turbo generators

A Presentation on Turbo Generator and Exciter BHEL Haridwar

Manufacture & Assembly of Turbo Generator BHEL HaridwarSubmitted by: Manish Snehi 11115051 BTech EE 4th year.

BHEL An OverviewBHELs first plant was set up in BHOPAL in 1960s under Indo-Soviet agreement.BHEL is the largest engineering and manufacturing enterprise in India.It has been earning profits continuously since 1971-72.The wide network of BHEL has 14 manufacturing division, 150 project sites, eight service centers and 18 regional offices.

About BHEL Haridwar unit Two manufacturing units in BHEL.

HEEP (Heavy Electrical Equipment Plant) There are eight blocks in the HEEP namely 1-8.CFFP (Central Foundry And Forge Plant) Steel Melting Shop Steel Foundry Shop Light Foundry Shop Forge shop

HEEPBlock-1:- (Electrical Machine Final Assembly)Block-2:- (Gas & Steam Turbine Fabrication Block)Block-3:- (Gas & Steam Turbine Manufacturing Block)Block-4:- [CIM (Coil & Insulation Manufacturing)Block]Block-5:- (Heat Exchangers Fabrication Block)Block-6:- (Stampings Block)Block-7:- (Wooden Packing works Block)Block-8:- (Heat Exchanger Tubes Block)

Turbo-generatorA turbo generator is a turbine directly connected to electric generator for the generation of electricity. They are mostly used as large capacity generator driven by steam/gas turbine. Turbo generator operates on the fundamental principles of ELECTROMAGNETIC INDUCTION.E.M.F. (Voltage) is induced in a closed path due to change of flux linkages and is proportional to rate of change of flux linkages. It converts mechanical energy into electrical energy. It is a turbine directly connected to electric generator for the generation of electricity.

Basic equation for sizing of electrical machines P=K.As.B.D^2 L .ns Here P = MW output As = Electric Loading (Amp.) B = Magnetic Loading (gauss) D = Stator bore diameter (cm) L = Stator core length (cm) ns = Rated speed D^2 L = Volume of Rotor or Size of the Machine Features of TG & HG Turbo generators in Thermal, nuclear, Gas station High speed 3000 rpm No. of poles 2 poles Horizontal construction Cylindrical rotor

Hydro generators in hydel plants Low speed 500 to 1000 rpm No. of poles 6 or more Vertical construction Salient type of rotor

Types of Generator

The generator classified,as based upon the used cooling system in it such as: TARI, THRI, THDD, THDF, THDI, THFF. T= First word denotes type of generator i.e. turbo generator or hydro generator. A/H= Second word stands for medium used for the cooling of rotor as air or hydrogen gas. R/D/I/F= Third word signifies cooling of rotor as radial, forced,indirect, direct. D/I/F= Last word signifies type of cooling if stator as indirect cooling, forced cooling, direct cooling. W= Medium being used for cooling of stator coil as water Nomenclature of Turbo-generator

TARI 108/46THRI 108/44THDF 115/59MAIN PARTS OF TURBO GENERATOR

Stator - Stator Frame (Fabrication & Machining)Core Assembly - Stator Core, Core Suspension ArrangementEnd ShieldsStator Winding Assembly - Stator Winding, Winding Assembly, Connecting Bus barRotor - Rotor Shaft, Rotor Wedges, Rotor Coils, Wound Rotor, Rotor AssemblyCompleting Assembly - Bearing Assembly, Shaft Seal Assembly, Oil Catchers, Insert Cover etcExciterAuxiliary System

Stator Frame Rigid fabricated cylindrical frame and is the heaviest section in the generator Withstands weight of core & winding, forces & torques during operation Provisions for filling hydrogen gas. Provision for temperature measurements Foot plates for supporting on foundation Provision for H2 coolers

Stator CoreThe stator core is made from the insulated electrical sheet lamination to minimize eddy current losses. Each lamination layer is made of individual sections. The main features of core are: 1. To carry electric & magnetic flux efficiently. 2. To provide mechanical support. 3. To ensure perfect link between the core and rotor. The composition of silicon steel(used as material of core),for reduction of hysteresis loss is: Steel-95.8% Silicon-4.0% Impurities-0.2%

Stator winding Stator insulation Stator end cover

Rotor Rotating part of turbo generator A high strength alloy steel single forging prepared by vacuum cast steel. Longitudinal slots for housing field winding Damper winding is provided which safeguards the asymmetrical and asynchronous operative conditions. Rotor of cylindrical type used in turbo generator. Supported on two journal bearings. Provision of axial fan for forced ventilation.

Rotor WindingThe field winding consists of several series connected coils inserted into the longitudinal slots of rotor body. The coils are wound so that two poles are obtained. The conductors are made up of copper with a silver content of approximately of 0.1%. Rotor Insulation (HGL) Field connection (rotor field & exciter) Rotor Fan

Excitation System

The process of generating a magnetic field by means of an electric current is calledexcitation. It provides power to the field windings thus produce field for rotor.

Types of exciter:Brush type exciter / Static excitationBrush less exciter

Brush Type/Static ExcitationRotor Field Winding is connected to Slip ring mounted on Rotor.Excitation is provided by current transfer by contact through Carbon Brushes, Slip ring and field lead.

BRUSH LESS EXCITATION SYSTEM Main parts are:Pilot exciterMain exciterRectifier wheelAutomatic voltage regulator

Rectifier wheel

Components in the rectifier wheel are as follows: 1. Silicon diodes 2. Aluminium heat sink 3. Fuses 4. RC circuit The main component in the rectifier wheel is silicon diodes which are arranged in rectifier wheel in three phase bridge circuit. The direct current from rectifier wheel is fed to DC leads and then to the field winding of the rotor.

Advantage Of Brush Less Exciter Over Brush Type Exciter

Eliminates Slip Rings, Brush gear and Field BreakerEliminates all problems associated with transfer of current via sliding contactsMinimum operating and maintenance cost High response excitation with fast acting AVR Brush Losses are eliminated

Cooling SystemAIR COOLED TURBO GENERATOR: In Air Cooled Turbo generator stator winding is indirectly air cooled whereas the rotor winding and stator core is directly air cooled. This type of cooling is applicable for rating of 30 MW- 60 MW generators. In this type of turbo generator there are vertically side mounted cooler in a separate housing

HYDROGEN COOLED T.G.HYDROGEN/WATER COOLED T.G.

Advantages of Hydrogen as Cooling Medium:

a) Increased efficiency: The density of H2 is only 0.07 times the density of air and therefore the power required to circulate H2 is less than that required in air. b) Increase in rating: H2 has a heat transfer coefficient 1.5 times and its thermal conductivity is 7 times that of air. Consequently when H2 is used as a coolant, the heat is more rapidly taken up from the machine parts and dissipated. c) Elimination of fire hazard: The outbreak of fire inside the machine is impossible as H2 does not support combustion. d) Smaller size of coolers: The size of cooler required is smaller in size.

Generator technical data

REFERENCES

http://www.bhel.com/about_publication.php http://en.wikipedia.org/wiki/Turbo_generator http://en.wikipedia.org/wiki/Hydrogen-cooled_turbogenerator A text book of electrical machines by P.S.BIMBRA A text book of electrical technology by B.L.THERAJA BHEL Internal material THANK YOU