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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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