.  The output is verified.

RESULT: Thus the fluorescent lamp circuit connection was given and studied. 19

CIRCUIT DIAGRAM:

(0 – 10A) MI P

10 A

230 V, 1 Φ 50 Hz, A.C.

N

A C

D P S T S

300V, 10A, UPF M

L V

V

L O A D

(0 – 300V) MI

10 A 1 Φ Variac (0 – 270V)

TABULATION: Multiplication Factor = ……………. S.No.

Voltage

Current

(Volts)

(Ampere)

Wattmeter Reading (Watts) Observed value

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Actual value

MEASUREMENT OF POWER USING WATTMETER AIM: To measure the Power consumed by a Single Phase Resistive Load by using Wattmeter. REFERENCE: 1.Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2.Engineering Practice by M.S. Kumar – D D Publications. APPARATUS REQUIRED: S.No.

APPARATUS

TYPE / RANGE

QUANTITY

1.

Ammeter

(0 – 10A) MI

1

2.

Voltmeter

(0 – 300V) MI

1

3.

Wattmeter

300V, 10A, UPF

1

4.

Single Phase Resistive Load

5.

Connecting Wires

1 Required

FORMULA USED:  Multiplication Factor = Current Coil Rating x Voltage Coil Rating x Power Factor Full Scale Reading of Wattmeter  Actual Power in Watts = Observed Reading x Multiplication Factor THEORY: A wattmeter is an instrument specially designed to measure average power consumed by a load. It has two coils:A current coil that measures the current and a voltage coil that measures the voltage. The wattmeter takes into the phase shift, if there is any between the current sensed by its current coil and the voltage sensed by its voltage coil. If the voltage drop across as measured the voltage coil is Vm cos(ωt + Ф) A, then the average power P measured by the wattmeter in watts is ½ Vm Im Cos Ф,where Ф = is the power factor angle. The voltage coil of the wattmeter, its reading will be 0.707 Vm. 21

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PRECAUTIONS:  Single phase variac should be kept at minimum position, during starting period.  No load should be connected when the DPSTS is closed or opened. PROCEDURE:  The connections are made as per the circuit diagram.  Rated Voltage is set in the voltmeter, by gradually varying the single phase variac.  Resistive load is switch ON.  Load is gradually increased and the ammeter, voltmeter & wattmeter readings are noted.

RESULT: Thus the power consumed by a single phase resistive load was measured.

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CIRCUIT DIAGRAM: (0 – 10A) MI P

230 V, 1 Φ 50 Hz, A.C.

10 A

A

D P S T S

N

Energy Meter

V

S1

C1

P1

C2

P2

(0 – 300V) MI

10 A

S2

L1

L O A D

L2

1 Φ Variac (0 – 270V)

TABULATION: Energy Meter Constant = ………………… Sl.

Voltage

No.

(Volts)

Current

Power

Time

Number of

(Ampere) (Watts) (Seconds) Revolutions

24

Actual

True

Energy Energy (KWh)

(KWh)

% Error

MEASUREMENT OF ENERGY USING SINGLE PHASE ENERGY METER AIM: To measure the Energy consumed by a Single Phase Resistive Load by using Single Phase Energy Meter. REFERENCE: 1.Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2.Engineering Practice by M.S. Kumar – D D Publications. APPARATUS REQUIRED: S.No.

APPARATUS

TYPE / RANGE

QUANTITY

1.

Ammeter

(0 – 10A) MI

1

2.

Voltmeter

(0 – 300V) MI

1

3.

Single Phase Energy Meter

4.

Stop Watch

5.

Single Phase Resistive Load

6.

Connecting Wires

1 Analog

1

3 KW, 230 V

1 Required

FORMULA USED:  Actual Energy in KWh = Power in Watts x Time Taken in Seconds 1000 x 3600  Power in Watts = Voltage in Volts x Current in Amperes  True Energy in KWh = No. of Revolution / Energy Meter Constant  % Error = True Energy – Actual Energy Actual Energy

x

100

THEORY: An induction type meter is commonly used. It consists of two magnets, the upper and lower magnets. The upper magnet carries a pressure coil, which is made up of a thin wire and has large number of turns. This coil has to be connected in parallel with the supply. The lower magnet carries the current coil which is made

25

26

up of a thick wire and has only few turns. This coil is to be connected in series with the load. An aluminum disc mounted on the spindle is placed between the upper and lower magnets. The disc can rotate freely between the magnets. Another permanent magnet called as brake magnet is used for providing breaking torque on the aluminium disc. The power consumed is measured in of number rotations of the disc. For example 1800 revolutions of the disc means 1 KWH power consumed by the load connected to the energy meter. PRECAUTIONS:  Single phase variac should be kept at minimum position, during starting period.  No load should be connected when the DPSTS is closed or opened. PROCEDURE:  The connections are made as per the circuit diagram.  Rated Voltage is set in the voltmeter, by gradually varying the single phase variac.  Resistive load is switch ON.  Load is gradually increased and the ammeter, voltmeter & Energy meter readings are noted.

RESULT: Thus the Energy consumed by a single phase resistive load was measured.

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RESISTOR COLOUR CODING:

RESISTOR STANDARD COLOUR CODE TABLE: Colour Black Brown Red Orange Yellow Green Blue Violet Grey White Gold Silver None

Value Digit 0 1 2 3 4 5 6 7 8 9

Multiplier x100 x101 x102 x103 x104 x105 x106 x107 x108 x109 x10-1 x10-2

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Tolerance ±1% ±2%

±0.5% ±0.25% ±0.1% ±0.05% ±5% ±10% ±20%

STUDY OF MEASUREMENT OF RESISTANCE USING COLOR CODING AIM: To study the measurement of value of resistance using color coding REFERENCE: 1. Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2. Engineering Practice by M.S. Kumar – D D Publications. MATERIALS REQUIRED: 1. Resistors 2. Multimeter THEORY: A resistor is a ive component. It introduces resistance in the circuit. Resistance is basic property of conducting material and is given by R = ρL/ A Where, ρ

-

Specified resistivity.

L

-

Length of the material.

A

-

Area of cross section of material.

We have a number of type of resistors such as carbon composition, metal film, carbon film wire wound and variable resistors. In our laboratory carbon resistors are used. For resistance of the order of mega ohms, we use powdered carbon mixed with a suitable building material in the proper proportion. Carbon resistors are quite cheap, but the value of resistance may be easily affected by atmospheric changes and is also susceptible to high tolerance.

29

TABULATION:

Sl. No.

Resistance Value by

Resistance Value

Colour Coding (Ω)

by Multimeter (Ω)

30

IDENTIFICATION MARKING OF RESISTORS Universally recognized approaches have been established to identify the electrical values. Two such markings are (i)

Colour code.

(ii)

Alpha numeric code.

Normally in our laboratories low wattage general purpose resistors are used. In this colour coding method is used to identify the value of the resistance. In our colour coding method the value of the resistance is coded on the resistor using three or four colour bands. The first two colour band gives the first two significant digital values. The third band gives the value of multiplier. Fourth band gives the tolerance value.

RESULT: Thus the value of resistor using colour coding was studied and measured. 31

CIRCUIT DIAGRAM: Measurement of AC Voltage amplitude and frequency

AFO

CRO

TABULATION:

Maximum voltage ,

Peak- to-

RMS

Vm in Volts

Peak

Voltage

Voltage

Vrms

Vpp= 2Vm

= Vm /

in Volts

In Volts

Sl. No

Per

No of

Actual

division

divisions

Value

1. 2. 3. 4.

32

Time in Seconds

Frequency

Per

No of

Actual

division

divisions

Value

f = 1/T in Hz

MEASUREMENT OF AC SIGNAL PARAMETERS USING CRO AIM: To measure the following when a sinusoidal voltage is applied. 1.

Peak – Peak Magnitude of the Voltage,

2.

RMS Value of the Voltage

3.

Time Period

4.

Frequency,

REFERENCE: 1. Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2. Engineering Practice by M.S. Kumar – D D Publications. APPARATUS REQUIRED: S.NO. NAME OF THE EQUIPMENT

TYPE

RANGE

QUANTITY (NO.S)

1.

Cathode Ray Oscilloscope (CRO)

Analog

30 MHz

1

2.

Audio Frequency Oscillator

Digital

2 MHz

1

3.

Bread Board

4.

Connecting Probes, wires

1 As Required

FORMULA USED: Measurement of unknown frequency = FV / FH … (Hz) = Number of loops cut in the horizontal axis Number of loops cut in vertical axis Where, FV – frequency of waveform given to the vertical plane FH – frequency of waveform given to the horizontal plane VRMS = Vm / √ 2 … (Volts) f = 1 / T … (Hz) ω = 2 π f … (radian)

33

MODEL GRAPH: (Using CRO) AC input Voltage:

Measurement of DC Voltage amplitude and frequency:

+ CRO

RPS (0-30V) -

TABULATION: SI.No.

Applied Voltage

Number of

(V)

divisions

1. 2. 3. 4.

34

Volt/Division

Measured Voltage (V)

THEORY: The Cathode Ray Oscilloscope is an extremely useful and versatile as laboratory instrument for studying wave shapes of alternating currents and voltages as well as for measurement of voltage, current and frequency. It generates the electron a high velocity, deflects the beam to create the image and contains a phosphor beam, to screen where the electron beam becomes visible. For accomplishing these tasks various electrical signals and voltages are required, which are provided by the power supply circuit of the oscilloscope. Low voltage supply is required for the heater of the electron gun for generation of electron beam and high voltage is required for cathode ray tube to accelerate the beam. Normal voltage supply is required for other control circuits of the oscilloscope. Electron beam deflects in two directions horizontal on X axis and vertical on Y axis. For measurement of direct voltage, firstly the spot is centered on the screen without applying signal any voltage to the deflection plates. Then direst voltage to be measured is applied between a pair of depletion plates and deflection of the spot is observed on the screen. The magnitude of the deflection multiplied is the deflection factor gives the value of direct voltage applied. In case of measurement alternating voltage of sinusoidal waveform it is applied between a pair of deflection plates and the length of the straight line is measured. Knowing be determined the deflection sensitivity the peak to peak value of applied ac voltage can be determined. PROCEDURE: 1. The circuit connections are given as per the circuit diagram. 2. The sinusoidal voltage is applied with the help of AFO. 3. Readings are taken for different magnitudes and frequencies.

RESULT: Thus the Peak – Peak Magnitude of the voltage, RMS Value of the Voltage, Time Period, Frequency are measured with help up CRO.

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AND GATE

OR GATE

LOGIC DIAGRAM:

LOGIC DIAGRAM:

PIN DIAGRAM OF IC 7408 :

PIN DIAGRAM OF IC 7432 :

CIRCUIT DIAGRAM:

CIRCUIT DIAGRAM:

TRUTH TABLE:

TRUTH TABLE: S.No 1. 2. 3. 4.

INPUT A B 0 0 0 1 1 0 1 1

OUTPUT Y=A.B 0 0 0 1

S.No 1. 2. 3. 4.

36

INPUT A 0 0 1 1

B 0 1 0 1

OUTPUT Y=A+B 0 1 1 1

STUDY OF BASIC LOGIC GATES

AIM: To the truth table of basic logic gates of AND, OR, NOT, NAND, NOR, EX-OR gates. REFERENCE: 1. Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2. Engineering Practice by M.S. Kumar – D D Publications. APPARATUS REQUIRED: S.No

Name of the Apparatus

Range

Quantity

1.

Digital IC trainer kit

2.

AND gate

IC 7408

1

3.

OR gate

IC 7432

1

4.

NOT gate

IC 7404

1

5.

NAND gate

IC 7400

1

6.

NOR gate

IC 7402

1

7.

EX-OR gate

IC 7486

1

8.

Connecting wires

As required

1

THEORY: a. AND gate: An AND gate is the physical realization of logical multiplication operation. It is an electronic circuit which generates an output signal of ‘1’ only if all the input signals are ‘1’. b. OR gate: An OR gate is the physical realization of the logical addition operation. It is an electronic circuit which generates an output signal of ‘1’ if any of the input signal is ‘1’. 37

NOT GATE

NAND GATE

LOGIC DIAGRAM:

LOGIC DIAGRAM:

PIN DIAGRAM OF IC 7404:

PIN DIAGRAM OF IC 7400 :

CIRCUIT DIAGRAM:

CIRCUIT DIARAM:

TRUTH TABLE:

TRUTH TABLE:

S.N o 1. 2.

INPUT A 0 1

OUTPUT Y = A’ 1 0

S.No 1. 2. 3. 4.

38

INPUT A B 0 0 0 1 1 0 1 1

OUTPUT Y = (A. B)’ 1 1 1 0

c. NOT gate: A NOT gate is the physical realization of the complementation operation. It is an electronic circuit which generates an output signal which is the reverse of the input signal. A NOT gate is also known as an inverter because it inverts the input. d. NAND gate: A NAND gate is a complemented AND gate. The output of the NAND gate will be ‘0’ if all the input signals are ‘1’ and will be ‘1’ if any one of the input signal is ‘0’. e. NOR gate: A NOR gate is a complemented OR gate. The output of the OR gate will be ‘1’ if all the inputs are ‘0’ and will be ‘0’ if any one of the input signal is ‘1’. f. EX-OR gate: An Ex-OR gate performs the following Boolean function, A

B = ( A . B’ ) + ( A’ . B )

It is similar to OR gate but excludes the combination of both A and B being equal to one. The exclusive OR is a function that give an output signal ‘0’ when the two input signals are equal either ‘0’ or ‘1’.

PROCEDURE:

 Connections are given as per the circuit diagram  For all the ICs 7th pin is grounded and 14th pin is given +5 V supply.  Apply the inputs and the truth table for all gates.

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NOR GATE LOGIC DIAGRAM:

LOGIC DIAGRAM

PIN DIAGRAM OF IC 7402 :

CIRCUIT DIAGRAM:

1. 2. 3. 4.

INPUT A B 0 0 0 1 1 0 1 1

PIN DIAGRAM OF IC 7486 :

CIRCUIT DIAGRAM:

TRUTH TABLE:

TRUTH TABLE: S.No

EX-OR GATE

OUTPUT Y = (A + B)’ 1 0 0 0

S.No 1. 2. 3. 4.

40

INPUT A B 0 0 0 1 1 0 1 1

OUTPUT Y=A B 0 1 1 0

RESULT:

The truth table of all the basic logic gates were verified. 41

CIRCUIT DIAGRAM: Half Wave Rectifier: P IN 4007 230 V, 50 Hz 1 Φ Supply

N

100 μF 1 KΩ

CRO

Step-down Transformer (0 – 12V)

Full Wave Rectifier: P D1

D2

D4

D3

230 V, 50 Hz 1 Φ Supply 100 μF 1 KΩ

N

CRO

TABULATION: Without Filter Rectifier

Vm (V)

T (mS)

Half Wave Rectifier Full Wave Rectifier

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With Filter Vm (V)

T (mS) Charging

Discharging

HALF WAVE AND FULL WAVE RECTIFIER AIM: To obtain the output of Half wave and Full Wave rectifier and to plot the characteristics. REFERENCE: 1. Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2. Engineering Practice by M.S. Kumar – D D Publications. APPARATUS REQUIRED: S.NO. NAME OF THE EQUIPMENT 1

Diode

2

Resistor

3

Capacitor

4

TYPE

RANGE

QUANTITY (NO.S)

IN 4001

Transformer

Step-down

4 1 KΩ

1

100 μF

1

230 V /

1

(12 – 0 – 12) V

5

CRO

6

Bread Board

7

Connecting wires and probe

Analog

30 MHz

1 1 As Required

THEORY: Half wave rectifier converts alternating voltage into unidirectional pulsating voltage. The half wave rectifier circuit using a diode with a load resistance R. The diode is connected in series with the secondary of the transformer and the load resistance R, the primary of the transformer is being connected to the supply mains. The AC voltage across the secondary winding changes polarities after every half cycle. During the positive half cycles of the input AC voltage i.e. when upper end of the secondary winding is positive with respect to its lower end, the diode is forward biased and therefore 43

WAVEFORMS: Vin (V) Vm

0

Time

Vout (V)

Output of Half Wave Rectifier without filter

0

Time

Vm

Output of Half Wave Rectifier with filter

0 Time filter

Vm

Output of Full Wave Rectifier without

0 Time

Vm

Output of Full Wave Rectifier with

filter

0

Time

44

current conducts. During the negative half cycles of the input AC voltage i.e. when lower end of the secondary winding is positive with respect to its upper end, the diode is reverse biased and does not conduct. Thus for the negative half cycles no power is delivered to the load. Since only one half cycles of the input wave is converted as output, it is called as Half Wave Rectifier. In Full Wave Rectifier the diode D2 and D4 will conduct during the positive half of the input signal and during the negative half cycle of the input signal the diode D1 andD3 conducts. Hence both the half cycles are converted into output and the efficiency is high compared with the half wave rectifier.

PROCEDURE: 1. Circuit connections were given as per the circuit diagram. 2. Input waveform’s magnitude and frequency was measured with the help of CRO. 3. Supply is switched ON and the output waveform was obtained in the CRO. 4. Output waveform’s magnitude and time period was measured. 5. Graphs were plotted for Half wave and Full wave rectifier outputs.

RESULT: Thus the output of Half wave and Full wave rectifiers were obtained and the curves were plotted.

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MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL EQUIPMENT AIM: To measure the resistance to earth / insulation resistance of the order of mega ohms. REFERENCE: 1. Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers. 2. Engineering Practice by M.S. Kumar – D D Publications. THEORY: Megger is the equipment used in this experiment. It is an instrument for testing the insulation resistance of the order of mega ohms. PRINCIPLE: A megger consists of an EMF source and a Voltmeter. The voltmeter scale is calibrated in ohms. In measurement, the EMF of the self contained source should be equal that of the source used in calibration. The deflection of the moving system depends on the ratio of the currents in the coils and is independent of the applied voltage. The value of unknown resistance can be found directly from the scale of the instrument. Figure shows the detailed diagram of a megger. It consists of hand driven dc generator and ohmmeter, a small permanent magnet. Hand driven dc generator generates a EMF about 500V. The permanent dc meter has two moving coils. First one is deflecting coil and another one controlling coil. The deflecting coil is connected to the generator through a resistor R. The torque due to the two coils opposes each other. It consists of three terminals E, L and G. OPERATION: When the terminals are open circuited, no current flows through the deflecting coil. The torque due to the controlling coil moves the pointer to one end of the scale. When the terminals are short circuited, the torque due to the controlling coil and the pointer is deflected to the other end of the scale, i.e. 47

48

zero mark. In between the two extreme positions the scale is calibrated to indicate the value of unknown resistance directly. The unknown insulation resistance is connected across E and L terminals. The effective insulation resistance is the combination of insulation volume resistance and surface leakage resistance. The guard wire terminal makes the surface leakage current to by the instrument hence only insulation resistance is measured.

RESULT: Thus the resistance to earth / insulation resistance of the order of mega ohms can be measured.

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