ELECTRICAL AND ELECTRONICS ENGINEERING - kgr.ac.inkgr.ac.in/beta/wp-content/uploads/2018/09/BEE.pdf · verification of thevenin’s and norton’s theorems AIM: To Verify Kirchhoff’s

BASIC ELECTRICAL ENGINEERING LAB

Department Of Electrical And Electronics Engineering

DEPARTMENT

OF

ELECTRICAL AND ELECTRONICS ENGINEERING

NAME OF THE LABORATORY: BASIC ELECTRICAL ENGINEERING

YEAR AND SEM: III B.TECH II SEM (R16)

REGULATION/LAB CODE: R16/ EE605PC

BASIC ELECTRICAL ENGINEERING LABARATORY



DEPARTMENT VISION

To be renowned department imparting both technical and non-technical skills to the students

through implementing new engineering pedagogy and research to produce competent new age

electrical engineers

DEPARTMENT MISSION

To transform the students into motivated and knowledgeable new age electrical engineers.

To advance the quality of education to produce world class technocrats with an ability to adapt to

the academically challenging environment.

To provide a progressive environment for learning through organized teaching methodologies,

contemporary curriculum and research in the thrust areas of electrical engineering.



Program Educational Objectives (PEO’s):

PEO 1: Apply knowledge and skills to provide solutions to Electrical and Electronics

Engineering problems in industry and governmental organizations or to enhance student

learning in educational institutions

PEO 2: Work as a team with a sense of ethics and professionalism, and communicate

effectively to manage cross-cultural and multidisciplinary teams

PEO 3: Update their knowledge continuously through lifelong learning that contributes to

personal, global and organizational growth



Program Outcomes(PO’s):

A graduate of the Electrical and Electronics Engineering Program will demonstrate:

PO1: Engineering knowledge: Apply the knowledge of mathematics, science, engineering

fundamentals, and an engineering specialization to the solution of complex engineering

problems.

PO2: Problem analysis: Identify, formulate, review research literature, and analyze complex

engineering problems reaching substantiated conclusions using first principles of

mathematics, natural sciences, and engineering sciences.

PO3: Design/development of solutions: Design solutions for complex engineering problems

and design system components or processes that meet the specified needs with appropriate

consideration for the public health and safety, and the cultural, societal, and environmental

considerations.

PO4: Conduct investigations of complex problems: Use research-based knowledge and

research methods including design of experiments, analysis and interpretation of data, and

synthesis of the information to provide valid conclusions.

PO5: Modern tool usage: Create, select, and apply appropriate techniques, resources, and

modern engineering and IT tools including prediction and modeling to complex

engineering activities with an understanding of the limitations.

PO6: The engineer and society: Apply reasoning informed by the contextual knowledge to

assess societal, health, safety, legal and cultural issues and the consequent responsibilities

relevant to the professional engineering practice.

PO7: Environment and sustainability: Understand the impact of the professional engineering

solutions in societal and environmental contexts, and demonstrate the knowledge of, and

need for sustainable development.

PO8: Ethics: Apply ethical principles and commit to professional ethics and responsibilities and

norms of the engineering practice.

PO9: Individual and team work: Function effectively as an individual, and as a member or

leader in diverse teams, and in multidisciplinary settings.

PO10: Communication: Communicate effectively on complex engineering activities with the

engineering community and with society at large, such as, being able to comprehend and

write effective reports and design documentation, make effective presentations, and give

and receive clear instructions.

PO11: Project management and finance: Demonstrate knowledge and understanding of the

engineering and management principles and apply these to one’s own work, as a member

and leader in a team, to manage projects and in multidisciplinary environments.

PO12: Life-long learning: Recognize the need for, and have the preparation and ability to engage

in independent and life-long learning in the broadest context of technological change.



Program Specific Outcomes(PSO’s)

PSO-1:Apply the engineering fundamental knowledge to identify, formulate, design and

investigate complex engineering problems of electric circuits, power electronics, electrical

machines and power systems and to succeed in competitive exams like GATE, IES, GRE,

TOEFL, GMAT, etc.

PSO-2: Apply appropriate techniques and modern engineering hardware and software tools in

power systems and power electronics to engage in life-long learning and to get an employment in

the field of Electrical and Electronics Engineering.

PSO-3: Understand the impact of engineering solutions in societal and environmental context,

commit to professional ethics and communicate effectively.



Course Outcomes (CO’s)

After completion of this course, the student is able to:

Co1) Verify the theorems in practical and theoretical

Co2) Calculate the efficiency of the DC and AC motors

Co3) Find the losses in the AC and DC machines

Co4) Analyze the readings and graphs of the machines and theorems



List of Experiments

S. No Name of the Experiment

Any eight experiments should be conducted

1 Verification of KVL and KCL.

2 Serial and Parallel Resonance – Timing, Resonant frequency, Bandwidth and Q-factor

determination for RLC network.

3 Time response of first order RC/RL network for periodic non-sinusoidal inputs – time

constant and steady state error determination

4 Two port network parameters – Z-Y Parameters, chain matrix and analytical verification.

5 Two port network parameters -ABCD and h parameter

6 Verification of Superposition and Reciprocity theorems.

7 Verification of maximum power transfer theorem. Verification on DC, verification on AC

with Resistive and Reactive loads

8 Experimental determination of Thevenin’s and Norton’s equivalent circuits and

verification by direct test.

Any two experiments should be conducted

9 Magnetization characteristics of D.C. Shunt generator. Determination of critical field

resistance.

10 Swinburne’s Test on DC shunt machine (Predetermination of efficiency of a given DC

Shunt machine working as motor and generator).

11 Brake test on DC shunt motor. Determination of performance characteristics.

12 OC & SC tests on Single-phase transformer (Predetermination of efficiency and regulation

at given power factors and determination of equivalent circuit).

13 Brake test on 3-phase Induction motor (performance characteristics).

14 Regulation of alternator by synchronous impedance method.

15 Load test on single phase transform



EXPERIMENT -1

VERIFICATION OF THEVENIN’S AND NORTON’S THEOREMS

AIM: To Verify Kirchhoff’s Voltage Law (KVL) and Kirchhoff’s Current Law (KCL) using

mesh and nodal analysis of the given circuit..

APPARATUS:

NI – ELVIS Board

Assorted Resistors.( 1 KW (2) ,1.2 KW (2), 2.4 KW)

THEORY:

1. Kirchhoff’s Voltage Law states that the algebraic sum of all the voltages around any closed

path (loop or mesh) is zero.

Applying Kirchhoff’s voltage law to the first and the second loops in the circuit shown

in Figure 1 yields:

Loop 1: -Vs +V1 +V2 +V5 = 0 (1a)

Loop 2: -V2 +V3 +V4 = 0 (1b)

Figure 1

2. Kirchhoff’s Current Law states that the algebraic sum of all the currents at any node is zero.

Applying Kirchhoff’s current law to the first four nodes in the circuit shown in

Figure1 yields the following equations;

Node a: -Is + I1 = 0

Node b: -I1 + I2 + I3 = 0

Node c: -I3 + I4 = 0



Node d: -I2 - I4 + I5 = 0

PROCEDURE:

1. Construct the circuit shown in Figure 1 using the values below:

R1 = 1 KW

R2 = 2.4 KW

R3 = 1.2 KW

R4 = 1 KW

R5 = 1.2 KW

2. Set the Variable Power Supply (Vs) to 5 Volts.

3. Accurately measure all voltages and currents in the circuit using the Digital Multi-Meter

(DMM).

4. Record the measurements in a tabular form containing the measured voltage and current

values as shown below.

5. Verify KVL for the loops in the circuit using equations 1a and 1b.

6. Verify KCL for the nodes in the circuit using equations

Result:



EXPERIMENT-2

SERIAL AND PARALLEL RESONANCE – TIMING,

RESONANT FREQUENCY, BANDWIDTH AND Q-

FACTOR DETERMINATION FOR RLC

NETWORK.



Circuit Diagram of Series Resonance:







Tabular forms:

Series Resonance

S.no Frequency

(f)

Current

(Is)

Parallel Resonance

S.no Frequency

(f)

Current

(Ip)



Result Table

Series resonance Parallel Resonance

Theoretical Practical Theoretical Practical

Resonant

Frequency(Fo)

Band width(BW)

Quality Factor(Q)

Precautions:

1. Making loose connections are to be avoided

2. Readings should be taken without parallax error

Result:



EXPERIMENT-3

TIME RESPONSE OF FIRST ORDER RC / RL NETWORK FORPERIODIC

NON – SINUSOIDAL INPUTS – TIME CONSTANT AND STEADY STATE

ERROR DETERMINATION.

AIM:

To draw the time response of first order series RL and RC network for periodic

non-sinusoidal function and verify the time constant

APPARATUS:

S.no Name of the equipment Range Type Quantity

1 Function generator 1

2 DRB 1

3 DIB 1

4 DCB 1

5 CRO 1

6 CRO Probes As required

7 Connecting wires

Theory:

Theoretical Calculations:

Formula required

For RL Series circuit, time constant T= L/R

For RC Series circuit, Time constant r = RC



Series RL Circuit

Series RC Circuit

Model Graph:

Procedure:

Series RL Circuit:

1. Connections are made as shown in the fig-1.

2. Input voltage (Square wave) is set to a particular value.

3. The waveform of voltage across inductor is observed on CRO and the waveform is drawn on a

Graph sheet.

4. The time constant is found from the graph and verified with the theoretical value.

Series RC Circuit:

1. Connections are made as shown in the fig-2.

2. Input voltage (Square wave) is set to a particular value.



3. The waveform of voltage across the capacitor is observed on CRO and the

waveform is drawn

On a graph sheet. 4. The time constant is found from the graph and verified with the theoretical value

Result Table

Series resonance Parallel Resonance

Theoretical Practical Theoretical Practical

Time constant (T)

Precautions:

1. Making loose connections are to be avoided

2. Readings should be taken without parallax error

Result:



EXPERIMENT – 4

TWO PORT NETWORK PARAMETERS – Z – Y PARAMETERS,

ANALYTICAL VERIFICATION.

AIM: To obtain experimentally Z parameters and Y parameters of a given two port network.

APPARATUS:


1 Trainer kit 1

2 Multi meters MC 2

3 Connecting wires As Required

CIRCUIT DIAGRAM:



Calculation of Z11 and Z21

Calculation of Z12 and Z22

Calculation of Y11 and Y21



Calculation of Y12 and Y22

THEORY:

Open Circuit Impedance Parameters (Z-Parameters):

Z-parameters can be defined by the following equations

V1 = Z11I1 + Z12I2 …………………… (1)

V2 = Z21I1 + Z22I2 …………………… (2)

In Matrix form:

If port 2-21 is open circuited, i.e., I2 = 0, then Z11 = V1/I1 & Z21 = V2/I1

If port 1-11 is open circuited, i.e., I1 = 0, then Z12 = V1/I2 & Z22 = V2/I2

Here,

Z11 is the driving point impedance at port 1-11 with 2-21open circuited. It can also be called as

open circuit input impedance.

Z21 is the transfer impedance at port 1-11 with 2-21 open circuited. It can also be called as open

circuit forward transfer impedance.

Z12 is the transfer impedance at port 2-21 with 1-11 open circuited. It can also be called as open

circuit reverse transfer impedance and

Z22 is the driving point impedance at port 2-21 with 1-11 open circuited. It can also be called as

open circuit output impedance.

Network is

a) Reciprocal then V1/I2 (where I1 = 0) = V2/I1 (where I2 = 0) i.e., Z12 = Z21

b) Symmetrical then V1/I1 (where I2 = 0) = V2/I2 (where I1 = 0) i.e., Z11 = Z22



Short Circuit Admittance Parameters (Y-parameters):

Y-parameters can be defined by the following equations

I1 = Y11V1 + Y12V2 ………………. (1)

I2 = Y21V1 + Y22V2 ………………. (2)

In matrix form

If port 2-21 is short circuited, i.e. V2 = 0 then Y11 = I1/V1 & Y21 = I2/V1

If port 1-11 is short circuited, i.e. V1 = 0 then Y12 = I1/V2 & Y22 = I2/V2

If the network is

a) Reciprocal then I2/V1 (where V2 = 0) = I1/V2 (where V1 = 0) i.e. Y21 = Y12

b) Symmetrical then I1/ V1 (where V2 = 0) = I2/ V2 (where V1 = 0) i.e. Y11 = Y22

PROCEDURE:

1. Open Circuiting Output Terminals (I2 = 0):

Connections are made as per the circuit diagram shown in fig (2). Output terminals are

kept Open via a voltmeter. Supply is given to input port. Note the readings of ammeter as

I1 and Voltmeter as V2.

2. Short circuiting output terminals (V2 = 0):


short circuited via an ammeter. Supply is given to input port. Note the readings of

ammeters as I1 and I2.

3. Open circuiting input terminals (I1 = 0):

Connections are made as per the circuit diagram shown in fig (3). Input terminals are kept

open via an voltmeter. Supply is given to output terminals. Note the readings of ammeter

as I2 and voltmeter as V1.

4. Short circuiting input terminals (V1=0):

Connections are made as per the circuit diagram shown in fig (5). Input terminals are short

circuited via an ammeter. Supply is given to output port. Note the readings of ammeters as

I1 and I2.

4. Calculate Z, Y Parameters values.

OBSERVATION TABLES:

When I1=0

When I2=0



When V1=0

When V2=0

RESULT TABLE:

Z-Parameters Y-Parameters

Z11 Z12 Z21 Z22 Y11 Y12 Y21 Y22

Theoretical

Values

Practical

Values

PRECAUTIONS:

1. Avoid making loose connections.

2. Readings should be taken carefully without parallax error.

3. Avoid series connection of voltmeters and parallel connection ammeters.

RESULT:



EXPERIMENT – 5

TWO PORT NETWORK PARAMETERS – A, B, C, D & HYBRID

PARAMETERS, ANALYTICAL VERIFICATION

AIM: To obtain experimentally ABCD parameters and Hybrid parameters of a given two port

network

APPARATUS:


1 Trainer kit 1

2 Multi meters MC 2

3 Connecting wires As Required

CIRCUIT DIAGRAM:

Calculation of A And C:



Calculation of B and D

CALCULATION OF H11 And H21

Calculation of h12 and h22



THEORY:

ABCD Parameters:

ABCD parameters can be defined by the following equations

In matrix form

If port 2-21

is open circuited i.e., I2=0 then

A is called reverse voltage ratio and C is known as transfer admittance.

If port 2-21 is short circuited i.e., V2=0 then

B is called transfer impedance and D is called reverse current ratio.

Hybrid Parameters (h-Parameters):

h-parameters can be defined by the following equations



In matrix form:

If port 2-21

is short circuited, i.e. V2 = 0 then

h11 is called input impedance and h21 is called forward current gain.

If port 1-11 is open circuited, i.e., I1=0 then

h22 is called output admittance and h12 is called reverse voltage gain.

PROCEDURE:

1. To find A and C Parameters (I2 = 0):


kept Open via voltmeter. Supply is given to input port. Note the readings of ammeter as I1

and Voltmeters as V1, V2.

2. To find B and D Parameters (V2 = 0):


short circuited via an ammeter. Supply is given to input port. Note the readings of

ammeters as I1, I2 and voltmeters as V1.

3. To find h11 and h21 (V2 = 0):


short circuited via an ammeter. Supply is given to input port. Note the readings of ammeter

as I1 and voltmeter as V1.

4. To find h12 and h22 (I1 = 0):

Connections are made as per the circuit diagram shown in fig (5).Input terminals current is

zero. Supply is given to input port. Note the readings of voltmeter as V1 and ammeter as I2.

5. ABCD, Hybrid parameters using formulae and verify them with theoretical values.



OBSERVATION TABLES: When I2=0

S.No. V1 I1 V2

When V2=0

S.No. V1 I1 I2

When I1=0

S.No. V1 I2 V2

When V1=0

S.No. I2 I1 V2

RESULT TABLE:

PRECAUTIONS:

1. Avoid making loose connections.

2. Readings should be taken carefully without parallax error.

3. Avoid series connection of voltmeters and parallel connection ammeters.

RESULT:



EXPERIMENT -6

MAXIMUM POWER TRANSFER THEOREM

AIM: To verify the Max power transfer theorem for a given circuit.

APPARATUS:

S.No Equipment Range Quantity

1 DC.RPS-Voltage Source 0-30 Volts/2A 1

2 Trainerkit ------------------ 1

3 Ammeter-DC 0-200 m.Amps 1

4 Voltmeter-DC 0-20V or 0-30V 2

5 Connecting wires Single lead As required

THEORY:

SUPERPOSITION THEOREM:

This theorem states that “The response (voltage or current) in any branch of a bilateral

linear circuit having more than one independent source equals the algebraic sum of the responses

caused by each independent source acting alone, where all the other independent sources are

replaced by their internal resistance”.

A given response in a network regulating from a number of independent sources(including

initial condition source) may be computed by summing the response to each individual source

with all other sources made in operative( reduced to zero voltage or zero current)

This statement describes the property homogeneity in linear networks. So it is the

combined properties off additivity and homogeneity off linear network. It is a result of the linear

relation between current and volt in circuits having linear impedances.

MAX POWER TRANSFER THEOREM:

Max power will be delivered by network to the load, if the impedance of network is

Complex conjugate of load impedance and vice versa.

(or)

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

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



The maximum transformer states that “A load will received maximum power from a linear

bilateral network when its load resistance is exactly equal to the Thevenin’s resistance of

network, measured looking back into the terminals of network.

CIRCUIT DIAGRAM:

FIG. MAXIMUM POWER TRANSFER THEOREM

PROCEDURE:

1. Connect the 5v to the terminals provided.

2. Connect the ammeter and voltmeter.

3. Calculate the power drawn by the circuit for different values of load resistors provided on

board and tabulate them.

PL = ILVL

4. Observe that the maximum power is drawn when the load resistor is equal to the input

resistance.

5. Thus the Max power transfer theorem is proved.



MODEL GRAPH:

TABULAR COLUMN:

RESULT:

S. No IL(mA) VL(Volts) R=VL/IL (Ω) Power(P max)=I2*RL(mW)

1

2

3

4

5

6

7

8

9

10



EXPERIMENT -7

VERIFY THE SUPERPOSITION & RECIPROCITY THEOREMS

AIM: To verify the Superposition theorem for a given circuit.

APPARATUS:



2 Trainerkit ------------------ 1




Super position theorem

PROCEDURE:


1. Connect the circuit as per circuit diagram.

2. Set V1= 15v, for this connect fixed 15v supply.

3. Set V2= 10v, for this adjust the variable supply to 10v.

4. Note the current ( I ) through E & F , when both V1& V2 are applied.

5. For the same circuit apply voltage V1 and make sure that the V2 to be shorted (V2 = 0) and



6. note down the current (I1) through E & F.

7. For the same circuit apply voltage V2 and make sure that the V1 to be shorted (V1 = 0) and

note down the current (I2) through E & F.

8. The superposition theorem is verified. i.e., I = I1 + I2.

9. Repeat the same procedure for different variable supplies

TABULAR COLUMN:


Super Position

Theorem

I1(mA) I2(mA)

I (mA)

V1=10V , V2=0V V1=0V , V2=15V

Theoretical

Values

Practical Values

PRECAUTIONS:

1. Reading must be taken without parallax error.

2. Measuring instruments must be connected properly & should be free from errors.

3. All connections should be free from loose contacts.

4. The direction of currents should be identified correctly



VERIFICATION OF RECIPROCITY THEOREM

AIM: To verify the Reciprocity Theorem

APPARATUS REQUIRED:



2 Trainer kit ---------------- 1

3 Ammeter-DC 0-200 mAmps 1



THEORY:

RECIPROCITY THEOREM:

The theorem states that “In any linear bilateral network the ratio of voltage source E volts

in one branch to the current I in another branch is the same as the ratio obtained if the positions of

E and I are interchanged, other emf’s being removed.”

CIRCUIT DIAGRAM:

RECIPROCITY THEOREM:

PROCEDURE:


2. Set the voltage V1 and connect it across A and B.

3. Connect C and D through meter and note the current (I1).

4. Interchange the position of ammeter and voltmeter note the current (I2 ).



5. Observe that the both currents are same.

6. Calculate the ratio of voltage introduced between A & B to the current through C & D.

7. Calculate the ratio of voltage introduced between C & D to the current through A & B.

8. Note that the both ratios are equal. Thus the theorem is proved.

9. Repeat the same procedure for different voltages.

TABULAR COLUMN:

Reciprocity Theorem Case-1 ( I AB ) mA Case-2 ( ICD) mA

Theoretical Values

Practical Values

RESULT:



EXPERIMENT -8

VERIFICATION OF THEVENIN’S AND NORTON’S THEOREMS

AIM: To verify the Thevenin’s theorem & Norton’s theorem for a given circuit.

APPARATUS:



2 Trainer kit ----------------- 1




THEORY:

THEVENIN’S THEOREM:

The Thevenin’s Theorem states that “Any two terminals linear bilateral DC network can

be replaced by an equivalent circuit consisting of a voltage source Vth in series with all equivalent

resistance Rth”.

(OR)

Thevenin's theorem states that “in any two terminal, linear, bilateral network having a

number of voltage, current sources and resistances can be replaced by a simple equivalent circuit

consisting of a single voltage source in series with a resistance, where the value of the voltage

source is equal to the open circuit voltage across the two terminals of the network, and the

resistance is the equivalent resistance measured between the terminals with all energy sources

replaced by their internal resistances.”



NORTON’S THEOREM:

Norton's theorem States that “in any two terminal, linear, bilateral network with current

sources, voltage sources and resistances can be replaced by an equivalent circuit consisting of a

current source in parallel with a resistance. The value of the current source is the short circuit

current between the two terminals of the network and the resistance is the equivalent resistance

measured between the terminals of the network with all the energy sources replaced by their

internal resistances.”

CIRCUIT DIAGRAM:

THEVENIN’S THEOREM:

RloadVt h

R2

100ohm

Thevenin’s Equivalent circuit diagram

NORTON’S THEOREM:

Rload

Rn

100ohmI n

Norton’s Equivalent circuit diagram



PROCEDURE:

THEVENIN’STHEOREM:


2. Measure the current through the load resistor in the linear circuit.

3. Calculate the Thevenin’s equivalent resistance of the circuit Rth, when the source is set to

zero.

Rth = ( 82 // 150) + 47 = 100 ohm.

4. Calculate the open circuit voltage across the terminals A & B which is equal to the voltage

across 150 ohm resistance.

Vth= ( 15 x 150) / (82+150)

= 9.69 v

5. Measure the voltage drop across 150 ohm resistor after disconnecting terminals A & C

6. Find it to be equal to calculated value of Vth.

7. Now set the voltage to the obtained Vth in the Thevenin’s equivalent circuit using variable

power supply.

8. Measure the current through the load resistor in the Thevenin’s equivalent circuit.

9. Note the measured through the load resistor in the linear circuit as well as in the equivalent

circuit is same.

10. Repeat the above procedure for different values of resistors provided on the board.

Thus the Thevenin’s theorem is proved.

NORTON’STHEOREM:


2. Measure the current through the load resistor in the linear circuit by connecting ammeter

between A & C.

3. Calculate the Norton’s equivalent resistance of the circuit Rth, when the source is set to

zero.

Rth = ( 82 // 150) + 47 = 100 ohm.

4. Measure the Norton’s equivalent current which is the short circuit across the terminals A

& B by connecting current meter across A &B .this will be equal to 96.9 mA.

5. Now connect the circuit as shown in Norton’s equivalent circuit where RN=100 ohm and

IN=96.9 mA.

6. To get current source, after connecting circuit components R load, RN and points A & C



7. shorted connect variable supply in series with the current meter in place of current meter in

place of current source shown. Adjust the voltage supply such that you read 96.9 mA in

the current meter.

8. Now switch of the power, remove the meter short the positive terminal of battery to

terminal A. Remove the short between A & C and connect the current meter A & C.

9. Note the current through RL. Observe it to be equal to the current through RL measured in

the linear circuit.

10. Repeat the above procedure for different values of resistors provided on the board. Thus

the Norton’s theorem is proved.

TABULAR COLUMNS:

THEVENIN’STHEOREM:

S.No

Vth

Rth

RL

IL ( mA)

Practical

IL ( mA)

Theoretical

NORTON’STHEOREM:

S.No IN Rth RL IL ( mA)

Practical

IL ( mA)

Theoritical

PRECAUTIONS:

1. Reading must be taken without parallax error.

2. Measuring instruments must be connected properly & should be free from errors.



3. All connections should be free from loose contacts.

4. The direction of currents should be identified correctly

RESULT:



EXPERIMENT -9

MAGNETISATION CHARACTERISTICS OF DC SHUNT GENERATOR

AIM: To draw the Open Circuit Characteristics Curve of DC Shunt generator and to determine critical

field resistance and critical speed.

Apparatus Required:

Sl No Name of the apparatus Rating Type Quantity

1. Volt meter 0 – 300V MC 1 No

2. Ammeter 0 – 2A MC 1 No

3. Tachometer 0 – 10k RPM Digital 1 No

Name plate Details:

S.No Specifications Motor Generator

A Rated Armature Voltage

B Rated full load Current

C Rated Speed

D Rated Power

E Type of excitation

Fuse rating: For Open Circuit test 10% of rated full load current

Theory:

The open circuit characteristics for a DC generator are determined as follows. The field winding of

the DC generator (series or shunt) is disconnected from the machine and is separately excited from an

external DC source. The generator is run at fixed speed (i.e. rated speed). The field current (If) is increased

from zero in steps and the corresponding values of generated e.m.f (E0)read of an voltmeter

connected across the armature terminals are tabulated. On plotting the relation between E0 and If , we get

the open circuit characteristics.





Tabular Column:

Rated Speed of the Generator = ………….

i) For Ascending Order of If and Descending order of If:

Sl No: Field Current

If (A)

Generated EMF Eg(V)

Ascending

Generated EMF Eg(V)

Descending

The following points may be noted from the OCC:

(i) When the field current is zero, there is some generated e.m.f which is due to residual

magnetism in the field poles

(ii) Over a fairly wide range of field current (in the initial portion) the curve is linear. It is because

in this range reluctance of iron is negligible as compared with that of air gap. The air gap

reluctance is constant and hence linear relationship.

(iii) After that the reluctance of iron also comes into picture. Consequently, the curve deviates from

linear relationship.

(iv) Finally the magnetic saturation of poles begins and E0 tends to level off



Procedure:

1. Connections are given as per the circuit diagram.

2. Set the field rheostat of motor should be in minimum resistance position.

3. Switch on the supply and start the motor with the help of the 3-point starter.

4. Adjust the Speed of the motor generator set to the rated speed of the generator by controlling

the Motor field resistance and see the speed is to be maintained constant throughout the

experiment.

5. Note down the voltmeter reading at zero field current.

6. Increase the field Current uniformly in steps, by moving rheostat divider jockey.

7. Simultaneously noting down the field current and the terminal Voltage across the generator

armature Terminals.

8. Continue the experiment till saturation of the field is reached.

Expected Graphs:

The graph is drawn in between Field Current (I f) on X-Axis Vs Generated EMF EG on y-Axis for both

increasing and decreasing values of field current and the average curve is

Result:

Eg

Z

X

Y



EXPERIMENT -10

SWINBURNE’S TEST ON DC SHUNT MACHINE

Aim: To Predetermine the efficiency of the given DC Shunt machine by Swinburne’s test as a Motor

operation and Generator operation.

Apparatus Required:

Sl No Name of the apparatus Rating Type Quantity

1. Volt meter 0-300V MC 1 No

2. Ammeter 0-1A MC 1 No

0-5A MC 1 No

3. Tubular Rheostat 0 - 270 / 2.8A Wire Wound 1 No

0 -100 / 5A Wire Wound 1 No

4. Tachometer 0 – 10K rpm Digital 1 No

Name Plate Details:

Fuse Rating: For No load 10% of rated full load current

Theory:

There are several tests that are conducted upon a DC machine (Motor or Generator) to judge its

performance. One important test is performed measure the efficiency of the DC machine. Efficiency

depends on its losses. The smaller the losses the greater is its efficiency and vice versa. The consideration

of losses in a DC machine is important because they determine the efficiency of the machine and

appreciably influences its operating cost. And also they determine heating of the machine and hence the

power output that may be obtained without undue deterioration of the insulation.

S. No Specifications DC Shunt Motor

1 Rated Voltage

2 Arm Full Load Current

3 Rated Speed

4 Excitation current





In Swinburne’s method the DC machine is run as a motor at no load, and the losses

of the machine are determined. Once the losses of the machine are known its efficiency at any desired load

can be determined in advance. It may be noted that this method is applicable to those machines in which

flux is practically constant (e.g. Shunt & Compound Machines).

Observations:

(a) For Motor operation:

Rated voltage V =…………..Volts

Line Current I LO = ………… Amps

Field Current I f =………….. Amps

Sl No

IL (A)

Input =

V IL watts

Ia = IL - I f

(A)

Copper

losses =

Ia2 Ra

Output

Power =

V IL - WT

%Efficiency

=

(O.P / I.P) x

100.

Part I:

Procedure:

1. Connect the circuit as shown in figure.

2. Insert the correct rating of fuse wires in the circuit.

3. Close the DPST switch and keep field rheostat in minimum resistance position.

4. Start the motor with the help of starter and by adjusting the field regulator of the Motor Such That it runs

at its rated speed given on the nameplate.

5. Now open DPST switch and note down the values of supply voltage V, Line Current I Lo, Field current I f

.



6. Calculate the efficiency of the machine as a Motor and as a Generator for Different Assured Values of

load current I L.

Predetermination of efficiency for motor:

Assume a line current IL

Armature current Ia = IL - If

Input Power = V IL

Copper losses = Ia2 Ra

Output = input – (Copper losses + Constant losses).

Efficiency = (Output / Input) x100.

Observations:

(b) For Generator operation:

Rated voltage V =…………..Volts

Line Current I LO = ………… Amps

Field Current I f =………….. Amps

S. No

IL

( A )

Output =

V IL

Watts

Ia = IL+I

f ( A )

Copper

loss = Ia2

Ra in

Watts

In put

Power =

V IL +

WT

%Efficiency

=

(O.P / I.P) x

100.



Predetermination of Efficiency for Generator:

Output = V IL

Armature current Ia = IL +If

Copper losses = Ia2 Ra

Total losses ( WT ) = Cu loss + Constant loss

Input = Out put + (Cu loss + Const loss)

% Efficiency = (Output / Input) x 100.

Circuit diagram:

Tabular Column:

Sl No

Va ( V )

IL ( A )

Ra = (Va / IL)

Avg Ra =……..……..



Part II:

Measurement of Armature circuit resistance of the machine:

Procedure:

1. Make the connections as per circuit diagram.

2. Keep the Rheostat in maximum resistance positions

3. Switch on the LV DC supply

4. Adjust the resistance in steps, Note down the readings of Voltmeter and ammeter

5. Calculate the value of Armature resistance Ra = ( V / I )

6. Take the average value Ra to nullify the errors on the scale of Voltmeter and Ammeter

Sample Calculation’s:

Armature current Iao = I Lo – I f

No load input = V I LO

Constant Power Losses Pc = V I Lo – Iao2 Ra watts.

Armature Resistance Ra =



Expected graphs:

The graph drawn between Load current Vs Efficiency

Y

Xo

% E

ffici

ency

Load Current IL

in Amps

as a Generator

as a Motor

Result:



EXPERIMENT -11

BRAKE TEST ON DC SHUNT MOTOR

Aim: To perform the Brake test on the given DC Shunt motor and to obtain the performance

characteristics of the motor.

Apparatus Required:

S. No Name of the apparatus Rating Type Quantity

1 Ammeter (0-25A) MC 1No

2 Voltmeter (0-300V) MC 1No

3 Tachometer Digital 1No

Name plate details:

S. No Specifications Shunt Motor

1 Rated Voltage

2 Rated Current

3 Speed

4 Type of Excitation

5 Power

Fuse Rating: 125% fuse rating of Rated full load Current.

Theory:

There are several tests that are conducted upon a DC machine (Motor or Generator) to judge its

performance. One important test is performed to measure the efficiency of the DC machine. Efficiency

depends on its losses. The smaller the losses the greater is its efficiency and vice-versa. The consideration

of losses in a DC machine is important because they determine the efficiency of the machine and

appreciably influences its operating cost. And also they determine heating of the



machine and hence the power output that may be obtained without undue deterioration of the insulation.

In this method a brake drum is connected in the shaft of the motor with spring balances to

measure the load. The mechanical output of the motor is calculated with the help of spring balances

readings and speed of the machine.



Tabular Column:

SL

No

VL

(V)

IL

(A)

F1

(kg)

F2

(kg)

Speed

‘N’ in

RPM

Input

Power

(w)

Torque

( T ) in

‘Newton

meter’s

Output

Power in

%Efficie

ncy

Watts

BHP

Calculations:

Radius of the Brake drum r = …….. Mtrs

Torque (T) = (F1- F2) r.g N.mtr

Power Output = (2 π NT / 60) watts

%Efficiency = (Output / Input) X 100.

Procedure:

1. Make the connections as per circuit diagram.

2. Keep the field rheostat of the Motor at minimum Resistance position.

3. At the time of starting check that the belt on the pulley is free, so that there is no load on the pulley.



4. Start the motor slowly by using stator

5. Adjust the field rheostat so that motor runs at its rated speed.

6. Apply load on the pulley gradually in steps by adjusting of tension of spring Balance.

7. Take the readings of the Ammeter and Voltmeter and two spring balance readings and the speed for each

step.

8. Cool the pulley through out the loading period by pouring water.

9. Continue the experiment till full load of the motor is reached.

Expected Graphs:

i. % Efficiency Vs Output Power in BHP

ii. Speed Vs Output Power in BHP

iii. Torque Vs Output Power in BHP

iv. Load Current Vs BHP.

% Efficiency

Torque

Load Current

X

Y

O

Out Put Power in BHP

% Ef

ficien

cy

Load

Cur

rent

Torq

ue

Spee

d

Speed

Result:



EXPERIMENT -12

O.C. AND S.C. TESTS ON SINGLE PHASE TRANSFORMER

AIM :1. To predetermine the efficiency and regulation of the given single phase

Transformer at different power factors.

2. To draw equivalent circuit referred to the primary.

APPARATUS:

THEORY:

OPEN CIRCUIT TEST:

The main purpose of conducting this test is to determine core losses and no load

parameters Ro and X0 . While conducting this test one winding of the transformer usually high

voltage winding is kept open and the low voltage winding is engaged with measuring instruments

like voltmeter and ammeter.

From open circuit test data

Rcl=Vo/Ic

Xml=Vo/Im

SHORT CIRCUIT TEST:

This test is an economical method for determining the following

1. Equivalent quantities like Ro1, R02, X01, X02, Z01 , Z02 as referred to the winding in which

the instruments are connected.

2. Copper losses at full load can be determined which is useful for finding the efficiency.

3. Regulation of transformer can also be calculated

In this test one winding usually the low voltage winding is short circuited by a thick gauge of wire

and measuring instruments are connected in HV winding.

From short circuit test data:

S.No: Apparatus Type Rating Quantity

1. Ammeter Moving iron 0-20A 1

2. Voltmeter Moving iron 0-300V 1

3. Wattmeter Dynamometer 5A/150V,LPF 1

4. Wattmeter Dynamometer 20A/150V,UPF 1



Z2=Vsc/Isc

R2=Wsc/Isc2

X2=(Z22-R2

2 )1/2

Referred to LV side

R1= R2*(N1/N2)2

X1=X2*(N1/N2)2

Efficiency curve:

Efficiency at any load (X times full load) and at a given power factor can be calculated as follows.

Output at X times full load =X*rated KVA*PF

Iron loss=Wo

Copper loss at x times full load =X2 *full load copper loss

%Efficiency = output*100/(output+losses)

Efficiency at different assumed loads for a given power factor are calculated and tabulated.

Regulation curve:

Percentage regulation= rCos ± X sin

r, percentage resistance=I*R1*100/V

x, percentage reactance=I*X1*100/V

I, rated LV side current

V, rated LV side voltage

Positive sign for lagging power factor and negative sign for leading power factor percentage

regulation for full load for different power factors are calculated and results are tabulated.



CIRCUIT DIAGRAM:

OPEN CIRCUIT DIAGRAM:

SHORT CIRCUIT DIAGRAM:

PROCEDURE:

Open circuit test:

1. Connections are made as per the circuit diagram

2. HV side is kept open and rated voltage is applied to the low voltage winding by adjusting

the autotransformer

3. The meter readings are noted down and tabulated

Short circuit test:

1. Connections are made as per the circuit diagram

2. LV side is short circuited and adjusting the autotransformer, rated current is send on the

HV side

3. The meter readings are noted down and tabulated



TABULAR FORMS:

Open circuit test:

Vo

(V)

Io

(A)

Wo

(W) Coso=Wo/(Vo*Io)

Ic=Io* Coso

(A)

Im=Io*Sino

(A)

Short circuit test:

Vsc(V) Isc(A) Wsc(Watts)

PRECAUTIONS:

1. Wattmeter connections must be done as per the rating of the transformer

2. LPF wattmeter to be used for open circuit test

RESULT:



EXPERIMENT-13

BRAKE TEST ON THREE PHASE INDUCTION MOTOR

AIM :

1. Perform load test on 3-phase induction motor

2. Compute Torque, output power, input power, efficiency, input power factor and slip

for every load Setting.

APPARATUS:

THEORY:

The load test on induction motor is performed to compute its complete performance

i.e. torque, slip, efficiency, power factor etc. During this test, the motor is operated at rated

voltage and frequency and normally loaded mechanically be brake and pulley arrangement from

the observed data, the performance can be calculated, following the steps given below.

SLIP :

The speed of the rotor, Nr droops slightly as the load on the motor is increased. The

synchronous speed, Ns of the rotating magnetic field is calculated field is calculated, based on the

number of poles, P and the supply frequency, i.e.

Synchronous speed, Ns =

Then, slip, S =

S. No. Name Type Range Quantity

1. Ammeter MI 0-10/20 A 1

2. Voltmeter MI 0-300/600 V 1

3. Wattmeter Dynamometer 10/20 A, 2

4. 3-phase variac Fully variable 200/400 V 1

5. Tachometer Digital 15 A, 400/0-

400 V, 0-2000

rpm

1



Normally, the range of slip at full load is from 2 to 5 per cent.

TORQUE :

Mechanical loading is the most common type of method employed in laboratories.

A brake drum is coupled to the shaft of the motor and the load is applied by tightening the belt,

provided on the brake drum. The net force exerted at the brake drum in kg is obtained from the

readings S1 and S2 of the spring balances i.e.

Net force exerted, W = (S1 – S2) kg

Then, load torque, T = W X d/2 kg –m

= W X d/2 X 9.8 Nw-m

where, d- effective diameter of the brake drum in meters.

OUTPUT POWER, P0 :

The output power in watts developed by the motor is given by,

Output power, P0 = watts

where, N is the speed of the motor in r.p.m.

INPUT POWER :

Input power is measured by the two wattmeters, properly connected in the circuit

i.e.

Input power = (W1 + W2) watts

Where, W1 and W2 are the readings of the two watttmeters.

INPUT POWER FACTOR :

Input power factor can also be calculated from the readings of two wattmeters for

balanced load. If φ is the power factor angle, then

tan φ = 3

Knowing the power factor angle, φ, from the above, power factor, cos φ can be

calculated. It may be noted clearly at this stage, that the power factor of the induction motor is

very low at no load, hardly 0.1 to 0.25 lagging. As such, one of the wattmeter will record a

negative reading, till the power factor is less than 0.5, which may be measured by reversing the

connections of either the current coil or pressure coil of this wattmeter.



EFFICIENCY :

Percentage efficiency of the motor, = X 100

Full load efficiency of 3 phase induction motor lies in the range of 82 % (for small

motors) to 92 % (for very large motors).

CIRCUIT DIAGRAM:

PROCEDURE:


2. Ensure that the motor is unloaded and the variac is set at zero output voltage.

3. Switch-on 3 phase ac mains and start the motor at reduced applied voltage. Increase

the applied voltage, till its rated value.

4. Observe the direction of rotation of the motor. In case, it is reverse, change the

phase sequence of the applied voltage.

5. Take-down the readings of all the meters and the speed under no load running.

6. Increase the load on the motor gradually by turning of the hand wheels, thus tighting

the belt. Record the readings of all the meters and the speed at every setting of the load.

Observations may be continued upto the full load current rating of the motor.

7. Reduce the load on the motor and finally unload it completely.

8. Switch-off the supply to stop the motor.

9. Note-down the efficiency diameter of the brake drum.



TABULAR COLUMN:

S. No. Line

Voltage

Input

current

W1 W2 S1 S2 speed

PRECAUTIONS:-

1. Ensure that the starter arm is at extreme left position.

2. Avoid loose connections

3. Note down the readings form the meters without any parallax error

RESULT:

S.No. Current Input

power

Torque Output

power

Slip Power

factor

Efficiency



EXPERIMEMT-14

REGULATION BY SYNCHRONOUS IMPEDANCE METHOD

AIM :

1. Perform no load and short circuit tests on a 3-phase alternator.

2. Measure the resistance of the stator winding of alternator.

3. Find out regulation of alternator at full load and at (i) unity p.f. (ii) 0.85 p.f. lagging

(iii) 0.85 p.f leading, using synchronous impedance method.

APPARATUS:

S.No. Name Type Range Quantity

1.

2.

3.

4.

5.

Ammeter

Ammeter

Voltmeter

Rheostat

Techometer

MC

MI

MI

Single tube

digital

0-1/2 A

0-10/20 A

0-300/600 V

370Ω, 1.7 A

0-2000 rpm

1

1

1

2

1

THEORY

To find out the regulation of alternator by synchronous impedance method,

following characteristics and data has to be obtained experimentally,

1. open circuit characteristic at synchronous speed.

2. short circuit characteristic at synchronous speed.

3. ac resistance of the stator winding, per phase i.e. Ra.

The open circuit and short circuit characteristics of a 3 phase alternator, plotted on

the phase basis. To find out the synchronous impedance from these characteristics, open circuit

voltage, E1 and short circuit current, I1 (preferably full load current), corresponding to a particular

value of field current is obtained. Then , synchronous impedance per phase is given by,

Synchronous impedance, Za =

Then, Synchronous reactance, Xz = Z2S - R

2a



The phasor diagram of the alternator, supplying full load current of Ia ampere, lagging the terminal

voltage V by an angle φ. The open circuit voltage E of the alternator is given by, E = V + Ia

Ra + Ia Xa (Phasor sum)

The diagram has been drawn with the current as the reference phasor and is self

explanatory. The open circuit voltage as finally obtained from the phasor diagram, corresponding

to this loading condition is E volts. Then the regulation of the alternator under the above loading

condition is given by,

Regulation = X 100 percent

An approximate expression for the open circuit voltage can be establish referring to

the phasor diagram.

Open circuit voltage, E = OD2 + DC2

= (OF + FD)2 + (DB + BC)2

or E = (V cos φ + Ia Ra )2 + (V sin φ + Ia Xa)

2 ( for lagging p.f. load)

The above expression is for lagging power factor load. In case, alternator is

operating at leading power factor, open circuit voltage, E can be found out in a similar way and is

given by,

E = (V cos φ + Ia Ra)2 - (V sin φ + Ia Xa)

2 (for leading p.f. load)



The value of regulation obtained by this method is higher than obtained from as actual load test,

as such it is called the pessimistic method.

CIRCUIT DIAGRAM

PROCEDURE


2. Adjust the position of rheostat, R1 for maximum possible current in the field circuit of

dc motor, to

3. Ensure (i) low starting speed (ii) high starting torque.

4. Set the position of rheostat, R2 for minimum current in the field circuit of alternator, to

ensure low value of generated emf at starting.

5. Switch on the dc mains, feeding the dc motor and the field circuit of alternator.

6. Start the dc motor, using the starter properly. Various resistance steps of the starter

should be cur out slowly, so that the motor does not draw high current during starting.

7. Set the speed of the motor and hence the alternator at its rated value by varying

rheostat, R1, provided in the field circuit of the motor.

8. Note-down the open circuit voltage of the alternator and the field current.



9. Repeat step 7 for various value of field current (can be obtained by varying the

rheostat, R2 provided in the field circuit of alternator). Observation should be

continued, till the open circuit voltage is 25 to 30 percent higher than its rated value.

10. Set the position of rheostat, R2 again for minimum possible current in the field circuit

of alternator.

11. Short-circuit the stator winding of the alternator, by closing the switch, provided for

this purpose in the circuit diagram.

12. Note-down the short circuit current and the field current.

13. Repeat step 11, for various values of field current, till the short circuit current

becomes equal to the full load current of alternator.

14. Readjust the setting of rheostats R1 and R2 to their initial positions and then switch-

off the dc supply to stop the dc motor.

15. Measure the dc resistance of the stator winding by usual voltmeter-ammeter method.

To obtain ac resistance, skin effect must be taken into account. As such, ac resistance

may be taken approximately 1.3 times the dc resistance measured.

TABULAR COLOUMN:

Open Circuit Test Short Circuit Test

S. No. If E If Isc

RESULT:

Documents

ELECTRICAL AND ELECTRONICS ENGINEERING - kgr.ac.inkgr.ac.in/beta/wp-content/uploads/2018/09/BEE.pdf · verification of thevenin’s and norton’s theorems AIM: To Verify Kirchhoff’s