This document provides an overview of an industrial training seminar at Bharat Heavy Electricals Limited. It discusses the need for training, then describes the key components of a turbo generator including the stator, rotor, insulation, excitation system, and cooling systems. Different cooling methods for turbo generators are also explained, such as air cooling, hydrogen cooling, and hydrogen/water cooling.

1. INDUSTRIAL TRAINING SEMINAR
Bharat Heavy Electricals
Limited, Ranipur, Haridwar
Submitted to:
Department of Electrical Engineering,
INSTITUTE OF TECHNOLOGY
for the partial fulfillment
of
Degree
Bachelors of Technology
Presented by: Unknown
15
11/09/2020

2. CONTENT
 Need of training
 Abstract
 Introduction
 Stator
 Rotor
 Insulation
 Excitation system
 Cooling system
 References

3. NEED OF TRAINING
• Higher productivity
• Quality improvement
• Reduction of learning time
• Interest in work
• Technology update
• Effective management
• Effective communication skill

4. ABSTRACT
 Training at B.H.E.L. has proved to be quite
faithful. It proved an opportunity for
encounter with such huge machine like
turbo-generators.
 It provides an opportunity to learn tech. Used
at proper place and time can save a lot of
labour.

5. INTRODUCTION
 A turbo generator is a turbine directly
connected to electric generator for the
generation of electricity quickly.
 They are mostly used as large capacity
generator driven by steam/gas turbine.

6. PRINCIPLE OF OPERATION
 Rotor winding is supplied with dc current
(through slip rings or brushless exciter) which
produces constant magnetic field.
 Three phase stator winding is laid in stator core.
 When generator is rotated (by turbines)
magnetic flux produced by rotor winding winding
also rotates.
 Voltage is induced in stator winding according to
Faraday’s law.

7. FARADAY’ S LAW
 E.M.F. (Voltage) is induced in a closed path due to
change of flux linkages and is proportional to the
rate of change of flux linkages.
 The change in flux linkages can be caused by
change in flux in a stationary coil or by motion of
coil with constant flux or both.
E = -N(dØ/dt )

8. COMPONENTS OF TURBO GENERATOR
 Stator
 Rotor
 Excitation System
The following auxiliaries are required for
operation :
 Bearings
 Cooling System
 Oil Supply System

9. STATOR
The stator consists of following parts:
1. Stator Frame
2. Stator Core
3. Stator Winding
4. Stator End Covers
5. Bushings
6. Generator Terminal Box

10. STATOR FRAME
 Rigid fabricated cylindrical
frame and is the heaviest
section in the generator.
 Withstands weight of core
and winding forces and
torques during operation.
 Provision for H₂/CO₂ filling.
 Foot plates for supporting on
foundation.
 Provision for H₂ coolers.

11. STATOR CORE
 The stator core is made from the insulated
electrical sheet laminations to minimize eddy
current losses. Each lamination layer is made of
individual sections.
Purpose of stator core :
 Support the stator winding.
 To provide mechanical support.
 To ensure the perfect link between the core and
rotor.
 To carry the magnetic flux generated by rotor
winding.

12. STATOR WINDING
 The stator winding of turbo
generator is three phase two layer
lap winding with the pitch of
winding so adjusted as to reduce
the 5th and 7th harmonics.
 The number of slots of three phase
power must be a multiple of 3 or 6.
 Each stator slot accommodates
two stator bars.

13. STATOR END COVERS
 The end covers are made up
of non magnetic material
(Aluminium casting) to reduce
stray load and eddy current
losses.
 They are employed with guide
vans on inner side for
ensuring uniform distribution
of air or gas.

14. BUSHINGS
 The bushings are bolted to the stator frame
at the exciter end.
 The beginning and ends of the three phase
windings are brought out from the stator
frame through bushings, which provides high
voltage insulation.

15. ROTOR
 Rotating part of turbo generator.
 A high strength alloy steel single forging
prepared by vacuum cast steel.
 Rotor of cylindrical type used in turbo generator.
 Rotor revolves in most modern generator at
speed of 3000 revolutions per minute.

16. ROTOR SHAFT
 The rotor shaft is cold rolled forging 26N1 or
MOV116 grade and it is imported from Japan
and Italy.
 Details of shaft are given here –
Length = 9 meter (approx.)
Diameter = 1 meter(approx.)
Material – alloy steel
Number of poles = 2

17. ROTOR WINDING
 The rotor of turbo generator accommodates
field winding.
 The winding consist of several coils inserted
into the slots and the series connected such
that two coils group to form one pole.
 The individual turn of coil are insulated
against each other by interlayer insulation.

18. INSULATION
 L-shaped strip of laminated epoxy glass fiber
with nomex filter(interlines) are used for slot
insulation.

19. EXCITATION SYSTEM
 The basic use of an excitation system is to
produce necessary DC for turbo generator
system.

20. PILOT EXCITER
 The three phase pilot exciter
has a revolving field with
permanent magnet poles.
 The armature winding is
housed on the stator.
 The three phase a.c.
generated by pilot exciter is
rectified and controlled by
AVR to provide variable d.c.
for exciting the main exciter.

21. AUTOMATIC VOLTAGE REGULATOR
(AVR)
 The main component in the
rectifier wheel is silicon
diode which are arranged in
AVR 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.

22. MAIN EXCITER
 The three phase main exciter
has stationary field and rotating
armature.
 Thus, three phase a.c. power
is produced in main exciter
which is rectified by rotating
rectifier bridge and is fed to the
field winding of rotor (turbo
generator) through dc leads.

23. COOLING METHODS FOR TURBO
GENERATOR
 Air cooled T.G.
 Hydrogen cooling and hydrogen cooled
T.G.(THRI)
 Hydrogen/Water cooled T.G.(THDF)

24. AIR COOLED TURBO GENERATOR
Hot air
Cold air
 This type of cooling is
applicable for rating 30
MW-60 MW generators.
 In this type of turbo
generator there are
vertically side mounted
cooler in a separate
housing.

25. HYDROGEN COOLING AND HYDROGEN
COOLED TURBO GENERATOR
 To push up generator ratings hydrogen is used as
cooling medium.
 Size of cooler is small.
 Density of H₂ is only 0.07 times that of air and
therefore, power required to circulate H₂ is less.
 H₂ has heat transfer coefficient 1.5 times and thermal
conductivity is 7 times that of air.

26. HYDROGEN WATER COOLED TURBO
GENERATOR
 In large rating, hydrogen cooling is not
sufficient to remove the entire heat
generated.
 For additional cooling, a Primary Water(PW)
cooling system with demineralised water
flowing through the hollow stator conductor is
used.
 The rotor conductors are hydrogen cooled.