18054917 Bee Lab Manual

SERIES AND PARALLEL RESONANCEExp. No. 1Date:

AIM:

To find the resonant frequency, quality factor, and band width of a series and parallel

resonant circuit.

Apparatus:

S. No. Apparatus Range Type Quantity1 Function generator2 Decade resistance box3 Decade inductance box4 Decade capacitance box5 Ammeter

Circuit Diagram:Series resonance:

Parallel resonance:

Procedure: 1. Connect the circuit as shown in fig.1 for series resonant circuit & fig.2 for parallel

resonant circuit.

2. Set the voltage of the signal from function generator to 5V.

3. Vary the frequency of the signal from 100 Hz to 1KHz in steps and note down the

corresponding ammeter readings.

4. Observe that the current first increases & then decreases in case of series resonant

circuit & the value of frequency corresponding to maximum current is equal to resonant

frequency.

5. Observe that the current first decreases & then increases in case of parallel resonant

circuit & the value of frequency corresponding to minimum current is equal to resonant

frequency.

6. Draw a graph between frequency and current & calculate the values of bandwidth &

quality factor.

MODEL GRAPHs:

f1= lower cutoff frequencyf2 = upper cutoff frequencyfr=Resonating Frequency

Observation Table:-

Series Resonance

S. No. Frequency(Hz)

Current(mA)

1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.

Observation Table:-

Parallel Resonance

S. No. Frequency(Hz)

Current(mA)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

Result:

Comments:

L

R =10KΩ

TIME RESPONSE OF FIRST ORDER RL/RC NETWORK Exp. No. 2Date:

Aim:

To design and analyze RL/RC first order network circuit with short, medium and long time

constants.

Apparatus:

S.

No.

Apparatus Quantity

1. Circuit Board2. CRO3. BNC Adaptors4. Function Generator5. Patch Cards

Circuit Diagrams:

R-L Network:

R-C Network:

10 P-P1KHz

C

1

10 P-P1KHz

Output

Output

Fig (a)

Fig (b)

Procedure:

1. Connect the circuit as shown in the fig. (a)

2. Apply the square wave input of 10V P-P at 1KHz

3. Observe the output at short, medium and long time constants by choosing appropriate

inductance

4. Repeat the same procedure for RC network shown in fig. (b) by choosing appropriate

capacitance.

5. Plot the wave forms for both RL and RC for all cases

Wave forms:

Result:

Comments:

Circuit Diagram :

1 2

Port – 1 Network Port - 2

11 21

Network

TWO PORT NETWORK PARAMETERSExp. No. 3Date:

Aim: To find the Z & Y parameters of a two port network.

Apparatus:

S.No. Apparatus Range Type Quantity1 Circuit board2 RPS 3 Ammeter4 Voltmeter

Procedure:-

Z – Parameters

1. Connect the circuit as shown in fig.

2. Open circuit port-2 (i.e I2 = 0 ) and measure V1,I2 and V2 and calculate Z11 & Z21

using the formulae

021

111 == I

I

VZ 02

1

221 == I

I

VZ

3. To Measure Z12 and Z22, open circuit port-1 (i.e. I1=0) and measure V1, V2 and I2

and calculate Z12 & Z21 using the formulae

012

112 == I

I

VZ 01

2

222 == I

I

VZ

Y – Parameters

1. Connect the circuit as shown in fig.

2. Short circuit port-2 (i.e V2 = 0 ) and measure V1, I1 & I2 and

calculate Y11 & Y21 using the formulae

021

111 == V

V

IY 02

1

221 == V

V

IY

3. To Measure Y12 and Y22, short circuit port-1 (i.e. V1=0) and measure V2, I1 and I2

and calculate Y12 & Y22 using the formulae

012

112 == V

V

IY 01

2

222 == V

V

IY

Tabulation

S. No.

Parameter Theoretical Value

Practical Value

1. Z11

2. Z12

3. Z21

4. Z22

5. Y11

6. Y12

7. Y21

8. Y22

Result:

Comments:

Circuit Diagram:

Fig. 1 Fig. 2 Fig. 3

Tabulation:

ParametersTheoretical Practical

Values ValuesI1

I2

I

SUPERPOSITION THEOREM & RECIPROCITY THEOREM Exp. No. 4

Date:

Aim: To verify the Superposition theorem and Reciprocity theorem.

Apparatus:

S. No. Apparatus Range Type Quantity1 Circuit board 2 RPS3 Ammeter

SUPERPOSITION THEOREM:

Statement: Superposition theorem states that "In any linear bilateral network containing two

or more sources, the response in any element is equal to the algebraic sum of the responses

caused by individual sources acting alone, while the other sources are non-operative i.e., while

considering the effect of individual sources, other ideal voltage sources and ideal current

sources in the network are replaced by short circuit and open circuit across their terminals”.

Procedure:

1. Make the connections as shown in fig.1 and measure the current 'I'.

2. Short circuit E2 (assuming the internal resistance of E2 source to be zero) as shown in

fig.2 and note down the current I1 when only E1 is acting.

3. Short circuit E1 (assuming the internal resistance of E1 source to be zero) as shown in

fig. 3 and note down the current I2 when only E2 is acting.

4. By superposition theorem I = I1+I2.

Tabular column Circuit Diagram:

RECIPROCITY THEOREM

Statement: Reciprocity theorem states that “In any linear, bilateral, single source network the ratio of excitation to response is constant even when their positions are

interchanged”.

Procedure:

1. Connect the circuit as shown in fig. 1.

2. Measure the current 'I’ in the branch CD.

3. Interchange voltage source and response as shown in fig.2 and note down the

current in the branch AB.

4. Observe that the current is same in both the branches AB in Fig. 2 and CD in Fig. 1.

Tabular column:

Parameters Theoretical PracticalValues Values

Before interchange

VI

V/IAfter Interchange

VI1

V/I1

Result:

Comments:

Given Circuit:

A

B

Practical Circuit:

RL

Fig. 1

Model Graphs:

For DC Circuit:

For AC Circuit:

Given Circuit

Given Circuit

A

V

‘P’ in Watts

MAXIMUM POWER TRANSFER THEOREMExp. No. 5Date:

Aim:- To verify the maximum power transfer theorem for DC & AC circuits.

Apparatus:

S. No. Apparatus Range Type Quantity1 Ammeter2 Voltmeter3 Variable Resistor4 R.P.S

Statement:

DC Circuit:The maximum power transfer theorem states that “maximum power is delivered from a source

resistance to a load resistance when the load resistance is equal to source resistance.”

Rs = RL is the condition required for maximum power transfer.

AC Circuit:a. The maximum power transfer theorem states that maximum power is delivered from a

source impedance to load impedance when the load impedance is equal to the complex

conjugate of the source impedance.

b. The maximum power transfer theorem states that maximum power is delivered from a

source impedance to load resistance when the load resistance is equal to the magnitude

of the source impedance.

Procedure:

1. Connect the circuit as per the practical circuit shown in fig.1

2. Vary the load resistance in steps and note down voltage across the load and current

flowing through the circuit.

3. Calculate power delivered to the load by using formula P=V X l

4. Draw the graph between resistance and power (resistance on X- axis and power on Y-

axis).

5. Verify the maximum power is delivered to the load when RL = Rs for DC * and RL = Zs

for AC.

Tabular Column: (DC Circuit)

R VL IL P=VLIL

Tabular Column: (AC Circuit)

R VL IL P=VLIL

Theoretical Calculations

Maximum Power = PMax = V2 / 4RL

Parameters Theoretical Value (PMax) Practical Value (PMax)

D.C. Circuit

A.C. Circuit

Result:

Comments:

Given Circuit Diagram:

A

B

Practical Circuit Diagram for Vth:

A

B

Fig. (1)

Practical Circuit Diagram for Rth:

A

V

B

Fig (2)

Given Network

V

Voltage & current sources are to be replaced by open ckt and short ckt

respectively

A

THEVENIN'S AND NORTON'S THEOREMSExp. No. 6

Date:

Aim: - To Verify Thevenin's and Norton's theorems.

Apparatus:

S.No. Apparatus Range Type Quantity1 Ammeter2 Voltmeter3 Circuit board

Thevenin's theorem.

Statement: - 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.”

PROCEDURE:

(a) To find Vth

1. Connect the circuit as per the practical circuit. (Fig. 1)

2. Measure Voc between A and B terminals.

(b) To find Rth

1. Connect the circuit as per the practical circuit (Fig. 2)

2. Replace the voltage and current sources by open circuit and short circuit

respectively and connect a voltage source and series with an ammeter between the

terminals A&B

3. Note down the ammeter readings for different voltages.

4. Calculate Rth = V/I

5. Draw the thevenins equivalent circuit

Tabular Column

S. No. V (volts) I (mA) R=V/I kΩ

Theoretical calculations

Given Circuit Diagram:

A

B

Theoretical Calculations

A

B

Practical Circuit Diagram for Rth:

A

V

B

Given Network

Given Network A

Voltage & current sources are to be replaced by open ckt and short ckt

respectively

A

Norton's theorem:

Statement: 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.”

Procedure: (a) To find IN

1. Connect the circuit as per the practical circuit. (Fig. 1)

2. Measure the current Isc (or) IN through 'AB' by short-circuiting the resistance between A

and B.

(b) To find Rth

1. Connect the circuit as per the practical circuit (Fig.2)

2. Replace the voltage and current sources by open circuit and short circuit respectively

and connect a voltage source and series with an ammeter between the terminals A&B

3. Note down the ammeter readings for different voltages.

4. Calculate Rth = V/I

5. Draw Norton's equivalent circuit.

Tabulation

S. No. V(volts)

I (mA)

R=V/I kΩ

Parameters TheoreticalValues

PracticalValues

VocIscRTH

RN

Result:

Comments:

Circuit Diagram:

MOTOR

Voltage : 230v

Current :

Speed :

Field Current :

GENERATOR

Voltage :

Current :

Speed :

Field Current :

Model Graph:

Circuit

MAGNETIZATION CHARACTERISTIC OF A DC GENERATOR Exp. No. 7

Date:

Aim:

To find critical field resistance of a separately excited DC generator from its open circuit

characteristic.

Apparatus Required:

S.

No.

Name of the Equipment Range Type Quantity

1. Voltmeter

2. Ammeter

3. Rheostat

4. Tachometer5. Potential Divider

Precautions:

a) Motor field rheostat must be kept in minimum resistance position.

b) Potential divider must be kept in minimum potential position.

c) Starter arm must be in OFF position.

Procedure:

1) Connect the circuit as shown in the circuit diagram.

2) Observing the precautions close the DPST Switch and switch ON 220V DC supply.

3) Start the Motor-Generator set with the help of starter.

4) Adjust the speed of motor to a fixed value by adjusting field rheostat and maintain the

speed constant throughout the experiment.

5) Increase the excitation of the generator in steps by adjusting the potential divider and note

down the corresponding voltmeter readings.

6) Take the readings up to a value little higher than the rated voltage of the generator.

7) Again decrease the excitation in the same steps till field current is zero by adjusting the

potential divider noting down the corresponding voltmeter readings.

8) Observing the precautions switch OFF the supply.

Tabulation:

Speed of the Generator: r.p.m.

From Graph

Critical field resistance, Rcf=

S. No. If

(A)

Eg(V)

(Increasing)

Eg(V)

(Decreasing)

Result:

Circuit Diagram:

Swinburne’s Test:

fig. (a)

To find Armature Resistance:

fig. (b)

Name Plate Details:

Voltage :

Current :

Speed :

Field Current :

Model Graph:

SWINBURNE’S TESTExp. No. 8

Date:

Aim:

To pre-determine the efficiency of a DC shunt machine when run both as generator and motor.

Apparatus Required:

S. No. Name of the Equipment Range Type Quantity

1. Voltmeter

2. Ammeter

3. Rheostat

4. Tachometer

Precautions:

d) Field rheostat must be kept in minimum resistance position.

e) Armature rheostat must be kept in maximum resistance position.

Procedure:

1) Connect the circuit as shown in the circuit diagram.


3) Start the Motor with the help of starter keeping the switch ‘S’ connected across the

ammeter closed.

4) Adjust the speed of motor to it’s rated value by adjusting field and/or armature rheostats.

5) Now open the switch ‘S’ and note all the meter readings.


To find the armature and series field resistance:

1) Connect the circuit as shown in circuit diagram (fig.(b))

2) Keeping the rheostat in its maximum resistance position close the DPST Switch and switch

ON 220V DC supply.

3) By adjusting the rheostat for different values of current note down the meter readings.


Tabulation:

For Swinburne’s Test:

Speed of the motor: r.p.m.

S. NO. Supply voltage

(Volts)

Line current IL

(amps)

Shunt current

If

(amps)

To find Armature resistance:

S. No. Va

(V)

Ia

(A)

Ra

(Ohms)

Average Ra

Machine when run as Motor:

S. No. Voltage

(V)

IL

(A)

If

(A)

Ia

(A)

I.P

(W)

Wcu

(W)

WT

(W)

O.P

(W)

η=

0.P / I.P

(%)

Machine when run as Generator:

S. No. Voltage

(V)

IL

(A)

If

(A)

Ia

(A)

O.P

(W)

Wcu

(W)

WT

(W)

I.P

(W)

η=

0.P / I.P

(%)

Model Calculation:

IL = ; If = ; V =

Ia = IL - If =

Constant Loss, WC = V Х IL - Ia2 Х Ra

Reading No.

Machine When run as Motor

IL = ; If = ; V =

Ia = IL - If =

Input = V Х IL =

CU Loss, WCU = Ia2 Х Ra =

Total Loss, WT = WC + WCU =

Output = Input - WT =

Efficiency, η = 0.P / I.P =

Machine When run as Motor

V = ; IL = ; If =

Ia = IL + If =

Output = V Х IL =

CU Loss, WCU = Ia2 Х Ra =

Total Loss, WT = WC + WCU =

Input = Output + WT =


Result:

Circuit Diagram:

Name Plate Details:

Voltage :

Current :

Speed :

Power :

Field Current :

Model Graph:

BRAKE TEST ON DC SHUNT MOTOR Exp. No. 9

Date:

Aim:

To obtain the performance characteristics of DC shunt motor by direct loading.

Apparatus Required:


1. Voltmeter2. Ammeter3. Rheostat4. Tachometer

Precautions:

f) Motor field rheostat must be kept in minimum resistance position.

g) Starter arm must be in OFF position.

Procedure:

To conduct Load Test:

1) Connect the circuit as shown in circuit diagram.


3) Start the motor with the help of starter.

4) Now load the motor in steps to its full-load and note down all the meter readings.


Tabulation:

For Load Test:

Radius of Brake Drum:

S.

No.

VL

(V)

IL

(A)

Speed

(r.p.m.

)

Spring Balance

readings

(Kgs)

S1 S2 S1∼S2

Torque

(N-m)

I.P

(KW)

O.P

(KW)

η0.P / I.P

(%)

Model Calculations:

Reading No.

V = ; IL = ; N = ; R = ; S1 = ; S2 =

Torque, T =

Input = V Х I =

Output = (2 Х ∏ Х N Х T) / 60


Result:

Circuit Diagram:

(a) OC Test

(b) SC Test

MODEL GRAPHS:

Name Plate Details 1Φ T/F:

KVA =

LV Voltage =

HV Voltage =

Frequency =

OC & SC TESTS ON SINGLE PHASE TRANSFORMERExp. No. 9Date:

Aim:

(a) To predetermine the efficiency and regulation of Single Phase Transformer by

conducting no-load test and short circuit test.

(b) To draw the equivalent circuit of single phase transformer referred to LV side as well as

HV side.

Apparatus Required:


1. Single Phase Variac

2. Ammeter

3. Voltmeter

4. Wattmeter

Precautions:

a) There should not be loose and wrong connections in the circuit

b) Single phase auto transformer should be in minimum output voltage position

c) Before making or breaking the circuit, supply must be switched OFF

Procedure:

1) Connect the circuit for O.C. test as per the circuit diagram.

2) Keep the variac in minimum output voltage position and switch ON the supply.

3) Apply the rated voltage to the transformer by properly adjusting the variac.

4) Note down the readings of various meters and switch OFF the supply.

5) Connect the circuit for SC test as per the circuit diagram, with appropriate ranges of

meters.

6) Keep the variac in minimum output voltage position and switch on the supply.

7) Apply proper voltage (low voltage) to the transformer by adjusting the variac such

that rated current flows through the transformer.

8) Note down the readings of various meters and switch OFF the supply.

OC Test Observations

Where

M. F. = Multiplication factor = FSD

VI φcos

FSD Full scale divisions

SC Test Observations

S.No. VSC (V) ISC (A) WSC = W x M.F (w)

Equivalent Circuit of the Transformer:

(i) Referred to L.V. side

(ii) Referred to H.V. side

S.No. Vo (V) Io (A) Wo = W x M.F (w)

Calculations:

(a)Calculation of Equivalent circuit parameters:

Let the transformer be the step-up transformer

Primary is L. V. side.(V1) , Secondary is H. V. side (V2)

(i) Parameters calculation from OC test

cos φ0 = oo

o

IV

W =

Iw = I0 cos φ0 = KII ww /1 = =

wI

VR 1

0 = =2

010 KRR = =

Iμ = I0 sin φ0 = KII /1µµ = =

µI

VX 1

0 = =2

010 KXX = =

K = 1

2

V

V =

(ii) Parameters calculation from SC test

202

sc

SC

I

WR = =

SC

SC

I

VZ =02 =

202

20202 RZX −= =

2

0201 / KXX = =

20201 / KRR = =

20201 / KZZ = =

Tabulation:

(a) Efficiency at different loads and P.fs

cos φ1 = ___________ cos φ2 = ___________

S.No. Load Cu.loss

(W)

Output

(W)Input

(W)

η(%)

1.

2.

3.

4.

¼F.L.

½F.L.

¾F.L.

F.L.

Xx S.No. Load Cu.loss

(W)

Output

(W)

Input

(W)

η(%)

1.

2.

3.

4.

¼F.L.

½F.L.

¾F.L.

F.L.

(b) Regulation at full load

Lagging Pf Leading Pf

S.

No.P.F. % Reg.

S.

No.P. F. % Reg.

1. 0.3 1. 0.32. 0.4 2. 0.43. 0.5 3. 0.54. 0.6 4. 0.65. 0.7 5. 0.76. 0.8 6. 0.87. Unity 7. Unity

(b) Calculations to find efficiency:

For ½ full load

Cupper losses = Wsc x (1/2)2 watts =

where Wsc = full – load copper losses

Constant losses = W0 watts =

Output = ½ KVA x cos φ = [cos φ may be assumed]

Input = output + Cu. Loss + constant loss =

% 100xInput

Outputefficiency = =

(c) Calculation of Regulation at full load:

I2 = Load (KVA) X 103 / V2 =

100sincos

Re%2

022022 xV

XIRIgulation

φφ ±= =

‘+’ for lagging power factors

‘-‘ for leading power factors

Result:

Comments:

Circuit Diagram:

Name Plate Details:Power =

Voltage =

Current =

Speed =

Conn. =

Type =

Frequency =

MODEL GRAPH:

W1

W2

I

V

3Φ IM

Brake Drum

Spring Balance

BRAKE TEST ON THREE PHASE INDUCTION MOTOR Exp. No. 11Date:

AIM: To conduct brake test on the given 3 phase induction motor and to plot its performance

characteristics.

Apparatus Required:

S. No. Equipment Range Type Quantity

1. 3 Phase Variac

2. Ammeter

3. Voltmeter

4. Wattmeter

5. Tachometer

Precautions:

d) There should not be loose and wrong connections in the circuit

e) Three phase auto transformer should be in minimum output voltage position

f) Initially there should be no load on the motor

g) Apply water into brake drum during operation to control the heat of the brake drum.

h) Before making or breaking the circuit, supply must be switched OFF.

Procedure:

1. Connect the circuit as per the circuit diagram.

2. Observing precautions, close the TPST switch.

3. Apply the rated voltage to the stator windings of 3 φ induction motor with the help of

3-phase auto transformer.

4. Note down the readings of all meters on no-load.

5. Load the induction motor in steps using the brake-drum arrangement. At each step note

down the readings of all meters up to full load of the motor.

6. Gradually release the load and switch OFF the supply.

7. Using thread, measure the circumference of the brake-drum when motor is at rest.

Tabulation:

S. No.

Voltage V

(volts)

Current I

(Amps)

Wattmeter reading (W)

MF = MF =

W1 W2

Speed N(rpm)

Spring balance reading

S1

KgS2

Kg

%Slip Powerfactor

TorqueN-m

OutputWatts

η%

Model calculations:

S. No.:

Input power drawn by the motor W = (W1 + W2) watts

=

R Radius of drum in meters = (Circumference of brake drum in mtrs) / 2π =

Shaft Torque, Tsh = 9.81 (S1 ~ S2) R N-m

=

Output power in watts = wattsTN sh

60

2π

=

100% xwattsinpowerInput

wattsinpoweroutputefficiency =

=

p

fxN s

120= =

100% xN

NNslip

s

s −=

=

power factor of the induction motor LL IV

W

3cos =φ =

Result:

Comments:

Circuit Diagram:

(a) OC & SC Test

(b) Armature Resistance

Name Plate Details:

Parameter DC Motor Alternator

Power

Voltage

Current

Speed

type

Excitation Voltage

Excitation Current

P.F.

REGULATION OF ALTERNATOR USING SYNCHRONOUS IMPEDANCE METHOD Exp. No. 12

Date:

AIM: To pre-determine the regulation of a given three-phase alternator by conducting O. C.

and

S. C. tests by synchronous Impedance method (EMF method)

Apparatus Required:

S.No. Equipment Range Type Quantity

1. Tachometer

2. Ammeter

3. Voltmeter

4. Rectifier

5. Rheostat

PROCEDURE:

1. OC test:

(i) Connections are made as shown in the circuit diagram for OC & SC test.

(ii) With the rectifier in the zero voltage position, TPST switch open and the

rheostats in their proper positions, the d.c. supply to the motor is switched ON.

(iii) The dc motor is brought to rated speed of the alternator by properly varying the

field rheostat of motor.

(iv) Now, the alternator field is excited by applying the dc voltage through the

rectifier in steps. At each step, note down the field current and the

corresponding generated voltage. This procedure is repeated till the voltage

generated is much beyond rated value.

(v) Reduce the alternator field excitation to zero level.

MODEL GRAPHS

Tabulation:

a) OC & SC Test:

O. C. Test S. C. Test

Speed =

S.No. Field current

(A)

Phase voltage

(V)

xxxx Speed =

S.No. Field

current,

(If) (A)

Short circuit

current (ISC), (A)

2. SC test

(i) with the rectifier in the minimum voltage position, the TPST switch is closed.

(ii) Increase field excitation gradually till the S.C. current of the alternator reaches

the rated current of alternator.

(iii) Note down all the meter readings.

b) Armature Resistance:

S.No. I (A) V (volts) Rdc = V/I Ω

Percentage regulation at _______ load at different power factors

Power

factor

(Cosφ)

E0 (V) % Reg

Lagging Leading Lagging Leading

Model Calculations:

From Graph SC

OCS I

VZ = for the same If and speed: =

Ra = (1.6) RdC =

22aSS RZX −= =

Assume p.f. (CosΦ) =

Assume armature current (Ia) =

Generated emf of alternator on no load is

( ) ( ) 220 sincos Saaa XIvRIvE ±++= φφ =

+ for lagging p.f.

- for leading p.f.

The percentage regulation of alternator for a given p.f. is

100Re% 0 xV

VEg

−= =

where

E0 – Generated emf of alternator per phase voltage

V – Full load, rated terminal voltage per phase.

Result:

Comments:

18054917 Bee Lab Manual

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Transcript of 18054917 Bee Lab Manual