THIS PRESENTATION WILL GIVE A GREAT KNOWLEDGE OF MANUFACTURING OF PRACTICAL AS WELL AS THEORETICAL TRANSFORMERS.

1. Prepared by:
Jimit Dhruv
Elect.Engg,Dept.
Valiya Institute Of Technology-Valiya

2. Introduction
 Core material:
 Basic material are Alloy Steel having main
content Silicon & carbon
 Which increases permeability & reduces losses

3.  HRS:
 HRS not used now a days
 As it has random direction &hard to measure
Magnetic properties
 CRGOS:
 CRGOS shows excellent Magnetic properties
 So CRGOS is more used

4. Core construction
 Due to Pulsating flux, core should be
laminated
 Transformer of larger size may forms in
cut “C” or cut “E” type.
 Types of Interleaving:
I. Simple Interleaving
II. Meter core Interleaving:
1)45 ˙
2) 33 ˙ /55 ˙ overlapping
 In 3-Ø Shell type transformer middle
winding is reversed
 If not then 73% more core is used
which leads in increase in over all cost

5. Transformer winding

6. Concentric
Sandwich
 Spiral: It is used 100
A& for low Voltage
Winding
 Mechanically very
strong  Sandwich: mostly used
 Helical :Intermediate for shell type transformer
range of current  Control leakage
 Suitable for LV winding
reactance
of large transformer  HV & LV are near so
leakage flux is reduced
 Cross-over: suitable of
 mmf of each section is
current not exceeding 20
same.
A
 Use for HV winding of
small transformer
 Continuous disc: no of
turns wound radially over
one another
 separated by spacers
 HV winding
 Mechanically strong

7. Insulations
Two main kinds of Insulations:
1. Major Insulation:
 Insulating cylinder between LV & core
 Also between HV & LV
 Insulating barriers between limbs, coils & core
yoke
 Oil impregnated paper used as it has high
dielectric strength
2. Minor Insulation:
 Insulation between
individual turns & between layers
 Conductor Insulation: paper&cotton
 Air insulated Transformer
insulation used is glass tap

8. Bushing
 Up to 66kv non-condenser bushing are used is
porcelain & oil filled
 Above 66kv condenser bushing are used for
economic reasons.
 Condenser type bushing: It is formed by
inserting Aluminum foiled layers into a paper
winding at predetermined radius.
 “Partial capacitance”
 In outdoor substation the
bushing are covered by a
porcelain rain shade

9. Tapping
 Main two location:
1. Inside Tank
2. Outside Tank
 Considered as integral part of transformer
Tapping operation
(1)On load (2)Off load
tap changer tap changer
 Tapping is terminated just bellow oil level
 External handle
 Taping is done on HV winding
 Provided in middle (axial & radial force)

10. Transformer Tank
 Plain sheet steel
Tank
 Tube Tank
 Corrugated Tank
 Radiator Tank
 Tank with separate
coolers

11. Conservator
 What is Conservator ?
 The expansion of oil from Transformer
tank takes up in Conservator
 When oil contracts, air from
atmosphere enters in Conservator .
 Risk of contamination of oil in transformer
 Breather valve is mounted to avoide
moisture
 Breather contain silica in it

12. Buchholz Relay
 Operation:
 Gas operated relay
 AT the time of fault to maintain the continuity
of the supply
 Fault detected particularly in incipient stage ,
major fault can be avoided
 Which is placed between conservator
and transformer tank

13. Transformer oil
 Double purpose :
 ie cooling & Insulating
 Permittivity is 2.5
 As per I.A.S breakdown strength of oil
used must be 50kv RMS
 Major disadvantage is sluging
 To overcome this, synthetic oil is prefered
 One of the e.g is Chlorinated dephenyl is a
synthetic oil its permittivity is 4.5

14. WORKSHOP(TPT DEPT.)
WINDING SHOP
CORE & ACTIVE PART
FINAL ASSEMBLY
QUALITY TEST
FINAL TESTING

15. WINDING SHOP
 TYPES OF WINDING
i. NORMAL WINDING
ii. INTERLEAVE WINDING
iii. TERITARY WINDING
ROTARY
HORIZONTAL HELICAL
K-
MACHINES TRANSPOSITION
TYPE
CONTINUOUS
VERTICAL
DISC
• End Rings & shielding for prevention purpose

16.  Conductor Insulation:
1. Precompressed press board insulation(CRIP
PAPER)
2. Craft paper
3. Also spacers as insulation
 Moisture Control
 Winding Auto Clave: Uses temp. of 110º
C to 130º C and Vacuum of about 0.4 to
0.5 mbar.
 Insulating Oven : Uses Heating Only
 Pressure Machine
 Brazing Machine with use of SILPHOS
ALLOY
 Post Insulation

17.  PROCEDURE:

18. CORE & ACTIVE
PART
 ACTIVE PART
 C.R.G.O. STRIPS
 1-STRIP HAS WIDTH OF 0.27 mm
 COIL OR WINDING ASSEMBLY
 PROCEDURE:
 Manufacturing of LIMB
 Core Insulation
 Removal of TOP FRAM for Coil assembly
 Winding insulation detail
 TOP YOKE FILLING
 VAPOUR PHASE OVEN
 HV & LV leads from top & bottom to the bushings
 REGULATING COILS to the tap changer

19. FINAL ASSEMBLY
 Installation of active part and assembly of
accessories
 TRANSFORMER TANK
• JOINED AT
BELL TYPE BOTTOM
SIDE
• JOINED AT
CONVECTIONAL
TYPE
UPPER
SIDE

20.  ACCESSORIES:
 Blanker : Leakage of oil & Radiators
adjointment
 Buchholz Relay: To trip the transformer
 OSR (oil serge relay): To indicate the level
and quality of oil
 MOLG(magnate oil gage): It indicates the
level of oil in the conservator
 Breather Valve: Provide dry air using silica
gel and have air seal of neoprene
 Cooling Equipment: Generally for cooling
of oil in a tank
1. Radiators
2. Thermosyphan

21.  Method of Cooling:
i. ONAN
ii. ONAF
iii. OFAF
iv. For very high temp using HEAT
EXCHANGER
 CT(Current Transformer):Two
purposes;
1. Winding temp indicator (WTI)
2. Oil temp indicator (OTI)
 BUSHINGS: The leads from top and
bottom of the winding are brought out to a
length of few cm only and the outdoor
terminal of the transformer are provided
by bushings

22.  PROCEDURE
 Vacuuming of Tank(up to 0.3 mbar) for about
24hrs to 36hrs
 The Leak Rate Test with the use of water & air
 Oil Test which includes BDV & PPM
 Oil Filling
 After the IMPREGNATION TIME the whole
accessories are to be attached.

23. QUALITY TEST
 ANALYSIS WITH “SIGMA CARD”
 Sigma card includes below required data
 Design
 Process Time
 M/C size specification
 Process of manufacturing
 Dimension specification
 Testing specification
 Information about control points

24. FINAL TESTING
ROUTINE TESTS TYPE TESTS
NO LOAD TETS
TEMPRETURE
TEST
LOAD LOSS
INSULATION IMPULSE TEST
TEST
CAPACITANCE & ZERO SEQUENCE
TAN δ IMPEDANCE
TEST
SEPARATE
SOURCE HARMONIC AND
NOISE LEVEL
TEST
INDUCED OVER
VOLTAGE
WINDING TEST
VOLTAGE RATIO

25. CT (CURRENT TRANSFORMER)
 Generally CT is use for the below four
purposes:
 Measurement of Current
 Measurement of Power
 Isolation between High voltage and Low Voltage
 Inputs to Relays & Protection Systems
 PROCEDURE OF CURRENT
TRANSFORMER:
 CO NDUCTORS USES :ALUMINIUM OR
COPPER(HIGH CURRENT RATING)
 In the manufacturing of the primary winding or
protection core there will be the creation of the
capacitance as below.
 GRADING & SUB GRADING.
 MAIN GRADING HAS WRAPPED
ALUMINIUM FOIL & CRIP PAPER
 AT 300MM DISTANCE PERFORATED ALU.
FOIL (400MM) AND CRIP PAPER.
 SIMULTANEOUSLY INSULATION MAKE
CAPACITANCE

27.  Quartz in CT
 Reduces the quantity of oil
 Provides mechanical strength for the
conductors
 Improves the quality of oil by absorbing
moisture
 Being a bad conductor of heat, it allows slow
heating /cooling of the CT.
 Finally expansion tank is attached and after
that evacuation of oil and gas filling will be
there .
 There is also one imp term is D3 point which
is also called the earth point.

28. Thank You