Basic electrical lab manual 2018 scheme

Prepared By Prashanth Krushi ,Mtech,MSc,(PhD) SSCE Blore. Page 1
BASIC ELECTRICAL LABAROTARY
EXPERIMENT MANUAL
18EEL17/27
[As per Choice Based Credit System (CBCS) scheme]
DEPARTMENT OF ELECTRICAL AND ELECTRONICS
SRI SAIRAM COLLEGE OF ENGINEERING ,ANEKAL ,BENGALURU
Prepared by
Prashanth krushi .Mtech,Msc ,(Ph.D)
Mail ID: prashanthgate14@gmail.com

CIRCUIT DIAGRAM-
KCL
KVL

EXPERIMENT-1
VERIFICATION of KCL & KVL THEOREM
AIM:
To Verify KCL & KVL from the given circuit
APPARATUS REQUIRED:
S.NO. Name of the Apparatus Range Quantity
1 Bread Board - 1
2 Resistor 1 KΩ 3
3 Ammeter 0-25 mA 3
4 Voltmeter 0-30 V 2
5 RPS 0-30 V 1
THEORY:
Kirchhoff’s Current Law (KCL):
states that the sum of the currents entering into any node/point/junction is equal to
the sum of the currents leaving that node/point/junction. In the figure 1.1, if KCL is
applied then the equation is
IT = I1 + I2 + I3

Figure 1.1
Kirchhoff’s Voltage Law (KVL): states that the algebraic sum of all branch
voltages around any closed path in a circuit is always zero at all instants of time.
In the figure 1.2, if KVL is applied then the equation is
Vs = V1+V2+V3
Figure 1.2
PROCEDURE:
a. Verification of KCL
1. Give the connection according to circuit shown in figure 1.3
2. Vary the supply voltage and take the corresponding readings of IL, I1 & I2
from the ammeter.
3. Verify the reading.

b. Verification of KVL
1. Connection are made as per the circuit diagram shown in figure 1.4
2. Vary the supply voltage and take the corresponding readings V1 & V2 from
the voltmeter.
3. Verify the reading.
Tabulation:
Table 1(for KCL):
Vin I1 (mA) I2 (mA) IL = I1 + I2 (mA)
(v)
Theoretical Practical Theoretical Practical Theoretical Practical

Table 2 (for KVL):
Vin V1 (v) V2 (v) Vin = V1 + V2 (v)
(v)
Theoretical Practical Theoretical Practical Theoretical Practical
RESULT :

CIRCUIT DIAGRAM-FL
IL

EXPERIMENT-2
MEASUREMENT OF CURRENT,POWER
AND POWER FACTOR OF INCANDESCENT
LAMP,FLUORESCENT LAMP AND LED LA
MP
Aim : To Measure the current,power and power factor of incandescent
lamp,fluorescent lamp and LED lamp
Apparatus Required:
Apparatus
Required: Sl
No
Components Specification Type Quantity
01 Ammeter 0-2A MI 1
02 Voltmeter 0-300V MI 1
03 Wattmeter 230V,5/10A DM 1
04 Choke 40W,230V IRON CORE 1
05 Starter 230V,50Hz GLOW 1
06 Fluorescent
Tube/
incandescent/LE
D
40W,230V,50H
z
- 1
07 Variac 1-PH,0-
300V,5A
- 1
08 Connecting
Wire
3/20SWG PVC L
THEORY:
Fluorescent lamp constitutes a glass tube whose inside is coated with a fluorescent
powder. When the two filaments of the lamp are maintained at potential difference
sufficient enough t produce electric discharge through the gap, then electron are
emitted from one electrode and move towards the other electrodes. In the mean

time, these electrons collide with the fluorescent coating and emit cool light. In
most fluorescent lamp, a mixture of argon and mercury gas contained in a glass
tube is stimulated by an electric current, producing ultraviolet ray. These rays
strike fluorescent phosphorous coating on the interior surface of the bulb.
Unfortunately a fluorescent lamp can’t just work as is case of incandescent lamp.
The main reason is that it is normally takes a voltage greater than the typical line
voltage to start. It requires several hundreds of volts (700-800v).
PROCEDURE:
1 Do the connection as per the circuit diagram.
2 Keep the variac in the zero position and switch on the power supply.
the variac voltage slowly until the fluorescent tube flickers and glows. Measure the current,
voltage, and power.
3 Take another 4 sets of ammeter, voltmeter, and wattmeter reading at different positions of
variac while the tube is glowing.

4 Record the reading in observation table.
5 Switch off the power supply.
OR
Procedure:
1. Connect the circuit as shown in the diagram with the switch (S/W) is in off position. .
2. Switch on D.C supply, close the switch and vary the rheostat to obtain different voltage
and current values. Note the voltage and corresponding current values. Record the
Calculate percentage error.
3. Switch of supply then open the switch
Precautions:
1. Make the connections properly.
2. Note the readings of voltmeters and ammeters properly.
3. Remove insulations from the connecting wire so as the current will flow properly
TABULATION:CFL
SL NO Voltmeter
Reading(V)
Ammeter
Reading(A)
Wattmeter
Reading(W)
Power Factor
INCANDESCENCE LAMP
LED LAMP
CALCULATION:

(I) Power Factor, Cos ɸ= W/VI.
(II) (II) Calculate mean power factor.
RESULT:

CIRCUIT DIAGRAM:

EXPT-3
MEASUREMENT OF RESISTANCE AND
INDUCTANCE OF A CHOKE-COIL USING 3
VOLTMETER METHOD.
AIM- Measurement of power consumed,powerfactor and inductance of achoke by 3 –
Voltmeter
Apparatus required:
Sl.No Name of the apparatus Quantity
1 2 Amps, Auto – transformer 1 No
2 0 -300 V, A.C. Voltmeter 1 No
3 Load – Choke-R &L 1 No
THEORY-
Three Voltmeter method :
In this method, three voltmeters and a known non inductive resistance is used. This
resistance is connected in series with the load. As shown in the circuit one
voltmeter is used in the experiment to measure the supply voltage V1, Voltage V2
across the resistance and voltage V3 across the load (choke). The circuit diagram
and phasor diagram are as shown

Procedure :
1. Connect the circuit as shown in figure.
2. Set the Auto transformer at zero position.
3. Close switch
4. Increase the input supply gradually and note down the readings V1, V2 and V3.
The voltage across the load shall not be increased beyond its rating.
5. Tabulate the values as shown in the table.
6. Switch off the supply.

Tabulation/Observations:
3 – Voltmeter Method
S.No VS-1
(volts)
VR-2
(volts)
VL-3
(volts)
COS θ PL
(watts)
Result:

CIRCUIT DIAGRAM :-

EXPT-4
DETERMINATION OF PHASE AND LINE
QUANTITIES IN THREE PHASE STAR AND
DELTA CONNECTED LOADS
AIM :- Measurement of various line and phase quantities for a three phase ac circuit
Apparatus Required :-
SL.no Name of the component and range type Quantity
1 Voltmeter-(0-300) 2
2 Ammeter(0-2amp) 2
3 3 phase auto transformer(0-300) 1
4 Connecting loads
5 Resistive load 1
S
Theory:-
Three phase supply system:-
an A.C. system having three equal voltages of same frequency arranged to have
equal phase difference between adjacent e.m.f. is called a three phase supply
system.
Three phase supply system is divided into two categories.
(1) 3-phase balanced system: -
A supply system is said to be balanced when the tree voltages of the same
frequency have equal magnitude and one displaced from another by equal time

angle i.e. 120 electrical degree with respect to each other is called three phase
balanced system.
(2) 3-phase unbalanced system:-
A three phase supply system will be unbalanced when either of the three phase
voltages are unequal in magnitude or the phase angle between them is not equal to
120 electrical degree with respect to each other is called three phase unbalanced
system.
Procedure:-
1) Connect the voltmeter and ammeter to the load through three phase auto
transformer as shown in figure and set the autotransformer at zero position.
2) Switch on the three phase supply and adjust the auto transformer till a suitable
voltage. Note down the readings of voltmeter and ammeter.
3) Vary the voltage by the autotransformer and note down the various readings.
4) Now after the observation switch off and disconnect all the equipments.
Observation table:-
(1) FOR STAR CONNECTED LOAD:-
Sl
.No
Voltmeter reading Ammeter reading
Line voltage Phase
voltage
Line
current
Phase
current
(2) FOR DELTACONNECTED LOAD:-
Sl
.No
Voltmeter reading Ammeter reading
Line voltage Phase
voltage
Line
current
Phase
current

.
Result:-
(1) In star connected load :- Line voltages are √3 times of phase voltages
Line currents are equal to phase currents
(2) In delta connected load :-
Line currents are √3 times of phase currents
Line voltages are equal to phase voltages
Precautions:-
(1) Make the connections as shown in figure.
(2) Connections should be tight.
(3) Ensure that auto transformer should be at zero position before switching on the
main supply.
(4) Please get the circuit checked before switching on the main supply.
(5) Do not touch any live wire.
(6) Supply should be off after the completion of experiment
REFERENCES
Books:
1. Fundamentals of Electrical engineering by Ashfaq Husain.
2. A Textbook of Electrical Technology by B.L Thereja.
3. Electrical Science by J. B. Gupta
URLS:
1. www.nptel.iitm.ac.in

OR

EXPERIMENT - 5
MEASUREMENT OF THREE PHASE POWER
USING TWO WATTMETER METHOD
AIM:To MeasureThree Phase Power By 2 Watt Meter Method.
APPARATUS REQUIRED:
SLNO NAME OF ITEM SPECIFICATION QUANTITY
1. Watt meter 5A/600V 2
2. Volt meter MI(0-300V) 1
3. Ammeter MI(0-5A) 3
4. Rheostat 50Ω/5A 3
5. 3 phase variac 0-100V 1
THEORY:
A watt meter is an instrument for measuring power directly in a circuit. It
has two coils which when connected in series give the lower current range of
the instrument and when connected in parallel gives the double the range. The
pressure circuit has a coil of high resistant. The current coil is connected in
series with the circuit in which power is measured and pressure coil across the
circuit. Two wattmeter’scan be used to measure power in a three phase 3-wire
circuit, by making the connections as shown in below. The load may be
balanced or unbalanced. The current coils are connected in series with two
phases and the pressure coils between either phase and the third. If one of the
wattmeters tends to read negative, the current coil is reversed, but reading of

this instrument must be regarded as negative the total power consumed=
w1+w2(alzebric sum).
Here current through the current coil W1=IR and W2=IB
While potential difference across voltage coil of W1=VRY
and W2=VBY According to the phasor diagram given below
W1=VRYIRcos(30+ ) and
W2=VBYIB cos(30- )

Procedure:
1. Make the connections as per the circuit diagram.
2. Switch on A.C supply
3. For balanced load condition measured the values of wattmeters, ammeters and
voltmeter
. 4. Repeat the same process for unbalance load condition.
5. Switch off all the loads and supply

TABULAR COLOUMN
SL .NO
LINE
Voltage LINE Current Power W1 Power W2 Power Power factor
`
TOTAL POWER=
RESULT---
Precautions: 1. All the connections should be tight and clean.
2. The readings in ammeters should not exceed the current ratings of wattmeters.
3. With negative deflection in wattmeter the connection should be reversed.

CIRCUIT DIAGRAM:
Two way control :
THREE WAY CONTROL OF LAMP

EXPERIMENT-6
TWO WAY AND THREE WAY CONTROL OF
LAMP AND FORMATION OF SWITCHING
TABLE
AIM: controlling the condition of lamp by using two switches and three switches
Apparatus Required:
Sl.no Name of the apparatus Quantity
1 Lamp 2
2 SPDT switches 4
3 Intermediate switch 1
THEORY :
Two-way control is usually used for staircase lighting. The lamp can be controlled
from two different points: one at the top and the other at the bottom - using two-
way switches which strap wires interconnect. They are also used in bedrooms, big
halls and large corridors. The circuit is shown in the figure.
Switches S1 and S2 are two-way switches with a pair of terminals 1&2, and 3&4
respectively. When the switch S1 is in position1 and switch S2 is in position 4, the
circuit does not form a closed loop and there is no path for the current to flow and
hence the lamp will be OFF. When S1 is changed to position 2 the circuit gets
completed and hence the lamp glows or is ON. Now if S2 is changed to position 3
with S1 at position 2 the circuit continuity is broken and the lamp is
off. Thus the lamp can be controlled from two different points.
Three- way Control of lamp:
In case of very long corridors it may be necessary to control the lamp from 3
different points. In
such cases, the circuit connection requires two; two-way switches S1and S2 and an
intermediate

switch S3. An intermediate switch is a combination of two, two way switches
coupled together. It
has 4 terminals ABCD. It can be connected in two ways
a) Straight connection
b) Cross connection
In case of straight connection, the terminals or points AB and CD are connected as
shown in
figure 1(a) while in case of cross connection, the terminals AB and
PROCEDURE:
Before switching ON the supply to the circuit,
1. The pipe layout of the respective wiring is laid on the board.
2. The PVC pipes are fixed to the wooden board.
3. The junction box and switch box are fixed at appropriate positions.
4. The round blocks are tightened in their position with the help of a screw driver.
5. The wires are inserted into the pipes and the connections for different types of
switch connections are made as per the circuit diagram.
6. Switch ON the supply to the circuit and verify the operations using table
After switching ON the supply to the circuit,
1. The lamp is checked for its glow.
2. After making all the changes in the circuit, the sequential process for the lamp
glow is checked.
1,Connect the circuit as per circuit diagram
2,switch on the supply
3, change the switching connection
4,condition of lamp is noted on switching table
SWITCHING TABLE:
SL.no Switch -1 Switch-2 Condition of lamp
1
2
3
4
Theory –
Case-1

Case-2
Case-3
SWITCHING TABLE:
SL.no s-1
switch-1
s-2
switch-2
s-3
switch-3
Lamp
condition
Theory
Case-1
Case-2
Case-3
Case-4
Case-5
Case-6
Case-7
Case-8
Result:

CIRCUIT DIAGRAM:
1. CURRENT ELECTRODE
2. POTENTIAL ELECTRODE
3. EARTH

EXIPERIMENT-7
MEASUREMENT OF RESISTANCE TO
EARTH OF
AN ELECTRICAL EQUIPMENT
AIM:To measure the earth resistance using Megger
APPARATUS REQUIRED:
1.Megger
2.Electrodes
3.Hammer
4.Connecting Wires
5.Tester
THEORY:
Earthing means generally connected to the mass of the earth. It shall be in such a
means as to ensure at all times an immediate & safe discharge o f electric current
due to leakage, fault etc. All metallic parts of every electrical insulation such as
conduit, metallic sheathing, metallic panels, motor, gear, Transformer regulator
shall be earthed using continuous bus wire if one earth bus for installation is found
impracticable move than one earthing system shall be introduced the earthing
conductors when taken outdoors to the earthing point, shall be incased in pipe
securely supported and continued upto point not less than 0.3m below the ground.
No joints are permitted in earth bus whenever there is lighting conductors system
installed in a building. Its earthing shall not be bonded to the earthing of electric
installation. Before the electric supply on apparatus is energized all earthing
system shall be tested for electrical resistance to ensure efficient earthing. It shall
not be more than 2ohms including the ohmic value of earth electrode.

PROCEDURE:
1. Collect the materials required for this experiment.
2. The terminal of ohmmeter E is first connected to earth.
3. The two earth rods are fixed to feet away from the ohmmeter. So that they are
triangle with base 50 feet.
4. The wires are connected to each rod and the ohmmeter terminals are shown.
5. The ohmmeter is ranked and the readings are taken.
RESULTS:

CIRCUIT DIAGRAM

EXPERIMENT-8
STUDY OF OPEN AND SHORT CIRCUIT OF
SIMPLE CIRCUIT
AIM: To Study Of Open And Short Circuit Of Any Simple Circuit
Apparatus required
1,Lamp
2,Connecting Wires
3,Rps
THEORY:
You need a closed path, or closed circuit, to get electric current to flow. If there’s a
break anywhere in the path, you have an open circuit, and the current stops flowing
— and the metal atoms in the wire quickly settle down to a peaceful, electrically
neutral existence.

PROCEDURE:
1,Connect the circuit as per Circui diagram
2,Switch ON the supply
3,place one Switch series with circuit
4,Place one Switch parallel with circuit
5,keep open for open circuit
6,close all the switches for short sircuiting
Result:

Basic electrical lab manual 2018 scheme

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