1

ELECTRICAL MEASURMENTS LAB

DEPARTMENT OF

ELECTRICAL AND ELECTRONICS ENGINEERING

ACADEMIC YEAR 2012-2013

IV B.Tech EEE I-SEMESTER

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PREFACE

The significance of the Electrical Measurements Lab is renowned in the various fields of

engineering applications. For an Electrical Engineer, it is obligatory to have the practical ideas

about the Electrical Measurements. By this perspective we have introduced a Laboratory manual

cum Observation for Electrical Measurements Lab.

The manual uses the plan, cogent and simple language to explain the fundamental aspects

of Electrical measurements in practical. The manual prepared very carefully with our level best.

It gives all the steps in executing an experiment.

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ACKNOWLEDGEMENT

It is one of lifes simple pleasures to say thank you for all the help that one has extended

their support. I wish to acknowledge and appreciate Assoc Prof K Ram Krishna, Assist. Prof.

R.Munishwar, Foreman. P Prabhu Dass, and A Ramesh for their sincere efforts made

towardsdeveloping the Electrical Measurements Lab manual. I wish to thank students for their

suggestionswhich are considered while preparing the lab manual.

I am extremely indebted to Sri.Col Dr. T. S. Surendra, Principal and Professor,

Department of Electrical and Electronics Engineering, BVRIT for his valuable inputs and sincere

support to complete the work.

Specifically, I am grateful to the Management for their constant advocacy and incitement.

Finally, I would again like to thank the entire faculty in the Department and those people

who directly or indirectly helped in successful completion of this work.

(Prof. N. BHOOPAL)

HOD - EEE

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GUIDELINES TO WRITE YOUR OBSERVATION BOOK

1. Experiment Title, Aim, Apparatus, Procedure should be on right side.

2. Circuit diagrams, Model graphs, Observations table, Calculations table should be left side.

3. Theoretical and model calculations can be any side as per your convenience.

4. Result should always be in the ending.

5. You all are advised to leave sufficient no of pages between experiments for theoretical or

model calculations purpose.

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DOS AND DONTS IN THE LAB

DOS:-

1. Proper dress has to be maintained while entering in the Lab. (Boys Tuck in and shoes, girls with apron)

2. All students should come to the Lab with necessary tools. (Cutting Pliers 6, Insulation remover and

phase tester)

3. Students should carry observation notes and record completed in all aspects.

4. Correct specifications of the equipment have to be mentioned in the circuit diagram.

5. Student should be aware of operating equipment.

6. Students should be at their concerned experiment table, unnecessary moment is restricted.

7. Student should follow the indent procedure to receive and deposit the equipment from the Lab Store

Room.

8. After completing the connections Students should verify the circuits by the Lab Instructor.

9. The reading must be shown to the Lecturer In-Charge for verification.

10. Students must ensure that all switches are in the OFF position, all the connections are removed.

11. All patch cords and stools should be placed at their original positions.

DONTs:-

1. Dont come late to the Lab.

2. Dont enter into the Lab with Golden rings, bracelets and bangles.

3. Dont make or remove the connections with power ON.

4. Dont switch ON the supply without verifying by the Staff Member.

5. Dont switch OFF the machine with load.

6. Dont leave the lab without the permission of the Lecturer In-Charge.

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JAWAHARLAL NEHRU TECHNOLOGICAL

UNIVERSITY HYDERABAD

IV Year B.Tech. EEE I-Semester L T/P/D C

0 -/3/- 2

(57602)ELECTRICAL MEASUREMENTS LAB

The following experiments are required to be conducted Compulsory experiments.

1. Calibration and testing of a 1- Energy meter

2. Calibration of Dynamometer Power Factor meter

3. Crompton D.C Potentiometer -Calibration of PMMC Ammeter and PMMC voltmeter

4. Kelvins Double Bridge - Measurement of Resistance Determination of Tolerance

5. Dielectric Oil Testing using H.T. testing Kit

6. Schering Bridge and Anderson Bridge

7. Measurement of 3- Reactive Power using 1- Wattmeter

8. Measurement of Parameters of a choke coil using 3 voltmeter and 3 ammeter methods.

In addition to the above experiments, at least any two of the experiments from the following list are

required to be conducted.

9. Calibration of L.P.F Watt Meter by Phantom testing

10. Measurement of 3- Power with single Watt meter and 2 Nos of C.T.

11. C.T. Testing using mutual Inductor Measurement of % ratio error and phase angle of given C.T

by Null method.

12. P.T. testing by comparison V.G as Null detector Measurement of % ratio error and phase

angle of given P.T.

13. LVDT and Capacitance pickup - characteristics and calibration.

14. Resistance strain gauge strain measurements and calibration.

15. Transformer terms ratio amusement using A.C. Bridge

16. Measurement of % Ratio error & phase Angle of given Current Transformer (C.T) by comparison.

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ELECTRICAL MEASUREMENTS LAB

EEE IVth

YEAR 1ST

SEMESTER Academic year 2012-2013

LIST OF EXPERIMENTS CONDECTED BY EEE DEPARTMENT:

S. No Name of the Experiment Page no 1 Calibration and testing of a 1- Energy meter

2 Calibration of Dynamometer Power Factor meter

3 Calibration of PMMC voltmeter using Crompton D.C Potentiometer

4 Measurement of Resistance using Kelvins Double Bridge

5 Testing of transformer Oil

6 Schering Bridge and Anderson Bridge

7 Measurement of 3- Reactive Power using 1- Wattmeter

8 Measurement of Parameters of a choke coil using 3 voltmeter and 3ammeter

Additional experiments

9 Calibration of L.P.F Watt Meter by Phantom testing

10 Measurement of % Ratio & phase Angle Error of A Current Transformer

11 Calibration of Domestic Applications

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100/5A

0-5A,MI

0-300V,MI

N

R

230V,1- AC

Supply,50Hz

Y

B

415V,3- AC

Supply,50Hz

A

5/10A, 300V, 1500W,UPF 5/10A, 300V, 1- Energy Meter

Circuit diagram: - Calibration of 1- Energy meter

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1. Calibration of 1- Energy meter

Aim:- To determine the error of a 1- Energy meter for different loadings & draw the % error Curve.

Apparatus:-

Theory:-

The construction varies in details form one manufacture product to the next how ever the

differences are vary minor in nature. There are four main parts of the operating mechanism.

1) Driving system.

2) Moving system .

3) Braking system.

4) Registry system.

A permanent magnet positioned near the edge of the aluminum disc from the braking system

the aluminum disc moves in the field of this magnet and there provide a breaking torque. The

positioned as explained earlier.

Procedure:-

1) Connect the circuit as show in circuit diagram.

2) Apply rated voltage to the pressure coil of energy meter.

3) Vary the current through the current coil in different steps by 1A,2A,3A using 1- variac.

4) Note down the time for 10 Revolutions of energy meter.

5) Note down the readings of voltmeter, Ammeter & wattmeter for different currents that is 1A,2A,3A etc.

S.NO Equipment Range Type Quantity

01 Voltmeter (0-300)v MI 1

02 Ammeter (0-5)A MI 1

03 1- Auto transformer 230/(0-270)V 1

04 Rheostat 100/5A Wire Wound 1

05 1- Energy meter 240V,5A 1

06 Wattmeter 5/10A,30V/1500W UPF 1

07 Connecting wires set

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6) Compare the theoretically & practically founded values.

7) Calculate the % Errors.

% Error=

8) Plot the graph between % error Vs power.

Precautions:-

1) Avoid loose connections.

2) Avoid parallax errors.

Result:-

The error of 1- energy meter for different loadings have been determined.

Observation Table:-

S.No Volts I (Ams) Px2(watts) Time for 10 rev(Sec)

No. of Revolutions

PxT(KWH) % Error

Result:-

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230

V, 1

- A

C Su

pp

ly, 5

0Hz

5/10A, 300V

1500W, UPF

5/10A, 300V

1500W, UPF

0-300V,MI

N

R

415V,3- AC

Supply,50Hz

Y

B

100/5A

0-5A, MI

R

Y

B

Phase Shifting T/F

3KVA,1- Variac

Fuse

N

Circuit Diagram: - Calibration of Dynamometer Power Factor meter

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2. Calibration of Dynamometer Power Factor meter

Aim:- Calibration of Dynamo meter Power factor Meter by phantom loading.

Apparatus:-

Theory:-

The connections of a single phase electro dynamo type. Power factor meter is show in figure.

It consists of fixed coil which acts as the current coil. This is split up in two parts and carries the current

of the circuit under test. Therefore the main current two identical pressure coils. A and B Provided on a

spindle constitute the moving system. Pressure coil A has a non inductive resistance R connected in

series with it. The two coils are connected across the voltage of the circuit the value of R&L are so

adjusted that the two coils carry the same value of current at normal frequency that is RL

Procedure:-

1) Connect the circuit as per the circuit diagram.

2) By adjusting the variac the rated voltage is applied across the pressure coil of wattmeter & power factor meter.

3) Rated current is made to pass through the coils.

4) Now adjust rotor position of phase shifting transformer for different values of power factor meter.

5) Tabulate the readings.

6) From wattmeter readings find values of power factor &compare from with value of power factor meter.

S.NO Equipment Range Type Quantity

01 Phase shifting T/F 1

02 Voltmeter (0-300)v MI 1

03 Ammeter (0-5)A MI 1

04 P.F Meter 5/10A,300v,1500W 1

05 I- Variac 230V/(0-270)V 1

06 Rheostat 100/5A 1

07 Wattmeter 5/10A,300V,300W 1

07 Connecting wires set

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Precautions:-

1) Avoid loose connections.

2) Avoid parallax errors.

Observation Table:-

S.No Voltmeter(V) I (Amps) P.F Meter Cos

Wattmeter (W)

Theoretical Cos

% Error

Result:-

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100/5A - +

Working battery 0-2V

RPS

0-30v

Fine

Coarse

Coarse

Fine

Stranded cell

1.0186V

Unknown R

1.5 To Potentiometer

5V

10V

50V

300V

0-30V,MC

G

Circuit diagram: - Calibration of PMMC voltmeter using Crompton D.C Potentiometer

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3. Calibration of PMMC voltmeter using Crompton D.C Potentiometer

Aim: To Determine Error given by voltmeter with DC potentiometer.

Apparatus:-

Theory:-

There are two types of potentiometers.

1.D.C potentiometer

2.A.C Potentiometer.

The potentiometer is extensively used for a calibration of voltmeters and ammeters and has

infect became the standard for the calibration of these instrument. The principle of operations of all

potentiometers is based on the circuit, all the resistors in a potentiometer with the exception of slide

wires are made of manganin. This is because manganin has a high stability a low temperature coefficient

and has freedom fro thermo electric effect against copper.

The slide wire is usually made of platinum sliver alloy and the sliding contacts are of a copper gold

sliver alloy .this combination of materials for slide wire and sliding contacts results in a good contact,

freedom from thermo electric emf and minimum wear of slide wire.

Procedure:-

1.connect the circuit elements as per the circuit diagram.

2.standeredise the given potentiometer.

3.Apply the voltage to potentiometer terminal.

4. Adjust the dial resistor for zero deflection of galvanometer.

5.compare the obtained value.

%Error=Instrument reading-actual reading Actual reading

S.NO Equipment Range Type Quantity

01 RPS (0-30)v 1

02 Voltmeter (0-30)v MC 1

03 Volt Ratio box 1

04 Potentiometer 1

05 Standard cell 0.0186 1

06 Connecting wires set

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Precautions:

1. Avoid loose connections.

2. Avoid Parallax Errors.

OBSERVATIONS TABLE:-

S.No Voltmeter(V) Potentiometer output

Potentiometer input

Result:-

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C

V=5V

+ -

R2

S

n m a

p 2

D Q

b

P

R

Measurement of Resistance using Kelvins Double Bridge

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4. Measurement of Resistance using Kelvins Double Bridge

Aim:-

To measure unknown low resistance using Kelvins double bridge.

Apparatus:-

Theory:-

The problem involved in the measurement of low resistance with an ordinary wheat stone

bridge an be eliminated using Kelvins double bridge. This bridge uses two ratio ARMS &a four terminal

low resistance standard resistor (S)

The outer ratio Arms consists of P&Q inner ratio ArmsP,2 Both

the arms are connected to the potential terminals so as to eliminate the effect of leads

Under balanced condition no current flow through the galvanometer and

hence the potential drop across the resistor of an outer Arms is equal to sum of drop across the low

resistance and inner arm resistance.

Procedure:-

1) Connect the circuit as per circuit diagram.

2) Connect the unknown resistance R.

3) Switch on the power supply.

4) By varying the standard resistance S obtain the balance condition (Null deflection ).

5) Calculate the unknown resistance by using the Formula.

SQ

PR

Precautions:-

1) Avoid loose connections.

S.NO Equipment Quantity

01 Kelvins Bridge board 1

02 Null detector 1

03 Supply voltage 1

04 Unknown Resistance 1

05 Connecting wires set

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2) Avoid parallax errors.

Result:-

The unknown resistance is calculating by using Kelvins double bridge.

Observation table:-

S.No R1() R2() R3() Rx (Theory) R3(Practical)()

Result:-

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Main

Fuse

r

Main

HT

HF

Charging Volt(0-60V)

Memory Dust

H.T Relay

Unit relay

115V 230V

11KV

Oil container

10

0

/5A

1- A

C 2

30

V

High Voltage

ON

HF

OFF

ON

Circuit Diagram:- Testing of transformer Oil

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5. Testing of transformer Oil

Aim:-

To test oil transformer determine the dielectric strength of oil.

Apparatus:-

Transformer oil test kit.

Name plate details:-

Input voltage:230/240V 1- 50HZ AC supply

Output voltage: (0-60)KVA

Capacity: 600 KVA

Theory:-

The oil transformer kit is used to determine the dielectric strength of oil these are generally

used in substations. It contains two electrodes of a small gap between there when ever break down

voltage occurs there will be a spark is observed at the high voltage side of the transformer. For

calibration the gap in between the two electrodes is 4MM. the voltage that is obtained when flash over

occurs is rapidly applied voltage.

Procedure:-

1) The oil is poured in a container known as test cell the electrodes are polish spheres perfectly of brass arranged horizontally a suitable gauge is used to adjust the gap.

2) While pouring the oil sample the test cell(container should )be thoroughly cleaned & the moisture & sypended particles should be avoided in fig shown below & experimental setup for finding out the dielectric strength of the give sample of oil.

3) The voltmeter is the connected on the primary side of high voltage side transformer for calibration.

4) Adjust the gap between the spheres is to 4MM with the help of gauge then pour transformer oil till a depth slurries are immersed.

5) Then increase the voltage gradually & continuously till a flashover of the gap is seen on the MCB apparatus note down this voltage. This voltage is known as rapidly applied voltage.

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6) The breakdown of the gap has taken please mainly due to field effect. The thermal effect is main as the time of application is short.

7) Next bring the voltage back Zero & star with 40% of rapidly applied voltage & weight for one min.sec if the flashover by take occurred if not

increase the voltage every time by 2

12 of the rapidly applied voltage and wait for one

min till the flash over is seen on the MCB trips. Note the voltage.

8) Repeat the experiment with different values of voltage.

9) The acceptable value is 30KV for 4mm & 2.5mm for 11KV the oil should be set for secondly.

Precautions:-

It is to be noted that the electrodes are immersed vertically in the oil. It is due to the fact

that when oil decomposes. Carbon particles being lighter rice up & if electrons are vertical

configurations, this well bridge the gap & the breakdown will take place.

Result:-

The dielectric strength of oil is determined.

Observation table:-

S/No Dielectric voltage Average value

Result:-

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Circuit Diagram:- Schering Bridge and Anderson Bridge

Schering Bridge:-

L1 R1

F

r

E1 E2

E4 E3

R2

D

R4

R1 R2

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Anderson Bridge:

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6. Schering Bridge and Anderson Bridge

I1/wc1

IIr1 Ir2

I2

C2

C1

a

b

c

I2

I1

I1

Cx

E1 E3

E4 E2

D

r1 R3

d R4

I2

Phasor Diagram:-

Ic I2

2

I1

2

E1=E2=I2/wc2

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Aim:-

To determine the unknown capacitance using Schering bridge & inductance using Anderson bridge.

Apparatus:-

Theory:-

Anderson Bridge:-

This bridge in fact is a modification of the self Maxwell s inductance Capacitance

bridge. In this method the self inductance is measured in terms of a standard capacitor. This method is

applicable for precise measurement of self inductance over a very wide range of values.

14

321 r

R

RRR

42244

31 )( RRRRr

R

RCL

The disadvantage of Anderson bridge is more complex than its proto type Maxwells

and is more parts and is more complicated to set up and manipulate. The balance equation are not

simple and in fact are much more tedious. An additional junction point increases the difficulty to

shielding the bridge.

Schering Bridge:-

The connection and phasor diagram of the bridge under balance conditions are show

in figure.

r1 =R3 C4/C2

c1 =C2 R4/R3

therefore values of capacitance c1 and its dissipation factor are obtained from the value of bridge

elements at balance permanently set up Schering bridges are sometimes arranged so that balancing is

done by adjustment of R2 & C4 with C2 & R4 remaining fixed. Since R3 appears in both the balance

S.NO Equipment Quantity

01 Schering Bridge kit 1

02 Anderson Bridge kit 1

03 Unknown Capacitor 1

04 Unknown Inductor 1

05 Connecting wires set

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equation and therefore there is some difficulty in obtaining balance but it has certain advantages as

explained below. The equations for C1=R4/R3 x C2 and since R4&C2 are fixed. The dial of R3 may be

calibrated to read the capacitance directly.

Procedure:-

Shearing Bridge:-

1) Connect the circuit as per circuit diagram.

2) By varying the balanced the condition.

3) Note down the value of C2,R2,R1

4) Calculate the value of Cx

1

22

R

RCCx

Anderson Bridge:-

1) Connect the circuit as per circuit diagram

2) By the varying r and R balanced the bridge.

3) Note down the values.

4) Calculate self inductance.

L1=C.R (Q+2r)

Precautions:-

1) Avoid loose connections.

2) Balance the bridge accurately.

Result:-

The unknown inductance & unknown capacitance had been found using Anderson &

Schering Bridge.

Shearing Bridge:-

Observation table:-

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S.No R2() C2(F) R1()

1

21

R

RCC (MF) RC

CR

1

2 ()

Anderson Bridge:-

Observation table:-

S.No C (F) R() r(K) L=CR(Q=2r)MH

Result:-

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Fuse 10A

3 Auto Transformer

414

V

3- I

N

D

U

C

T

I

V

E

L

O

A

D

(0-600)V

MI

V

M L

C V

A

M L

C

R

Y

B

N

Circuit Diagram:-Measurement of 3- Reactive Power using 1- Wattmeter

7. Measurement of 3- Reactive Power using 1- Wattmeter

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Aim:- Measurement of Reactive power of an 3- balanced inductance load using one 1-

Wattmeter.

Apparatus:-

Theory:-

For the measurement of reactive power in balanced 3- circuit only a single Dynamometer

type wattmeter is required.

The current coil is connected in series with load and the pressure coil is connected Across

the remaining two phase.

Let the current through current coil be Iph & potential appliance across the pressure coil be

V

VI=VY-VB=3 VPH.

This potential VI is leading R by 90o IR by hence wattmeter reading indicates.

WI=3 VPH IPH. Cos (-90o+)= =3 VPH IPH sin

Total reactive power (Q) obtained by Multiplying the wattmeter reading with =(-3)i.e Q=3 WI

Procedure:-

1) connect the apparatus as shown as circuit diagram.

2) Vary the auto transformer and set it to rated voltage .

3) Now Vary the 3- balanced load gradually.

4) Note down the reading of voltmeter, Ammeter & Wattmeter.

5) Calculate theoretical and Practical values of reactive power from the given formula.

Precautions:-

1) Avoid lose connections.

S.NO Equipment Range Type Quantity

01 Wattmeter 5/10A,600v,1500W UPF 1

02 5/10A,300v,300W

03 Voltmeter (0-600)v MI 1

04 Ammeter (0-10)A MI 1

05 3- inductive balanced --------------- 1

06 3- Auto Transformer --------------- 1

07 Connecting wires --------------- set

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2) Avoid parallax errors.

Result:-

The measurement of 3- Reactive power using 1- Wattmeter has been clone and theoretical & practical values has been compared.

Observation Table:-

S.No W1 W2 Volts P=3* W1 S=3VI =tan-1(Q/P)

Q=3VI sin

Q=S2-P2 I(Amps)

Result:-

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Fuse 10A

230V

V

115V

V

(0-10)A

MI

(0-30)V

MI

1-

230V

50 Hz AC

Supply

Ph

N 1 -Transformer

3KVA, 230V/ 115V

DPST

Variac

230V/ (0-270)V,10A

V

A1

(0-10)A

MI c A3

(0-5)v

MI

100/5A

A2

Fuse 10A

230V

V

115V

V

(0-15)A

MI

(0-50)V

MI

1-

230V

50 Hz AC

Supply

Ph

N 1 -Transformer

3KVA, 230V/ 115V

DPST

Variac

230V/ (0-270)V,10A

V1

A

V2

100/5A

(0-30)v

MI (0-30)v

MI

V3

Measurement of Parameters of A coil

3-AmmeterMethod:-

3-Voltmeter Method:-

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8. Measurement of Parameters of A coil

Aim:- Measurement of Parameters of a choke coil using 3 voltmeter and 3ammeter

To obtain the parameters of given coil using

A) 3 Voltmeter method

B) 3 Ammeter method

Apparatus:-

3 Voltmeter Method

3 Ammeter Method

Theory:-

The parameters of a coil like Inductance & Resistance can be calculated by using 3-Voltmeter

& 3-Ammeter methods.

In the three voltmeter method a suitable current is passed through the coil, in

series with a non inductive resistance R and the voltage drops across both parts of the circuit and across

the calculated and the R&L can be easily determined using the power factor.

In the 3-Ammeter method the non-inductive resistance R, together with an ammeter is

connected in parallel with the coil whose inductance is to be measured.

Procedure:-

3-voltmeter Method:-

S.NO Equipment Range Type Quantity

01 Voltmeter 0-230V MI 3

02 Ammeter 0-1A MI 1

03 1- Auto transformer 230V/(0-270)V MI 1

04 Rheostat 100/5A Wire wound 1

05 Connecting wires 1 Set

S.NO Equipment Range Type Quantity

01 Voltmeter 0-230V MI 1

02 Ammeter 0-10A MI 2

03 Ammeter 0-5A MI 1

04 1- Auto transformer 230V/(0-270)V MI 1

05 Rheostat 100/5A Wire wound 1

06 Connecting wires 1 Set

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

2) Vary the auto transformer knob till rated current flows in the circuit.

3) Not down the voltmeters & Ammeter readings.

4) Calculate the resistance and reactance of the coil.

3-Ammeter Method:-

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

2) Vary the auto transformer knob till we get rated voltage.

3) Note down the voltmeter & Ammeters readings.

4) Calculate the resistance & Reactance of the coil using above formula.

Observation Table:-

3-Voltmeter Method:

S.NO I (Amps) V1 (V) V2(V) V3(V)

3-Ammeter Method:

S.NO V (Volts) I1 (Amps) I2(Amps) I3(Amps)

Precautions:-

1) Avoid parallax errors.

2) Avoid lose connections.

Result:-

The parameters of a coil Referred to primary are calculated.

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ADDITIONAL EXPERIMENTS:-

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230

V, 1

- A

C Su

pp

ly, 5

0Hz

5/10A, 300V

1500W, UPF

5/10A, 300V

1500W, UPF

0-300V,MI

N

R

415V,3- AC

Supply,50Hz

Y

B

100/5A

0-5A, MI

R

Y

B

Phase Shifting T/F

3KVA,1- Variac

Fuse

N

Circuit Diagram:- Calibration of L.P.F Watt Meter by Phantom testing

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9. Calibration of L.P.F Watt Meter by Phantom testing

Aim:- Calibration of I- Power factor Meter by (L.P.F) phantom loading.

Apparatus:-

Theory:-

The connections of a single phase electro dynamo type. Power factor meter is show in figure.

It consists of fixed coil which acts as the current coil. This is split up in two parts and carries the current

of the circuit under test. Therefore the main current two identical pressure coils. A and B Provided on a

spindle constitute the moving system. Pressure coil A has a non inductive resistance R connected in

series with it. The two coils are connected across the voltage of the circuit the value of R&L are so

adjusted that the two coils carry the same value of current at normal frequency that is RL

Procedure:-

7) Connect the circuit as per the circuit diagram.

8) By adjusting the variac the rated voltage is applied across the pressure coil of wattmeter & power factor meter.

9) Rated current is made to pass through the coils.

10) Now adjust rotor position of phase shifting transformer for different values of power factor meter.

11) Tabulate the readings.

12) From wattmeter readings find values of power factor &compare from with value of power factor meter.

Precautions:-

3) Avoid loose connections.

S.NO Equipment Range Type Quantity

01 Phase shifting T/F 1

02 Voltmeter (0-300)v MI 1

03 Ammeter (0-5)A MI 1

04 P.F Meter 5/10A,300v,1500W 1

05 I- Variac 230V/(0-270)V 1

06 Rheostat 100/5A 1

07 Wattmeter 5/10A,300V,300W 1

07 Connecting wires set

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4) Avoid parallax errors.

Result:-

The L.P.F wattmeter has been calibrated by phantom loading. An average error of 5% is found.

Observation Table:-

S.No Voltmeter(V) I (Amps) P.F Meter Cos

Wattmeter (W)

Theoretical Cos

% Error

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Circuit Diagram:- Measurement of % Ratio & phase Angle Error of A Current Transformer

A

V

A

L

O

A

D

(0300)V

MI

(0-10)A

MI

(0100)MA

MI

3KW,10A

I-

Fuse 10A

Fuse 10A

DPST

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10. Measurement of % Ratio & phase Angle Error of a Current Transformer

Aim:

To test current transformer by direct loading.

Apparatus:-

Theory:-

Depending open the construction of primary winding used C.TS are two types.

1)Wound type Current transformer.

2) Bar type Current Transformer.

In wound type of C.TS the primary winding consists of more than one complete turn which is wound

on the core.

For a wound type C.T either rectangular or standing or ring shaped cores are used the material to be

used for core should have high permeability and low magnetic loss, so core is made up of nickel iron

alloy or oriented electrical steel. The bare type C.Ts are used when the primary current is large it has

robust construction among all the C.Ts the core is ring shaped.

Procedure:-

1) Connect the circuit as for circuit diagram.

2) Set the input voltage to 230V rated by varying 1- Variac.

3) Note down the readings of Ammeter in primary & Secondary circuit of current transformer at Various loads.

4) Repeat the steps for various positions of primary and current T/F in middle corner etc.

S.NO Equipment Range Type Quantity

01 Current T/F 100/5A 1

02 1- Variac 230/(0-270)V

03 Voltmeter (0-300)v MI 1

04 Ammeter (0-15)A,(0-100)MA MI 1

05 Resistive load 1- 3KW,10A,230V 1

06 Connecting wires set

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5) Compare the current transformer ratio with its value and % error is found.

Precautions:-

1) Avoid loose connections.

2) Avoid parallax errors.

Result:-

Current T/F has been tested by direct loading.

OBSERVATION TABLE:_

S.NO Current Transformer (Center) Current Transformer (Near)

Primary(A) Secondary(MA) Primary(MA) Secondary(MA)

Calculation Table:-

Center: Near:

I1/I2 % Error

I1/I2 % Error

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Circuit Diagrams:- Calibration of Domestic Applications

V

A

L

O

A

D

(0300)V

MI

(0-10)A

MI Fuse 5A

Fuse 5A

DPST

1-

230V

50 Hz AC

Supply

1- ,VARIAC

3KVA

V

A

(0300)V

MI

(0-2)A

MI

Bulb

Fuse 2A

Fuse 2A

DPST

M L

C 1-

230V

50 Hz AC

Supply

V

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11. Calibration of Domestic Applications

Aim:-

To test and determine the Functioning of 5A fuse A 100W bulb And a 70w Ceiling Fan.

Apparatus:-

S.no Apparatus Type Range Quantity

01 I- Variac 230/(0-270) 1

02 Wattmeter UPF 5A,300V,3000W 1

03 Voltmeter MI (0-300)V 1

04 Ammeter MI (0-10)A 1

05 Rheostat Wire Wound 100 1

06 Bulb 100W 1

07 Fuse 5A 1

08 Ceiling Fan 80W 1

09 Connecting Wires Set

Theory:-

Fuse Wire:-

A Fuse is a thin wire which has a current rating. The current about this fuse wire break.

Bulb:-

A Bulb is a glowing thing which has a power rating when the voltage is excited the bulb

V

A

(0300)V

MI

(0-10)A

MI Fuse 5A

Fuse 5A

DPST

M L

C V

ff Fan

1-

230V

50 Hz AC

Supply

1- ,VARIAC

3KVA

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filament blows off.

FAN:-

A Fan is a rotating motor finding the efficiency.

Procedure:-

Fuse:-

1 Connect the circuit as for the circuit diagram.

2 Switch on the power supply and gradually increase current through the fuse by increasing load.

3 note the value of current rating for which the fuse wire blows.

Electrical Bulb:-

1 Connect the circuit as for the circuit diagram.

2 By gradually varying the variac . apply rated voltage to the bulb indicated by voltmeter across bulb.

3 Note the readings.

Ceiling FAN:-

1 Connect the circuit as for the circuit diagram.

2 Apply rated voltage.

3 Note down readings of voltmeter by varying regulator.

Precautions:-

1 Avoid the loose connections.

2 Avoid the parallel errors.

OBSERVATION TABLE:-

S.NO Equipment Voltage(V) Current(A) Ratting Wattmeter(W)

01

02

03

Result:-

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