1. ➢ Name of the, organization :-Indrajeet Power lines india pvt ltd
➢ Name of the intence student ID & and session:-
➢ Submission Date of the internship report:-
➢ Name of the university:-
2. Dedication
To all those who have supported, encouraged, challenged, and inspired
us. And specially to our Beloved Parents, honorable teachers and
friends for all their guidance, love & attention which has made it
possible for us to make it up to this point and as well as the Internship
Supervisors who bestowed us with the courage, the commitment and
the awareness to follow the best possible route, by their unmatchable
style and by best possible training.
3. ACKNOWLEGEMENT
I express my deep gratitude towards Prof.Shinde.P.S.(INTERNSHIP
Guide And Lecturer, Department of Electrical Engineering) for his
consistent guidance, support and suggestions. I am grateful to Dr. S.A
Deokar (Principal of Sharadchandar Pawar College of Engineering and
technology Someshwarnagar)for her kind support.
I would like to thank Prof. Ghadhave.G.G .(I/C Head of Electrical
Engineering Department) for her support and suggestions.
Finally, I am thankful to all those who have directly or indirectly
helped us for this project. This project has given us great learning
experience and sense of satisfaction.
Thanking You,
Miss.Pawar Pratiksha Bhanudas.
4. Executive Summary
The company has always been contributing towards the advancement and development of the
engineering sector introducing a range of quality electrical equipments by producing hundreds of
engineers, skilled workers and technicians through its apprenticeship schemes and training
programmes.
We recently have done our internship in Indrajeet Power lines , in which we got training from its
Distribution Transformer unit. The internship basically revolved around the transformer design,
manufacturing, I&QC and maintenance. The system, the style of working & the commitment of the
employees is really exemplary.
The difference between the success & failure is doing things right and doing things nearly right, & has
always tried for success.
In this report we have given a very brief review of what we have seen and learnt during our
internship. We have mentioned all these as we have made an internship as according to the schedule.
This report will give its reader knowledge about and power division especially about transformer unit.
We have made it possible to write each and every thing that we have learnt here. We have all our
practical efforts in the form of this manuscript that’s the asset for our future career.
5. INTRODUCTION
Indrajeet Power lines India Private Limited is a private limited company based in
Pune, India and it was incorporated officially on 10/06/2019. The corporate identification
number (CIN) of this company as per the official records is U40106PN2019PTC184693 and the
company registration number is 184693. Its email address is indrajeetpowerlines@gmail.com
and its registered office address is WAGHALWADI, M NO. 460 BARAMATI, Pune, Maharashtra,
India, 413102.
Indrajeet Power lines India Private Limited is a mca provider company with the industrial
and NIC / SIC code of 40106 as per the official records. The company was registered in the year
2019 and its authorized share capital is INR 1,000,000 and paid up capital is INR 100,000. The
company’s business is based in the city of Pune.
The company is duly registered at Registrar of Companies, Pune (RoC-Pune) and is
classified as the Non-govt company.The major activities of this company as per the listed official
records are Generation of electric power by tapping solar energy,#Generation of solar energy#,
Solar energy, generation of, Solar energy tapped for production of electric power.
Indrajeet Power lines India Private Limited’s Annual General Meeting (AGM) was last held on N/A
and as per records from Ministry of Corporate Affairs (MCA), its balance sheet was last filed on 31 March
2022.
Directors of Indrajeet Power lines India Private Limited are Indrajeet Jagtap and Rajendra Tukaram
Jagatap.
Current status of Indrajeet Power lines India Private Limited is – Active.
Policy
❖ We are committed to manufacture, service & timely supply of Power, Distribution and
special type of transformers conforming to the specifications as per the client
requirements.
❖ Our supplier chain is well assessed as per our QAP which serves as a solid foundation for
us to put up the best quality product in the market.
❖ Close inspection of incoming materials, controlling in-process parameters, timely
assessment, upgradation of supplier chain, thorough inspection and testing of the
transformer ensure consistent high quality standards.
❖ We are committed to continuous improvement in performance through effective
implementation of quality management system.
6. INTRODUCTION OF TRANSFORMERS
WHAT IS TRANSFORMER?
A transformer is a device that transfers electrical energy from one circuit to
another through inductively coupled conductors-the transformer’s coils. A
varying current in the first or primary winding creates a varying magnetic
flux in the transformer’s core and thus a varying magnetic field through the
secondary winding. This varying magnetic field induces a varying
electromotive force (EMF), or “voltage”, in the secondary winding. This
effect is called inductive.
If a load is connected to the secondary, current will flow in the secondary
winding, and electrical energy will be transferred from the primary circuit
through the transformer to the load. In an ideal transformer, the induced
voltage in the secondary winding (V.) is in proportion to the primary voltage
(V) and is given by the ratio of the number of turns in the secondary (N.) to
the number of turns in the primary (₂) as follows: Vs/ Np=Vp/Np
By appropriate selection of the ratio of turns, a transformer thus enables an
alternating current (AC) voltage to be “stepped up” by making N. greater
than No, or “stepped down” by making N. less than No. The windings are
coils wound around a ferromagnetic core, air-core transformers being a
notable exception.
Transformers range in size from a thumbnail-sized coupling transformer
hidden inside a stage microphone to huge units weighing hundreds of tons
used to interconnect portions of power grids. All operate on the same basic
principles, although the range of designs is wide. While new technologies
have eliminated the need for transformers in some electronic circuits,
transformers are still found in nearly all electronic devices designed for
household (“mains”) voltage. Transformers are essential for high- voltage
electric power transmission, which makes long-distance transmission
economically practical.
7. PRINCIPLE OF TRANSFORMER:-
The transformer works on the principle of ‘MUTUAL INDUCTION’. An
alternating flux in the primary coil will create an alternating flux in the
transformer core, which is linked with the other coil which produces a
mutually induced emf according to faraday’s laws of electromagnetic
induction.
A current flowing through a coil produces a magnetic field around the coil. The
magnetic field strength H, required to produce a magnetic field of flux density B, is proportional
to the current flowing in the coil. Figure 1 shown below explains the above principle
Magnetic flux out (B)
Figure 1: Relationship between current, magnetic field strength and flux
8. A transformer is a static piece of apparatus used for transferring power from one circuit to
another at a different voltage, but without change in frequency. It can raise or lower the voltage
with a corresponding decrease or increase of current.
A transformer is a static piece of apparatus used for transferring power from one circuit to
another at a different voltage, but without change in frequency. It can raise or lower the voltage
with a corresponding decrease or increase of current.
When a changing voltage is applied to the primary winding, the back e.m.fs generated by
the primary is given by Faraday’s law,
EMF Vp -Np AAt (1)
A Current in the primary winding produces a magnetic field in the core. The magnetic field
is almost totally confined in the iron core and couples around through the secondary coil. The
induced voltage in the secondary winding is also given by Faraday’s law
Vs = -Ns AAB --- (2) At
The rate of change of flux is the same as that in primary winding. Dividing equation (2) by
(1) give
9. Vs/Vp= Ns= Np
In Figure 2, the primary and secondary coils are shown on separate legs of the magnetic
circuit so that we can easily understand how the transformer works. Actually, half of the primary
and secondary coils are wound on each of the two legs, with sufficient insulation between the
two. Coils and the core to properly insulate the windings from one another and the core. A
transformer wound, such as in Figure 2, will operate at a greatly reduced effectiveness due to the
magnetic leakage. Magnetic leakage is the part of the magnetic flux that passes through either
one of the coils, but not through both. The larger the distance between the primary and secondary
windings, the longer the magnetic circuit and the greater the leakage. The following figure shows
actual construction of a single phase transformer.
The voltage developed by transformer action is given by E = 4.44xfxNxBmaxxAcore
Where, Erated coil voltage (volts), f operating frequency (hertz), N = number of turns in the
winding, Bmax = maximum flux density in the core (tesla), and Acore cross-sectional area of the
core material in Sq. meters.
10. In addition to the voltage equation, a power equation expressing the volt-ampere rating in
terms of the other input parameters is also used in transformer design. Specifically, the form of
the equation is
. VA 4.44xfxNxBmaxxAcorexJxAcond
Where, N, Bmax, Acore and fare as defined above, J is the current density (A/ sq. mm), and
Acond is the coil cross-sectional area (mm2) in the core window; of the conducting material for
primary winding. J depends upon heat dissipation and cooling
Mainly there are two types(divisons) in this company which are as
follows:
1.Manufacturing of Transformer
2. Maintenance of transformers
And I was given the maintenance department because there was more
maintenance work than manufacturing.
MANUFACTURING PROCESS OF TRANSFORMER
1. Winding Construction
2. Core Assembly
3. Core & Winding(Coil) Assembly (CCA)
4. Tapping &Tap Changer
5. Drying Process
6. Tank Construction
7. Tanking & Final Fitting
8. Fittings & Accessories
9. Painting
10. Oil Filling & Filtration
11. Testing
.1.Winding Construction:-
Conducting material is used in the windings of the transformer. Usually the
windings are in concentrically to minimize the flux leakages. There are two types
of windings. The coils are wound on the limbs and are insulated from each other in
the basic transformer the two windings wound on the two different limbs. Due to
this leakage flux increases which affects the transformer efficiency or performance
11. so it should be necessary that the windings should be very close to each other to
increase the mutual inductance and stray capacitance to improve the high
frequency response. Such cylindrical coils are used in core type transformers and
sandwich coils are very commonly used in shell type transformer here each high
voltage winding lies between two low voltage windings such subdivisions. Of
windings into small portions reduce the flux leakages.
Transformer windings are designed to meet three fundamental requirements,
viz. mechanical, thermal and electrical. They are cylindrical in shape and are
assembled concentrically. Paper insulated conductors of high conductivity & soft
drawn E.C. Grade copper is used which comply with the latest Indian as well as
international Standards. Windings are made with great care by well experienced
skilled. Workers in dust free & temperature controlled environment. Insulation
between layers and turns is based upon the electrical and Mechanical strength
level. Interlayer cooling ducts (Axial & Radial) are Provided to minimize the
temperature gradient between windings and oil, and hence the hot spot temperature
is kept to a minimum. This also ensures that the rate of insulation deterioration is
minimized and high life expectancy is achieved.
Transpositions are made in multiple conductor windings, to ensure uniform
current distribution, minimize circulating currents, decrease eddy current loss and
improve the lamination factor.
.2.Core Assembly:-
Core is built with Cold Rolled Grain Oriented Silicon Steel, low loss. Silicon steel
lamination. Bonded core design/ technique is used to eliminate hole punching and
to minimize fixed losses and Magnetizing Current. Use of HiB grade & Laser
scribed Laminations and Rigid clamps significantly reduce vibrations and noise
level. Cooling ducts are provided in large transformers for efficient circulation of
oil to keep temperature of core well within limit without affecting the flux
distortion and also in the core suitable insulation paper are inserted between some
laminations for the purpose of reducing eddy currents and also minimizing
magnetic short circuit.
Core of the transformer is either in square or rectangular in size. It is further
divided into two parts. The vertical position of the core is limbs and horizontal
position of the core is yoke of the core. Core is made up of laminations to reduce
12. the eddy current losses get minimized. This lamination is insulated by using
insulations line varnish or thick paper. Paper insulation is used for low voltage
transformer and varnish is used for high voltage transformer.
The step lap or Mitred joints at the core corners ensure a stream line magnetic
flux path. The core limb are held with resin bonded glass bands to eliminate limb
bolts. Yokes are clamped by solid mild steel plates with yoke stud ensuring high
rigidity for withstanding mechanical socks during transportation & Short Circuits.
The leg core in a which hard wooden bars are inserted, are tighten with synthetic
resin impregnated fibre glass tape.
.3. Core & Winding(Coil) Assembly (CCA):-
L.V. Windings are normally placed near core over insulating cylinder and oil ducts.
HV Windings are assembled co-axially placed with respect to LV. Spacers between
coils are T shaped for added firmness. Coils are assembled with best insulating
materials and are adequately clamped. SPA methodology is now a day widely
adopted to have it’s special beneficial characteristics. The winding is rigidly
supported by a common spacer ring of densified wood at the top and bottom for
precise alignment. Well profiled angled rings are placed between LV & HV
windings to reduce voltage stress level. The ends & tapping leads of all windings
are connected by special extra flexible, insulated copper cables which are rigidly
braced in position.
.4. Tapping &Tap Changer:-
Generally Taps are provided on HV Windings for HV Variation or LV Variation as
specified by customer. These are brought up to a gang operated switch, suitable for
external manual operation and can be locked in any desired position to avoid
unauthorized operation. All the moving contacts are spring loaded to ensure proper
pressure and good contacts. To achieve precise voltage regulation on load tap
changer is used instead of OCTC. Usually Higher capacity transformers i.e above
5000 KVA ratings, can be supplied with On Load Tap Changer along with
necessary controls to make it suitable for manual, local electrical or remote
Electrical operation.
.5 Drying Process:-
The core coil assembly is placed in Vacuum Auto Enclave to eliminate moisture
content which is targeted less than 0.5% moisture. Drying process is to be carried
13. out @ 90°C & respective vacuum cycle at rated interval to improve Insulation
resistance and remove ingress of moisture in insulation. Material. Drying of grain
involves exposing grain to air with low relative humidity (RH) which will lead to
evaporation of the moisture in the grain and then the moisture’s removal away
from the grain. Since drying practices can have a big impact on grain or seed
quality, it is important to understand some fundamentals of grain drying.
5.1. Moisture removal:-
In paddy grain, moisture is present at two places: at the surface of the grain,
‘surface moisture’, and inside the kernel, internal moisture. Surface moisture will
readily evaporate when grain is exposed to hot air. Internal moisture evaporates
much slower because it first has to move from the kernel to the outside surface. As
a result, surface moisture and internal moisture evaporate at a different rate. This
difference results in a different. ‘drying rates’for different period of drying. The
drying rate is defined as the rate at which grain moisture content declines during
the drying process.
.6.Tank Construction:-
Small capacity tanks are fabricated from sheet steel while larger ones are
assembled with cast aluminium. For cooling purpose the tank is welded with
cooling tubes. These are some types of transformer tanks.Protection of active part
in transformer is very important. While achieving the optimized size of transformer
to suit the site condition for installation.
The main role of the tank is to protect the active part and tank is
manufacture to have sufficient strengths to withstand internal & external faults that
may occur during operation. Tanks are fabricated from low carbon M.S. Sheet of
best quality proceed by qualified welders. The tank is designed to withstand
vacuum and pressure test as per Indian / International standards. A robust skid
under base is provided, and guide bars are located inside the tank to securely fix
the core and windings assembly in position, and to prevent any movement during
transportation.
14. .7. Tanking & Final Fitting:-
Dried out Core & Coil Assembly is tightened before application of hot oil
shrinkaging for 24 hours. The oil shrinkaging process avoids looseness of active
parts during it’s service at site. At last uniform pressing is done on Core & Coil
Assembly. High mechanical rigidity is achieved by hydraulic pressing at circulated
force and tightening all pressure screws. Pressed Core & Coil Assembly is put in to
the tank with proper locating & locking arrangements which is of prime
importance to achieve high resistivity against transient damages, vibrations during
service and Forces develop during fault occurrence.
After completion of Core & Coil Assembly insertion in tank, hot, degassed oil
is then allowed into the transformer tank under vacuum. This oil is then circulated
through the transformer and the oil degassing plant until all gas trapped in the core,
windings, and the insulation is removed. This ensures a high degree of stability in
the insulation structure and early attainment of its mature condition, which would
not otherwise be achieved until the transformer had been in service for some time.
.8.Fitting & Accessories:-
The transformer is supplied with rating and terminal marking plate made out of
non-corrosive metal. The plate contains information concerning the rating, voltage
ratio, weights, oil quantity, vector group, etc. The plate also includes unit Sr. no.
and year of manufacturing.
15. Training Program :-
Discription of operation perform by department Work:-
OPERATION OF MAINTENANCE:-
L.S.2026-1977 states that a Power Transformers loaded at its rated KVA will
fulfill its normal life when its hottest spot temperature H.S.T. is 98°C for an air
temperature of 32°C As the ambient air temperature exceeds 32°C the H.S.T.
exceeds 98°C The insulation ageing (which decides the life of transformer
increased with increase of H.S.T. increase of H.S.T. by 6°C doubles the rate of
ageing | i.e. reduces the life by 50%). When the ambient air temperature is lower
than 32°C the H.S.T. is lower than 98°C. The insulation ageing decreases thus
increases the life of transformer.It Is considered (by the I.S. 6600-1973) that
periods of accelerated ageing due to higher ambient temperature are compested by
the period of reduced ageing due to lower ambient temperature.
Some times a transformer may be required to deliver load higher than its
rating. Guidance on overloading it provided by 1.S. 6600 Basis for the
recommendation is an follows. In a 24 hours loading. If ambient temperature is low
and loaded for a substantial time duration is also low a short time over load may be
16. permitted such that equivalent aging due to this varying load will be the same as
that of loading over a period of 24 hours.
Maintenance:-Following points are checked for maintenance
of transformer:
1. OIL
2. Care & Winding
3. On Load Tap Changer
4. Conservator & Oil level Indicator
5. Silica Gel Dehydrating Breather
6. Buchholz Relay
7. Pipe work
8. Explosion Vent
9. Bushing.
10. External connections Include Earthling
❖General:-
Compared to most electrical equipments transformer requires relatively
less maintenance. However in order to obtain a long and trouble free service
from the transformer. It must be properly maintained. Maintenance consist
of regular inspection testing and reconditioning When necessary. Principal
17. object of maintenance is to maintain the insulation in good condition.
Moisture dirt and high temperature causes insulation deterioration i.e.
ageing. Hence they must be prevented.
No work should be done on the transformer unless It is Disconnected
from all external circuits and all windings have been solidly earthed. Naked
lights and flames should be kept well away from theTransformer.Precautions
must be taken to secure tools with tapes to prevent them from falling inside
the tank. Maintenance hints on main constituents of the transformer are
given in the following paragraph. Recommended frequency of maintenance
is given at the end of the chapter. Detailed guidance on Maintenance is given
in I. S. 10028 part- II 1981.
.1.OIL:-
In the transformer, oil is used as an insulating liquid as well as for cooling, It
is necessary to maintain required oil level and also to maintain this oil in good
condition I.S. 1866. Gives recommendations in details for the maintenance of oil.
A few guide lines are given here.Check if there is any leakage of oil. It noticed,
corrective action. Must be immediately taken.
The oil level should be checked at frequent intervals and if necessary, topping
up should be done with oil complying with I.S. 335. Samples of oil should be taken
at regular intervals and tested. If the dielectric strength is below the value
recommended in I.S. 1866, the oil should be duly filtered. It may be noted that. The
products of decompositions with, water acids etc. remain. In the oil and accelerate
the rate of aging. Thus, timely treatment of oil is a must. The filteration will
remove moisture, dust sludge etc. Removal of sludge is important as otherwise it
can stick to coils and hamper the heat dissipation from coils. However if the results
indicate that acidity needs to be improved. Them a simple filteration would not be
sufficient and a Fullers Earth treatment would be required.
.2. care & Winding:-
18. It id recommended that the core and windings are removed from the tank
for visual inspection as per the maintenance schedule given. Depending upon the
arrangement provided, tap switch handle, connections to bushings etc., may have
to be disconnected before lifting up core and wings assembly
The windings should be examined and If sludge has been deposited it should
be washed away with oil jet. Any loose nut and bolt should be tightened. Adjust the
rods/coil clamping screws provided to remove any slackness of windings. This is
important as slackness in winding will permit movement of coils under the action
of Short Circuits forces and repeated coil movement can wear out insulation and
give rise to a fault.
.3. On Load Tap Changer:-
On load tap changer is, normally, mounted on the tank in the separate
housing and connected to winding leads through copper studs fixed. On insulated
terminal board. Terminal board is oil-tight. Hence oil in the tank need not be
lowered for attending O. I. T. C.In some other types O. I. T. C. is housed in the
main tank by suitable mounting on the top cover Here again O.L.T.C. oil in which
arcing tanks place is not allowed to mix with the man tank oil. Please refer to
O.LT.C. menual for operation and maintenance instruction of O.L.T.C.
.4.Conservator & Oil level Indicator:
The Inside of conservator should be cleaned by flushing, clean Transformer oil to
remove sludge and other impurities. In bigger transformers, detachable end plate is
provided to facilitate cleaning of conservator.Oil gauge glass should be cleaned if
then glass is found broken, the same should be replaced.
Magnetic oil guageto be attended while cleaning the conservator. The
mechanism should be inspected and cleaned Float should be checked to see that
there is no oil in the float. This operation of alarm and trip contacts should to be
checked.
.5.Silica Gel Dehydrating Breather:-
Breather should be examined to ascertain if the silica gel requires.
Changing. More frequent inspection are needed when the climate is humid and
when transformer is subjected to fluctuating load. The colour of silica. Gel crystals
in the breather acts as an indicator as an indicator as it changes from blue to pink
when saturated with moisture. When majority of crystal have turned pink. The
19. silica gel should be reactivated by beating in. oven of a shallow pan at a
temperature of 150°C to 200°C until the original colour is gained. This usually
takes 2 or 3 hours. Oil cup should be cleaned. To remove dust and dirty oil. Oil seal
should be filled with fresh oil.
.6. Buchholz Relay:-
Routine operation and mechanical inspection should be carried out as per the
manufacturing instruction..
.7.Pipe work:- The pipe work should be inspected for leakages, which may be
due, to bad seated joints, joints should be re-made and leakage stopped.
.8.Explosion Vent:-
The diaphragm at the exposed end of the exposion vent should be inspected
and replaced if damaged Failure to replace the diaphragm quickly may allow the
ingress of moisture in the transformer,Whenever button diaphragm ruptures. Oil
rises inside the explosion vent pipe and visible in the oil level indicator on
explosion vent. It diaphragm is broken because of fault in the transformer.
Inspection should be carried out to determine the nature and case of their fault.
.9. Bushing:- Porcelain insulators should be cleaned and minutely examined for
any cracks, chipping off & other defects. All such bushings should be replaced. In
case of any sign of oil leakage from the condenser bushings the matter should be
referred to us.
.10.External connections Include Earthling:-
Check all external electrical connections including earthing. They should be
tight. If they appear blackened or corroded, unbolt the connection and clean with
emery paper. Remake the connections and give a heavy coating of conducting
grease. It is particularly important that heavy current carrying connections are
properly made as any loose connections give rise to eat generation & temperature
rise which could be detrimental to the connection.
