The document discusses the manufacturing process of stator winding bars for 500/600MW generators at BHEL. It describes the key sections of the manufacturing process, including conductor cutting, insulation, impregnation and assembly. It provides details on the size and number of conductors, insulation classifications, transposition process, resin systems, testing procedures and specifications of 600MW generators. The training gave insights into the complex architecture and coordinated working of various units in a large power plant.

1. MANUFACTURING OF 500/600MW
STATOR WINDING BAR (BHEL)
SUBMITTED TO:-
Mr. A.K DHIMAN (MGR-
CIM)
SUBMITTED BY:-
AVINASH KUMAR
K.N.G.D MEC (EEE)
ROLL NO.- 495

2. introduction
 It is quit difficult to manufacture, handle and wind in
the stator slot of generator of higher generation
capacity because of its bigger size and heavy weight
called BAR.
 Bar is make in to two part
 Upper Bar
 Lower Bar
 Bottom part of the bar is called lower bar.
 Top part of the bar is called upper bar.

3. PROCESS OF BAR FINISHING
1) CONDUCTOR CUTTING SECTION
It is equipped with
 Conductor cutting (Robal machine).
 Insulation and transposition section.
 Stack consolidation section, forming and lug brazing
sections.
 Insulation taping sections with automatic taping.
2) INSULATION SECTION
It is equipped with
 Small size lathes.
 Milling and radial drilling machines.

4. Jet cutting saw.
Electrical ovens & Hydraulic presses.
Plastic Molding Section.
3) IMPREGNATION SECTION
It is equipped with
Impregnation tank.
Ovens for impregnation of DC pole coils.
4) Assembly Section
It is equipped with small size
Drilling machines.
Welding sets.
Hydraulic testing equipment for
manufacturing turbo-generator mechanical
assemblies.

5. SIZE OF CONDUCTOR
For Lower Bar CONDUCTOR
SIZE
LENGTH NO. OF
CONDUCTOR
For Lower Bar 8*4.6*1.5*mm 10200mm 20 (Hollow)
For Lower Bar 8*2.8*mm 10200mm 20 (Solid)
For Upper Bar CONDUCTOR
SIZE
LENGTH NO. OF
CONDUCTOR
For Upper Bar 8*4.6*1.5*mm 10050mm 20 (Hollow)
For Upper Bar 8*1.3*mm 10050mm 40 (Solid)

6. NUMBERS OF BAR
TYPES
OF BAR
UPPER
ORDINA
RY
UPPER
TERMIN
AL
LOWER
ORDINA
RY
LOWER
TERMIN
AL
TOTAL
BARS
NO. OF
BUS
BAR
600MW
THDF
42 6 42 6 96 6
500MW
THDF
42 6 42 6 96 6
250MW
THRI
48 12 48 12 120 9

7. COIL & INSULATION OF BAR’S
 High voltage insulation is provided with
thermosetting system .
 A voltage insulation obtained by vaccum press
impregnation is particularly void free with excellent
electrical, mechanical and thermal properties.
 To prevent corona discharge between the
insulation and slot wall, a final layer of conductive
tape is applied to the surface of all bars with in the
slot range.

8. INSULATION CLASSIFICATION
Class-
A
Upto-105˚c
Reinforced Class-
Y materials with
impregnated
varnish.
Class-
B
Upto-130˚c
Inorganic material
is hardened with
adhesives.
Class-
C
>180˚c & <220˚c
Made of 100%
inorganic
material.

9. INSULATION CLASSIFICATION
Class-
E
Upto-120˚c
Cotton
lamination &
paper
lamination.
Class-
F
Upto-150˚c
Class-B
materials that
are upgraded
with adhesives.
Class-
Y
Upto-90˚c
Cotton, Silk, or
Paper.

10. Transposition means changing/shifting of position
of each conductor in active core (slot) part.
 After cutting the required number of conductors.
 The conductors are arranged on the comb in
staggered manner and then bends are given to
the conductors with the help of bending die at
required distance.
 Then the conductors are taken out from the comb
and placed with their ends in a line and
transposition is carried out.
TRANSPOSITION

11. TRANSPOSITION PROCESS
Half Pitch Transposition: In this transposition, the
first conductor at one end of the bar because the
last conductor at the other end of the bar.
Full Pitch Transposition: In this method of
transposition, the first conductor at one end of the
bar because the last conductor in the mid of the
bar and then again becomes the first conductor at
the other end of the bar.
Need of transposition
1. To reduce eddy current losses.
2. Equalize the voltage generator.
3. To minimize skin effect of ac current.

12. RESIN SYSTEM
 Rich Resin or Thermo-reactive insulation
system
In this type of insulation system the bond content in
resin is 35-37%. The raw materials are ready to
use and require preservation and working on
temperature 20-25˚c. Its shelf life is one year when
kept at a temperature of 20˚c which could be increased
when kept at temperature of 5˚c.
 Poor Resin or Micalastic insulation system
In this type of insulation the bond content in the resin is
5-7% and insulation material is prepared with
accelerator treatment.

13. The temperature control need is not required. The
insulating material is applied on job and then same
impregnated (fully dipped) in the resin.

14. TESTING
֎ TAN TEST
 This test is carried out to ensure the
healthiness of dielectric (Insulation) i.e. dense
rare & measured the capacitance loss.
 Bar will act as capacitor when it is laid in the
stator of the generator.
 Schearing Bridge which works on the principal
oh wheat-stone bridge is used to find the
unknown capacitance of the bar.
 For good efficiency, capacitance of the bar
should be high but never approach pure
capacitance.

15. ֎ TAN TEST
 Bar is wrapped with aluminum to make the bar
conduction throughout the outer surface of the
bar. The two conduction material i.e. the
aluminum sheet and the conductors of the bar
as two parts of the capacitor and the bar
insulation on the act dielectric medium for the
capacitor thus as found.
 Of angle of deviation to impurity in the
insulation is obtained from the formula
C4*R4*10˄-4=tanδ

16. Tan Test
Loss Angle Test Loss Angle Test

17. H.V. TEST
 Each bar is tested momentary at high voltage
increased gradully to three times higher than
rated voltage.
 This test is also known as insulation test
because this test is performed to check the
insulation of the bar.
 For 600 MW the working voltage of the bar is
64.5 KV & for 210 MW the working voltage of
the bar is 63 KV.
 In this test the bar which is already wrapped
with aluminum is used.

18. H.V. TEST
 High voltage is applied to the bar using auto-
transformer and it is increased in steps
according to the working voltage of the
generator. If the insulation is weak the bar will
puncture at the place of weaker insulation.
 If any of the bar fails this test i.e. bar is
punctured at any point then the bar is sent
back for re-insulation and the processes are
repeated again.
 Formulae for H.V Test
1Up=2Un+1 ;Un=21kw for 500MW

19. 600 MW Turbo Generators At a Glance
2 Pole Machine Features
 Direct cooling of stator winding with water.
 Direct hydrogen cooling for rotor.
 Micalastic insulation system.
 Spring mounted core housing for effective
transmission of vibrations.
 Brushless excitation system.
 Vertical hydrogen coolers.

20. Ratings of 600MW Generators
 Rated output :- 588 MVA , 600MW
 Terminal voltage :- 21 KV
 Rated stator current :- 16 KA
 Rated frequency :- 50 Hz
 Rated power factor :- 0.85 Lag
 Efficiency :- 98.55 %
DIMENSION & WEIGHT
 Stator weight :- 255 Tons
 Rotor weight :- 68 Tons
 Stator dimension :- 8.83*4.1*4.02*m
 Rotor dimension :- 1.15*m & 12.11*m (Dia. &
Len.)

21. Stator Bar

22. CONCLUSION
This training has proved to be quite
faithful.This gave me , a chance to have an
encounter with such heavy machines like
turbo generator 500/600MW.The
architecture of BHEL the way the various
units are linked and the way the working of
whole plant controlled , makes the student
realize that engineering is not just the
structural description but more of planning
and management .It has provide an
opportunity to learn that optimization of
technology used at proper place and time

23. The training has proved to be immensely helpful as it
has helped me to have an exposure of the practical
implementation of the theoretical knowledge.