57980852 Em II Manual Final

8/6/2019 57980852 Em II Manual Final

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ELECTRICAL MACHINES LAB - IILABORATORY MANUAL

(III YEAR B.E. EEE)

Prepared by

Mr. K. Balasubramaniam

Mr. M. Vijayakumar

Mr. K. Prakasam

Mr. A. Gowrishankar

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

K.S.R. COLLEGE OF ENGINEERING,

TIRUCHENGODE 637 215


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K.S.R. COLLEGE OF ENGINEERING

TIRUCHENGODE 637 215

Reg. No.

Certified that this is the work done by Selvan / Selvi

.... of the fifth semester Electrical & Electronics

Engineering branch during the year 2009 2010 in the Electrical Machines -II

Laboratory.

Staff in charge HoD

OBSERVATION NOTE BOOK


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INS

ION TO THE STUDENTS

Th stu ts must r th i stru ti s car u and follow th same throu hout

the semester

1. Studentshave to go to respective lab classes according to the lab time table.2. They have to wearthe shoes and the prescribed uniform.3. They have to know aboutthe procedure ofthe experimentbefore startdoing the

Experiment. Itwill be checked by the staff members.

4. Afterthe Circuitcorrection in the observation note book and viva voce, they haveto getthe indentslip from stores and getthe required apparatus.

5. They have to give the circuitconnections by involving themselvesin their batch.6. They have to take readingsin proper mannerwithout any error and getverifiedfrom the staff.

7. They have to get signature in result within two days after completion of theexperiment.

8. They have to submittheir completed previous experiment record atthe time ofentering the laboratory and they should enterthe mark in the log book withthe

lab in-charge.

9. After completing the experiment, they have to return all the apparatus to thestores and getback the indentslip.

10.Strictdiscipline issolicited inside the laboratory.


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CONTENTS

S.No D

Exp

ri

P

No.Mar

Si

wi

Date


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S

ABUS

ELECTRICAL MACHINES - II LABORATORY

LIST OF EXPERIMENTS

1. Regulation ofthree-phase alternator by EMF, MMF and ZPF methods.

2. Load teston three-phase alternator.

3. Regulation ofthree-phase salientpole alternator by sliptest.

4. V and Inverted V curves of Three Phase SynchronousMotor.

5. Load teston three-phase squirrel cage induction motor.

6. Load teston three-phase slipring induction motor.

7. No load and blocked rotorteston three-phase induction motor.

8. Separation of No-load losses ofthree-phase induction motor.

9. Losssummation method on three-phase induction motor.

10. Load teston single-phase induction motor

11. Determination ofEquivalentcircuitofsingle-phase induction motor

12. Speed control ofthree phase induction motor by V/f method


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Exp. No: Date:

REGULATION OF THREE-PHASEALTERNATOR BY EMF METHOD

AIM:

To predetermine the voltage regulation of a three phase non-salient polealternator by EMF method.

APPARATUS REQUIRED:

S.No. Apparatu Name Range Type Quantity

1 Voltmeter(0-600)V MI 1

(0-30)V MC 1

2 Ammeter (0-2)A MC 1(0-10)A MI 1

3 Rheostat 300/1.2 A Variable 3

4 Tachometer - Digital 1

PRECAUTIONS:1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time of starting.4. Keepthe prime-mover filed rheostatatminimum resistance position andalternator field rheostatatmaximum resistance position atthe time ofstarting.

PROCEDURE:

Open Circuit Test

1. Circuitconnections are given asperthe circuitdiagram.2. Field rheostatof motoris keptatits minimum position atthe time ofstarting.3. DPST Switchis closed. The motorisstarted by means ofstarter.4. The motor is set to run at rated speed of the alternator by varying the field

rheostatofthe motor.

5.

The residual emf of the alternator is noted for the zero field current of thealternator.6. Field rheostat of the alternator is gradually varied and the corresponding

induced emf and the field currentis noted between 0 to 120 % ofrated voltage.7. Then the field rheostatofthe alternator is broughtback to its original position.

i.e., the induced emfis broughtback to almostzero voltage.8. Open circuit characteristic is drawn for the above values i.e., between Eg per

phase and If.


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Isc OCC

Vph rated

Field current (If) Amps

Armaturecurrent,

(Ia

)Amps

SCC

Generated

voltageVph,

Volts

TABULATION

OPEN CIRCUIT CHARACTERISTICS

S.No.Fieldcurrent(If)inAmps

Line voltage(

l)in VoltsPhase voltage(Vph)in Volts

SHORT CIRCUIT CHARACTERISTICS


Shortcircuit current(Isc)inAmps

MODEL GRAPH

OPEN CIRCUITANDSHORT CIRCUIT CHARACTERISTICS:


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ShortCircuit Test

1. In shortcircuittestalternator outputterminalsshortcircuited asper circuitdiagram.2. For ShortcircuittestTPST switchis closed.3. Field rheostat of the alternator is varied slowly up to the rated current (short circuitcurrent) ofthe alternator.4. The corresponding field currentistabulated.5. Shortcircuitcharacteristic is drawn forthe noted valuesi.e., between Isc and If .

Synchronousimpedance =sc

ratedph

I

Vforthe same field current.

6. Various power factors are assumed and the phasor diagrams are drawn for both laggingand leading power factors. The voltage induced is obtained from the phasor diagrams and

the voltage regulation corresponding to the power factors are calculated using theformulae.

7. Regulation characteristics i.e., power factor Vs voltage regulation are drawn for thevarious load currents.

FORMULAE USED

i. Synchronousimpedance = Zs=sc

ratedph

I

forthe same field current.

Where,Voc = Rated Open circuitvoltage for face, (V)Isc = Shortcircuitcurrent, (A) ata Field currentcorresponding to the rated

Voltage

ii. Synchronousreactance (Xs)Xs = 22 acs RZ

Where,Rac = Ra (dc) X (1.6)

iii. % voltage regulation = {(Eg -VT)/ VT } X 100


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COMPUTATION OFARMATURE RESISTANCE (R a):

TABULATION TO FIND Ra

S.No.

Voltage drop acrossthe armature

(Va)in voltsArmature Current

(Ia )inAmps

ArmatureResistance

(Ra = Va/ Ia)inohm

Mean Ra

MODEL PHASOR DIAGRAM

(i) Lagging current

Ia

IaRaVT IaXs

Eg


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(ii) Leading current:

VT = Rated voltage

S.No. Sin Cos Generated Voltage Eg

% VoltageRegulation

Lag Lead Lag Lead

REGULATION CHARACTERISTICS

Ia

VTIaRa

IaXsEg


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VIVA QUE TIONS:

1. What is meant by voltage regulation?2. What is meant by Synchronous Impedance?3. What is OC test ?4. What is SC test?5. What is meant by mmf or field ampere turns?

RESULT:


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Exp. No: Date:

REGULATION OFALTERNATOR BY MMF METHOD

AIM:

To predetermine the voltage regulation of a three phase non-salientpole alternator by

MMF method.

APPARATUS REQUIRED:

S.No. Apparatus Name Range Type Quantity

1 Voltmeter (0-600)V MI 1

2 Voltmeter (0-30)V MC 1

3 Ammeter (0-2)A MC 1

4 Ammeter (0-10)A MI 1

5 Rheostat 220/1.2 A Variable 3

6 Tachometer - Digital 1

PRECAUTIONS:1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.4. Keepthe prime-mover filed rheostatatminimum resistance position and alternator field

rheostatatmaximum resistance position atthe time ofstarting.

FORMULA:

% Voltage Regulation = {(E g -Vt) / Vt } X 100

PROCEDURE:1. Circuitconnections are given asperthe circuitdiagram.2. Field rheostatof motoris keptatits minimum position atthe time ofstarting.3. DPST Switchis closed. The motorisstarted by means ofstarter.4. The motorissetto run atrated speed by varying the field rheostatofthe motor.5. The residual emf ofthe alternatoris noted forthe field currentof zero value.6. Field rheostatofthe alternatoris varied and the corresponding emfinduced and the field

currents are noted.

7. Step 6 isrepeated till the emfreaches 25% more than rated voltage.8. Open circuitcharacteristics are drawn forthe above valuesi.e., between Eg perphase and

If.


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COMPUTATION OFARMATURE RESISTANCE (RA):

TABULATION TO FIND Ra:

S.No.Voltage drop across

theArmature(Va)in volts

Armature Current(Ia)inAmps

ArmatureResistance

(Ra = Va/ Ia)in ohm

Mean Ra


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SCC

OCC

Field current (If) Amps

GeneratedvoltageEg

/J,

Volts

TABULATION:(ii) Open CircuitCharacteristics:


Generatedline voltage

Vl(volts)

Generatedperphase voltage

Vph (volts)

(iii)ShortCircuitCharacteristics:

S.No. FieldCurrent(If)inAmps ShortCircuitCurrent(Isc)inAmps

MODEL GRAPH :

OPEN CIRCUITANDSHORT CIRCUIT CHARACTERISTICS


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MODEL PHASOR DIAGRAM:

1. Drawrated voltage (Vt) perphase asreference vector and then draw Iawith an angle of + (+ for lagging power factor and for leading power factor).

2. Draw a line IaRa, parallel to Ia, then join pointO and the end pointof I aRa and itis knownasEt.

3. From OCC curve, find I f1 forthe corresponding value of E t and draw If1 normal to Et.4. From SC curve find I f2 forthe value of Ia and draw If2in phase opposition to I a.5. Add the currentvectors If1 and If2, getthe resultantfield currentvectors If.6. From OCC curve find Eg forthe value of Ifand drawEg normal to If.

(i) Lagging power factor

Ia

IaRa

Vt

Et

Eg

If2

If1

If

If1 Field current corresponding to Et

If2 Field current corresponding to Ia

If Resultant field current of If1 andIf2

Eg Generated voltage per phase corresponding to field

current If

O


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Vt

IaRa

Et

Eg

If1

If!

Ia

If

(ii) Leading power factor

Rated current = A Rated voltage er hase = V

S.No.PowerFactor

Induced voltageer hase

Eg volts

% Voltage Regulation

Lagging Leading Lagging Leading

REGULATION CHARACTERISTICS


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MODEL CALCULATIONS


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RESULT:


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EXP.NO. DATE:

REGULATION OF 3-PHASEALTERNATOR BY POTIER TRIANGULAR METHOD

AIM:To predetermine the regulation ofthree phase alternator by ZPF method and drawthe

vector diagrams.

APPARATURS REQUIRED:

S.NO Name of theApparatus Type Range Quantity

1 Ammeter MC 0 1/2 A 12 Ammeter MI 0 5/10 A 13 Voltmeter MC 0 10 V 14 Voltmeter MI 0 600 V 15 Rheostat Wire wound 250 , 1.5 A 16 Rheostat Wire wound 1200, 0.8 A 1

7 Tachometer Digital --- 18 TPST knife switch -- -- 1

FORMULAE USED:

PRECAUTIONS:(i) All the switchesshould be in open position while making the connection.(ii) Check the fuse and meters are in required specifications.(iii) Check all the load terminals are in offposition atthe time ofstarting.(iv) Keepthe prime-mover filed rheostatatminimum resistance position and alternator

field rheostatatmaximum resistance position atthe time ofstarting.

PROCEDURE TO DRAW THE POTIER TRIANGLE (ZPF METHOD):(All the quantities are in perphase value)

1. Drawthe Open CircuitCharacteristics (Generated Voltage perphase VS Field Current)2. Mark the pointA atX-axis, whichis obtained from shortcircuittestwith full load armature

current.3. From the ZPFtest, mark the pointB forthe field currentto the corresponding rated

armature currentand the rated voltage.4. Drawthe ZPF curve whichpassing throughthe pointA and B in s uch a way parallel to the

open circuitcharacteristics curve.5. Drawthe tangentforthe OCC curve from the origin (i.e.) air gap line.6. Drawthe line BC from B towards Y-axis, whichisparallel and equal to OA.7. Drawthe parallel line forthe tangentfrom C to the OCC curve.


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OPEN CIRCUIT TEST:

S.No.Field

Current(If)

in amps

Open circuitlineVoltage (vol)

in volts

Open circuitphase voltage

(voph)in volts


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8. Join the points B and D also drop the perpendicular line DE to BC, where the line DErepresents armature leakage reactance drop (IXL) BE represents armature reactionexcitation (Ifa).

PROCEDURE TO DRAW THE VECTOR DIAGRAM (ZPF METHOD)

1. Selectthe suitable voltage and currentscale.2. Forthe corresponding power angle ( Lag, Lead, Unity) drawthe voltage vector and current

vector OB.3. Drawthe vector AC withthe magnitude of IRa drop, whichshould be parallel to the vector

OB.4. Drawthe perpendicular CD to AC from the pointC withthe magnitude of IX L drop.5. Join the points O and D, whichwill be equal to the air gap voltage (Eair).6. Find outthe field current(Ifc) forthe corresponding air gap voltage (Eair) from the OCC

curve.7. Drawthe vector OFwiththe magnitude of Ifcwhichshould be perpendicularto the vector

OD.

8.

Drawthe vectorFG from Fwiththe magnitude Ifa in such a way itisparallel to the currentvector OB.9. Join the points O and G, whichwill be equal to the field excitation current(If).10.Drawthe perpendicular line to the vector OG from the pointO and extend CD in such a

mannerto intersectthe perpendicular line atthe pointH.11.Find outthe open circuitvoltage (Eo) forthe corresponding field excitation current(If)

from the OCC curve.12.Find outthe regulation from the suitable formula.


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SHORT CIRCUITANDZPF TEST:

S.No

ShortCircuit Test ZPF Test

Field

current(If)inAmps

RatedArmatureCurrent(Ia)

inAmps

Field

current(If)inAmps

RatedArmatureCurrent

(Ia)Amps

RatedArmature

Voltage (Va)in Volts

W"

in Watts W#

in W

Act. =(Obs. X MF)

Act.(Obs. X

MF


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VIVA QUESTIONS:

1. What is meant by ZPF Test?2. What is Poitier reactance? How is it determined by Poitier triangle?3. What is meant by armature reaction reactance?4. What is the significance of the ASA modification of MMF method?5. What is air gap line in Poitier method?

RESULT:


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Exp. No: Date:

LOAD TEST ON THREE-PHASEALTERNATORAIM:

To conduct a load test on three phase alternator and to draw the following

characteristicsa) voltage regulation curve b) output Vs efficiency curve

APPARATUS REQUIRED:

SerialNo.

Name of theapparatus

Range Type Quantity

1.

2.

3.

4.

5.

Voltmeter

Ammeter

Rheostat

Tachometer

Three phaseLoading Unit

(0-600V)

(0-250V)

(0-50A)

(0-2A)(0-10A)

220/1.2A

-

5KW

MI

MC

MC

MCMI

Variable

Digital

Resistive

1

1

1

11

3

1

1

PRECAUTIONS:

1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.4. Keepthe prime-mover filed rheostatatminimum resistance position and alternator field

rheostatatmaximum resistance position atthe time ofstarting.PROCEDURE:

1. The connections are made asperthe circuitdiagram and the DPST is closed.2. Startthe motorwiththe help ofthree pointstarter.3. By adjusting the field rheostatof motor, run the alternator atsynchronousspeed.4. The alternator field rheostatresistance is adjusted and setthe voltmeterreading to rated

voltage ofthe alternator.5. Atno load take the readings of voltmeter, ammeter.6. Now, close the TPST switch and apply the load. Look for any change in the speed and

voltage if so brings back to the previous values. Now take the corresponding reading ofammeter.

7. Now open TPST switch and note down the alternator side voltage reading as Eg andimmediately the TPST is closed.

8. Repeatthe above procedure until the machine is loaded upto 120% ofrated current.


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TABULATION:

S.No

MOTOR ALTERNATOR

Inputvoltage(Vm)inVolts

InputCurrent(Im)inAmps

Inputpower(Wmi)

inWatts

Outputpower(Wmo)

inWatts

Loadvoltage(VA)inVolts

LoadcurrentIAin

Amps

Output

power=3VLILCos in

watts

Fieldwindingvoltage(Vf)inVolts

Fieldwindingcurrent

(If)inAmps

Fieldwinding

input(VLIL)

In Watts

a


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FORMULA USED:

Motor InputPower = Vm Im

Motor OutputPower = mVmIm [Assume motor efficiency]

Inputto the Field Winding = V fIf

Alternator InputPower = Motor OutputPower + Inputto the Field WindingAlternator OutputPower = 3VLILCos [Where Cos = 1]

% of AlternatorEfficiency ( A) = (OutputPower/ InputPower)X100

% Voltage Regulation = [(Eg1-Vr) / Vr]X100 %

MODEL CALCULATION:


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Exp. No: Date:

REGULATION OF THREE-PHASE SALIENT POLEALTERNATOR BY SLIP TEST

AIM:To predetermine the voltage regulation ofthe given three-phase alternator by slip

test.

APPARATUS REQUIRED:

S.No.Apparatus

NameRange Type Quantity

1 Voltmeter

(0-600) V MI 1

(0-100) V MI 1

(0-30) V MC 1

2 Ammeter(0-10) A MC 1

(0-10) A MI 1

3 Rheostat 220 / 2.2 A Variable 1

PRECAUTIONS:1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time of starting.PROCEDURE:

1. Circuitconnections are given asperthe circuitdiagram.2. After closing the DPST switch, the motorisstarted by using three pointstarters.3. Nowthe alternator is made to run at a speed slightly lessthan synchronous speed using

field rheostatofthe motor.

4. By using the three phase auto transformer, a low voltage is applied acrossthe stator ofthealternator. Suppose, if the voltmeter across the field winding, reads some value, thenchange the direction ofrotation ofthe alternator orifthe same voltmeterreads zero, thenthe speed ofthe alternator and voltage applied are slightly adjusted in such a mannerthatthe pointer in the voltmeter and ammeter ofthe alternator oscillateswith maximum andminimum amplitude.

5. The maximum and minimum values ofthe readings of boththe meters are noted.


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TABULATION

MinimumVoltage in

Volts

Maximumvoltage in

Volts

Minimumcurrentin

Amps

Maximumcurrentin

Amps

Xsdin;

Xsqin ;

Xsd/Xsq

Ia = Amps

Sl.No. Power factorEo in Volts % Regulation


Ia = Amps

Sl.No. Power factorEo in Volts % Regulation



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MODEL CALCULATION

Maximum voltage/ph. = Vmax/ 3

Minimum voltage/ph. = Vmin / 3

Synchronousreactance of directaxis Xsd = (Max. voltage/Ph.) / (Min.current/ph.)

Synchronousreactance of quatrature axis Xsq = (min. voltage/ph) / (max.current/ph.)

% Regulation = (E0 Vph.) / Vph. X 100


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COMPUTATION OF ARMATURE RESISTANCE (RA):

TABULATION TO FIND Ra:

S.No.

Voltage drop across

the Armature

(Va) in Volts

Armature

Current

(Ia) inAmps

Armature

Resistance

(Ra = Va/ Ia) inohm

Mean Ra

Average value ofRa = --------- ;

Ra.c = Rd.c * 1.1 = ------- ;

REGULATION CHARACTERISTICS:


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PROCEDURE TO DRAW THE VECTOR DIAGRAM

Assume rated voltage V perphase asthe reference vector and mark the endpointas a. Draw a line la lagsthe voltage V by an angle *. From pointa draw a drop l aRa in parallel with la and mark itaspointb. From pointb draw a drop l aXq in quadrature with la and mark itaspointc Join the points o & c. The angle between oc & V is H and the angle between oc & la isU. Drawthe currents Iq & Id where Iq & Id are quadrature & directcomponents of Ia

where Iq =la cosU, Id = lasinU

From pointb draw a line I dXdin quadrature with Id and mark itaspointd. From pointddraw a line IqXqin quadrature with Iq and mark itaspointe.

Join the points o and e itwill give the value ofthe generated voltage E o perphase


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VECTOR DIAGRAM FOR 0.8PF LAGGING

Ia Xq

IdX

e

d

c

Eo

bIaRa

aVP

Iq

IaId

o


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VIVA QUESTIONS:

1. What is the purpose of slip test on 3 phase alternator?2. Define Slip3. How is the regulation of alternator predetermined by slip test?4. What is the purpose of damper winding?

RESULT


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Exp. No: Date:

VAND INVERTED V CURVES OF THREE PHASE SYNCHRONOUS MOTOR

AIM:

To draw V and inverted V curves of a given three phase synchronous machine.

APPARATUS REQUIRED:


1. Voltmeter(0 300 V) MC 1

(0 600 V) MI 1

2. Ammeter

(0 2A) MC 1

(0 20A) MC 1

(0 10A) MI 1

3.Rheostat 50;/4.9A Variable 1

360 ;/ 1.1A Variable 3

4. Wattmeter 300V/10A UPF 1

5. PowerFactor meter 600V/10A Analog 1

6. Synchronizing switch - Manual 1

PRECAUTIONS:1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.PROCEDURE

1. Connections are made asperthe circuitdiagram.2. DPST switchis closed and DPDT switchisthrown to position 1.3. Nowthe armature rheostatofthe motoris broughtto its minimum resistance position. At

thisinstantthe SPST switchis closed.


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TABULATION

1. at no loadcondition

S.No. VdcinVolts

Field

current(If)in

Amps

VacinVolts

IacinAmps

Wattmeterreading W1in Watts

PowerW1 x MF

inWatts

PowerFactor

* MFisthe wattmeter multiplication factor

2. at any loadcondition

S.No.VdcinVolts

ILinAmps

Fieldcurrent

IfinAmps

VacinVolts

IacinAmps

Wattmeterreading W2

in Watts

PowerW2 x MF

in Watts

PowerFactor

* Where MFisthe wattmeter constant


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4. The field rheostatresistance ofthe motoris adjusted so thatthe motorruns atnearly to itssynchronousspeed.

5. The supply voltage on the alternatorside is measured.6. By varying the filed rheostat resistance of the alternator the generated voltage is made

equal to the supply voltage ofthe three phase side.

7. Nowthe TPST switchis closed and the lamp flickers. By adjusting the filed rheostatofthemotor, bring the frequency ofthe flickering to very minimum. During the dark period, thesynchronous switch is closed. Now the synchronous machine is synchronized with themain supply.

8. Nowthe DPDT switchis opened.9. By varying the field rheostat resistance of the alternator, find the point where the field

currentis low and armature currentin approximately 110% ofthe full load current. Notedown all the meterreadings.

10.Gradually move the rheostatresistance position suchthat, the field currentincreases andthe alternator armature currentdecreases. Note down the readings for various armaturecurrents. At one stage, the field current will still increase and the armature current willalso increase. Take the readingsupto the 110% ofrated currentofthe armature.

11.Now DPDT switchisthrown to position 2. Apply some load on the DC generator.12.Repeatthe previousprocedure.13.Draw the curves between field current Vs power factor and field current Vs armature

current.


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MODEL GRAPH:


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VIVA QUESTIONS:

1. Why Synchronous motor is not self starting?2. What are the starting methods used for synchronous motor?3. List the application of Synchronous motor?4. What are the readings considered for inverted V curve?5. What is synchronous condenser?

RESULT:


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Exp. No: Date:

LOAD TEST ON THREE-PHASE SQUIRREL CAGE INDUCTION MOTOR

AIM:

To conductthe load teston the given three phase squirrel cage induction motor and

to drawitsperformance characteristics.

APPARATUS REQUIRED:

S.No. Apparatus Range Type Quantity

1. Voltmeter (0-600)V Ml 1

2. Ammeter (0-10) A Ml 1

3. Wattmeter 600 V, 10A UPF 2

4. Tachometer -- Digital 1

PRECAUTIONS:1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.PROCEDURE

1. Circuitconnections are given asperthe circuitdiagram.2. After closing the TPST switch, motorisstarted by using star-delta starter.3. Note down the no load readings of V 1, I1, W1, W2, S1, S2 and N.4. By applying the load, take differentreadings till the currentreaches 120% ofthe rated

current.

5. Using the formula, efficiency, torque, power factor and slip are calculated and the curvesare plotted.


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TABULATION

S.No.

Line

Voltage(VL)inVolts

Load

current(IL)inAmps

Spring balanceReadings (Kg)

Speed

(N)inRPM

Wattmeterreadings

Inputpower(Pt)in

Watts

Torque

(T)inN-m

Outppow(Po)

WatS1 S2 S1~ S2 W1xMF W2xMF


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FORMULAE USED

1. InputPower (Pi) = (MF x W1 + MF x W2) watts2. Torque (T) = 9.81 * (S1 ~ S2) * Reff N-m3. OutputPower (Po) = 2 N T / 60 watts 4. Efficiency (L) = (OutputPower/ InputPower)* 1005. % of Slip (S) = (Ns N / Ns) X 1006. PowerFactor = InputPower/ ( 3 * VL *IL)

Where,

S1, S2 p Spring balance readingsin Kg.

Reff p Effective radius ofthe brake drum in meters.

Reff = (Brake drum radiusin cm + ofthickness of beltin cm)

T p Torque in N-m

N p Speed in RPM

Ns p Synchronousspeed in RPM

MF p Multiplication factors ofwattmeter


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MODEL GRAPH


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MODEL CALCULATION


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VIVA QUESTIONS:

1.What is meant by RMF?2. Why an induction motor is called rotating transformer?

3.Why an induction motor will never run at its synchronous speed?4.What are slip rings?

5.What are the advantages of cage motor?6.What is meant by magnetic logging?

RESULT


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Exp. No: Date:

LOAD TEST ON THREE-PHASE SLIP RING INDUCTION MOTOR

AIM

To conduct a load test on slip ring induction motor and draw its performancecharacteristics.

APPARATUS REQUIRED

S.No.Name of theapparatus

Range Type Quantity

1. Voltmeter (0 -600)V MI 1

2. Ammeter (0-10A) MI 1

3. Wattmeter 600V/10A UPF 24. Tachometer ---- Digital 1

PROCEDURE

The connections are made asperthe circuitdiagram. The rotorresistance startershould be atthe maximum resistance position. The TPST switchis closed. The rotorresistance starteris adjusted by means ofstep by step and bring itin to

minimum resistance position.

Atno load take the readings of voltmeter, ammeter and wattmeter and also the speed inRPM

Load the machine upto 120% of full load and note down all th e meterreadings.


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TABULATION:

S.No

Linevoltage(VL) inVolts

Linecurrent(IL) inAmps

Speed(N) inrpm

Wattmeterreadings

in Watts

Spring balancereadingin kgs. Torque

(T) inN-m

%slip(S)W1 x

MFW2 xMF

W1+W2S1 S2 S1~S2

WithoutExternal

Resistance

WithExternal

Resistance


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Release the load fully and bring the machine to offposition. Repeatthe above procedure when external resistance isincluded in the rotor circuit.

FORMULA:

i). Inputpower P in = W1 + W2 in watts

Where,

W1, W2 - wattmeterreadingsin watts

ii). Torque T = 9.81x (S 1~S2) x Reff. N-m

Where,

S1, S2 - Spring balance readingsin KgsReff - Effective radius of brake drum in m

iii). Outputpower Po= (2NT) / 60 in watts

Where,N - Speed ofrotorin rpmT - Torque in N-m

iv). % Slip = ((NS-N) / NS) x100

Where,Ns- Synchronousspeed in rpm

v). % efficiency () = (Outputpower/ Inputpower) x 100

vi). Power factor (cos) = Inputpower/ (3VL IL)

Where,

VL- Supply voltage in volts IL- Line currentin amps


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VIVA QUESTIONS:

1. Mention different types of speed control of slip ring induction motor?2. What is meant by crawling of induction motor?3. What are the advantages of 3-phase induction motor?4. What is the difference between slip ring and split ring?5. What is reason for inserting additional resistance in rotor circuit of a slip ring induction

Motor?

RESULT:


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69/109

Exp. No: Date:

NO LOADANDBLOCKED ROTOR TEST ON THREE-PHASE INDUCTION MOTOR

AIM

To predetermine the performance characteristics of a three phase squirrel cageinduction motor from equivalentcircuitand circle diagram approach.

APPARATUS REQUIRED


1. Ammeter

0-5A MI 1

0-15A MI 1

0-15A MC 1

2. Voltmeter

0-600V MI 1

0-150V MI 1

0-30V MC 1

3. Wattmeter600V/5A LPF 2

150V/20A UPF 2

PRECAUTIONS

TPST should be opened before verifying the circuitconnections Autotransformershould be in the minimum voltage position


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TABULATIONS

NO LOAD TEST

Line

Voltage(VL)

in Volts

LineCurrent

(Ia)inAmps

Wattmeterreading

in Watts No loadinputPowerin Watts= W1 +W2

Speed(N)in rpm

W1 x MF W2x MF

BLOCKED ROTOR TEST

LineVoltage(VL)inVolts

LineCurrent

(Ia)inAmps

Wattmeterreading

in Watts Copperloss inWatts= (W1 +W2)W1 X M.F W2 X M.F

TO FINDSTATOR RESISTANCE

S.No.

Voltage dropin the stator

(V)in Volts

Statorcurrent(Is)inAmps

Statorresistance(Rs = V / Is)in

Mean (Rac)

StatorresistanceR1 = Rac x 1.6 in


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PROCEDURE

NO LOAD TEST

The connection are made asshown in the circuitdiagram After observing all precautionsthe TPST switchis closed By adjusting autotransformer bring the voltmeterreading to rated voltage ofthe motor

then note down voltmeter, the ammeter and the wattmeterreadings.

BLOCKED ROTOR TEST

Block the rotor by applying a load After observing all the precautionsthe TPST switchis closed By gradually adjusting the auto transformer bring the ammeterreading to the rated

currentofthe motorthen note down ammeter, voltmeter and wattmeterreadings

TO FIND THE STATOR RSISTANCE

The connection are made asshown in the circuitdiagram Apply different voltage to stator winding up to the full load current note down the

ammeter and the voltmeterreadings

FORMULAE

NO LOAD TEST

No load line voltage = V0 inVolts

No load line current = I0 in Amps

No load power = W0in Watts

BLOCKED ROTOR TEST

Blocked rotorline voltage = VscinVolts

Blocked rotorline current = Iscin Amps

Blocked rotorpower = Wscin Watts


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No load voltage perphase V0 = VL0 in V

No load currentperphase I0 = IL0 / 3 in A

No load powerperphase W0 = WL0 / 3 in W

Blocked rotorvoltage perphase Vsc = VLsc in V

Blocked rotorcurrentperphase Isc = ILsc / 3 in ABlocked rotorpower perphase Wsc = WLsc/ 3 in W

Cos 0 = Wo/ V0 I0

0 = Cos-1(Wo/ V0 I0)

Find Sin 0

Magnetizing branchresistance R0 = V0/ (I0 Cos 0) in

Magnetizing branchreactance X0 = V0/ (I0 Sin 0) in

Total resistance Rsc = Wsc / Isc2in

Total impedance Zsc = Vsc/ Isc in

Total reactance Xsc = Zsc2- Rsc2in

X1 = X21 = Xsc/ 2 in

R21 = Rsc R1 in

Where

X1 - Statorreactance in X21 - Rotorreactance referred to statorin

R1 - Statorresistance in

R21 - Rotorresistance referred to statorin

For any slip S, R L = R21 (1 - s) /sin

Z = (R1+ R21 /s) + j(X1 + X21 /s) in

I111 = (V r0 / Z) in A

No load currentperphase = I0in A


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TABULATION FOR EQUIVALENT CIRCUIT METHOD

MODEL GRAPH (EQUIVALENT CIRCUIT)

S.No.

LineVoltage(VL)inVolts

% Slip(assume)

Speed(N)in

RPM

Phasecurrent(IPh)inAmps

Linecurrent(IL)inAmps

Inputpower(Pt)inWatts

Outputpower(Po)inWatts

Torque(T)in

N-m


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I1 = I0+ I111

= I in A

Line current IL = 3 I in A

Power factor = Cos

Speed = NS (1 - s) in rpmInputpower = 3 x V phx Iph x Cos in W

Outputpower = 3 x (I1)2 x RLin W

Where ns synchronousspeed in rps

Repeatthe above calculation for variousslips.


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MODEL GRAPH (CIRCLE DIAGRAM)


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VIVA QUESTIONS:

1. What is purpose of Equivalent circuit?2. What is meant by crawling of induction motor?3. How will you calculate Cu loss of 3-phase induction motor?4. How will you calculate core loss of 3-phase induction motor?5. List out the starting methods for 3 phase induction motor.

RESULT:


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79/109

Exp. No: Date:

SEPARATION OF NO-LOAD LOSSES OF THREE-PHASE INDUCTION MOTOR

AIM

To separate the no load losses of a three-phase induction motorto its components

a) Iron lossb) Mechanical loss

APPARATUS REQUIRED

S.No Apparatus Range Type Quantity

1. Voltmeter0-600 V MI 1

0-30 V MC 1

2. Ammeter0-5 A MI 1

0-10 A MC 1

3. Wattmeter 600 V/5 A LPF 2

PRECAUTIONS:

1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.

PROCEDURE

The connections are made asperthe circuitdiagram. By adjusting the autotransformer, the rated voltage is applied. The readings of Voltmeter, Ammeter and Wattmeters (W1W2) are noted. By adjusting the autotransformer, apply slightly lessthan the previous voltage and

the meterreadings are noted.

Repeatthe above procedure until the voltmeterreadsthe minimum voltage. A graph connecting Vph2 Vs No Load Loss is drawn. From the curve mechanical

loss and iron loss atrated voltage are calculated.


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TABULATION SEPARATION OF NO LOAD LOSSES

S.No

Linevoltage(VL)inVolts

Linecurrent(IL)inAmps

Phasecurrent(Iph)inAmps

Vph2

Watt meterreading in

Watts No loadinputPowerin Watts

(W1+W2)

Copperloss inWatts

No loaloss inWatts

W1xMF

W2xMF


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FORMULA

No load losses = No load in ut No load Cu loss


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VIVA QUESTIONS:

1. What are losses in 3-Phase induction motor?2. How will you separate losses of induction motor?3. What is meant by Hysteresis loss?4. What is meant by Eddy Current loss?5. How to minimize the eddy current and hysteresis losses?

RESULT:


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85/109

Exp. No: Date:

LOSSSUMMATION METHOD ON THREE-PHASE INDUCTION MOTOR

AIM

To predetermine the performance characteristics of a given 3 phase induction

motor by losssummation method.

APPRATUS REQUIRED


1. Voltmeter

0 600 V MI 1

0 150 V MI 1

0 30 V MC 1

2. Ammeter0 10 A MI 1

0 10 A MC 1

3.Wattmeter 600 V / 10 A UPF 2

150 V / 10 A UPF 2

PRECAUTIONS:1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.

PROCEDURE

NO LOAD & LOAD TEST

Connections are made asperthe circuitdiagram. By adjusting the autotransformerthe rated voltage is applied. The NO LOAD readings of Voltmeter, Ammeter and Wattmeters (W1, W2) are noted. Nowthe motoris gradually loaded and the corresponding readings are noted. Thisprocedure isrepeated till 125% ofrated currentis obtained.

Note: The brake drum spring balance readings are ignored.


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BLOCKED ROTOR TEST

Connections are made asperthe circuitdiagram. The rotoris blocked. The autotransformer is adjusted such that the ammeter reads the same value of

current as in the load test (i.e. rated current) and the corresponding readings ofVoltmeter and Wattmeters (W3, W4) are noted.


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TABULATION LOSSSUMMATION METHOD

S.No

Line

voltage(VL)inVolts

Line

Current(IL)inAmps

Speed(N)inrpm

Wattmeterreadingsinwatts Input

power(W)(W1+W2)in

Watts

Culoss

(W)(W3+W4)in

Watts

Outputpowerin

WattsTor(T)in

MF xW1

MF xW2

MF xW3

MF xW4


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FORMULAE

Constantlosses (Wo) = No load input No load Cu loss

No load input 3 I02 * Ra

Inputpower = W1 + W2

Cu loss = W3 + W4

Outputpower = Inputpower Cu loss Constantloss

= (W1 + W2) (W3 + W4) W0

Torque (T) = (Output/ 2TN) * 60 N m

Slip (%) = (Ns N) / Ns * 100

PowerFactor = Input/ (3 VL *IL)

Efficiency (%) = (Output/ Input) * 100


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VIVA QUESTIONS:

1. Why the three phase induction motor is called as rotating transformer?2. How will you separate losses of induction motor?3. What is the relationship between load current and loss?4. Why the induction motors are generally called as asynchronous motor?5. Name the applications of 3 phase squ. Cage induction motor?

RESULT


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93/109

Exp. No: Date:

LOAD TEST ON SINGLE-PHASE INDUCTION MOTOR

AIM

To conduct the load test on single phase capacitor start induction motor and to

drawthe performance characteristics curve.

APPARATUS REQUIRED


1. Voltmeter 0-300V MI 1

2. Ammeter 0-20A MI 1

3. Wattmeter 300V/20A UPF 1

4. Single Phase Auto Transformer230V/(0-270)V,

20AVariable 1

5. Tachometer - Digital 1

PRECAUTIONS:

1. All the switchesshould be in open position while making the connection.2. Check the fuse and meters are in required specifications.3. Check all the load terminals are in offposition atthe time ofstarting.PROCEDURE

The connections are made asshown in the circuitdiagram. The supply is given and the DPST switchis closed. By adjusting autotransformer, bring the voltmeter reading to rated voltage of the

motor.

Under no load condition note down all the metersreading. Now apply the load in step by stepupto the 125% ofrated current, note down all

the readings ofthe meters.


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TABULATION

S.No.

Supplyvoltage(Vs)in

Volts

Linecurrent(IL)in

Amps

Inputpower

(W1xMF)

(Watts)

Speed

(N)in

rpm

Spring balancereading in kg

Torque

(T)in

N-m

Outputpower

(Po)inWatts

%Sli

S1 S2 S1~ S2


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FORMULAE

1. Torque = 9.81 (S1 ~ S2) * Reff in N-m

Where S1, S2 - Spring balance reading in Kg

Reff- Effective radius ofthe brake drum in metre.

2. Outputpower = 2NT / 60 in watts

3. % Slip = (N s N) / Ns* 100

Where Ns - Synchronousspeed ofthe machine.

N - Rotorsped ofthe machine.

4. PowerFactor = Inputpower/ VLIL

5. % Efficiency = (Outputpower/ Inputpower) * 100


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VIVA QUESTIONS:

1. What are the various methods available for making a single-phase motor self-starting?2. What is the function of capacitor in a single-phase induction motor?3. State any four use of single-phase induction motor.4. State the advantages of capacitorstart- run motor over capacitorstartmotor.

RESULT


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99/109

Exp. No: Date:

DETERMINATION OF EQUIVALENT CIRCUIT OFSINGLE-PHASE INDUCTION MOTOR

AIM:To drawthe performance characteristics of a single phase induction motor by

conducting the no-load and blocked rotortest.

APPARATUS REQUIRED:

S.NoName of

ApparatusRange Type Quantity

1 Voltmeter(0-300)V

MI1

(0-150)V 1

2 Ammeter(0-10)A 1(0-2)A 1

3 Wattmeter(330V,10A) UPF 1(300V,5A) LPF 1

THEORY:

A 1- induction motor consists of stator, rotor and other associated parts. In the

rotor of a single phase winding isprovided. The windings of a 1- winding(provided) are

displaced in space by 120.A single phase currentis fed to the windingsso thata resultant

rotating magnetic flux is generated. The rotor starts rotating due to the induction effect

produced due to the relative velocity between the rotorwinding and the rotating flux.

PRECAUTIONS:NO LOAD TEST:

y Initially DPST Switchis keptopen.y Autotransformeris keptatminimum potential position.y The machines mustbe started on no load.BLOCKED ROTOR TEST:

y Initially the DPST Switchis keptopen.y Autotransformeris keptatminimum potential position.y The machine mustbe started atfull load(blocked rotor).


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PROCEDURE:NO LOAD TEST:

1. Connections are given asperthe circuitdiagram.2. Precautions are observed and the motorisstarted atno load.3. Autotransformeris varied to have a rated voltage applied.BLOCKED ROTOR TEST:

1. Connections are given asperthe circuitdiagram.2. Precautions are observed and motorisstarted on full load or blocked rotor

position.3. Autotransformeris varied to have rated currentflowing in motor.4. Meterreadings are the noted.

Reff= 1.5*Rdc

FORMULAE-

NO LOAD TEST-y cos = Wo/VoIoy Iw = Io cosy Im = Io sin y Ro = Vo/Iw y Xo = Vo/ImBLOCKED ROTOR TEST-

Zsc = Vsc/Isc

Rsc = Wsc/Isc2 Xsc = (Zsc2 Rsc2)


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TABULATION

NO LOAD TEST

S.No.

No Load

Voltage (Vo)involts

No LoadCurrent

(Io)inamps

No LoadPower(Wo)in watts

Actual = Observed x MF

BLOCKED ROTOR TEST

S.No. ShortCircuitVoltage (Vsc)involts

Short

CircuitCurrent(Isc)inamps

ShortCircuitPower(Wsc)in watts

Actual = Observed x MF


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VIVA QUESTIONS:

1. What are losses in Single Phase induction motor?

2. Name the types of single phase induction motor?

3.What is the purpose of centrifugal switch?

4. State any four use of single-phase induction motor.

RESULT-


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105/109

Exp. No: Date:

SPEEDCONTROL OF THREE PHASE INDUCTION MOTOR BY V/F METHOD

AIM

To control the speed of a given Three-Phase Induction motor by V/f method and to

drawthe characteristics curves.

APPARATUS REQUIRED

S. NO Name of theApparatus Type Range Quantity

1 Voltmeter MI 0-600V 1

2 Three-Phase Autotransformer Variable 415V / (0-600)V 1

3 Tachometer Digital - 1

PROCEDURE

VOLTAGE CONTROL METHOD

1. Connections are given asperthe circuitdiagram.2. Using the three-phase autotransformer motorisstarted to run.3. The three-phase autotransformer is varied gradually and the corresponding voltage

and speed are noted upto 120% ofthe rated speed.

4. The motor is switched off using the TPST switch after bringing autotransformer istheirinitial position.


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TABULATION FOR VOLTAGE CONTROL METHOD

S.NOAPPLIED VOLTAGE

in VoltsSPEED IN RPM

(N)

MODEL GRAPH:

Vinin voltsSpeed(N)inr.p.m


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VOLTAGE CONTROL METHOD:

1. Circuitconnections are given asperthe circuitdiagram.2. Field rheostatof motoris keptatits minimum position atthe time ofstarting.3. DPST Switchis closed. The motorisstarted by means ofstarter.4. The motorissetto run atrated speed ofthe alternator by varying the field rheostatof

the motor.

5. Field rheostatofthe alternatoris gradually varied and setthe rated voltage.6. Then the field rheostat position of the motor is varied. i.e., the frequency of the

induced emf also changed.

7. Thisinduced voltage given to the induction motor.

8.

For differentfrequency speed ofthe induction motorreading is noted.


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TABULATION FOR VOLTAGE CONTROL METHOD

S.NOFrequency in Hz

f=PN/120SPEED IN RPM

(N)

MODEL GRAPH:

Frequency in HzSpeed(

N)inr.p.m


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Viva Questions:

1.Whatare the speed control methods ofinduction motor? 2.Write the speed equation forinduction motor? 3.Whatare the speed control methods for Slip-ring Induction motor.

4.Define Synchronousspeed.

RESULT:

57980852 Em II Manual Final

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