01 Synchronous Generator

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Heri Suryoatmojo, PhDHeri Suryoatmojo, PhD

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Review :Review :DC MachinesDC Machines

• Generators convert mechanical energy to electric energy.

• Motors convert electric energy to mechanical energy.

• Faraday’s Law -> Dynamically & statically induced.

• The construction of motors and generators are similar.

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DC generatorDC generator

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carbon brushes

DC Motor DC Motor PartsParts

Field magnet

stator

rotor

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AC Generators / AlternatorsAC Generators / Alternators• Same principles as DC generators ->

armature winding & magnetic field.• Armature winding -> stator

field winding -> rotor

MESIN SINKRON

• Stator

• Rotor kutub silindris (kec. Tinggi)

kutub salient / menojol (kec.Rendah)• Ada Kutub Luar dan Kutub Dalam Kebanyakan kutub dalam

Kutub Luar dan Kutub Dalam

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Why stationary armature?Why stationary armature?

• Without brush contact->The output current can be led directly from fixed terminals on the stator (armature windings) to the load circuit.

• Easier to insulate stationary armature winding for high AC voltages (may be as high as 30 kV or more)

• Sliding contacts i.e. slip-rings are transferred to the low-voltage, low-power DC field circuit-> easily insulated

• **Armature windings can be more easily braced to prevent any deformation produced by the mechanical stresses

Kenapa Kutub Dalam?• Tegangan yang dibangkitkan biasanya antara 18 kv

– 24 kv, maka tegangan ini tidak perlu dikeluarkan melalui cincin slip dan kontak geser tetapi dapat dikeluarkan langsung ke alat penghubung.

• Ada keuntungan mekanis, getaran lilitan jangkar berkurang dan gaya sentrifugal menjadi lebih baik

• Kumparan medan yang berputar dicatu dgn arus dc pd teg. 125, 250 atau 375 volt melalui cincin slip dan sikat, atau langsung dgn kabel antara medan dengan penyearah untk sistem eksitasi tanpa sikat.

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SYNCHRONOUS MACHINESSYNCHRONOUS MACHINES

Stator Rotor

Connections

Bearing

Stator winding

Rotor winding

Housing ,cooling ducts

Shaft

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Stator• Laminated iron

core with slots• Steel Housing

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Stator details• Coils are placed in

slots

• Coil end windings are bent to form the armature winding.

Slots

Coil

End winding

Iron core

http://thomasblairpe.com/PPE/lecture8.pdf

http://thomasblairpe.com/PPE/lecture8.pdf

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??

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BSE “Teknik Pembangkit Tenaga Listrik”

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**2 kinds of rotor**2 kinds of rotor• Round rotor• Salient Rotor

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Round rotorRound rotor• Usually for high alternators

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Round rotor

Steel ring

DC current terminals

Wedges

Shaft

Rotor Kutub SilindrisPutaran Tinggi- Turbin Uap/Gas

BSE “Teknik Pembangkit

Tenaga Listrik”

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Rotor Details

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Round rotor• The round rotor is used

for large high speed (3600rpm) machines.

• A forged iron core (not laminated,DC) is installed on the shaft.

• Slots are milled in the iron and insulated copper bars are placed in the slots.

• The slots are closed by wedges and re-enforced with steel rings.

Round rotor

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Round Rotor Machine• The stator is a ring

shaped laminated iron-core with slots.

• Three phase windings are placed in the slots.

• Round solid iron rotor with slots.

• A single winding is placed in the slots. Dc current is supplied through slip rings.

Concept (two poles)

N S

A-B

+

A+

C+

C-

B-

A

B

CStator with laminated iron-core

Slots withwinding

Rotor with dcwinding

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Salient rotorSalient rotor• Usually for low- & medium-speed alternators

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Rotor Kutub Menonjol (Salient)Putaran Rendah-Turbin air, Mesin Disel

Rotor Kutub Menonjol (Salient)

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Salient Rotor Machine• The stator has a laminated

iron-core with slots and three phase windings placed in the slots.

• The rotor has salient poles excited by dc current.

• DC current is supplied to the rotor through slip-rings and brushes.

• Concept (two poles)

N

S

A+

B+

C+B-

A-

C-

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Construction

• The picture shows the laminated iron core and the slots (empty and with winding).

• The winding consists of copper bars insulated with mica and epoxy resin.

• The conductors are secured by steel wedges.

• In large machines, the stator is liquid cooled.

• The iron core is supported by a steel housing.

• Construction

empty slots

insulated winding

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Salient pole rotor construction

• The poles are bolted to the shaft.• Each pole has a DC winding.• The DC winding is connected to the slip-rings (not shown).• A DC source supplies the winding with DC through brushes

pressed into the slip ring. • A fan is installed on the shaft to assure air circulation and

effective cooling.

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Construction• Low speed, large hydro-

generators may have more than one hundred poles.

-> relationship between speed & poles

• These generators are frequently mounted vertically.

• The picture shows a large, horizontally arranged machine.

• Exciter

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Exciter pada Generator AC Konvensional

• Arus dc diperoleh dari sebuah generator dc kecil - DC Exciter

Static Exciter Generator

• Exciternya tidak turut berputar, berupa penyearah

Brushless Generator

Brushless Generator

.menggunakan penyearah yg ikut berputar bersama dg rotor.

.Exciternya berupa generator ac kecil dgn kutub luar.

.Pada gen AC kecil: Kutubnya mendapatkan sumber dc seperti pd static exciter, sedang di rotornya timbul teg ac yang disearahkan dan langsung dimasukkan pada rotor generator utama. .Teg pd stator utama dipakai untuk beban dan sebagian kecil untuk eksitasi.

Brushless Generator

• Static exciter masih perlu sikat

• Brushless tidak, tapi menggunakan penyearah yg ikut berputar bersama dg rotor.

• Exciternya berupa generator ac kecil dgn kutub luar. • Kutubnya mendapatkan sumber dc seperti pd static

exciter, sedang di rotornya timbul teg ac yang disearahkan dan langsung dimasukkan pada rotor generator utama. Teg pd stator utama dipakai untuk beban dan sebagian kecil untuk eksitasi.

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• Thank You, see you next week

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• Different construction of synch. Gen & DC gen ->

• Which one precedes?

Date post:	10-Feb-2016
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01 Synchronous Generator

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