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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
S.No.Fieldcurrent(If)inAmps
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:
S.No.Fieldcurrent(If)inAmps
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
Lagging Leading Lagging Leading
Ia = Amps
Sl.No. Power factorEo in Volts % Regulation
Lagging Leading Lagging Leading
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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:
S.No. Apparatus Name Range Type Quantity
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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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
S.No. Apparatus Name Range Type Quantity
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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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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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
S.No. Apparatus Name Range Type Quantity
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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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
S.No. Apparatus Name Range Type Quantity
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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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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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: