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STUDY PROJECT ON MANUFACTURE OF TURBO GENERATORS

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INTRODUCTION

•when there is a change in the flux linkages relative to a circuit, an emf is induced

FARADAYS I LAW

•The amount of emf induced is directly proportional to the rate of change of flux linkages

FARADAYS II LAW

•The direction of induced emf is such that it opposes the very cause producing it

FARADAYS III LAW

WORKING PRINCIPLE OF GENERATOR

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Components of Turbo Generators1.stator

2.Rotor

3.bearings

4.Cooling system

5.Excitation system

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stator

Stator frame

Stator core

Stator windingsEnd

covers

STATOR

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STATOR FRAME

welding steel single piece construction in order to support the laminated core and windings

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STATOR CORE

PREPARATION OF LAMINATIONS

• Compounding • Blanking and

notching

ASSEMBLY OF CORE

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OPERATIONS IN MANUFACTURING OF LAMINATIONS

A .The cold rolled non grained oriented (CRNGO) steel sheets in the required shapes according to the size of the laminations are cut by the feeding the sheet into shearing press .

B .Compounding operation or blanking &notching operation.

C. Deburring operation D. VarnishingE. The prepared laminations are subjected to following tests:i) Xylol test-to measure the chemical resistanceii) Mandrel test-when wound around mandrel there should not be

any cracksiii) Hardness test-minimum 7h pencil hardnessiv) Ir value test-for 20 layers of laminations insulation resistance

should not be less than 1 mega ohm

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PURPOSE OF STATOR CORETo support stator windingsTo carry the electromagnetic flux generated by rotor winding.Hence selection of material for building up of core plays a vital role. The losses in the core are of two types:•Hysteresis losses Wh a bmax 1.6ft•Eddy current losses We a bmax2 f2 t2

In order to reduce the hysteresis loss silicon alloyed steel, which has the low hysteresis constant is used for the manufacture of the core. the composition of silicon steel isSteel-95.8% Silicon-4.0%Impurities-0.2%

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STATOR COILS1. Set the straightening and cutting machine

using guide pilot 2. Cut the conductor strips as per

requirement3. Set the press for “Roebel transposition”4. Assemble strips with respect to template

and transpose5.Assembling both halves of the coil sides to

formi)One roeble half barii)Inserting insulation in straight part

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6.Baking process

7. remove insulation at the ends of the strips and testing for the inter strips and inter halves shorts8. Set the universal former as per standards and bending the stator coils in roebel shape9.Tapping process

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STATOR END COVERS

•Phase connections•Resistance

Temperature detectors

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STATOR WINDINGS

Two types of coils•Diamond pulled multiturn coil (full coiled)•Roebel bar (half coil)

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Connecting RingsStator Terminals

Insulated Copper Bars are placed in the slots to form

3Ø winding

HGL End Winding Support

Clamping Plates & Rings

STATOR WITH ALL STATOR WINDINGS INTERCONNECTIONS

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ROTOR

Rotor

Rotor shaft

Rotor windings

ConstructionRotor slot wedgesEnd winding

braces Rotor

retaining rings

Rotor fans

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ROTOR SHAFT

SINGLE PIECE SOLID ROTOR BODY MILLING THE FIELD WINDINGS INTO THE ROTOR BODY

MACHINED ROTOR

Rotor Slots

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CONSTRUCTION Several series connected coils inserted into

the longitudinal slots of rotor body.CONDUCTOR MATERIALINSULATION

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ROTOR SLOT WEDGES

•Slot wedges are made of copper alloy featuring high strength +good electric conductivity•Protect the windings against the centrifugal forces .•Windings are secured in the slots with wedges

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END WINDING BRACESROTOR RETAINING RINGSROTOR FANS

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BEARINGS High mechanical stability and reduced vibration in operation To prevent damage to the journals due to the shaft currents,

bearings and oil piping on either side of the non-drive end bearings are insulated from the foundation frame. For facilitating and monitoring the healthiness of bearing insulation, split insulation is provided

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COOLING SYSTEMThere are various methods of cooling. They arei) Air cooling –60 MWii) Hydrogen cooling – 100 MWiii) Water cooling – 500 MWiv)Hydrogen and water cooling – 100 MWDISADVANTAGES OF HYDROGEN OVER AIR

COOLING:a) Hydrogen is explosive when it combines with

oxygen.b) Greater precautions are to be taken to avoid

leakage of Hydrogen.c) Cost of cooling system is high compared to air

cooling system

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AIR COOLINGFlow path 1: is directed into the rotor end winding space and cools the rotor winding, part of the cooling air flows past the individual coils for cooling the rotor end winding and then leaves the end winding space via bores in the rotor teeth at the end of the rotor body. Flow path 2:is directed over the stator end winding to the cold air ducts and into the cold air compartments in the stator frame space between the generator housing and the rotor core. Flow path 3: is directed into the air gap via the rotor retaining ring. core.

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EXCITORSExciter is brushless and takes the form of the stationary field generators

Rotor of Brushless Exciter

Rotating Diodes &

Fuses

Permanent Magnets

E/f Monitoring Slip Rings

Armature

Diode Wheel

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EXCITATION SYSTEM COMPRISES OF•ROTOR•ROTOR WINDINGS•RECTIFIER•VARISTORS•MAIN EXCITORS•ROTATING RECTIFIER WHEEL

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CONCLUSION AND FUTURE SCOPE

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THANK YOU

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QUERIES