This slide contains a slides on industrial training on manufacturing of large electrical machine

1. MANUFACTURING OF LARGE
ELECTRICAL MACHINE
AT BHEL BHOPAL
Presented by: Vaibhav Singh
Roll no. 1301421101
Branch: EN‘13’
S.R.M.S COLLEGE OF ENGINEERING AND TECHNOLOGY

2. Manufacturing of large electrical
machine
• Foundry
• Fabrication
• Machining
• Press
• Coil insulation
• Winding
• Assembly
• Testing

3. Foundry shop
• Stator frame
• Bay 1&2 non ferrous foundry
• Bay 3 ferrous foundry
• process:-
1. Pattern making
2. Molding
3. Metal melting
4. Pouring
5. Fettling
a) Knock out
b) Shot blast
c) Heat treatment
i. Annealing
ii. Normalizing
iii. Stress removing
d) Rough machining

4. Pattern making
1. Thermacol(high density)
2. Wooden(high density, laminated
permali wood)
3. Aluminum

5. Moulding
Silica sand+ phenol formaldehyde(20% of sand)+
cromide i.e. high temperature catalyst (15% of
phenol)
Electric arc furnace(1500kva cost-9000rs/h)

6. Metal melting
Induction furnace
On load No load
Voltage (V) 1300 622
Current(A) 349.7
Power(Kw) 1010 203
Frequency(Hz) 229 226

7. pouring

8. fettling
• Fettling is the process which involves the removal of
the cores, gates, runner, riser etc. all these are done
by these process
a. Knock out
b. Shot blast
c. Heat treatment

9. Shot blast-
• In this process we put the job
into a chamber and blasting the
iron particle on the job for
making the surface smooth and
clear.

10. Heat treatment
Annealing Normalizing Stress relieving
Soaking
temperature
920±15˚C 920±15˚C 550-580˚C
Soaking time 4hrs. minimum
(1inch/hr.)
4hrs. minimum
(1inch/hr.)
4hrs. Minimum
(1inch/hr.)
Cooling Inside the
furnace
Outside the
furnace
Inside the
furnace

11. Fabrication shop
shaft
fabrication
LEM
Rod and rib
assembly
corner
welding
summerge arc welding
DP test
stress
relieving
shot blast
MPI test
paint
IMM
Rod and rib
assembly
summerge
arc welding
corner
welding
DP TEST
Stress
relieving
shot blast
MPI test
paint

12. Shaft fabrication
• LEM shaft
• IMM shaft

13. High tensile mild steel

14. Corner welding
Manually done to fix the rib on the rod. In v
shaped

15. Submerged arc welding
• This welding is to provide the mechanical strength
to joint of rib and rod. Firstly the shaft have to
preheated up to 150˚C preheating temperature is
depend on the type of welding. Aluminum, Pb(led),
CaO is used as flux for the welding and for filling
material mild steel coated with copper. Copper is
used because it is a good conductor of heat and it’s
also a rust proof material. This welding is done by
the semi automatic machine.

16. Die penetration test:-
• The die penetration (DP) test is perform to found
the defect of welding or forging on the surface of
material. For this spread a die (liquid) on the
surface of material and left it 15min on the joint of
welding and for the forging left it on the surface for
an hour because the hole or crack in case of forging
is very small. After the time interval if there is any
hole or crack is on the surface it make a red spot at
defect. After punching at the defected part weld it
again and repeat this process again.

17. • Stress remover
• Shot blast:-In this process we put the job into a
chamber and blasting the iron practical on the job
for making the smooth and clear.
• Magnetic particle inspection:- Magnetic particle
inspection (MPI) is done for the inspection inside
the surface up to 6mm. In MPI spread a liquid on
the surface of the job and used two electrodes to
make high current flow to the surface of the job. It
make the black spot where the defect is. The
current flow in this test is approx 250A. The liquid is
made up of very small particle of iron and soap and
water.

19. Paint :-
• At last the shaft of LEM paint and dispatch
from this shop to other place. Painting is done
for make the shaft rust proof and for look
good.

20. FABRICATION OF THE
STATOR FRAME
• In this section LEM’s &IMM’s stator frame is
fabricate but some stator frame of IMM is made
up in forging.
• The main parts of stator frame-
• Rib
• Rapper (cast iron sheet)
• End stand (cast iron rod)
• Buffel (pipe is inserted in the stator frame) this is
used for the cooling purpose of the motor but it
is used only in IMM motor. Or it is not present in
the stator frame of LEM.

22. MACHINE SHOP
• Machining is done to get the proper dimension of
stator and rotor part. For this they use different
machine & process
• Machines-
• Lathe machine
• Drill machine
• Boring (horizontal and vertical)
• Milling
• Grinding

23. PRESS SHOP
• The core of LEM and IMM is made up of different
sheets of CRNGO steel. In this shop the core of
stator and rotor is made by stacking of different
sheets all these are electrically insulated from
each other to reduce the eddy current loss. The
eddy current loss is depends on the thickness of
the sheets.
• Thickness of individual sheet is approximate
• 0.65mm for normal motor
• 0.50mm for traction motor
• 0.35mm for transformer

24. • In B.H.E.L Bhopal the core is made up in the range of
550mm to 2600mm internal diameter.
• For a small machine core diameter range from 550mm
to 1250mm the sheets are in roll form which cuts in the
required shape and size.
• For a large machine core diameter range from 1350mm
to 2650mm the sheets are in segment form it’s directly
sends to blanking section.
• The core is prepared by different process which are-
Blanking
Notching (pressing)
Blur removing
Varnish
Spacer
Stacking

25. Blanking:-
• Blanking is done only in stator core of
machine after this the notching process will
done

26. NOTCHING(PRESSING)
• In notching process they make slots and teeth
in the sheet. In the stator core slots and teeth
are inward direction & in rotor core the slots
are in outward direction. There is manually
and automatic (CNC) machine are there. 12.5
ton impact machine is the smallest manually
operated notching machine.

28. • Different capacity of machine are installed in B.H.E.L
Bhopal-
• 1. 16 ton 6 stations CNC machine
• 2. 8 ton 8 stations CNC machine
• 3. 16 ton segment manually machine (for large
rotor & stator)
• 4. 250 ton segment
• 5. 1600 ton segment (biggest machine in B.H.E.L
Bhopal this machine is able to make a slots on 8mm
sheet)
• The tools of machine are Dia & punch, in nature
these tools are very brittle and the material of the
tool is high carbon steel.

29. Blur removing-
Blur remover process is not compulsory this
is only done if blur is present in the sheet. If the
blur is present sheets it can deform the shape of
core or it remove to prevent the core form uneven
height so the blur removing process is compulsory.
Varnishing :-
Varnishing is done for insulation between the
sheets and is also provide the coating to the sheet
for making it rust proof.

30. spacer
It is clear by name that spacer is thing
which is use to make a space between two or
more than two things. In this shop they use a
thin rectangular shape sheet which welded on
the sheet of core vertically. Projection welding
is used weld the spacer on plate.

31. Stacking
Stack means to arrange a number of things on
the top of one another in a good order. So in
stacking they arrange the sheets and make the
core of rotor or stator segment, for the small
machine core is made in this shop but for large
machine it’s made in the LEM section. After
stacking the consolidation is also important for
consolidation they add a end ring, weld it and
add a nut bolt to fix it. Spot welding is used to
weld the few sheets together.

32. CIM shop
• 1. Conductor cutting and insulation removing:-
This is the first step of coil making
they use a DGL (double glass laminated) copper to
make the coil of hydro generator in this conductor
copper is 99.99% pure and 0.01% is foreign
material. Insulation is removed from the both end
of conductor to connect the conductor to other
conductor and make a coil.

33. • 2. Transposition:-
In transposition they rotate the
conductor 360 to make the uniform electric
flux only active part of winding is rotated. To
make the conductor bars insulated from each
insulations are provided by Epoxy treated
glass cloth separator and gross over piece
(nomex composite).

35. • 3. Stack consolidation/pressing:-
In this process puts a
conductor heated at temperature 160±10˚C for 1 hour
after this cooling below 80˚C. For the heating purpose
they use a water steam only the DGL side heated. After
it again used some material for proper insulation
materials are Mica paper putty & Propylene tape.
• 4. Bar forming:-
To obtain the shape of coils/bars as per drawing
different bench are used or because all the machine
have different number of slots, number of poles, coil
span etc. so all the bars are skewed at different angle
and at different length so different bench are use to
skewed the conductors.

38. Testing
• After all these process for coil making
insulation providing testing is compulsory
for check the insulation is proper or not for
this they take two tests-
i. Inturn test
ii. High voltage test

39. WINDING
• Winding of a rotor and the stator are depends upon
the design consideration of the machine or it
depends on the work of the machine for an
example if we want a machine for power generation
we have to design a synchronous generation, which
runs at constant speed but variable torque the
speed of rotor is depends on the pole of generator
and frequency of generated voltage.

40. In B.H.E.L Bhopal different rating of machine are made the range
of that machines are
1. Squirrel cage induction motors
Power- 150Kw to 21Mw
3.3Kv to 15Kv
DOL and VED fed
2 pole to 36 pole
3. Synchronous
500Kw to 25Mw
3.3Kv to 15Kv
DOL and VED fed
4pole to 30 pole
2.Slip ring induction motor
150Kw to 10Mw
3.3Kv to 15Kv
DOL and VED fed
4 pole to 14 pole
4. Special design motors
150Kw to 21Mw
3.3Kv to 15Kv
2pole to 36pole

41. So the winding are depend on the purpose and
rating of the machine. Simplex winding are mainly
two types
1. Closed winding
2. Open winding
1. Closed winding
Closed winding is only used in D.C. machine and A.C.
commutator machine this winding is of two type
first one is lap winding and the second one wave
winding.
From any point of a winding after traversing the
whole winding we reach at that point from we
started means it’s a closed winding.

42. 2. Open winding
Open winding is used in A.C.
machine. There are two type of open winding –
1 Lap winding
2 Wave winding
• Lap winding is used for low voltage and high current
because in lap winding parallel path is equal to the
number of pole.
• The wave winding is for the high voltage low current
because in wave winding the number of parallel
path is equal to two.

44. Assembly
• For the assembly of the machine we take some step by step
process-
• 1. End shield preparation – for sleeve bearing IBC mounty is
done.
• For antifriction bearing, bearing housing is assemble on end
shield
• 2. Air guide fixing on end shields or frame.
• 3. Stator segment assemble and after this MTB (main
terminal box), NTB (neutral terminal box), RTD (resistance
temperature detector), heater, heating box C.T. (current
transformer), C.T. box are connected.
• 4. Air-inlet housing marking with stator to fix their position.
After this they send it to the machine shop for drilling.
• 5. Rotor threading i.e. to put the rotor into stator of machine.
• 6. Both end shield assemble to the stator

45. • 7. Bearing box up assembly
• 8. External fan and air inlet housing assembly, silencer
assembly all these are assemble to the stator.
• After this motor sends to testing area and if all the test
results are under prescribe limit then motor send to the
shipping area-
• In this few steps are also taken
• 1. Rating plate mono and GLL name plate fitted on the
stator.
• 2. Shaft polish & key fitting is done.
• 3. Motor painting is done.
• 4. Silver paint is painted at earthed place. To increase
the conductivity of that part and check earthing
symbols are at appropriate place.
• 5. Motor sends for packing after Q.C (quality control)
inspection with green tag.

46. Finally the LEM will look like this

47. IMM will look like this