engineering practices lab
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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
YEAR: I SEMESTER: I
LAB MANUAL[Group – B]
ENGINEERING PRACTICESLABORATORY
II
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
Class/ Semester : I/ I
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
Sub & Code : GE2116- Engineering Practices Laboratory – [Group – B]
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STUDY OF SYMBOLSAIM:
To study the various symbols used in electric circuits.
COMPONENT CIRCUIT SYMBOL DESCRIPTION
WIRE CONNECTIONS
Wire To pass current very easily from one partof a circuit to another.
Wires joined
A 'blob' should be drawn where wires areconnected (joined), but it is sometimesomitted. Wires connected at 'crossroads'should be staggered slightly to form two T-junctions, as shown on the right.
Wires not joined
In complex diagrams it is often necessaryto draw wires crossing even though theyare not connected. I prefer the 'bridge'symbol shown on the right because thesimple crossing on the left may be misreadas a join 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, butstrictly a battery is two or more cells joinedtogether.
Battery
Supplies electrical energy. A battery ismore than one cell. The larger terminal (onthe left) is positive (+). The smallerterminal (on the right) is negative (-).
DC supplySupplies electrical energy.DC = Direct Current, always flowing inone direction.
AC supplySupplies electrical energy.AC = Alternating Current, continuallychanging direction.
FuseA safety device which will 'blow' (melt) ifthe current flowing through it exceeds aspecified value.
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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 bythe magnetic field in the core. There is noelectrical connection between the coils.
Earth(Ground)
A connection to earth. For many electroniccircuits this is the 0V (zero volts) of thepower supply, but for mains electricity andsome radio circuits it really means theearth. It is also known as ground.
OUTPUT DEVICES: LAMPS, HEATER, MOTOR, etc.
Lamp (lighting)
A transducer which converts electricalenergy to light. This symbol is used for alamp providing illumination, for example acar headlamp or torch bulb.
Lamp (indicator)
A transducer which converts electricalenergy to light. This symbol is used for alamp which is an indicator, for example awarning light on a car dashboard.
Heater A transducer which converts electricalenergy to heat.
Motor A transducer which converts electricalenergy to kinetic energy (motion).
Bell A transducer which converts electricalenergy to sound.
Buzzer A transducer which converts electricalenergy to sound.
Inductor(Coil, Solenoid)
A coil of wire which creates a magneticfield when current passes through it. It mayhave an iron core inside the coil. It can beused as a transducer converting electricalenergy to mechanical energy by pulling onsomething.
Switches
Push Switch(push-to-make)
A push switch allows current to flow onlywhen the button is pressed. This is theswitch used to operate a doorbell.
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Push-to-BreakSwitch
This type of push switch is normally closed(on), it is open (off) only when the buttonis pressed.
On-Off Switch(SPSTS)
SPSTS = Single Pole Single ThrowSwitch. An on-off switch allows current toflow only when it is in the closed (on)position.
2-way Switch(SPDTS)
SPDTS = Single Pole Double ThrowSwitch. A 2-way changeover switch directsthe flow of current to one of two routesaccording to its position. Some SPDTswitches have a central off position and aredescribed as 'on-off-on'.
Dual On-OffSwitch
(DPSTS)
DPST = Double Pole, Single ThrowSwitch. A dual on-off switch which isoften used to switch mains electricitybecause it can isolate both the live andneutral connections.
Reversing Switch(DPDTS)
DPDT = Double Pole, Double ThrowSwitch. This switch can be wired up as areversing switch for a motor. Some DPDTswitches have a central off position.
Relay
An electrically operated switch, forexample a 9V battery circuit connected tothe coil can switch a 230V AC mainscircuit.NO = Normally Open, COM = Common,NC = Normally Closed.
Resistors
Resistor A resistor restricts the flow of current, forexample to limit the current passingthrough an LED. A resistor is used with acapacitor in a timing circuit.Some publications still use the old resistorsymbol:
Variable Resistor(Rheostat)
This type of variable resistor with 2contacts (a rheostat) is usually used tocontrol current. Examples include:adjusting lamp brightness, adjusting motorspeed, and adjusting the rate of flow ofcharge into a capacitor in a timing circuit.
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Variable Resistor(Potentiometer)
This type of variable resistor with 3contacts (a potentiometer) is usually usedto control voltage. It can be used like thisas a transducer converting position (angleof the control spindle) to an electricalsignal.
Variable Resistor(Preset)
This type of variable resistor (a preset) isoperated with a small screwdriver orsimilar tool. It is designed to be set whenthe circuit is made and then left withoutfurther adjustment. Presets are cheaperthan normal variable resistors so they areoften used in projects to reduce the cost.
CAPACITORS
Capacitor
A capacitor stores electric charge. Acapacitor is used with a resistor in a timingcircuit. It can also be used as a filter, toblock DC signals but pass AC signals.
Capacitorpolarized
A capacitor stores electric charge. Thistype must be connected the correct wayround. A capacitor is used with a resistor ina timing circuit. It can also be used as afilter, to block DC signals but pass ACsignals.
Variable Capacitor A variable capacitor is used in a radiotuner.
Trimmer Capacitor
This type of variable capacitor (a trimmer)is operated with a small screwdriver orsimilar tool. It is designed to be set whenthe circuit is made and then left withoutfurther adjustment.
DIODES
Diode A device which only allows current to flowin one direction.
LEDLight Emitting
Diode
A transducer which converts electricalenergy to light.
Zener Diode A special diode which is used to maintain afixed voltage across its terminals.
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Photodiode A light-sensitive diode.
TRANSISTORS
Transistor NPNA transistor amplifies current. It can beused with other components to make anamplifier or switching circuit.
Transistor PNPA transistor amplifies current. It can beused with other components to make anamplifier or switching circuit.
Phototransistor A light-sensitive transistor.
AUDIO AND RADIO DEVICES
Microphone A transducer which converts sound toelectrical energy.
Earphone A transducer which converts electricalenergy to sound.
Loudspeaker A transducer which converts electricalenergy to sound.
Piezo Transducer A transducer which converts electricalenergy to sound.
Amplifier(general symbol)
An amplifier circuit with one input. Reallyit is a block diagram symbol because itrepresents a circuit rather than just onecomponent.
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Aerial(Antenna)
A device which is designed to receive ortransmit radio signals. It is also known asan antenna.
METERS AND OSCILLOSCOPE
VoltmeterA voltmeter is used to measure voltage.Voltmeter must be connected across theterminal.
AmmeterAn ammeter is used to measure current. Itis always connected in series with thecircuit.
GalvanometerA galvanometer is a very sensitive meterwhich is used to measure tiny currents,usually 1mA or less.
OhmmeterAn ohmmeter is used to measureresistance. Most multimeters have anohmmeter setting.
Oscilloscope
An oscilloscope is used to display theshape of electrical signals and it can beused to measure their voltage and timeperiod.
SENSORS (INPUT DEVICES)
LDR
A transducer which converts brightness(light) to resistance (an electricalproperty).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 ofa NOT gate is the inverse (opposite) of itsinput, so the output is true when the inputis false. A NOT gate is also called aninverter.
ANDAn AND gate can have two or more inputs.The output of an AND gate is true when allits inputs are true.
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NAND
A NAND gate can have two or moreinputs. The 'o' on the output means 'not'showing that it is a Not AND gate. Theoutput of a NAND gate is true unless all itsinputs are true.
ORAn OR gate can have two or more inputs.The output of an OR gate is true when atleast one of its inputs is true.
NOR
A NOR gate can have two or more inputs.The 'o' on the output means 'not' showingthat it is a Not OR gate. The output of aNOR gate is true when none of its inputsare true.
EX-ORAn EX-OR gate can only have two inputs.The output of an EX-OR gate is true whenits inputs are different (one true, one false).
EX-NOR
An EX-NOR gate can only have twoinputs. The 'o' on the output means 'not'showing that it is a Not EX-OR gate. Theoutput of an EX-NOR gate is true when itsinputs are the same (both true or bothfalse).
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.
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CONDUCTOR:
Any pure metal which offers low resistance to the passage 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.
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LAYOUT DIAGRAM:
TABLULATION:
Sl.NO Switch A Switch B Output-Lamp
1 1 2 OFF
2
3
4
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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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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.
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CIRCUIT DIAGRAM:
(0 – 10A) MI 300V, 10A, UPF
P 10 A M L
C V
230 V, 1 Φ (0 – 300V) MI
50 Hz, A.C.
N 10 A
1 Φ Variac
(0 – 270V)
TABULATION:
Multiplication Factor = …………….
S.No.Voltage
(Volts)
Current
(Ampere)
Wattmeter Reading (Watts)
Observed value Actual value
V
A
LOAD
DPSTS
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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 1
5. Connecting Wires 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 account 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.
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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 Energy Meter
P 10 A S1 C1 C2 L1
P1 P2
230 V, 1 Φ (0 – 300V) MI50 Hz, A.C.
N 10 A S2 L2
1 Φ Variac(0 – 270V)
TABULATION:
Energy Meter Constant = …………………
Sl.
No.
Voltage
(Volts)
Current
(Ampere)
Power
(Watts)
Time
(Seconds)
Number of
Revolutions
Actual
Energy
(KWh)
True
Energy
(KWh)
%
Error
DPSTS
V
A
LOAD
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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 1
4. Stop Watch Analog 1
5. Single Phase Resistive Load 3 KW, 230 V 1
6. Connecting Wires Required
FORMULA USED:
Actual Energy in KWh = Power in Watts x Time Taken in Seconds1000 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 x 100Actual Energy
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
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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 terms 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 Value Digit Multiplier ToleranceBlack 0 x100
Brown 1 x101 ±1%Red 2 x102 ±2%
Orange 3 x103
Yellow 4 x104
Green 5 x105 ±0.5%Blue 6 x106 ±0.25%
Violet 7 x107 ±0.1%Grey 8 x108 ±0.05%White 9 x109
Gold x10-1 ±5%Silver x10-2 ±10%None ±20%
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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 passive 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.
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TABULATION:
Sl. No.Resistance Value by
Colour Coding (Ω)
Resistance Value
by Multimeter (Ω)
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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.
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CIRCUIT DIAGRAM:
Measurement of AC Voltage amplitude and frequency
TABULATION:
Sl.
No
Maximum voltage ,
Vm in Volts
Peak- to-
Peak
Voltage
Vpp= 2Vm
in Volts
RMS
Voltage
Vrms
= Vm /
In Volts
Time in SecondsFrequency
f = 1/T
in HzPer
division
No of
divisions
Actual
Value
Per
division
No of
divisions
Actual
Value
1.
2.
3.
4.
AFO CRO
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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 RANGEQUANTITY
(NO.S)
1. Cathode Ray Oscilloscope (CRO) Analog 30 MHz 1
2. Audio Frequency Oscillator Digital 2 MHz 1
3. Bread Board 1
4. Connecting Probes, wires 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)
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MODEL GRAPH: (Using CRO)
AC input Voltage:
Measurement of DC Voltage amplitude and frequency:
+
-
TABULATION:
SI.No. Applied Voltage
(V)
Number of
divisions
Volt/Division Measured
Voltage (V)
1.
2.
3.
4.
RPS (0-30V) CRO
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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:
PIN DIAGRAM OF IC 7408 :
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.NoINPUT OUTPUT
A B Y = A . B1. 0 0 02. 0 1 03. 1 0 04. 1 1 1
LOGIC DIAGRAM:
PIN DIAGRAM OF IC 7432 :
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.NoINPUT OUTPUT
A B Y = A + B1. 0 0 02. 0 1 13. 1 0 14. 1 1 1
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STUDY OF BASIC LOGIC GATES
AIM:
To verify 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 1
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
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’.
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NOT GATE NAND GATE
LOGIC DIAGRAM:
PIN DIAGRAM OF IC 7404:
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.No
INPUT OUTPUTA Y = A’
1. 0 12. 1 0
LOGIC DIAGRAM:
PIN DIAGRAM OF IC 7400 :
CIRCUIT DIARAM:
TRUTH TABLE:
S.NoINPUT OUTPUT
A B Y = (A. B)’1. 0 0 12. 0 1 13. 1 0 14. 1 1 0
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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 verify the truth table for all gates.
40
NOR GATE EX-OR GATE
LOGIC DIAGRAM:
PIN DIAGRAM OF IC 7402 :
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.NoINPUT OUTPUTA B Y = (A + B)’
1. 0 0 12. 0 1 03. 1 0 04. 1 1 0
LOGIC DIAGRAM
PIN DIAGRAM OF IC 7486 :
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.NoINPUT OUTPUTA B Y = A B
1. 0 0 02. 0 1 13. 1 0 14. 1 1 0
41
RESULT:
The truth table of all the basic logic gates were verified.
42
CIRCUIT DIAGRAM:
Half Wave Rectifier:
P
IN 4007100 μF
230 V, 50 Hz1 Φ Supply 1 KΩ CRO
NStep-down Transformer
(0 – 12V)
Full Wave Rectifier:
P
D1 D2
230 V, 50 Hz1 Φ Supply
D4 D3 100 μF
1 KΩ CRON
TABULATION:
Rectifier
Without Filter With Filter
Vm (V) T (mS) Vm (V)T (mS)
Charging Discharging
Half Wave Rectifier
Full Wave Rectifier
43
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 TYPE RANGEQUANTITY
(NO.S)
1 Diode IN 4001 4
2 Resistor 1 KΩ 1
3 Capacitor 100 μF 1
4Transformer Step-down 230 V /
(12 – 0 – 12) V
1
5 CRO Analog 30 MHz 1
6 Bread Board 1
7 Connecting wires and probe 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
44
WAVEFORMS:
Vin (V)Vm
0Time
Vout (V)Output of Half Wave Rectifier without filter
0Time
VmOutput of Half Wave Rectifier with filter
0
Time
Vm Output of Full Wave Rectifier withoutfilter
0
TimeVm
Output of Full Wave Rectifier withfilter
0Time
45
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.
46
47
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.
48
49
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 pass 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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