Post on 01-Feb-2023
Change Your Life
Change Your Life
Internship Report
Submitted To: Human Resource PEL
Submitted By: Ahmar Mumtaz
1 University of Engineering & Technology,Taxila.
Change Your Life
Supervisor: SE Muhammad Tayyab
Internship Department: Product Development
Internship Duration: 9June,2014-7 July,2014
Table of ContentsDedication…………………………………………………………3
Acknowledgement……………………………………………4
Executive Summary…………………………………….……....5
Introduction of PEL…………………………………….….…….6
Transformer……………………..…………………………………22
Transformer Design ……………………………………………..24
Transformer Manufacturing…………………………………25
Winding……………………………………………..25
Phasing……………………………………………….29
2 University of Engineering & Technology,Taxila.
Change Your Life
Reclamation-Unit 3……………………………29
Core Section………………………………………30
Assembly…………………………………………….32
Testing………………………………………………..35
Conclusion…………………………………………………………39
Reference…………………………………………….40
3 University of Engineering & Technology,Taxila.
Change Your Life
DedicationTo all those who have supported, encouraged,challenged, and inspired me. And specially to myBeloved Parents, honorable teachers and friends for alltheir guidance, love & attention which has made itpossible for me to make it up to this point and as wellas the Internship Supervisors who bestowed me with thecourage, the commitment and the awareness to follow thebest possible route, by their unmatchable style and bybest possible training.
4 University of Engineering & Technology,Taxila.
Change Your Life
AcknowledgementAll the praises are for the almighty, Allah whobestowed me with the ability and potential to completethis Internship. I also pay my gratitude to theAlmighty for enabling me to complete this InternshipReport within due course of time.
Words are very few to express enormous humbleobligations to my affectionate Parents for theirprayers and strong determination to enabling me toachieve this job.I also appreciate the cordial co-operation from all my Internship Supervisors in thedifferent departments of PEL and also of HR managementfor providing me requisite information and knowledgefor compilation of my complete Internship.
All the employers of PEL helped me a lot in performingall the activities and in gaining the practicalknowledge of industry. They gave me best environmentand knowledge to enhance my skills.
5 University of Engineering & Technology,Taxila.
Change Your Life
Executive SummaryPak Elektron Limited (PEL) is the pioneer manufacturer
of electrical goods in Pakistan. It was established in
1956 in technical collaboration with m/s AEG of
Germany. In October 1978, the company was taken over by
Saigol Group of companies. Since its inception, the
company has always been contributing towards the
advancement and development of the engineering sector
in Pakistan by introducing wide range of quality
electrical equipments and hoe appliance and by
6 University of Engineering & Technology,Taxila.
Change Your Life
producing hundreds of engineers, skilled workers and
technicians through its apprenticeship scheme and
training programs. I did my internship in Marketing AD
department of PEL.
I learned a lot during my internship period. How to
work individually as well as in groups under relaxed
and stressful environment. How to work under someone’s
supervision. How to manage affairs while launching new
products. Patience is very important in dealings, as
anger can lose your customer. To increase your sales
and stay in competition with top brands it is necessary
to keep your dealers happy by giving them incentives.
During a span of four weeks of training as intern I
thoroughly observed the functions of different
departments of PEL (Pak Elektron Limited). As
apprentice I analyzed the basic working of PEL and
especially Product(PD) development(Power Transformer)
and summarized this in my internship report.
Introduction of PEL7 University of Engineering & Technology,Taxila.
Change Your Life
Pak Elektron Limited (PEL) was in corporated in Pakistan on march
03,1956 as a public limited company under the companies Act, 1913
(replaced by companies ordinance 1984). Registered office of the
company is situated at 17 Aziz Avenue, canal bank Gulberg_ V
Lahore. The company is currently listed on all three stock
exchange of Pakistan. The principal activity of the company is
manufacturing and sales of electrical capital goods and domestic
appliances.
These activities are organized under following divisions.
Power division: manufacture of switchgear, energy meter, and transformers.
Appliances division: manufacture and assembling of refrigerators, air conditioner, microwave oven, television and
washing machine.
BRIEF HISTORY
PAK ELEKTRON LIMITED was set up in 1956 as a joint venture with
one of the largest and renowned manufacturers of electrical
equipment Messrs. AEG of West Germany for manufacturing
Transformers, Switchgears and Electric Motors etc. The entire job
of machinery requirements and layout of the factory building was
planned and implemented by AEG who produced very well balanced
8 University of Engineering & Technology,Taxila.
Change Your Life
facility for the design and manufacture of the above equipment
and the commercial production was commenced on 22 November 1956.
Up to 1962, when AEG finally phased out, the designing and
manufacturing of all equipment was carried out jointly by AEG
experts and PEL personnel. PEL staff, in the meantime, had
received specialized training in USA and West Germany which
enabled PEL to establish itself as the leading manufacturers of
electrical equipment in the country with an excellent reputation
for high quality and thus PEL came to be known as "THE QUALITY
CONSCIOUS COMPANY".
After conclusion of agreement with AEG, total share holding of
AEG was purchased by the then sponsors - Malik Brothers. The
production continued with AEG designs with much greater emphasis
on the quality and reliability of the products which earned
unique distinction of supplying electrical equipment to projects
of paramount national importance like Mangla Dam and Tarbela Dam
Projects. PEL equipment was approved by consultants of
international repute including Preece Cardew & Rider (England),
Binnie & Partners (England), Harza Engineering International
(USA) and Miner & Miner International Inc. (USA).
The majority shares were acquired from Malik Brothers by Saigol
Group on 11 October 1978 and immediately on takeover the new
management chalked out both long term and short term plans to put
the company back on the path of progress. As a part of first 9 University of Engineering & Technology,Taxila.
Change Your Life
phase of its BMR Programmer the new management injected the
additional working capital of Rupees 8.98 million and Bridge Loan
of Rupees 7.50 million (against the public issue of its shares)
was provided by the ICP-led Consortium. As a part of long term
plans, the manufacturing of window type Air conditioners was
taken up in 1981 and was immediately established for quality.
The company launched the second phase of its BMR and expansion of
the existing product line in the year 1987 and imported machinery
for the manufacture of Refrigerators and Deep-freezers for a
total value of Rupees 22.11 million. For the project National
Bank of Pakistan - the leading bank of the company provided the
financing. Like Airconditioners these products have also been
well received by the local market, which speaks highly of the
confidence, the consumer has developed in the quality products
manufactured by the company?
During the year 1990 the company has signed an agreement with
Messrs HITACHI of Japan for the manufacture of Vacuum Circuit
Breakers.
The company has entered into an agreement with Pakistan
Industrial Credit and Investment Corporation (PICIC) for a
foreign currency as well as local currency loan of Rupees 25
million for the expansion, balancing, modernization and
replacement of the
10 University of Engineering & Technology,Taxila.
Change Your Life
existing plant. The machinery has come into operation in October
1991 and with the balancing, modernization and replacement of
machinery, the production capacity of Refrigerator Section will
reach a level of 252,450 cubic feet.
The management of the Company decided to further expand its
operation by establishing a plant for the manufacture of
compressors for refrigerators and deep freezers. The technical
know-how agreement has been signed with M/S NECCHI Compressori,
Italy for the assembly and progressive manufacturing of
compressors for refrigerators and deep freezers.
Group Profile
In 1948, the Saigols migrated from Calcutta and initiated their
business in Lyallpur (later named to as Faisalabad), the textile
city of Pakistan, under the banner of Kohinoor Industries
Limited.
Kohinoor Textile MillsThe Saigols set up the first major textile unit - The Kohinoor
Textile Mills under the umbrella of Kohinoor Industries Limited.
The Kohinoor Textile Mill has state-of-the-art quality control
from raw material to finished product manufacturing. Its
laboratory is top rated amongst the best laboratories in Pakistan
for testing of textile raw materials, other inputs and yarn.
11 University of Engineering & Technology,Taxila.
Change Your Life
Initial Capacity:25,000 spindles
Current Capacity: 71,648 spindles
Pak Elektron Limited (PEL)
In 1978, the Saigol Group of Companies purchased major shares of
Pak Elektron Limited. At that juncture, the company was only
manufacturing transformers and switchgears. With the Saigols in
management, PEL started expanding its product range by entering
into Air Conditioner manufacturing.
Saritow Spinning Mills & Azam Textile Mills
In 1987, the Saritow Spinning Mills and Azam Textile Mills were
established under the banner of Saigol Group of Companies.
Saritow Spinning Mills is a spinning unit with 25,440 spindles
capacity. Facilitated with the most modern and efficient Japanese
and European machinery, its knitted yarn is renowned in the Far
East and Europe for its fine quality. Azam Textile Mills is
reputed for its carded and combed yarn, which is quite popular
for premier knitting and weaving.
Kohinoor Power Company Limited
12 University of Engineering & Technology,Taxila.
Change Your Life
In 1991, the first power unit commissioned in Pakistan, in the
Private sector, was Kohinoor Power Company Limited. Its present
production capacity is 15 MW.
Kohinoor Energy Limited
1995, another power unit, Kohinoor Energy Limited, was
established. Kohinoor Power Limited is a 120 MW power plant
located on the outskirts of the city of Lahore. This project has
an annual turnover of $80 million.
VISION STATEMENT
13 University of Engineering & Technology,Taxila.
Change Your Life
To excel in providing engineering goods and services
through continuous improvement.
MISSION STATEMENT To provide quality products & services to the
complete satisfaction of our customers and maximize
returns for all stakeholders through optimal use of
resources.
To focus on personal development of our employees
to meet future challenges.
To promote good governance, corporate values and a
safe working environment with a strong sense of
social responsibility.
14 University of Engineering & Technology,Taxila.
Change Your Life
Board of Directors
Mr. M. Naseem Saigol ChairmanMr. M. Azam Saigol
Mr. Murad Saigol
Mr. M. Zeid Yousaf Saigol
Mr. M. Abdullah Haroon Saigol
Mr. Haroon Ahmed Khan Managing Director
Mr. Syed Zubair Ahmed Shah NIT Nominee
Mr. Akbar Hassan Khan NBP Nominee U/S 182 of
the Ordinance
Ms. Tahira Raza NBP Nominee U/S 182 of
the Ordinance
Mr. Khalid Siddiq Tirmzi BOP Nominee U/S 182 of
the Ordinance
Mr. M. Khuram Khuwaja NBP Nominee U/S 182 of
the Ordinance
Audit Committee
Mr. Azam Saigol Chairman
Ms. Tahira Raza Member
Mr. Syed Zubair Ahmad Shah Member
Mr. Haroon Ahmad Khan Member
15 University of Engineering & Technology,Taxila.
Change Your Life
Company Secretary
Mr. M. Omar Faro
DEPARTMENTS IN PEL The departments which are currently in operation at PEL are as follows:
Common Departments: HR & D IR & A Finance IT FP & Commercial Accounts
Marketing and Sales: Marketing AD Marketing PD CMD CSD
Production Department:
Production AD
Production PD
16 University of Engineering & Technology,Taxila.
Change Your Life
PEL has divided the Production department into two
further departments:
Power Division
Appliance Division
POWER DIVISION
PEL’s Power Division manufactures transformers, switchgear,
energy meters, kiosks, compact stations, shunt capacitor banks
etc. All the power equipment is assembled under strict quality
control and in accordance with international standards.
PEL is a major power equipment supplier to Water and Power
Development Authority (WAPDA) and Karachi Electrical Supply
Corporation (KESC).In-spite stiff competition from emerging local
and multinational brands, PEL’s appliances and power equipments
have consistently gained marked share due to constant innovation
and high quality standards. Strategic partnerships with Copeland,
Danfoss, Samsung and others have enabled the Company to
17 University of Engineering & Technology,Taxila.
Change Your Life
incorporate new technologies into existing product ranges, thus
introducing new product features.
During the year 2006, PEL retained its market leadership in the
Power Equipment market, increasing its market share from 33% in
2005 to 36% in 2006 in the switchgear market and also maintained
share of 35% in 2006 as well in the energy meters market. PEL’s
leadership in the Power Equipment market is largely due to its
strong Research and Development knowledge and high product
quality.
PEL has the privilege of getting its equipment approved andcertified by well-reputed international consultants such as:
Preece, Cardew and Rider, England Harza Engineering Company, USA Snam Progeti, Italy Societe Dumezm, France Miner & Miner International Inc. USA Ensa, France
Power Division accounted for 47% of the Net Sales of the Company
as of June 30th 2006. The sales and profit participation by the
Division is high due to high quality standards and future growth
opportunities.
The Power Division comprises of three departments;
1. Manufacturing and Quality Control
18 University of Engineering & Technology,Taxila.
Change Your Life
2. Design and Development
3. Marketing
PRODUCTS POWER DIVISION
ENERGY METERS
TRANSFORMERS
SWITCH GEAR
TRANSFORMERSPEL has vast experience in design and manufacturing of standard
and special purpose transformers These transformers are available
for various applications.
Distribution Transformers
Auto Transformers
Furnace Transformers
Welding Transformers
PEL transformers have been successfully type tested for impulse
voltage and short circuit tests by KEMA Laboratories of
HollandTransformers are normally supplied in a period of 3 – 4
months after the receipt of orders from respective distribution
companies of WAPDA and varied supply time for private customers.
The Company provides one year after sales service warranty to
WAPDA, KESC and private sector customers. Main Competitors are
19 University of Engineering & Technology,Taxila.
Change Your Life
Siemens, Transfopower, Elmetec and Climax, while PEL having a
market share of 38 %.
ENERGY METERSFollowing types of meters are manufactured:
Electro mechanical
Single phase
Three phase_ Direct connected
Three phase _CT operated
Static/Digital
Single Phase
Three Phase Directed connected
Three Phase_CT operated
Three Phase_TOU
PEL manufactures three types of energy meters; Single Phase and
Poly Phase. The electro-mechanical energy meters are manufactured
under license from ABB of USA. The quality of PEL meters has been
certified by KEMA Laboratories of Holland.Single Phase energy
meters provide maintenance-free operations over a long period.
Energy meter orders from WAPDA are received annually and their
supply period is 9 -10 months. Energy meters to KESC are supplied
in a period of 3 - 4 months. The Company provides one year after
sales service warranty to WAPDA, KESC and other customers. In the
20 University of Engineering & Technology,Taxila.
Change Your Life
supply of Energy Meters PEL share accounts for 35 % of the total
supplies while the rest is shared by Syed Bhais, Escort and
Telephone Industries.
SWITCHGEARSSwitchgears are one of the highly technical and specialized power
products of PEL. They are produced for indoor and outdoor
installations complying with international installation
standards. A major customer for this product is WAPDA. The
Company provides one year after sales service warranty to WAPDA,
KESC and other customers. In Switchgear, PEL enjoys market share
of 33 % while competitors are Alstom, Siemens and Fico.
POWER TRANSFORMERS
Owing to massive growth in power sector, demand for power
transformers is also growing proportionately for all ratings from
66KV to500 KV. PEL has stepped into this activity by starting the
manufacturing of 132 KV transformers, being the most demanded
rating, and for this purposes has formed a strategies partnership
by signing the two agreement. Based on the demand forecast of
Power Transformers for WAPDA, KESC and other projects, PEL’s
market share is initially targeted to be 20%, growing in five
years.
The main Customers of PEL
21 University of Engineering & Technology,Taxila.
Change Your Life
The customers of PEL can be categorized in two categories i.e.home consumers and industrial consumers. Home consumers are thecommon individuals who mostly purchase the home appliances. Theindustrial consumers are as follows:
LESCO GEPCO FESCO IESCO PESCO MEPCO HESCO QESCO KESC AJK Electricity Department
Appliances DivisionBusiness in appliances division has shown mixed trend but the
Company is finally on the right track. Crystal Refrigerator with
Aero design and Danfoss compressor with performance
certification by Danfoss Germany was launched in the February
1999. This has been received very well in the market and our
refrigerator sales have shown an increase of ver 125% since 1999.
This thrust is expected to continue in the following year as a
22 University of Engineering & Technology,Taxila.
Change Your Life
result of company’s innovative approach in product development
coupled with an aggressive marketing strategy. Deep Freezer tested and certified by Danfoss Germany and with
improved aesthetics has also been well received by the market. We
have already been supplying our Deep Freezers to Coca-Cola
international and lever Brothers and intend to continue our focus
on institutional sales of this product.
Products of Appliance DivisionAppliance division has following products;
Refrigerators
PEL’s refrigerators are available in 6 series of different
colors, models, prices, and capacities. The series are as follow
Xpression Series
Premier Series
6-Series
Deluxe Series
Smart Series
Mini Series
Air Conditioners
The air conditioners are available in three types;
Split Air Conditioners
Window Air Conditioners
Floor Standing Air Conditioners
23 University of Engineering & Technology,Taxila.
Change Your Life
Microwave Oven
PEL also introduce model series of “PEL Silver line” Microwave
Oven. PEL presents 26 different models of oven with different
prices, models and capacities.
Washing Machine
PEL’s washing machines are available in different models. The
series are as follow;
Magic Clean PWM7700
Magic Clean PWM512
Water Dispensers
PEL also Introduce water dispensers. The main purpose to
introduce it is to increase their product line and give value to
their customers.
Generators
From long time Pakistan facing energy crisis, at that time
introduction of PEL Generator is very positive steps toward
appliance sector to facilitate their customers. And they are
working more to increase their product line, produce quality
products, and give value to their customers and become market
leader in home appliance
24 University of Engineering & Technology,Taxila.
Change Your Life
LG PRODUCTSLG has entered in a strategic partnership with PEL. According to
this agreement PEL has become the official distributor of LG
products in PAKISTAN from June 2009.
LG products in Pakistan are:
Refrigerator
Split air conditioner
Washing machine
Microwave oven
ISO 9001 Certification
PEL was 16th Company in Pakistan which got ISO 9002 Certification
in 1997, since then PEL Management is applying this International
Standard Practices for Effectively Managing Quality of Products
and Services that Company Offers. The International Standard
Practices in PEL have been Upgraded as per the Revised ISO 9001
Standards and its Scope of Application is expanding ever since
and Top Management is Committed to make PEL a Total Quality
Management (TQM) Company.
25 University of Engineering & Technology,Taxila.
Change Your Life
EPC Contracting
With restructuring of power sector in Pakistan and increase ineconomic, commercial and industrial activity, more and more powerutilities and other customers demanded high value packagedsolutions for their transmission system and enterpriseelectrification requirements. To meet this demand PEL establishedan Engineering Procurement and Construction division. PEL EPCDivision consists of human resource with high academicqualifications and experience of local as well as global market.The EPC division delivers custom designed and built solutions infollowing areas.
132kV and 220kV grid stations for power utility companies. 132kV and 11kV substations for industrial and commercial
customers. Integration of private captive power generation plants into
utility network for sale of their surplus power to utilitycompanies.
Electrification of housing projects and industrial parks.
26 University of Engineering & Technology,Taxila.
Change Your Life
Services include:
Engineering Project Management Project Execution Turnkey or customized projects Technical support and solution
Awards won by PEL:
Annual Environment Excellence Award-2009
Annual Environment Excellence Awards are instituted jointly
by National Forum for Environment and Health (NFEH), United
Nations Environment Program (UNEP), Ministry of Environment,
Government of Pakistan and the Federation of Pakistan
Chambers of Commerce & Industry (FPCCI). Annual Environment
Excellence Awards are designed to recognize and promote the
organizations which make an outstanding contribution to
sustainable development. They aim to highlight policies,
practices, processes and products from all sectors of
business in the country, which help to achieve economic and
social development without detriment to the environment and
natural resources.
Pak Elektron Limited (PEL) was awarded 6th Annual
Environment Excellence Award for best Health, Safety and
Environment performance. The Award was presented to Pak
Elektron Limited in a graceful ceremony; held on July 09,27 University of Engineering & Technology,Taxila.
Change Your Life
2009 at Hotel Sheraton, Karachi. Mr. Hameed Ullah Jan
Afridi, Federal Minister for Environment, honored the
ceremony by as chief guest whereas Mr. Askri Taqvi, Minister
for Environment, Sindh presided over. Javed jabber (Global
Vice President IUCN), Dr. Kaiser Waheed (Chairman NFEH) and
Naeem Qureshi (President NFEH) were also present on the
occasion. Mr. Yaqub Tabasum (Project Manager Unit-II)
received the Environment Excellence Award on behalf of PEL.
Health & Environment National Excellence Award-2008
On the basis of sound Health, Safety & Environmental
performance; PEL was selected for 4th Health & Environmental
National Excellence Award-2008. These awards are offered by
Help International Welfare Trust, Pakistan in collaboration
with Corporate Social Responsibility (CSR) Association of
Pakistan. The award presentation ceremony was held at Hotel
Regent Plaza, Karachi on April 15, 2009. Mr. Askari Taqvi,
Minister for Environment, Government of Sindh was Chief
Guest of the ceremony and Ms. Khadija Balkhi, President of
CSR Association of Pakistan was the Guest of Honor at the
occasion.
Best Environmental Reporting Award
Pak Elektron Limited (PEL) was awarded the Best
Environmental Reporting Award for 2008 at the 7th ACCA-WWF
28 University of Engineering & Technology,Taxila.
Change Your Life
Pakistan Environmental Reporting Awards (PERA) ceremony held
on Earth Day; April 22, 2009 at the Serena Hotel, Islamabad.
TransformerA transformer is an electrical device that transfers energy between two or more circuits through electromagnetic induction.A varying current in the transformer's primary winding creates a varying magnetic flux in the core and a varying magnetic field impinging on the secondary winding. This varying magnetic field at the secondary induces a varying electromotive force (emf) or voltage in the secondary winding. Making use of Faraday's Law in conjunction with high magnetic permeability core properties, transformers can thus be designed to efficiently change AC voltages from one voltage level to another within powernetworks.By Faraday's law of induction
. . . (1)[a]
. . . (2)Combining ratio of (1) & (2)
Turns ratio . . . (3) wherefor step-down transformers, a > 1for step-up transformers, a < 1
29 University of Engineering & Technology,Taxila.
Change Your Life
By law of Conservation of Energy, apparent, realand reactive power are each conservedin the input and output
. . . (4)Combining (3) & (4) with this endnote] yields the ideal transformer identity.
Classification of transformerAccording to the construction:
Core type Shell type
According to supply system: Single phase Three phase
According to use: Power transformer Distribution transformer
According to the mode of operation; Step up step down
According to the way of cooling dry type oil immersed self cooled oil immersed force air cooled oil immerse water cooled oil immersed force oil cooled air blast
30 University of Engineering & Technology,Taxila.
Change Your Life
Transformer DesignWhenever any client wants to purchase any transformer, it sendsits required specifications to the Marketing department of PEL;this is called Enquiry. The marketing department then sends thisenquiry to the design department. The design department performsthree main tasks:
Estimation of the Cost Dimensional Sketch Datasheet
These three things are then sent to the marketing department,which is the feedback to the client’s enquiry. If the clientfeels satisfied with these things, then it gives the order to themarketing department. The marketing department then sends theSales Advice to the design section, which mainly defines thenumber of transformers to be produced and the duration of thesupply.
When the order is confirmed, then the design department startsits working in full swing. The work is then divided into twosubsections; electrical team performs the electrical design,whereas the mechanical team is mainly concerned with mechanicaldesign.
The electrical design team is mainly involved in the designing ofthe Core, LT and HT windings. The mechanical design team works onthe layout, body of the transformer. The design is made on Pro-Eand AutoCAD software.
The electrical design generally works with a faster pace, becauseit has to inform the Material Planning Control section that thismuch material is required for the production. Same is the case
32 University of Engineering & Technology,Taxila.
Change Your Life
with the mechanical team, but since core and winding are toproduce first, so there production starts a bit earlier. Thedesign and its calculations are mainly done via software. Once adesign is finalized and is according to the requirements of theclient, a TR document is prepared that defines each andeverything regarding the design.Data sheet includes allspecification of a transformer.BOQ (Bills of Quantity) containsthe amount of material used for the construction of atransformer.
Transformer ManufacturingIt is divided into four sections:
Winding Section Core Section Assembly Section Testing Section
1.Winding SectionWinding material is usually copper but aluminum can alsobe used. 99.9% pure copper is used with enameled coating.Sheets of copper are drawn into various sizes and theninsulated with specified insulation paper according to therequirement. Insulation paper is normally 0.06mm to 3mm inthickness and the material most commonly used at PEL isprespone because it does not dissolves in oil and alsodoes not absorbs moisture.
Helical Winding
Helical winding is typically used for low voltage and high current winding of large generator transformers. It can have 54 connectors at a time. Each turn is transposed and
33 University of Engineering & Technology,Taxila.
Change Your Life
are wound in helix. The main purpose of transposition is to reduce eddy current losses.Unlike the conventional winding, the helical winding has no distinct division into activeand end regions, because each conductor follows a helical path ofconstant pitch and diameter from one end of the machine to the other. In the conventional winding, each conductor follows an axial path in the active region and only has a circumferential component to its path in the end regions.
To understand how a helical winding works, consider the winding length of a diamond lap winding shown in the adjacent figure
(a) to be progressively reduced as by eliminating the so-called central "active" region and allowing the two diamond end windings to coalesce and form a semi-helical winding
(b) The true helical winding evolves from the wave wound diamond winding.
One phase of a two pole helical winding is shown above. Each phase consists of two parallel-connected helical loops, each of which is termed a phase group. Each phase group comprises one right-hand (inner) helical phase band connected in series with a returning left-hand (outer) helical phase band; a right hand phase band being defined as that which traces a right hand screw.
Layer Winding
34 University of Engineering & Technology,Taxila.
Change Your Life
This is the most commonly used winding used in PEL forLow voltage and high voltage. It is normally used forvoltages ratings between 90V to 33 KV. It consists of anumber of spiral coils, which are arranged in layers.These layers are separated by cooling ducts in which oilis poured. A good advantage of using layer winding is thatit gives uniform voltage. Secondary winding is always lessthan the primary winding because most of thetransformers made in winding shop are distributiontransformers which are used at consumer station in orderto step down the voltage.
Very large “thermal mass” of conductor and insulation betweencoolingducts: difficult to calculate and control the hot spottemperatures.No radial ducts, some axial ducts, most of them just on ends, notallAround.
Inter-Leaved Disc Winding
A disc-type interleaved winding for transformers. Current is conducted through the winding by three conductors connected in
35 University of Engineering & Technology,Taxila.
Change Your Life
parallel and interconnected between the coil discs to provide three different conduction paths. The first and third conduction paths are transposed between adjacent coil discs and progress in radially opposite directions through adjacent coil discs. . Disc winding helps the coil to withstand high impulse voltage. The second conduction path forms a looping pattern throughout thewinding with the conductor forming the second conduction path physically positioned between the other two conductors in each
coil disc. All turns are in contact with MOVING oil to lower hotspot temperatures.
A disadvantage with continuous disc winding is that their strength against impulse voltages is not adequate.the withstand behaviour of disc winding can be increased if two adjacent conductors belong to two different turns.
Apart from interleaving between every double disc.it is also suitable to have more number of discs say four in each interleaved group.
Foil Winding36 University of Engineering & Technology,Taxila.
Change Your Life
This design for winding has been recently introduced at PEL due to its various advantages over other types of windings. Foil winding hasa single copper foil which serves as a single conductor. The advantage of using a single foil of copper is mainly to strengthen flux and to reduce losses. The transformers with this type of winding are more efficient.Moreover it reduces the labor and in turn decreases thecost of transformer. Copper foil is always used in LT because distribution transformers are mainly step down transformers so secondary is always at low voltage as compared to primary. On LT the HT is wound which is usually layer winded. The sheet of copper is passed through a machine which cuts the sheet into different sizes according to the desire rating of the transformer. There are thermo ducts with oil in them in order to keep the transformer cool.
Packet winding
Packet winding is normally used for high voltage. They have large number of turns. It cannot be used for low
37 University of Engineering & Technology,Taxila.
Change Your Life
voltages. At PEL 4 packets are normally used in each winding. Packet winding can be easily repaired because eachcoil is in the form of packets so if any single packetis damaged it can be removed and a new packet can be replaced by it which is more economical because in other types of windings the whole winding is to be replaced if it is burned due to short circuit or any other reason.
Foil and layer windings are usually used in LV. Layer, packet anddisc winding is usually used in HV.
Area is increased in foil winding and hence stray losses arereduced.
Disc and packet winding are easy to repair and also thatvoltage is distributed among each packet/disc here. Hencemainly used in high rating transformers.
Insulation Material
Diamond dotted paper (For inter-layer insulation) Press pan sheet (For end collars) Creep paper pipe (For insulation of terminal of tap
changer) Craft paper (Used for insulation in disc winding) Thermo ducts
PhasingIn phasing,first LV winding is placed.Over LV,HV winding is placed and then RV winding is placed.Phasing is done separately for each phase.Taps from LV,HV and RV are taken out.LV has 2 tapsformaking star connection.HV has 4 tapsi.e. 2 for making delta and two taps are given to RV for tap changing,RV has 11 taps for voltage regulation.
38 University of Engineering & Technology,Taxila.
Change Your Life
Reclamation-Unit 3 PELI went to reclamation unit for analyzing core,assemblyand testing section of Power transformer.
2.Core SectionIn the core section center, side and yoke limbs of the core aremade. In an electrical power transformer, there are primary,secondary and may be tertiary windings. The performance of atransformer mainly depends upon the flux linkages between thesewindings. For efficient flux linking between these windings, onelow reluctance magnetic path common to all windings should beprovided in the transformer. This low reluctance magnetic path intransformer is known ascore of transformer.
Material for Transformer CoreThe main problem with transformer core is, its hysteresis lossand eddy current loss in transformer. Hysteresis loss intransformer mainly depends upon its core materials. It is foundthat, a small quantity of silicon alloyed with low carbon contentsteel produces material for transformer core, which has lowhysteresis loss and high permeability. Because of increasingdemand of power, it is required to further reduce the core lossesand for that, another technique is employed on steel, which isknown as cold rolling. This technique arranges the orientation ofgrain in ferromagnetic steel in the direction of rolling.
The core steel which has under gone through both the siliconalloying and cold rolling treatments is commonly known as CRGOS
39 University of Engineering & Technology,Taxila.
Change Your Life
or Cold Rolled Grain Oriented Silicon Steel. This material is nowuniversally used for manufacturing transformer core.
Although this material has low specific iron loss but still; ithas some disadvantages, like, it is susceptible to increase lossdue to flux flow in direction other than grain orientation and italso susceptible to impaired performance due to impact of bendingand blanking the cutting CRGOS sheet. Both the surfaces of thesheet are provided with an insulating of oxide coating.
Manufacturing of Transformer Core
During core manufacturing in factory some factors are taken intoconsideration,
1. Higher reliability.2. Reduction in iron loss in transformer and magnetizing
current.3. Lowering material cost and labor cost.4. abatement of noise levels.
Quality checking is necessary at every step of manufacturing toensure quality and reliability. The steel sheet must be testedfor ensuring the specific core loss or iron loss values. Thelamination should be properly checked and inspected visually,rusty and bend lamination should be rejected. For reducing thetransformer noises, the lamination should be tightly clampedtogether and punch holes should be avoided as far as possible tominimize cross flux iron losses. The air gap at the joint oflimbs and yokes should be reduced as much as possible forallowing maximum smooth conducting paths for magnetizing current.
Hysteresis Loss:
40 University of Engineering & Technology,Taxila.
Change Your Life
The alternating voltage applied to a winding produces alternating magnetic flux and the crystals of silicon steel are subjected to such fluxes and result in spending of energy. This loss is called hysteresis.
Eddy Current Loss:
When alternating magnetic flux flows through the core, asmall emf is induced in the core which causes circulating current. This is called eddy current and the energy dissipated as a result of this is known as eddy current loss.
Machines
Slitting machine is used to cut the big roll of siliconsteel sheet in required sizes (widths) according to therating of transformer.
Power press machines are used to make limbs. They areoperated manually.
After cutting of limbs V punching is done on the yokelimb which is called yoke notching.
PLC cutting machines are also used to make limbs. Thereare two PLC machines. SDRI machine has a capacity of40,000 limbs per day. L.A.E machine has a capacity of60,000 limbs per day. In CNC machines length, width andangle are given as input.
CNC CUTTING MACHINE:
CNC cutting machine perform the same function as the cutting presses but in CNC, we program that machine according to our requirement. Then CNC machine cut the coil automatically. In CNC we do not require workers and work is done quickly.
41 University of Engineering & Technology,Taxila.
Change Your Life
3. Assembly Section Core Assembly:
In the core coil assembly coil is fitted in the core and upperyoke limb is inserted to complete the core, then core istightened using upper and lower pressing beams. For coil to coilinsulation and core to coil insulation press pan sheet is used.
Before Connection Test (BCT) In the BCT area turns ratio of the coil is checkedusing TTR meter. Before the transformer is being sent tofurnace it is being tested. This test basically testscore losses also called as iron losses. Turn ratio oftransformer is also checked by using turn ratio meter. Weapply 240V per phase on the LV of transformer and checkthe output current. A tolerance of 5% is acceptable, ifit is above that then the transformer is sent back tothe winding section.
HT, LT ConnectionsIn this section Y-Delta connections are made. Tap changer isconnected with the coil. Connections are made according towork order specifications given by the design department.
42 University of Engineering & Technology,Taxila.
Change Your Life
Taping is done on these connections to avoid any shortcircuit.
After Connection Test (ACT)In the ACT area turns ratio of the transformer is checkedusing TTR meter.
Furnace
After ACT transformer is kept in the furnace for 48 to 72 hours according to its rating. It is done to evaporate all themoisture from core or coil. Electric furnaces are also there for this purpose. . Each transformer needs 24 to 36 hours of proper heating inside the furnace. Initial temperature is 120 degrees. After 3 hours the temperature is decreased to 100 degrees. Diamond dotted paper needs proper heating so each transformer should be baked properly. After baking the connections of the transformers are checked. All nuts and bolts are tightened and the transformer is sent for assembling of further parts.
Conservator Tank It is an expansion vessel. The main purpose of conservator is to maintain oil in the transformer above a minimum level. It has a magnetic oil level gauge. It can give an alarm if the oil level falls below the certain limit. It has an oil filling provision along with an oil drain valve. Oil filled transformers witha conservator are equipped with Buchholz Relay. These are safety devices that detect the buildup of gases inside the transformer and switch off the transformer
43 University of Engineering & Technology,Taxila.
Change Your Life
in emergency. The conservator has an oil level indicator. It is necessary that the oil level in theconservator must be maintained above a predetermined minimum level.
Cover Plate AssemblyIn this section HT, LT bushings, through bolts, eye boltsconnectors and other parts are inserted in cover plate.
Pre Tanking SectionWhen transformer is unloaded from the furnace it is insertedin the tank as quickly as possible to avoid the getting ofmoisture in the live part. Live part of the transformershould be inserted in the tank in 45mins to 1 ½ hours.
Transformer Oil: The oil serves as dual purpose of insulating medium and coolant. The heat generated inside a transformer is dissipated to the atmosphere or water through the insulating oil. The dissipation of heat is necessary to control the temperature within limits of the class of insulation used. Low volatility is therefore a desirable feature. It will be recognized that fire and explosion are to some extent potential risks whenever petroleum oils are used in electrical equipment. It is therefore necessary that the temperature of the oil in service should be very much lower than the flash point.
44 University of Engineering & Technology,Taxila.
Change Your Life
Specification of insulating oil: Low viscosity. Low pour point. High flash point. Excellent chemical stability. High electrical strength. High specific heat. High thermal conductivity. Low solvent power. Low density Cheap and easily available.
Cooling Assembly: Cooling assembly is very important for safety of transformer. By forced cooling, the transformer capacity can be increased by more than 50%.
ONAN-Oil Natural, Air Natural: Asthe name implies this is a self cooled cooling system. Natural circulation utilizes the thermal head produced by heating of oil which rises through the windings as it is heated and through these coolers by natural phenomenonit is Oil natural. Heat is dissipated to atmosphere through radiator banks.
ONAF-Oil Natural, Air Forced: The capacity of the transformer can be increased to its fulldesigned capacity by installing cooler fans below or on surface of radiators to take away the heat at a faster rate. Oil is circulated by the same phenomenon as described above.
Temperature Indicators: Two temperature indicators are installed on the transformer:
1. Oil temperature2. Winding temperature
45 University of Engineering & Technology,Taxila.
Change Your Life
These temperature indicators indicate maximum temperature and current temperature. Each indicator has two sets of mercury switches operated by temperature to give alarm and trip.
Paint ShopIn this section,painting o transformers is done either by liquid paint or by powder paint.
4.Testing SectionThe whole assembly is placed in the tank for testing.
Tests done at factory
1. Type tests2. Routine tests3. Special tests
Type Test of TransformerTo prove that the transformer meets customer’s specifications anddesign expectations, the transformer has to go through differenttesting procedures in manufacturer premises. Sometransformertests are carried out for confirming the basic design expectationof that transformer. These tests are done mainly in a prototypeunit not in all manufactured units in a lot. Type test oftransformer confirms main and basic design criteria of aproduction lot.
Routine Tests of TransformerRoutine tests of transformer is mainly for confirming operationalperformance of individual unit in a production lot. Routine testsare carried out on every unit manufactured.
46 University of Engineering & Technology,Taxila.
Change Your Life
Special Tests of TransformerSpecial tests of transformer is done as per customer requirementto obtain information useful to the user during operation ormaintenance of the transformer.
Routine Tests:
1. Transformer winding resistance measurement.2. Transformer ratio test.3. Measurement of insulation resistance.4. High Voltage test.5. Measurement of impedance voltage/short circuit impedance
(principal tap) and load loss (Short circuit test).6. Measurement of no load loss and current (Open circuit test)7. Dielectric tests of transformer.8. Induced over Voltage Test9. Oil pressure test on transformer to check against leakages
past joints and gaskets.
1.Transformer Winding Resistance MeasurementTransformer winding resistance measurement is carried out tocalculate the I2R losses and to calculate winding temperature atthe end of a temperature rise test. It is carried out as a typetest as well as routine test. It is also done at site to ensurehealthiness of a transformer that is to check loose connections,broken strands of conductor, high contact resistance in tapchangers, high voltage leads and bushings etc.
There are different methods for measuring of transformer winding,likewise
47 University of Engineering & Technology,Taxila.
Change Your Life
1.Current voltage method of measurement of windingresistance.2. Bridge method of measurement of winding resistance.
3.Kelvin bridge method of Measuring WindingResistance. 4. Measuring winding resistance by AutomaticWinding Resistance Measurement Kit.
2.Transformer Ratio TestThe performance of a transformer largely depends upon perfectionof specific turns or voltage ratio of transformer. So transformerratio test is an essential type test of transformer. This testalso performed as routine test of transformer. So for ensuringproper performance of electrical power transformer, voltage andturn ratio test of transformer one of the vital tests.
The procedure of transformer ratio test is simple. We just applythree phase 415 V supply to HV winding, with keeping LV windingopen. The we measure the induced voltages at HV and LV terminalsof transformer to find out actual voltage ratio of transformer.We repeat the test for all tap position separately.
3.Insulation Resistance Test or Megger Test ofTransformer
Insulation resistance test of transformer is essential typetest. This test is carried out to ensure the healthiness ofover all insulation system of an electrical powertransformer.
1. First disconnect all the line and neutral terminals ofthe transformer.
2. Megger leads to be connected to LV and HV bushing studsto measure insulation resistance IR value in betweenthe LV and HV windings.
48 University of Engineering & Technology,Taxila.
Change Your Life
3. Megger leads to be connected to HV bushing studs andtransformer tank earth point to measure insulationresistance IR value in between the HV windings andearth.
4. Megger leads to be connected to LV bushing studs andtransformer tank earth point to measure insulationresistance IR value in between the LV windings andearth.
4. High Voltage Test: (Separate source voltage)
This test is used to check whether winding is insulated fromother parts of transformer or not. First, all the L.Vterminals and body of transformer are earthed. Than 33kvvoltage is applied on the H.V side. IT is checked whetherthe transformer will stand this voltage for 1 minute or not.
5.Load Losses (Short circuit test)
In this test L.V side is short and current is passed through theL.V side. Than V, I, PF and other quantities are measured
6.No Load Losses:(Open circuit test)
In this test H.V side is kept open and voltage is applied on theL.V side. Than V, I, PF and other quantities are measured.
49 University of Engineering & Technology,Taxila.
Change Your Life
7.Dielectric Tests of TransformerDielectric tests of transformer is one kind of insulation test.This test is performed to ensure the expected over all insulationstrength of transformer. There are several test performed toensure the required quality of transformer insulation, dielectrictest is one of them. Dielectric tests of transformer is performedin two different steps, first one called Separate source voltagewithstand test of transformer, where a single phase powerfrequency voltage of prescribed level, is applied on transformerwinding under test for 60 seconds while the other windings andtank are connected to the earth. it is observed that whether any failure of insulation occurs ornot during the test. Second one is induced voltage test ofTransformer where, three phase voltage, twice of rated secondaryvoltage is applied to the secondary winding for 60 second bykeeping the primary of the transformer open circuited. Thefrequency of the applied voltage should be double of powerfrequency too. Here also if no failure of insulation, the test issuccessful.In addition to dielectric tests of transformer there are othertype test for checking insulation of transformer, such aslightning impulse test, switching impulse test and partialdischarge test.8. Induced Over Voltage Test
This test is used to check the winding insulation. In this testvoltage is applied on the L.V side because it is easy to provide.On the L.V side twice the rated voltage at four times the normalfrequency is applied. Test time should be greater than 15seconds.
50 University of Engineering & Technology,Taxila.
Change Your Life
Conclusion
In spite of huge competition from emerging localand multinational brands, PEL transformers have remained in the spotlight due to constant innovation and priority of quality over cost. PELhelped me a lot in understanding the principlesof transformer design,manufacturing, construction, testing operation and maintenance. PEL helped me to update my knowledge on Power transformers. I learnt a lot during my internship at PEL. It was one heck of a time at PEL.
51 University of Engineering & Technology,Taxila.
Change Your Life
Referencewww.wikipedia.com
www.pel.com
www.electrical4u.com
www.antony-anderson.com/unusual/helical.htm
Book: Chapman 4th edition
52 University of Engineering & Technology,Taxila.