This industrial training report summarizes the process for manufacturing generating transformers at BHEL Bhopal. It discusses the key steps which include design and drawing, core building by stacking laminated silicon steel sheets, winding manufacturing using horizontal and vertical winding machines, coil assembling, power assembly by mounting the core and coils, case fitting to connect accessories like bushings and radiators, vapor phase drying to remove moisture, testing including routine and type tests, and final dispatch after successful testing. The report provides details on the types of materials, winding configurations, and tests used at each stage of manufacturing large power transformers.

1. INDUSTRIAL TRAINING REPORT
TOPIC-GENERATING TRANSFORMER MANUFACTURING
BHEL BHOPAL
PRESENTED BY :-
PRAVEEN KUMAR SINGH
ROLL NO. (1673520034)
EE FINAL YEAR
REC BIJNOR
PRESENTED TO :-
DR. NAVNEETKUMAR
ASSISTANT PROFESSOR
EE DEPARTMENT
REC BIJONR

2. GENERATING TRANSFORMER-
• The generator transformer is the largest transformer on a power station and connects the
generator output to the grid.
• The generator transformers, in most present day stations will have a voltage ratio of 23.5/400
kV.
• The important criteria which influence the generator transformer design are as follows:
• The HV volts are high — usually 400 kV.
• The LV current is high — almost 20 000 A for an 800 MVA transformer.

3. STEPS IN MANUFACTURING OF GENERATING
TRANSFORMER-
 Design and drawing
 Core building
 Winding manufacturing
 Coil assembling
 Unlacing of core
 Core coil assembling and TG mounting
 Case fitting
 Process in plant
 Testing
 Preperation for dispatch

4. Core and coil
assembling
and TG
mounting
Coil
winding
Coil
assembling
Mechanica
l
componen
t
Core
Building
Insulating
componen
t
PICC/CTC
procuremen
t
Mould
component
Process in
plant
Insulating
component
Test lab
CRGO
Case
fitting
Prepration
for
dispatch
Tank fabrication
and
manufacturing
Bottom
tank
Top tank
Radiator
/cooler
Bushin
g
M/C
compone
nt
Tap
changer
Insulating
component

5. DESIGN AND DRAWING-
 Phase
 Rating
 Frequenc
y
 Purpose
1-phase
3-phase
KVA
MVA
50 Hz
60 Hz
Generating
Substation
Distribution

6. TRANSFORMER CORE BUILDING:-
Following steps are involved in power transformer core construction:
Material used-
CRGO(cold rolled grain oriented) silicon steel
Laminated sheets of CRGO are made by slitting and cropping machine.
 Slitting machine decides width of lamination.
Cropping machine decides shape and size of lamination.
Stacking of CRGO
End Frame insulation and Insulated Bolting of End Frame.

7. CRGO
Slitting and cutting
End Frame insulation & End Frame
bolted Stacking of CRGO

8. WINDING MANUFACTURING:-
TYPES OF WINDING MACHINES –
Winding Machines are of two types:
Horizontal Winding machines
Vertical Winding machines
Horizontal Winding machine Vertical Winding machine

9. TYPE OF WINDING IN TRANSFORMER:-
Halical winding(mainly used for LV winding)
Disc winding(mainly used for HV winding)
Halical winding
Disc winding

10. TYPES OF WINDING CONDUCTORS:-
The various types of conductors used in coil winding
are-
CTC (Continuously Transposed Conductor)
PICC (Paper Insulated Copper Conductor)
BPICC (Bunch Paper Insulated Copper Conductor)

11. COIL ASSEMBLY:-
The coils are specified in the design may be of following types on the basis of
operating voltage:-
L.V. Coil Winding
H.V. Coil Winding
Tap Coil Winding
L.V. Coil is placed adjacent to the CRGO steel core and H.V coil outside, in order
to minimize the amount of insulation required.
While assembling the different coils (i.e. Tap coil, L.V. Coil & H.V. Coil) tap coil can
be placed in either of three positions depending upon the length of tap coil i.e. if
tap coil is small it is placed inside of LV coil, if it is medium then between LV & HV
coil, and if large then outside of HV coil.

12. Horizonta
l Winding
(LV &
Tap)
Vertical
Windin
g (HV)
Coil Assembly
Oven BakingHydraulic Press

13. POWER ASSEMBLEY:-
Core - Coil Assembly
Unlatching of core
Fitting of bottom insulation
Core coil assembly as per
drawing/electrical specification
Fitting of top insulation
Relacing of core
Unlatching of core Core coil assembly as per
drawing
Relacing of core

14. Terminal Gear Mounting
Crimping & Brazzing
Insulation Wrapping
OLTC Connection
Vapour Phase Drying
Servicing(due to porous in
insulation)
Terminal Gear Mounting
Vapour Phase Drying of core &
winding

15. CASE FITTING:-
Case Fitting involves connecting accessories of
transformer, these accessories include following :
 CT connections & Feed positions
 Conservator
 Bushing Connections
 Oil Temperature Indicator
 Buchholz Relay
 Radiator
 Breather
 Control panel(marshalling box)
1. Transformer tank
2. High voltage bushing
3. Low voltage bushing
4. Cooling radiator
5. Cooling fans
6. Conservator tank
7. System ground terminal
8. Drain valve
9. Breather
10. Oil temperature gauge
11. Current transformer terminals
12. Control panel

16. PROCESS IN PLANT:-
VPD(vapour phase drying) process is done after case fitting.
To start VPD 7 mbar pressure is created.
Solvant is heated to increase the pressure.
Solvant started to flow to transformer under pressure.
So dust and moisture is removed from transformer.
Extra heating in transformer is provided transformer by steam.
After that oil is poured in transformer.
24 hrs sucking of oil by insulation.
Oil is removed after that transformer goes for servicing.
Again oil is filled for cooling and insulation and oil is tested(resistivity,breakdown
voltage etc.)

17. TESTING OF TRANSFORMER:-
Routine tests-
I. Measurement of voltage ratio,polarity,magnetic balance and mag current.
II. Measurement of no load loss/core loss and no load current.
III. Seprate source voltage.
IV. Switching impulse voltage withstand test.
T- type tests
I. Temperature rise test
II. Zero sequence impedence test
III. Measurement of harmonics in no load current
IV. Measurement of sound level

18. DISPATCH:-
After successful completion of testing, transformer is handed over to dispatch sections.
At this stage after checking oil leakage, dismantling of all bushings, turrets etc. and
covered with the blanking plates and the tank is fitted with nitrogen gas and then the
transformer is dispatched to the concerned site.

19. THANK YOU