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PENGANTAR Motor Induksi
OlehGigih Prabowo
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Mesin Listrik
Transformator
Mesin Arus Bolak-balik
Mesin Arus Searah
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Mesin Arus Bolak-balik
Mesin SinkronMotor SinkronGenerator Sinkron
Mesin AsinkronMotor AsinkronGenerator Asinkron
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Jumlah fasaMesin tiga fasa
Motor InduksiMotor kondensor sinkronGenerator Sinkron
Mesin satu fasa
Motor Split-phaseMotor CapasitorMotor Shaded-poleMotor UniversalMotor reluctanceMotor Hysterisis
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Mesin Listrik yang lainMesin DC
Motor DCPenguat terpisahPenguat sendiri
• Serie• Shunt• Compound (long, short, differentiative,
commulative)Generator DC
Spesial MotorStepper motorLinier stepper motorServo Motor AC dan DC
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Jenis Konstruksi Rotor danKutub
Jenis Rotor Sangkar (squerell-cage rotor)
Jenis Rotor Lilit ( wound rotor)
Jenis kutub rata (salient pole)
Jenis kutub menonjol ( non salient pole)
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Keuntungan Motor AC
Konstruksi kuatEffisiensi tinggiBiaya pemeliharaan murahStarting mudahEffisiensi tinggi padakondisi normal
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Kerugian Motor AC
Kontrol Putaran SusahTorsi start kecilPutaran akan turun bilabeban bertambah
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Konstruksi Mesin ACBagian Stator : Inti dan Lilitan stator
Bagian Rotor : Inti dan Lilitan rotorRotor sangkar (sqeurell-cage rotor)Rotor Lilit (wound rotor)
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Konstruksi MI
Some motor frames are sized so that just the surface area is suitable to dissipate motor heat w/o the need
of a fan or blower
Some motor frames are sized so Some motor frames are sized so that just the surface area is suitable that just the surface area is suitable to dissipate motor heat w/o the need to dissipate motor heat w/o the need
of a fan or blowerof a fan or blower
Blowers may be added to motors to allow operation at low speed including “0” RPM with 100% Torque continuous
Blowers may be added to Blowers may be added to motors to allow operation at motors to allow operation at low speed including low speed including ““00”” RPM RPM with 100% Torque continuouswith 100% Torque continuous
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Types of AC Motors
Definite purpose “laminated frame”designs provide higher power densities & improved torque to inertia performance.
Definite purpose Definite purpose ““laminated framelaminated frame””designs provide higher power designs provide higher power densities & improved torque to densities & improved torque to inertia performance.inertia performance.
T-Frame Construction Motors allow commonality in footprint & shaft height.
TT--Frame Construction Motors allow Frame Construction Motors allow commonality in footprint & shaft commonality in footprint & shaft height.height.
Match Motor type to meet your needs!
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Bagian motor InduksiMotor Frame Motor Frame
AssemblyAssembly
Rotor & ShaftRotor & ShaftAssemblyAssembly
Stator Winding Stator Winding AssemblyAssembly
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Penggunaan
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Persamaan yang digunakanHukum Ampere
Hukum Farady
Hukum Kirchoff
∫ ∑= NIH.dl
dtNd φe =
∑ = 0I ∑ =VIZ
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Medan PutarMedan putar terjadi pada sumber tiga fasa yang diberikanpada lilitan stator tiga fasa
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Belitan Stator
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Prinsip Kerja motor induksi3fasa
Kumparan stator diberi tegangan 3 fasa akantimbul medan putar dengan kecepatan :
Ns = 120f / p
Medan putar akan memotong konduktor padarotor, sehingga akan menimbulkan teganganinduksi pada lilitan rotor sebesar
• E2s = 4,44 f2 n2 Φ
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Karena lilitan rotor merupakan lilitan yang tertutup, maka akanada arus yang mengalir pada rotorAdanya arus dalam medan magnet, akan timbul gaya F padarotorGaya dikalikan dengan jari-jari koduktor rotor akanmenghasilkan kopel (torsi)Jika torsi yang dihasilkan lebih besar dibandingkan dengan torsi beban, maka rotor akan berputar sesuai dengan arahmedan putarAgar tagangan E2s tetap ada, maka diperlukan perbedaanrelatif antara putaran medan (ns) dengan putaran rotor (nr)
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Perbedaan antara ns dengan nr dinyatakan dengan persamaanslip (s)
• S = {(ns – nr)/ns} 100%
Kemungkinans = 0 Kondisi motor diams = 1 kondisi motor start
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( ) ( ) ( ) ( )222
2
22
22
2
22
SXR
SE
XR
EIs
s
+=
+=
( ) ( )222
2
22
/ XSR
EI+
=Atau
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⎟⎠⎞
⎜⎝⎛ −
+=SSRRSR 1/ 222
Karena
Maka
⎟⎠⎞
⎜⎝⎛ −SSR 1
2
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E
sI0I
1I
1R 1X
mRmX
G BV
⇒ E
sI
mI
1R
mX
sI
1X
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V1
R’2 X’2
⎟⎠⎞
⎜⎝⎛ −SSR 1
2'
R1 X1
mJX
sI RImI
>>
v
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22
222
21
2)()/(
'XaSRa
EI+
=
22
222
2
22
)()/(/cos
XaSRaSRa
impedansitahanan
+==ϕ
ϕωω cos3 2'
1 IEPT ==
( ) ( ) ( )2222222
22
21
3XaSRa
RSaVT+
= ω
2
2X
RS ±=2
2
21
2)(3 Xa
VTmaks ω±=
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Diagram daya
Daya input
Daya output stator (daya input rotor)
Daya output rotor (daya mekanis)
Daya output (daya yang digunakan)
φCosVIPin 3=
sRIP ''3 2
22 =
⎟⎠⎞
⎜⎝⎛ −
=ssRIPm
1''3 22
mNdalamPout −
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Diagram alir Daya
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Input powerPsup
Stator Copper loss3 Ista
2 Rsta
Rotor Copper loss3 Irot
2 RrotStator Iron loss
3 Vsta2 / Rc
Ventilation andfriction losses
Output powerPout
Air gappower Pag
Developed powerPdv = 3 Irot
2 Rrot (1-s)/s
Air gap
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Karakteristik Torsi-Slip
Gambar 4
22
222
22
'''3XsR
sRVT+
=ω
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Starting Torque Pull-up TorqueBreak down TorqueNormal Operation
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Pengaruh Tahanan Rotor
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Pengaturan Putaran Motor Induksi
Tegangan InputFrekuensi inputTahanan RotorJumlah kutubArus medan motor
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METODA STARTINGPada rotor belit :
digunakan tahanan mula yang besarnya dipilihsedemikian sehingga torsi start = torsimax. Setelah motor berputar, dalam keadaannominal rotor dihubung singkat.
Pada rotor sangkar : a. Untuk daya kecil dapat distart langsungb. Start dengan auto trafoc. Start dengan saklar Y – Δ
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Machine designSpeed sensorlessMachine Theory
Non-linear controlReal-time controlDSP applicationPFCSpeed sensorlessPower electronic converters
Utility interfaceRenewable energy
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Tahanan rotor
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VVVF control
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Klasifikasi Motor Induksiberdasar temperatur
Motor Induksi Klas A ()Motor Induksi Klas B (80oC)Motor Induksi Klas C ()Motor Induksi Klas D ()Motor Induksi Klas E (40oC)Motor Induksi Klas F (75o C)
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Berdasar operasiDrip-proof motorSplash-proof motorTotally enclose. Non-ventilated Totally enclose, fan-cooled motorExplosion-proof motor
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Klasifikasi NEMA
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Name plate motorJenis Motor dan jumlah fasaTegangan nominalArus nominalFrekuensi kerjaPower factorJenis isolasiTemperatur operasi
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Pengaman Motor InduksiThermal OverloadOver current/ over loadUnder/over voltageUnder frequencyPole slipOut of excitationOver fluxNegative sequenceDe-rating FactorEarth Foult
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Pemilihan dan PenggunaanMotor Induksi
Standar dan klasifikasi motorKlasifikasi pendinginan
Drip-proof, splash-proof, totally enclose, totally enclose fan-cooled, Explosion-proof,
Klasifikasi sesuai dengan sifat listrik dan mekanis ;Standart, Torsi start tinggi, slip tinggi.
Ukuran motor dalam HPPemilihan putaran, pengereman,Beban Motor
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INTRODUCTION TO ELECTRIC DRIVES - MODULE 1
Torque and speed profile
10 25 45 60 t (ms)
speed (rad/s)100
The system is described by: Te – Tload = J(dω/dt) + Bω
J = 0.01 kg-m2, B = 0.01 Nm/rads-1 and Tload = 5 Nm.
What is the torque profile (torque needed to be produced) ?
Speed profile
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INTRODUCTION TO ELECTRIC DRIVES - MODULE 1
Torque and speed profile
10 25 45 60 t (ms)
speed (rad/s)100
0 < t <10 ms Te = 0.01(0) + 0.01(0) + 5 Nm = 5 Nm
10ms < t <25 ms Te = 0.01(100/0.015) +0.01(-66.67 + 6666.67t) + 5= (71 + 66.67t) Nm
25ms < t< 45ms Te = 0.01(0) + 0.01(100) + 5 = 6 Nm
45ms < t < 60ms Te = 0.01(-100/0.015) + 0.01(400 -6666.67t) + 5= -57.67 – 66.67t
le TBdtdJT +ω+ω
=
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INTRODUCTION TO ELECTRIC DRIVES - MODULE 1
Torque and speed profile
10 25 45 60
speed (rad/s)100
10 25 45 60
Torque (Nm)
72.6771.67
-60.67
-61.67
56
t (ms)
t (ms)
Speed profile
torque profile
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INTRODUCTION TO ELECTRIC DRIVES - MODULE 1
Torque and speed profile
10 25 45 60
Torque (Nm)
70
-65
6
t (ms)
For the same system and with the motor torque profile given above, what would be the speed profile?
J = 0.001 kg-m2, B = 0.1 Nm/rads-1 and Tload = 5 Nm.
Electric Drives 55
Example 1.3. gear - box drive torque / time curveLet us consider an electric drive for an elevator with the data shown in
figure 1.11.
Figure 1.11. Elevator electric drive with multiple mechanical transmissions and counterweight
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