Presentation

On

Manufacturing Process of 500MW Turbo GeneratorAt

Electrical Machinery Block I

B.H.E.L., Haridwar

Manish Kumar Verma

Contents• Introduction

• Basic Arrangement of TG in Industries

• Parts of Turbo Generator

• Excitation System

• Testing of Turbo Generator

• Cooling System of Turbo Generator

• Conclusion

Introduction

• What is a TURBO GENERATOR ?

• Principle of Electrical Generator

• Basic Arrangement of TURBO

GENERATOR in industries

Generator

Turbine

Exciter

Constituents of Turbo Generator• Stator Frame

• Stator Core

• Stator Winding

• Overhang Base

• Rotor

TG Stator Core

• 500 MW Stator Core Made by Spiral Stacking

Made of CRGO Si Steel Stampings.

Advantage of Spiral Stacking- Better Locking

500 MW TG Core Bar Used for locking of

stampings

Made of Mild Steel or

Stainless Steel

WedgeTeeth

Winding Slot

Holes for

CoolingHoles for

Studs

Core Bar

Slot

TG Stator Winding

Double Layer Winding is Used

Double Layer Winding Concept

Stator Bars

Winding in Stator Core

Manufacturer Data for 500MW TG Stator

Mechanical Specifications• No of Slots : 48

• No. of Core Bars : 24

• Stator bars numbering:[1-48 : Lower Stator Bars

51-98 : Upper Stator Bars]

• No. of Baskets : 6

Electrical Specifications• Terminal Voltage = 21kV

• Rated Current = 28000 A

• Rated P.F. = 0.85 Lagging

• Efficiency = 99.75%

TG Rotor Core and Winding• Rotor has Concentric Winding.

• 500 MW rotor is made of 2 Poles.

• Rotor Winding bars are placed and

connected in Rotor slots in a opposite

manner (one CW and other ACW)

• Opposite pole windings are connected

using Z conductor

Manufacturer Data for Rotor

V = 400 V ; I = 6000 A

DC Excitation System

Diode Wheel/Rectifier Wheel on Exciter

Schematic of Brushless Exciter

• Automatic Voltage Regulator (AVR)

• Permanent Magnet Pilot Exciter

• Measuring Slipring with Brushes for Field

• Quadrature axis Measuring Coil

• Three Phase Main Exciter

• Diode Rectifier Set

• Three Phase Lead

• Multicontact Connector

• Rotor Winding of TG

• Stator Winding of TG

Manufacturer Data for Exciter

V = 400 V ; I = 6000 A

Testing of Turbo Generator• Winding Resistance:

[Resistance Measurement of Stator winding, Exciter Stator

and Exciter Rotor Winding using RTD.]

• Insulation Resistance: [Performed before and after HV Test]

[use Meggar to measure IR of Winding w.r.t. earth]

[apply Meggar Voltage for 60 seconds and 600 seconds]

[Calculate PI(Polarization Index) = IR(600 sec)/IR(60 sec)]

PI should be > 2.0 [Lower values of PI indicate bad insulation resistance of machine]

• High Voltage Test:

[use formula : V = (2Vn + 1)kV ; Vn = rated voltage of Generator & V = Applied High Voltage]

[Apply High Voltage between each phase and ground; connect other phases to ground]

[Duration for High Voltage Applying = 1 Minute]

Testing of Turbo Generator Continued…

• Mechanical Heat Run Test:

[RTD, Bearing, Body and Ambient

Temperatures are recorded at equal

intervals till thermal equilibrium is

achieved, then Machine is stopped & Hot

resistance of winding is also measured]

[Over Speed Test : Machine is run at 120%

rated speed for 2 Minutes]

[500 MW TG Test Bed at BHEL, Haridwar, BLK-I]

• Open Circuit Heat Run Test:

[ Machine is run at rated speed and rated voltage. ]

[Power input to Prime Mover, Generator Voltage, Exciter voltage and Current, RTD, Bearing, Body

and Ambient Temperatures are recorded at equal intervals till thermal equilibrium is achieved, then

Machine is stopped & Hot resistance of winding is also measured]

[Sine wave of 3-Phase Voltage is recorded by C.R.O.]

[Phase sequence is tested by using phase sequence indicator]

[All the three phases are checked for balance]

[Noise Level Test: Noise level is measured from different locations of machine and background

noise level is also measured after stopping the machine and actual noise level of machine is

calculated]

[Shaft Voltage measurement: measure using multimeter between D.E. and N.D.E. of Shaft]

[Vibrations Measurement: Vibrations at Horizontal, Vertical, Axial directions at both D.E and N.D.E

are measured using Piezo Electric Sensors]

Testing of Turbo Generator Continued…

Testing of Turbo Generator Continued…• Short Circuit Heat Run Test:

[ Machine terminals are shorted and machine is run at rated speed and rated

current. ]

[Power input to Prime Mover, Generator Current, Exciter voltage and Current,

RTD, Bearing, Body and Ambient Temperatures are recorded at equal intervals

till thermal equilibrium is achieved, then Machine is stopped & Hot resistance of

winding is also measured]

[Momentary overload Test: Machine is excited to 150% of rated current for 30

Seconds]

• Impedance Test of Rotor:

[A 1-ϕ variable voltage is applied to field winding and currents at 25%, 50%,

75% and 100% voltage are measured]

Cooling System of Turbo Generator• Hydrogen Cooling is used for Core and Body

• Water Cooling is used for Windings (Distilled Water is used)

Process:

1. Dry air pressure is given to machine using Si

Gel.

2. CO2 Pressure is given to remove air from

machine (Air removed).

3. N2 Pressure is used to take the machine

temperature down. (CO2 removed).

4. Hydrogen Pressure is given to the machine

and maintained.

5. Hydrogen is sucked at high pressure and sent

to chiller which cools the Hydrogen.

Chiller

Conclusion

Experience in Bharat Heavy Electricals Ltd, Haridwar being a Vocational Trainee was very

interesting and inspiring. Though 45 days duration is very little to explore even a single

block of the plant, yet I have tried to learn as much as I could. I got to know about the

industrial equipment which are generally used in an industry.

Besides Technical Knowledge, I also observed management system of plant and working

environment and being one of the leading manufacturing companies of industrial products

B.H.E.L. has very inspiring and positive working environment. This company has very

talented personnel who answered me everything what I asked. This company is doing very

good to improve Power System Efficiency and Power Quality and Safety.