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A

SEMINAR REPORT

ON

KOTSONS PVT. LTD.

K.P.L.

ALWAR, RAJASTHAN

THE UNIVERSITY OF RAJASTHAN IN PARTIAL FULFILLMENT FOR THE AWARD OF DEGREE OF BACHELOR IN ENGG. IN

ELECTRICAL BRANCH OF THE UNIVERSITY OF RAJASTHAN, JAIPUR

SESSION 2008-09

Submitted To: - Submitted By:-Mr.Maal Singh Shekhawat Ghanshyam Meena Seminar Incharge VIIth Sem (Electrical Engg) Lect. Of Electrical Deptt. KITE-SOM, JaipurKITE-SOM, Jaipur

DEPARTMENT OF ELECTRICAL ENGINEERING KUTILYA INSTITUTE OF TECHIOLOGY &

ENGINEERING

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DEPARTMENT OF ELECTRICAL ENGINEERINGKUTILYA INST. OF TECH. & ENGG.

SITAPURA, JAIPUR (RAJ.) 302022

SESSION 2008-2009

CIRTIFICATE

This is to certify that the seminar entitled “Kotsons Pvt. Ltd.” was successfully presented by Mr. Ghanshyam Singh Meena of the B.E. Final Year (VII semester) under my supervision for the partial fulfillment of B.E.

Date:

Mr. M. Sashilal Mr. Maal Singh ShekhawatHOD, Electrical Engg. Seminer InchargeKITE, Jaipur Lect. Of Electrical Deptt.

KITE, Jaipur

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AKNOWLEGMENT

First and the foremost, I would like to thank my respected parents, who always encouraged me and tough me to think and work out innovatively whatever be the field of life.

I wish to express my sincere thanks to the UNIVERSITY OF RAJASTHAN which has taken an initiative in providing of practical training to the B.E. student.

I feel a deep sense of gratitude to Mr. M. SASHILAL, Head of Department of Electrical engineering of “KAUTILYA INSTITUTE OF TECHNOLOGY & ENGINEERING”, Jaipur for all kind of help has been granted. My heartily thanks to our training incharge Er. SANDEEP JAIN for all kind of help.

I greatly thankful to Hr. Mr. Devendra Jain at K.P.L, Alwar for granting me the permission for training and for describe the manufacture of x-mer as possible as.

Last but not least, I am also thankful to all the staff member of KITE and my friends.

GHANSHYAM MEENAIV B.E (ELECTRICAL)

PREFACE

A rapid rise in the use of electricity is placing a very heavy responsibility on electrical undertakings to maintain their electrical network

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in perfect condition, so young engineers is called upon to do design system planning and construction and maintenance of electric system before he had much experience and practice soon he may be responsible for specialize operation in an ever expanding industry. Theoretical knowledge gained in their college courses need to be supplemented with practical know-how to face this professional challenge, so…....

As a part of our practical training we have to attempt the rule of university of Rajasthan, Jaipur. I took my practical training at K.P.L. Alwar, Rajasthan.

Since my training centre was of Manufacture of transformer hence I have included all updated information, to the extent possible, including general introduction and brief description of starting K.P.L. in this study report.

During my 45 working days practical training, I had undertaken my training at K.P.L. Alwar, Rajasthan.

The period of training was from 28/07/08 to 10/09/08.This report dealt with the practical knowledge of general theory and

technical data/details of equipments, which I have gained during the training period at K.P.L. Alwar, Rajasthan.

GHANSHYAM MEENAIV B.E (ELECTRICAL)

ABOUT KOTSON:- KPL (Kotsons Pvt. Ltd.) established its transformer manufacturing unit back in 1979 at Alwar, India to produce distribution & power transformers of 33 KV class voltage, to meet the needs of public utilities organizations and of private industrial sector in India. It was KPL vision of becoming integrated global transformer manufacturing company that the company's manufacturing facilities were later expanded and second & third plant was setup at

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Agra (U.P) and Bazpur (Uttranchal), India and product range was expanded up to 25 MVA with 33 KV class, to cater the needs of international demands. Today, with over more than two & half decades of experience in the manufacturing, KPL has grown in geographical reach, market size and product range to become one of the leading transformer manufacturing company Our product comprehensively fulfilled the requirements of local and international standard specifications and their stringent requirement.

KPL is ISO 9001:2000 & ISO 14001:2004 certification from Det Norske Veritas, The Netherlands and commits itself to introduce and maintain a quality system that ensures quality products and services to total satisfaction of the customer. The quality control department controls and monitor all quality control documents and carries out its inspection at all strategic points in the production process. TQM (Total Quality Management) programme is in place, which is backed by strong in house R & D and a crew of service engineers for providing after sales services. At transformer's quality & soundness point, KPL's transformer range from 100 KVA to 1000 KVA are being type tested for temperature rise test and impluse test at world's renowned testing laboratory , The Netherlands.

At KPL, R & D is a continuous process and department has consistently produced innovative concepts that have now become industry standards. A highly qualified and experienced technical personnel keeps an eye upon the latest development in technology and the product to supply a prime quality product at competitive price.

KPL has in house facilities for conducting all routine test as per IEC, DIN, BS, ANSI, NEMA & IS and temperature rise type test.

KPL Infrastructure:

Plant Year Total Land Area(Sq.Mtrs.); Covered Land Area (Sq.Ft.)

AGRA 1991 8500 40,000

ALWAR 1979 I – 6000 & II – 54000

50,000

Bazpur 2007 26000 1,50,000

Valuable Customers:

Overseas Customers Indian Customers

Central Electricity Torrent Power

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Board, Mauritius General

Establishment for Electricity Distribution in the middle, Baghdad, Iraq.

Rural Electrification Board, Dhaka, Bangaladesh.

General Company for Baghdad Electricity Distribution, Iraq

Schneider Electric Limited.

Limited. Schneider Electric

Limited. ABB Limited. Reliance Energy

Limited. BSES. JVVNL. JdVVNL. AVVNL. DVVNL. Areva T & D

Limited. L & T Ltd. Siemens Ltd. NDTV Ltd.

CPRI.

Awards :

Winner of highest prestigious export awards "Niryat Shree" for year 2000-01 from Vice President of India.

Received certificate in the Category of Export House-SSI for Excellent Export Performance for the year 2001-02 from Vice President of India.

Winner of Trophy for Highest Export in the Category of Capital Goods for the year 2000-2001 from EEPC.

Winner of UP State Export Award for the year 2001-02 from Chief Minister of U.P.

In 2005, Win excellent award for Export.

KOTSON PVT. LTD., ALWAR

Installation of kotson pvt. Ltd. , Alwar is situated in Matsya Industrial area (M.IA). MIA is about 10km from alwar city. This is usual factory area under consideration of RIICO. Here

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mainly distribution transformers are made.Transformers are made just of kva ratings.

Kotson private limited ,alwar is covered in 50,000 square feet area(including I & II). Here transformers with following ratings are made:- Transformers rating(kva) Connections(primary-secondary)5 Delta-Star10 Delta-Star16 Delta-Star25 Delta-Star50 Delta-Star100 Delta-Star200 Delta-Star

300 Delta-Star500 Delta-Star

Basic Principle of Transformer:-

The transformer is based on two principles: firstly, that an electric current can produce a magnetic field (electromagnetism) and secondly that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction). By changing the current in the primary coil, it changes the strength of its magnetic field; since the changing magnetic field extends into the secondary coil, a voltage is induced across the secondary.

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An ideal step-down transformer showing magnetic flux in the core

A simplified transformer design is shown to the left. A current passing through the primary coil creates a magnetic field. The primary and secondary coils are wrapped around a core of very high magnetic permeability, such as iron; this ensures that most of the magnetic field lines produced by the primary current are within the iron and pass through the secondary coil as well as the primary coil.

Induction law

The voltage induced across the secondary coil may be calculated from Faraday's law of induction, which states that:

where VS is the instantaneous voltage, NS is the number of turns in the secondary coil and Φ equals the magnetic flux through one turn of the coil. If the turns of the coil are oriented perpendicular to the magnetic field lines, the flux is the product of the magnetic field strength B and the area A through which it cuts. The area is constant, being equal to the cross-sectional area of the transformer core, whereas the magnetic field varies with time according to the excitation of the primary. Since the same magnetic flux passes through both the primary and secondary coils in an ideal transformer,[1] the instantaneous voltage across the primary winding equals

Taking the ratio of the two equations for VS and VP gives the basic equation[5] for stepping up or stepping down the voltage

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Ideal power equation

The ideal transformer as a circuit element

If the secondary coil is attached to a load that allows current to flow, electrical power is transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is perfectly efficient; all the incoming energy is transformed from the primary circuit to the magnetic field and into the secondary circuit. If this condition is met, the incoming electric power must equal the outgoing power.

Pincoming = IPVP = Poutgoing = ISVS

giving the ideal transformer equation

If the voltage is increased (stepped up) (VS > VP), then the current is decreased (stepped down) (IS < IP) by the same factor. Transformers are efficient so this formula is a reasonable approximation.

The impedance in one circuit is transformed by the square of the turns ratio.[1] For example, if an impedance ZS is attached across the terminals of the secondary coil, it

appears to the primary circuit to have an impedance of . This relationship is reciprocal, so that the impedance ZP of the primary circuit appears to the secondary to be

.

Detailed operation

The simplified description above neglects several practical factors, in particular the primary current required to establish a magnetic field in the core, and the contribution to the field due to current in the secondary circuit.

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Models of an ideal transformer typically assume a core of negligible reluctance with two windings of zero resistance.[6] When a voltage is applied to the primary winding, a small current flows, driving flux around the magnetic circuit of the core.[6]. The current required to create the flux is termed the magnetising current; since the ideal core has been assumed to have near-zero reluctance, the magnetising current is negligible, although still required to create the magnetic field.

The changing magnetic field induces an electromotive force (EMF) across each winding.[7] Since the ideal windings have no impedance, they have no associated voltage drop, and so the voltages VP and VS measured at the terminals of the transformer, are equal to the corresponding EMFs. The primary EMF, acting as it does in opposition to the primary voltage, is sometimes termed the "back EMF".[8] This is due to Lenz's law which states that the induction of EMF would always be such that it will oppose development of any such change in magnetic field.

Transformer types:- Autotransformer

Main article: Autotransformer

An autotransformer with a sliding brush contact

An autotransformer has only a single winding with two end terminals, plus a third at an intermediate tap point. The primary voltage is applied across two of the terminals, and the secondary voltage taken from one of these and the third terminal. The primary and secondary circuits therefore have a number of windings turns in common.[21] Since the volts-per-turn is the same in both windings, each develops a voltage in proportion to its number of turns. An adjustable autotransformer is made by exposing part of the winding coils and making the secondary connection through a sliding brush, giving a variable turns ratio. [22]

Polyphase transformers

For three-phase supplies, a bank of three individual single-phase transformers can be used, or all three phases can be incorporated as a single three-phase transformer. In this case, the magnetic circuits are connected together, the core thus containing a three-phase flow of flux.[23] A number of winding configurations are possible, giving rise to different attributes and phase shifts.[24] One particular polyphase configuration is the zigzag transformer, used for grounding and in the suppression of harmonic currents.[25]

Leakage transformers

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Leakage transformer

A leakage transformer, also called a stray-field transformer, has a significantly higher leakage inductance than other transformers, sometimes increased by a magnetic bypass or shunt in its core between primary and secondary, which is sometimes adjustable with a set screw. This provides a transformer with an inherent current limitation due to the loose coupling between its primary and the secondary windings. The output and input currents are low enough to prevent thermal overload under all load conditions – even if the secondary is shorted.

Leakage transformers are used for arc welding and high voltage discharge lamps (neon lamps and cold cathode fluorescent lamps, which are series-connected up to 7.5 kV AC). It acts then both as a voltage transformer and as a magnetic ballast.

Other applications are short-circuit-proof extra-low voltage transformers for toys or doorbell installations.

Resonant transformers

A resonant transformer is a kind of the leakage transformer. It uses the leakage inductance of its secondary windings in combination with external capacitors, to create one or more resonant circuits. Resonant transformers such as the Tesla coil can generate very high voltages, and are able to provide much higher current than electrostatic high-voltage generation machines such as the Van de Graaff generator.[26] One of the application of the resonant transformer is for the CCFL inverter. Another application of the resonant transformer is to couple between stages of a superheterodyne receiver, where the selectivity of the receiver is provided by tuned transformers in the intermediate-frequency amplifiers.[27]

Instrument transformers

Current transformers, designed to be looped around conductors

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A current transformer is a measurement device designed to provide a current in its secondary coil proportional to the current flowing in its primary. Current transformers are commonly used in metering and protective relaying, where they facilitate the safe measurement of large currents. The current transformer isolates measurement and control circuitry from the high voltages typically present on the circuit being measured.[28]

Voltage transformers (VTs)--also referred to as potential transformers (PTs)--are used for metering and protection in high-voltage circuits. They are designed to present negligible load to the supply being measured and to have a precise voltage ratio to accurately step down high voltages so that metering and protective relay equipment can be operated at a lower potential.[29]

Classification

Transformers can be classified in different ways:

By power level: from a fraction of a volt-ampere (VA) to over a thousand MVA; By frequency range: power-, audio-, or radio frequency; By voltage class: from a few volts to hundreds of kilovolts; By cooling type: air cooled, oil filled, fan cooled, or water cooled; By application function: such as power supply, impedance matching, output

voltage and current stabilizer, or circuit isolation; By end purpose: distribution, rectifier, arc furnace, amplifier output; By winding turns ratio: step-up, step-down, isolating (near equal ratio), variable.

Construction:-

Cores

Laminated core transformer showing edge of laminations at top of unit.

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Laminated steel cores

Transformers for use at power or audio frequencies typically have cores made of high permeability silicon steel.[30] The steel has a permeability many times that of free space, and the core thus serves to greatly reduce the magnetising current, and confine the flux to a path which closely couples the windings.[31] Early transformer developers soon realised that cores constructed from solid iron resulted in prohibitive eddy-current losses, and their designs mitigated this effect with cores consisting of bundles of insulated iron wires.[32] Later designs constructed the core by stacking layers of thin steel laminations, a principle that has remained in use. Each lamination is insulated from its neighbors by a thin non-conducting layer of insulation.[23] The universal transformer equation indicates a minimum cross-sectional area for the core to avoid saturation.

The effect of laminations is to confine eddy currents to highly elliptical paths that enclose little flux, and so reduce their magnitude. Thinner laminations reduce losses,[30] but are more laborious and expensive to construct.[33] Thin laminations are generally used on high frequency transformers, with some types of very thin steel laminations able to operate up to 10 kHz.

Laminating the core greatly reduces eddy-current losses

One common design of laminated core is made from interleaved stacks of E-shaped steel sheets capped with I-shaped pieces, leading to its name of "E-I transformer".[33] Such a design tends to exhibit more losses, but is very economical to manufacture. The cut-core or C-core type is made by winding a steel strip around a rectangular form and then bonding the layers together. It is then cut in two, forming two C shapes, and the core assembled by binding the two C halves together with a steel strap.[33] They have the advantage that the flux is always oriented parallel to the metal grains, reducing reluctance.

A steel core's remanence means that it retains a static magnetic field when power is removed. When power is then reapplied, the residual field will cause a high inrush current until the effect of the remanent magnetism is reduced, usually after a few cycles of the applied alternating current.[34] Overcurrent protection devices such as fuses must be selected to allow this harmless inrush to pass. On transformers connected to long, overhead power transmission lines, induced currents due to geomagnetic disturbances during solar storms can cause saturation of the core and operation of transformer protection devices.[35]

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Distribution transformers can achieve low no-load losses by using cores made with low-loss high-permeability silicon steel or amorphous (non-crystalline) metal alloy. The higher initial cost of the core material is offset over the life of the transformer by its lower losses at light load.[36]

Solid cores

Powdered iron cores are used in circuits (such as switch-mode power supplies) that operate above main frequencies and up to a few tens of kilohertz. These materials combine high magnetic permeability with high bulk electrical resistivity. For frequencies extending beyond the VHF band, cores made from non-conductive magnetic ceramic materials called ferrites are common.[33] Some radio-frequency transformers also have moveable cores (sometimes called 'slugs') which allow adjustment of the coupling coefficient (and bandwidth) of tuned radio-frequency circuits.

Toroidal cores

Small transformer with toroidal core

Toroidal transformers are built around a ring-shaped core, which, depending on operating frequency, is made from a long strip of silicon steel or permalloy wound into a coil, powdered iron, or ferrite.[37] A strip construction ensures that the grain boundaries are optimally aligned, improving the transformer's efficiency by reducing the core's reluctance. The closed ring shape eliminates air gaps inherent in the construction of an E-I core.[38] The cross-section of the ring is usually square or rectangular, but more expensive cores with circular cross-sections are also available. The primary and secondary coils are often wound concentrically to cover the entire surface of the core. This minimises the length of wire needed, and also provides screening to minimize the core's magnetic field from generating electromagnetic interference.

Toroidal transformers are more efficient than the cheaper laminated E-I types for a similar power level. Other advantages compared to E-I types, include smaller size (about half), lower weight (about half), less mechanical hum (making them superior in audio amplifiers), lower exterior magnetic field (about one tenth), low off-load losses (making them more efficient in standby circuits), single-bolt mounting, and greater choice of shapes. The main disadvantages are higher cost and limited rating.

Ferrite toroidal cores are used at higher frequencies, typically between a few tens of kilohertz to a megahertz, to reduce losses, physical size, and weight of switch-mode power supplies. A drawback of toroidal transformer construction is the higher cost of windings. As a consequence, toroidal transformers are uncommon above ratings of a few

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kVA. Small distribution transformers may achieve some of the benefits of a toroidal core by splitting it and forcing it open, then inserting a bobbin containing primary and secondary windings.

Air cores

A physical core is not an absolute requisite and a functioning transformer can be produced simply by placing the windings in close proximity to each other, an arrangement termed an "air-core" transformer. The air which comprises the magnetic circuit is essentially lossless, and so an air-core transformer eliminates loss due to hysteresis in the core material.[8] The leakage inductance is inevitably high, resulting in very poor regulation, and so such designs are unsuitable for use in power distribution.[8] They have however very high bandwidth, and are frequently employed in radio-frequency applications,[39] for which a satisfactory coupling coefficient is maintained by carefully overlapping the primary and secondary windings.

Windings:-

Windings are usually arranged concentrically to minimise flux leakage

Cut view through transformer windings. White: insulator. Green spiral: Grain oriented silicon steel. Black: Primary winding made of oxygen-free copper. Red: Secondary winding. Top left: Toroidal transformer. Right: C-core, but E-core would be similar. The black windings are made of film. Top: Equally low capacitance between all ends of both

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windings. Since most cores are at least moderately conductive they also need insulation. Bottom: Lowest capacitance for one end of the secondary winding needed for low-power high-voltage transformers. Bottom left: Reduction of leakage inductance would lead to increase of capacitance.

The conducting material used for the windings depends upon the application, but in all cases the individual turns must be electrically insulated from each other to ensure that the current travels throughout every turn.[11] For small power and signal transformers, in which currents are low and the potential difference between adjacent turns is small, the coils are often wound from enamelled magnet wire, such as Formvar wire. Larger power transformers operating at high voltages may be wound with copper rectangular strip conductors insulated by oil-impregnated paper and blocks of pressboard.[40]

High-frequency transformers operating in the tens to hundreds of kilohertz often have windings made of braided litz wire to minimize the skin-effect and proximity effect losses.[11] Large power transformers use multiple-stranded conductors as well, since even at low power frequencies non-uniform distribution of current would otherwise exist in high-current windings.[40] Each strand is individually insulated, and the strands are arranged so that at certain points in the winding, or throughout the whole winding, each portion occupies different relative positions in the complete conductor. The transposition equalizes the current flowing in each strand of the conductor, and reduces eddy current losses in the winding itself. The stranded conductor is also more flexible than a solid conductor of similar size, aiding manufacture.[40]

For signal transformers, the windings may be arranged in a way to minimise leakage inductance and stray capacitance to improve high-frequency response. This can be done by splitting up each coil into sections, and those sections placed in layers between the sections of the other winding. This is known as a stacked type or interleaved winding.

Both the primary and secondary windings on power transformers may have external connections, called taps, to intermediate points on the winding to allow selection of the voltage ratio. The taps may be connected to an automatic on-load tap changer for voltage regulation of distribution circuits. Audio-frequency transformers, used for the distribution of audio to public address loudspeakers, have taps to allow adjustment of impedance to each speaker. A center-tapped transformer is often used in the output stage of an audio power amplifier in a push-pull circuit. Modulation transformers in AM transmitters are very similar.

Certain transformers have the windings protected by epoxy resin. By impregnating the transformer with epoxy under a vacuum, one can replace air spaces within the windings with epoxy, thus sealing the windings and helping to prevent the possible formation of corona and absorption of dirt or water. This produces transformers more suited to damp or dirty environments, but at increased manufacturing cost.[41]

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Three-phase oil-cooled transformer with cover cut away. The oil reservoir is visible at the top. Radiative fins aid the dissipation of heat.

Coolant:-

High temperatures will damage the winding insulation. [42] Small transformers do not generate significant heat and are self-cooled by air circulation and radiation of heat. Power transformers rated up to several hundred kVA can be adequately cooled by natural convective air-cooling, sometimes assisted by fans.[43] In larger transformers, part of the design problem is removal of heat. Some power transformers are immersed in transformer oil that both cools and insulates the windings.[44] The oil is a highly refined mineral oil that remains stable at high temperatures. Liquid-filled transformers to be used indoors must use a non-flammable liquid, or must be located in fire-resistant rooms.[2]

The oil-filled tank often has radiators through which the oil circulates by natural convection; some large transformers employ forced circulation of the oil by electric pumps, aided by external fans or water-cooled heat exchangers.[44] Oil-filled transformers undergo prolonged drying processes to ensure that the transformer is completely free of water vapor before the cooling oil is introduced. This helps prevent electrical breakdown under load. Oil-filled transformers may be equipped with Buchholz relays, which detect gas evolved during internal arcing and rapidly de-energize the transformer to avert catastrophic failure.[34]

Polychlorinated biphenyls have properties that once favored their use as a coolant, though concerns over their toxicity and environmental persistence led to a widespread ban on their use.[45] Today, non-toxic, stable silicone-based oils, or fluorinated hydrocarbons may be used where the expense of a fire-resistant liquid offsets additional building cost for a transformer vault.[42][2] Before 1977, even transformers that were nominally filled only with mineral oils commonly also contained polychlorinated biphenyls as contaminants at 10-20 ppm. Since mineral oil and PCB fluid mix, maintenance equipment used for both

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PCB and oil-filled transformers could carry over small amounts of PCB, contaminating oil-filled transformers. [46]

Some "dry" transformers (containing no liquid) are enclosed in sealed, pressurized tanks and cooled by nitrogen or sulfur hexafluoride gas.[42].

Experimental power transformers in the 2 MVA range have been built with superconducting windings which eliminates the copper losses, but not the core steel loss. These are cooled by liquid nitrogen or helium.[47]

Terminals:-

Very small transformers will have wire leads connected directly to the ends of the coils, and brought out to the base of the unit for circuit connections. Larger transformers may have heavy bolted terminals, bus bars or high-voltage insulated bushings made of polymers or porcelain. A large bushing can be a complex structure since it must provide careful control of the electric field gradient without letting the transformer leak oil.[48]

History:-

The transformer principle was demonstrated in 1831 by Michael Faraday, although he used it only to demonstrate the principle of electromagnetic induction and did not foresee its practical uses. The first widely used transformer was the induction coil, invented by Irish clergyman Nicholas Callan in 1836.[49] He was one of the first to understand the principle that the more turns a transformer winding has, the larger EMF it produces. Induction coils evolved from scientists efforts to get higher voltages from batteries. They were powered not by AC, but DC from batteries which was interrupted by a vibrating 'breaker' mechanism. Between the 1830s and the 1870s efforts to build better induction coils, mostly by trial and error, slowly revealed the basic principles of transformer operation. Efficient designs would not appear until the 1880s,[50] but within less than a decade, the transformer was instrumental during the "War of Currents" in seeing alternating current systems triumph over their direct current counterparts, a position in which they have remained dominant.[50]

Russian engineer Pavel Yablochkov in 1876 invented a lighting system based on a set of induction coils, where primary windings were connected to a source of alternating current and secondary windings could be connected to several "electric candles". The patent claimed the system could "provide separate supply to several lighting fixtures with different luminous intensities from a single source of electric power". Evidently, the induction coil in this system operated as a transformer.

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A historical Stanley transformer.

Lucien Gaulard and John Dixon Gibbs, who first exhibited a device with an open iron core called a 'secondary generator' in London in 1882 and then sold the idea to American company Westinghouse.[32] They also exhibited the invention in Turin in 1884, where it was adopted for an electric lighting system.

Hungarian engineers Zipernowsky, Bláthy and Déri from the Ganz company in Budapest created the efficient "ZBD" closed-core model in 1885 based on the design by Gaulard and Gibbs.[51] Their patent application made the first use of the word "transformer".[32] Russian engineer Mikhail Dolivo-Dobrovolsky developed the first three-phase transformer in 1889. In 1891 Nikola Tesla invented the Tesla coil, an air-cored, dual-tuned resonant transformer for generating very high voltages at high frequency. Audio frequency transformers (at the time called repeating coils) were used by the earliest experimenters in the development of the telephone.

While new technologies have made transformers in some electronics applications obsolete, transformers are still found in many electronic devices. Transformers are essential for high voltage power transmission, which makes long distance transmission economically practical.

Single phase transformers:-

single phase transformers are mainly used where load is very small , generally in rural areas.Company makes two types of single hase transformers:-

1.CRGO CORE TRANSFORMERS

2.AMORPHOUS METALL TRANSFORMERS

SINGLE PHASE TRANSFORMER

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CRGO Core Transformers

Applicable standards

IEC (International Electro technical Commission) ANSI (American National Standard Institution) BS (British Standards) . IS (Indian Standard)

Specification :

Kotsons make conventional type, 1 Phase, 50 Hz, Oil immersed, naturally cooled, Pole mounted / Platform mounted, double wound with Aluminium / Copper, Step up/Step down core type continuous duty transformers having no load voltage ratio from 5 KVA to 167 KVA upto 33 KV Class with ‘A’ Class Insulation and designed to withstand Short Circuit, & Impulse Test in accordance to ANSI / IEC / BS / IS.

Completely self Protected type Transformers are also available for protection on both HV & LV Side.

Details of Characteristics & dimensions of Kotsons standard transformers with standard fittings manufactured in accordance with ANSI C 57 latest., readily available in stock and can be delivered within 1 weeks from the date of order confirmation.

The temperature rise will be 60/65° C in Oil/Winding respectively over a maximum ambienttemperature as per ANSI. The transformers will be manufactured as per ANSI C 57 latest, complete with fittings/accessories as stated below.

KVA Efficiency(%)

Voltage Regulation

(%)

W(mm)

D(mm)

H(mm)

Oil(l)

Weight(kg)

5 97.60 2.05 400 520 770 12 69

10 98.00 1.79 450 570 800 17 97

15 98.23 1.56 480 600 850 23 120

25 98.25 1.58 530 620 1030 65 205

37.5 98.58 1.26 650 650 900 38 244

50 98.29 1.60 670 650 950 45 253

75 98.53 1.30 740 720 950 62 340

100 98.72 1.18 795 750 1000 78 440

167 98.92 1.15 850 825 1065 116 675

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Note :

Due to improvements continuously taking place in design, the details given may vary marginally in respect of No Load Losses, Load Losses and overall dimensions. However the variations will be within permissible limits as per Applicable Standards.

The details given here are for kotsons standard transformer with standard fittings. The details may depend upon the optional fittings/specific requirement of customer. For details, Please contact our Marketing Office or fill our enquiry/feedback form.

Fitting & accessories provided with standard Transformer are as under.

S.No Accessories 5 to 25 KVA 26 to 167 KVA

1 Support Lug

2 Name Plate

3 Grounding Terminal

4 Hand Hole

5 Bird Guard

6 H.V Bushing with fittings

7 Pressure Release Valve

8 Lifting Lug

9L.V Bushings with fittings

10 Grounding Pad

11 Radiator X X

12 Capacity Mark

    Optional fittings can be provided on extra cost as per customer requirements.

Optional Fittings

1 Arrestor O O

2 Protective Fuse O O

3 Breaker O O

4 Extra Bushing O O

5 External Tap changer O O

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SINGLE PHASE TRANSFORMER Amorphous metal Transformers

“Kotsons” Amorphous metal transformers are manufactured in technical collaboration with Hitachi Met glass Inc., the only Producer of Amorphous Metal in the World. Kotsons has set up state of the art amorphous metal transformer manufacturing facility by importing the latest amorphous metal cores manufacturing equipment from M/S Bergers Machinenbau GMBH, Germany.

This plant has the latest equipment in India to produce energy efficient amorphous metal transformers. Quality of process is given overriding importance to the quantity. Cores are annealed under absolute inert atmosphere to get at most lower losses thereby enhancing the energy savings in comparison with the similar manufacturing facilities in this line in the world.

Advantages :

Energy Efficient AMDT can reduce No Load losses by 80 % Since No load losses represent a

major portion of the energy lost during Power distribution Hence reduce cost investment for power generation & translate into reduction in carbon di-oxide emissions created during power generation.

Lower Temperature Slower ageing of insulation Higher overloading capability Longer Life Superior electrical performance under harmonics conditions

Description : In order to achieve significant improvement in efficiency, amorphous metal is used to make transformer core. Amorphous metal exhibits a unique random molecular structure unlike rigid grain structure of silicon steel, which enables easy magnetization & demagnetization, thereby reducing hysteresis loss. Further processing of amorphous metal in very thin lamination (appropriate 1/10th of silicon steel lamination thickness) enable significant reduction in eddy current losses.

The Advantages of AMDT is not limited to reduction in losses alone. Since these losses are converted in to heat energy , cooling oil inside the transformer tank will be heated up and it will lead to emissions and significant fuel savings. AMDTs helps utilities reduce harmful emissions such as sulphur dioxide, Nitrogen Oxides and Carbon dioxide, the pollutants that cause acid rain & global warming.

Page no.23

Comparisons among typical silicon steel distribution transformer, high efficiency silicon steel distribution transformer & amorphous metal distribution transformer (AMDT) is given under:

Rating (KVA)Typical Silicon Steel

Hi-efficiency SiliconSteel

Amorphous Metal

Single Phase      

10 40 30 10

15 60 45 15

Three Phase      

25 100 80 25

63 180 150 45

100 260 195 60

Specification :

Kotsons make Amorphous Metal Single Phase transformers 50 Hz or 60 Hz with primary Voltage up to 33 KV class & Secondary voltage up to 250 Volts, 120/240 Volts or as required, Oil immersed, naturally cooled, Pole mounted , double wound with Aluminium / Copper, Step up/Step down core type continuous duty transformers having no load voltage ratio from 5 KVA to 167 KVA up to 33 KV Class with ‘A’ Class Insulation and designed to withstand Short Circuit, & Impulse Test in accordance to ANSI / IEC / AS / IS.

Details of Characteristics & dimensions of Kotsons standard transformers with standard fittings manufactured in accordance with ANSI C 57 latest readily available in stock and can be delivered within 1 weeks from the date of order confirmation.

Note :

Due to improvements continuously taking place in design, the details given may vary marginally in respect of No Load Losses, Load Losses and overall dimensions. However the variations will be within permissible limits as per Applicable Standards.

The details given here are for Kotsons standard transformer with standard fittings. The details may depend upon the optional fittings/specific requirement of customer. For details, Please contact our Marketing Office or fill our enquiry/feedback form.

Fitting & accessories provided with standard Transformer are as under.

Sl.No Accessories 5 to 167 KVA

1 Terminal Connector

Page no.24

2 Primary bushings

3 Secondary bushings

4 Pressure relief device

5 Mounting lugs/brackets

6 Lifting lugs

7 Rating & Diagram plate

8 Grounding/earthing terminal

    Optional fittings can be provided on extra cost as per customer requirements.

THREE PHASE TRANSFORMER(3 PHASE ISOLATION TRANSFORMER)

A 3 phase transformer, there is a three-legged iron core as shown below. Each leg has a respective primary and secondary winding.  Thus a 3 phase isolation transformers is a 3 phase transformer which has isolated primary and secondary windings to allow the power input to be isolated from the power output.

There a number of power transformer manufacturers of quality 3 phase isolation transformers today.  The primary 3 phase isolation transformers manufacturers are: GE Industrial, TEMCo Isolation Transformer, Marcus Transformer, Hammond Transformers, and Acme Transformers with capacity ranges 0.05 KVA through 5000 KVA. The isolation transformer manufacturer TEMCo also acts as a one stop wholesale outlet for the other transformer brands.

Standard 3 Phase Isolation Transformers

3 phase isolation transformers have 3 primary and 3 secondary windings that are physically separated from each other. Sometimes these isolation transformers are referred to as "insulated". This is because the windings are insulated from each other.

In a 3 phase isolation transformer the output windings will be isolated, or floating from earth ground unless bonded at the time of installation.

3 Phase Shielded Isolation Transformers

Shielded 3 phase isolation transformers have all the feature of the standard 3 phase isolation transformers plus they also incorporate a full metallic shield (usually copper or aluminum) between the 3 phase primary and 3 phase secondary windings. This electrostatic shield ("Faraday Shield") is connected to earth ground and performs two functions:

One, it attenuates (filters) voltage transients (voltage spikes). These shielded 3 phase isolation transformers have an attenuation ratio of 100 to 1.

Two, It also filters common mode noise. Attenuation of approximately 30 decibels.

 3 Phase Power Is More Efficient Than Single Phase

Page no.25

Three phase electricity powers large industrial loads more efficiently than single-phase electricity. When single-phase electricity is needed, It is available between any two phases of a three-phase system, or in some systems , between one of the phases and ground. By the use of three conductors a 3 phase system can provide 173% more power than the two conductors of a single-phase system. Three-phase power allows heavy duty industrial equipment to operate more smoothly and efficiently. 3 phase power can be transmitted over long distances with smaller conductor size.

(Also read about 3 phase isolation transformers here.)

In a three-phase transformer, there is a three-legged iron core as shown below. Each leg has a respective primary and secondary winding.

The three primary windings (P1, P2, P3) will be connected at the factory to provide the proper sequence (or correct polarity) required and will be in a configuration known as Delta. The three secondary windings (S1, S2, S3) will also be connected at the factory to provide the proper sequence (or correct polarity) required. However, the secondary windings, depending on our voltage requirements, will be in either ?Delta? or a ?Wye? configuration.  

3 Phase Transformers Overview

3 phase transformers are used throughout industry to change values of 3 phase voltage and current. Since 3 phase power is the most common way in which power is produced, transmitted, an used, an understanding of how 3 phase transformer connections are made is essential. In this section it will discuss different types of 3 phase transformers connections, and present examples of how values of voltage and current for these connections are computed.

3 phase Transformer Construction:

A 3 phase transformer is constructed by winding three single phase transformers on a single core. These transformers are put into an enclosure which is then filled with dielectric oil. The dielectric oil performs several functions. Since it is a dielectric, a nonconductor of electricity, it provides electrical insulation between the windings and the case. It is also used to help provide cooling and to prevent the formation of moisture, which can deteriorate the winding insulation.

Three-Phase Transformer Connections:

There are only 4 possible transformer combinations:

Delta to Delta - use: industrial applications

Delta to Wye - use : most common; commercial and industrial

Page no.26

Wye to Delta - use : high voltage transmissions

Wye to Wye - use : rare, don't use causes harmonics and balancing problems.

3 phase transformers are connected in delta or wye configurations. A wye-delta transformer has its primary winding connected in a wye and its secondary winding connected in a delta (see figure 1-1). A delta-wye transformer has its primary winding connected in delta and its secondary winding connected in a wye (see figure 1-2).

Delta Connections:

A delta system is a good short-distance distribution system. It is used for neighborhood and small commercial loads close to the supplying substation. Only one voltage is available between any two wires in a delta system. The delta system can be illustrated by a simple triangle. A wire from each point of the triangle would represent a three-phase, three-wire delta system. The voltage would be the same between any two wires (see figure 1-3).

Wye Connections:

In a wye system the voltage between any two wires will always give the same amount of voltage on a 3 phase system. However, the voltage between any one of the phase conductors (X1, X2, X3) and the neutral (X0) will be less than the power conductors. For example, if the voltage between the power conductors of any two phases of a three wire system is 208v, then the voltage from any phase conductor to ground will be 120v. This is due to the square root of 3 phase power. In a wye system, the voltage between any two power conductors will always be 1.732 (which is the square root of 3) times the voltage between the neutral and any one of the power phase conductors. The phase-to-ground voltage can be found by dividing the phase-to-phase voltage by 1.732 (see figure 1-4).

Page no.27

Description

Kotsons manufactures a wide range of distribution and power transformers ranging from 25 KVA to 20 MVA with voltage class of 33 KV. These transformers can be free

breathing or hermetically sealed. Conventional transformers are fitted with a conservator with breather for free breathing while hermetically sealed are without breathing with bolted cover. Hermetically sealed transformers are totally maintenance free and are particularly suited for use in exposed outdoor environments such as moisture, salt or dust laden atmospheres. They are used extensively in chemical plants, oil and gas terminals where poor accessibility makes regular maintenance undesirable. Transformers immersed in synthetic coolants are suitable for use indoors, with adequate ventilation, or near to the load centre where oil would not be considered environmentally acceptable.

The liquid filled transformers can be supplied with cooling either by corrugations on the side of the tank or Pressed steel radiators mounted on tank body. Transformers can be filled with either oil or one of several low flammability synthetic fluids such as midel. Both types can be supplied with HV and LV Switchgear incorporated into substations.

Kotsons can supply conventional/hermetically sealed/bolted type, indoor/outdoor type, pole/platform mounted 3 phase, 50/60 Hz, oil immersed, ONAN/ONAF/ OFWF cooled, step up/step down, double wound with Al/Cu conductor, Continuous duty transformers from 5 KVA to 20 MVA upto 33 KV Class with ‘A’ Class Insulation and designed to withstand Short Circuit, & Impulse Test in accordance to IEC / BS / ANSI / IS / NEEMA.

KOTSONS STANDARD TRANSFORMERS

In order to meet the growing demand of transformers with short deliveries, Kotsons have developed a separate production system called KST (Kotsons Standard Transformers). This range of KST are manufactured with standard losses and in accordance to IS : 2026 latest. Kotsons can supply a comprehensive range as depicted below in short delivery periods.

The second of our production system known as Kotsons Repeat transformer enables us to reproduce any of our previous transformer designs again in the shortest time with the object of keeping delivery time to a minimum.

Details of Characteristics & dimensions of Kotsons standard transformers with standard fittings manufactured in accordance with IS : 2026 latest., and can be delivered in short

Page no.28

delivery period upon order confirmation.

Specification for KST (Kotsons Standard Transformer)

Kotsons make outdoor type, 3 phase, 50 Hz, oil immersed, conventional bolted cover, ONAN cooled, Pole / Platform mounted, double wound with Cu conductor, step up, core type continuous duty transformers with + 2.5% to - 7.5% taps on HT side for HT variation and leads to be brought out on off circuit tap changing switch with locking device and outside indicator arrangement and connected in delta/star as per Vector group ref. Dyn11.

The temperature rise will be 50/55° C in Oil/Winding respectively over a maximum ambient temperature as per IS. The transformers will be manufactured as per IS: 2026 latest, complete with fittings/accessories as stated below.

Rated Primary Voltage : 11KVSecondary Voltage : 416/240V

ONAN Cooled, Outdoor type, Oil immersed Copper Wound, Open Type with Conservator

Capacity kVA

Efficiency at 100% load (%)

Voltage Regulation P.F.=1

(%)

Noise Level

db (A) : 1m

Outline Dimension

Approx. (mm)Oil qty (Litres

)

Total weigh

t (Kgs.)P.F.=

1P.F.=0.

8H L W

50 97.48 96.85 2.26 451300

1080

520 115 420

100 97.71 97.14 2.06 461400

1230

550 150 600

160 98.19 97.73 1.63 471480

1290

630 210 825

200 98.30 97.88 1.52 471580

1340

675 260 990

250 98.32 97.90 1.51 481655

1385

750 320 1200

315 98.33 97.92 1.50 501735

1385

830 360 1400

400 98.44 98.05 1.42 501800

1410

950 370 1600

500 98.50 98.13 1.37 52 1850

1520

1000

450 1920

Page no.29

630 98.62 98.27 1.31 521920

1620

1030

530 2230

800 98.56 98.20 1.37 542000

1830

1030

675 2700

1000 98.63 98.29 1.32 542100

2040

1040

780 3160

1250 98.72 98.40 1.29 562140

2070

1210

840 3400

1500 98.78 98.48 1.24 562240

2150

1240

970 3900

2000 98.81 98.51 1.2252/3cm

2350

2230

1390

1080 4625

2500 98.88 98.60 1.1852/3cm

2480

2300

1420

1375 5700

3000 98.92 98.65 1.1452/3cm

2570

2380

1450

1530 6330

Rated Primary Voltage : 22KVSecondary Voltage : 416/240V

ONAN Cooled, Outdoor type, Oil immersed Copper Wound, Open Type with Conservator

Capacity kVA

Efficiency at 100% load (%)

Voltage Regulation P.F.=1

(%)

Noise Level

db (A) : 1m

Outline Dimension

Approx. (mm)Oil qty (Litres

)

Total weigh

t (Kgs.)P.F.=

1P.F.=0.

8H L W

50 97.48 96.85 2.26 451300

1100

520 120 420

100 97.71 97.14 2.06 461410

1230

565 170 640

160 98.19 97.73 1.63 471500

1290

640 215 820

200 98.30 97.88 1.52 471620

1345

680 280 1025

250 98.32 97.90 1.51 481670

1390

760 335 1240

315 98.33 97.92 1.50 501735

1390

840 375 1475

400 98.44 98.05 1.42 501800

1420

960 415 1630

Page no.30

500 98.50 98.13 1.37 521850

1535

1015

495 2050

630 98.62 98.27 1.31 521920

1655

1045

580 2410

800 98.56 98.20 1.37 542000

1845

1050

715 2925

1000 98.63 98.29 1.32 542100

2050

1060

825 3460

1250 98.72 98.40 1.29 562140

2090

1230

930 3710

1500 98.78 98.48 1.24 562240

2165

1255

1050 4300

2000 98.81 98.51 1.2252/3cm

2350

2245

1410

1215 5000

2500 98.88 98.60 1.1852/3cm

2480

2340

1435

1460 6020

3000 98.92 98.65 1.1452/3cm

2570

2400

1465

1620 6650

Rated Primary Voltage : 33KVSecondary Voltage : 416/240V

ONAN Cooled, Outdoor type, Oil immersed Copper Wound, Open Type with Conservator

Capacity kVA

Efficiency at 100% load (%)

Voltage Regulation P.F.=1

(%)

Noise Level

db (A) : 1m

Outline Dimension

Approx. (mm)Oil qty (Litres

)

Total weigh

t (Kgs.)P.F.=

1P.F.=0.

8H L W

100 97.70 97.13 2.06 461420

1230

575 185 655

160 98.16 97.70 1.63 471520

1290

650 235 835

200 98.29 97.86 1.52 471580

1350

690 305 1070

250 98.30 97.88 1.51 481655

1390

770 360 1310

315 98.35 97.94 1.50 501735

1400

850 390 1535

400 98.50 98.13 1.42 501800

1430

980 435 1735

Page no.31

500 98.49 98.11 1.37 521850

1550

1030

520 2135

630 98.67 98.33 1.31 521920

1670

1060

610 2470

800 98.56 98.20 1.37 542000

1860

1070

740 2980

1000 98.63 98.29 1.32 542100

2060

1080

850 3580

1250 98.68 98.35 1.29 562140

2100

1250

985 3830

1500 98.78 98.48 1.24 562240

2180

1270

1080 4525

2000 98.79 98.48 1.2252/3cm

2350

2260

1420

1235 5200

2500 98.84 98.55 1.1852/3cm

2480

2380

1450

1565 6300

3000 98.92 98.65 1.1452/3cm

2570

2420

1480

1690 6860

Rated Primary Voltage : 33KVSecondary Voltage : 11KV

ONAN Cooled, Outdoor type, Oil immersed Copper Wound, Open Type with Conservator

Capacity kVA

Efficiency at 100% load (%)

Voltage Regulation P.F.=1

(%)

Noise Level

db (A) : 1m

Outline Dimension

Approx. (mm)Oil qty (Litres

)

Total weight (Kgs.)P.F.=

1P.F.=0.

8H L W

3150 99.02 98.75 1.0454/3m

3000

2800

2900

2000 8450

5000 99.39 99.02 0.7956/3m

3200

2500

3150

2400 11300

6300 99.51 99.14 0.6856/3m

3300

3000

3250

3200 15000

8000 99.62 99.21 0.6758/3m

3430

3300

3350

4100 18000

10,000 99.68 99.32 0.5958/3m

3600

3400

3800

5800 21000

Note :

Page no.32

The dimensions and weights shown above apply to a typical range of KST (Kotsons standard transformers) design to the specification IS : 2026. As all transformers are usually design and built to customers specification their exact dimensions and weights can vary.

Due to improvements continuously taking place in design, the details given here may vary marginally irrespective of Length, Width, Height, Oil and Total Weight . However the variations will be within permissible tolerance limits as per IS 2026 latest .

Standard Accessories

Oil Level Gauge, Pressure Release Device, Shut off valve, Off Load Tap Changer Handle, Breather, Name Plate, Sampling Valve, Drain Valve, Roller, Lifting Eye Oil Filling hole with Cap, H.V. Porceline Bushing, L.V. Porceline Bushing, Hand Hole, Lifting Lug, Filter Valve, Radiator/Corrugations, Conservator Drain Valve, Earthing Terminal, Pulling Eye, Jacking Pad.

Optional Accessories

Buchholz Relay, On load Tap Changer, RTCC, AVR, Marshalling Box, Oil Temperature Indicator, Winding Temperature Indicator, Skid base.

THREE PHASE TRANSFORMER

Amorphous steel transformer

Introduction

“Kotsons” Amorphous metal transformers are manufactured in technical collaboration with Hitachi Met glass Inc., the only Producer of Amorphous Metal in the World. Kotsons has set up state of the art amorphous metal transformer manufacturing facility by importing the latest amorphous metal cores manufacturing equipment from M/S Bergers Machinenbau GMBH, Germany.

This plant has the latest equipment in India to produce energy efficient amorphous metal transformers. Quality of process is given overriding importance to the quantity. Cores are annealed under absolute inert atmosphere to get at most lower losses thereby enhancing the energy savings in comparison with the similar manufacturing facilities in this line in the world.

Advantages:

Energy Efficient AMDT can reduce No Load losses by 80 % Since No load losses represent a

major portion of the energy lost during Power distribution Hence reduce cost investment for power generation & translate into reduction in carbon di-oxide emissions created during power generation.

Lower Temperature

Page no.33

Slower ageing of insulation Higher overloading capability Longer Life Superior electrical performance under harmonics conditions

Description

In order to achieve significant improvement in efficiency, amorphous metal is used to make transformer core. Amorphous metal exhibits a unique random molecular structure unlike rigid grain structure of silicon steel, which enables easy magnetization & demagnetization, thereby reducing hysteresis loss. Further processing of amorphous metal in very thin lamination (appropriate 1/10th of silicon steel lamination thickness) enable significant reduction in eddy current losses.

The Advantages of AMDT is not limited to reduction in losses alone. Since these losses are converted in to heat energy , cooling oil inside the transformer tank will be heated up and it will lead to emissions and significant fuel savings. AMDTs helps utilities reduce harmful emissions such as sulphur dioxide, Nitrogen Oxides and Carbon dioxide, the pollutants that cause acid rain & global warming.

Comparisons among typical silicon steel distribution transformer, high efficiency silicon steel distribution transformer & amorphous metal distribution transformer (AMDT) is given under:

Rating (KVA)Typical Silicon Steel

Hi-efficiency Silicon Steel Amorphous Metal

Single Phase      

10 40 30 10

15 60 45 15

Three Phase      

25 100 80 25

63 180 150 45

100 260 195 60

Specification :

Kotsons make Amorphous Metal Three Phase transformers 50 Hz or 60 Hz with primary Voltage up to 33 KV class & Secondary voltage up to 480 Volts or 480 Volts or as required, Oil immersed, naturally cooled, Pole or platform mounted , double wound with Aluminium / Copper, Step up/Step down core type continuous duty transformers having no load voltage ratio from 15 KVA to 1000 KVA up to 33 KV Class with ‘A’ Class Insulation and designed to withstand Short Circuit, & Impulse Test in accordance to ANSI / IEC / AS / IS.

Details of Characteristics & dimensions of Kotsons standard transformers with standard

Page no.34

fittings manufactured in accordance with ANSI C 57 latest readily available in stock and can be delivered within 1 weeks from the date of order confirmation.

Note:

Due to improvements continuously taking place in design, the details given may vary marginally in respect of No Load Losses, Load Losses and overall dimensions. However the variations will be within permissible limits as per Applicable Standards.

The details given here are for Kotsons standard transformer with standard fittings. The details may depend upon the optional fittings/specific requirement of customer. For details, Please contact our Marketing Office or fill our enquiry/feedback form.

Fitting & accessories provided with standard Transformer are as under.

Sl.No Accessories 5 to 167 KVA

1 Terminal Connector

2 Primary bushings

3 Secondary bushings

4 Oil Level Indicator/gauge

5 Pressure relief device/vent

6 Lifting lugs

7 Rating & Diagram plate

8 Dehydrating Silica gel breather

9 Drain Valve/Drain pipe

10 Filling plug

Optional fittings can be provided on extra cost as per customer requirements. :

Optional Fittings

1 Thermometer O

2 HT Fuse O

3 LT Circuit Breaker O

4 Lightning Arresters O

5 Filter Valve O

6 Conservator O

Page no.35

VENTILATED DRY TYPE THREE PHASE TRANSFORMER:-

Applicable Standards

IEC (International Electro technical Commission) IS (Indian Standard)

Page no.36

Introduction

Kotsons Pvt. Ltd. in collaboration with E. I. DuPont, U.S.A. has developed Ventilated Dry Type transformers in India with a DuPont ReliatraN® branded solution.

ReliatraN® Brand Transformers are manufactured with UL® Certified Insulation Materials and Systems, by a network of ISO 9000 Certified Manufacturers worldwide, meeting the highest of International Standards for Quality, Design, Construction and Performance.

Kotsons Pvt. Ltd. is the first and only Operating Licensed Manufacturer of DuPont's ReliatraN® Brand Transformers in India.

Description

Kotsons manufactures Ventilated Dry Type transformer ranging from 40 KVA to 5000 KVA with voltage class of 33 KV. These transformers are fitted in Enclosure confirming to IP 21 to IP 33 for Indoor location and IP 45 for out door location. Kotsons Ventilated Dry Type Transformer are totally maintenance free and safe from fire as material used are metals, ceramics, fiberglass and resin. It is environment friendly as there is no oil, hence handling becomes easier and there are no

chances of spillages and leakages and there is minimal non toxic smoke in case of fire.

Kotsons offers Ventilated Dry Type Transformers with Class H / C insulation which can bear heat upto 180 / 220 Deg C and can be used in humid and chemically polluted atmosphere.

Kotsons can supply Indoor/Outdoor, 3 phase, 50/60 Hz, Resin Impregnated, AN/FA cooled, step up/step down, double wound with Cu conductor transformer from 40 KVA to 5000 KVA upto 33

KV Class with H / C Class Insulation and designed to withstand Short Circuit, & Impulse Test in accordance to IEC / IS.

Process & Core :

Core structure is of nonaging, Cold Rolled Grain Oriented, high permeability silicon steel. All core laminations are free of burr and staked without gaps The core assembly is painted with a protective paint to protect against corrosion.

Winding :

LV & HV Windings are done in dust free air conditioned winding shops. Rectangular copper strips are used for LV winding insulated with

Page no.37

Nomex® while HV winding are of copper wire insulated with Nomex® or suitable material for temperature rise if wrapping is not possible due to small diameter.

VPI:

The Transformer coils are thoroughly dried in an PLC controlled oven and the coils are then completely sealed with an insulating Varnish / Resin (Class H/C) through an vacuum pressure impregnation process. Kotsons is having a state of art PLC controlled VPI (Vacuum Pressure Impregnation) Plant. The VPI process fully penetrates and seals the coils into a high strength composite unit for complete environment protection, hence can be used in humid and chemically polluted atmosphere. Coils are then cured to develop bonding.

Testing :

After the Core- Coil assembly. All transformers are tested for routine test. Kotsons has in house facilities for conducting all routine tests as per IEC & IS. Kotsons is equipped with adequate digital readout measuring devices wherever required and the digital sampling techniques with computer calculations. Precision digital meters such as digital power analyser, WT -130 of Yokogawa make are used for measuring of load losses, Impedance Voltage, No load losses, and no load currents. KPL is having in house Partial Discharge (PD) testing facility.

Warranty :

KPL VDT Transformer are guaranteed for satisfactorily performance for a period of 5 years* from the date of dispatch. Any part found defective during this period, as a consequence of bad design, manufacturing or workmanship should be repaired, free of cost, by us within mutually agreed schedule.

* Warrantee for 5 Years on active part only.

Environmental Impact Operational Aspects

Transformers insulated with NOMEX® brand materials are extremely safe, even when exposed to fire.

High flame resistance, and low smoke and no toxic off-gasses. Class H & C ventilated dry type transformers can be built smaller, reducing the

footprint to the environment, conserving space. Insulation is friendly to use during manufacturing - no skin irritants or surface

chemicals.

End-of-Life Aspects

NOMEX® insulation can be easily disposed of by incineration or burial, since it is inert to the environment.

Page no.38

NOMEX® insulated VDT transformers have low volumes of insulation, eliminating the burden of disposal of large amounts of resin.

Quality :

KOTSONS PVT. LTD., is certified for ISO 9001:2000 by DET NORSKE VERITAS, B.V., NETHERLANDS. Kotsons has set up a complete quality management system to offer the best customer satisfaction. Each and every Ventilated Dry Type Transformer is identified with ReliatraN ® identification labels.

Specification for KST (Kotsons Standard Transformer)

Kotsons makes Indoor/Outdoor, 3 phase, 50/60 Hz, Resin Impregnated, AN/FA cooled, step up/step down, double wound with Cu conductor transformer from 40 KVA to 5000 KVA upto 33 KV Class with H / C Class Insulation and designed to withstand Short Circuit, & Impulse Test in accordance to IEC / IS.

Sl.No.

Rating No

Load Loss

(Watts)

Load Loss

(Watts)

Total Loss(Watt

s)

Impedance (%)

Outline Dimension

(mm)Total

Weight (Kg)KV

AKV L W H

1 63011/0.433

1725 6920 8645 51850

1200

1750

2520

2 80011/0.433

1920 7880 9800 51900

1200

1850

2855

31000

11/0.433

2235 10145 12380 51950

1250

1950

3125

41250

11/0.433

2630 12600 15230 51950

1250

2100

3520

51600

11/0.433

3010 14765 17775 6.252050

1350

2250

4230

62000

11/0.433

3540 18375 21915 6.252150

1450

2450

4940

72500

11/0.433

4305 21260 25565 6.252250

1550

2550

5855

Note :

The dimensions and weights shown above apply to a typical range of KST (Kotsons standard transformers) design to the specification IS : 2026. As all transformers are usually design and built to customers specification their exact dimensions and weights can vary.

Page no.39

Due to improvements continuously taking place in design, the details given here may vary marginally irrespective of Length, Width, Height and Total Weight . However the variations will be within permissible tolerance limits as per IS 2026 latest.

ITEM No.

DESCRIPTION STANDAR

D OPTIONA

L

1. H.V. TERMINAL BUSBAR Yes No

2. L.V. TERMINAL BUSBAR Yes No

3.L.V. SEPERATE NEUTRAL EARTHING BUSHING

No Yes

4. SEPERATOR NEUTRAL EARTH BUSBAR No Yes

5. OFF CIRCUIT TAPPING LINK BOARD Yes No

6. TAP LINK POSITION PLATE Yes No

7.ACCESS DOORS/WINDOWS FOR TAP CHANGING LINKS

Yes No

8. VENTILATION LOUVERS Yes No

9. RAIN WATER GUARD Yes No

10. RATING AND DIAGRAM PLATE Yes No

11.LIFTING LUGS FOR TOP COVER & COMPLETE TRANSFORMER LIFTING

Yes No

12.LIFTING HOLES FOR CORE-COIL ASSY. LIFTING

Yes No

13.ENCLOSURE (DEGREE OF PROTACTION IP-21/23)

Yes No

14. MARSHLING BO-- Yes No

15. PHASE C.T. Yes No

16. WINDING TEMPERATURE INDICATOR Yes No

17. SPACE HEATER No Yes

18.DETACHABLE H.V. CABLE GLAND PLATE WITH 1 KNOCKOUT

Yes No

19. H.V. CABLE GLAND No Yes

20. H.V. CABLE LUG WITH INSIDE KNURLING No Yes

21. H.T. CABLE CLAMP Yes No

22. SURGE ARRESTER No Yes

23. SURGE ARRESTER GROUNDING BUSHING No Yes

Page no.40

24. SURGE ARRESTER GROUNDING BUSBAR No Yes

25.DETACHABLE L.V. CABLE GLAND PLATE WITH REQD. KNOCKOUTS

Yes No

26. L.V. CABLE GLAND No Yes

27. L.V. CABLE LUG WITH INSIDE KNURLING No Yes

28. L.T. CABLE CLAMP Yes No

29.SKID UNDER BASE WITH HAULAGE HOLES

Yes No

30. BI – DIRECTIONAL FLAT ROLLERS Yes No

31. BODY EARTHING TERMINALS Yes No

32. PHASE IDENTIFICATION PLATES Yes No

33. DANGER PLATES Yes No

34. H.V. CABLE BO-- No Yes

35. L.V. CABLE BO-- No Yes

36. L.V. BUSDUCT BO-- No Yes

37. Fans No Yes

38. OLTC, AVR, RTCC No Yes

NOTE:- OPTIONAL FEATURES ARE AVAILABLE ON BUYER'S REQUEST & AT EXTRA COST.

Oil Filled & Dry Transformer Design

HT Distribution and Power Transformer Design SoftwareThis transformer design software can get you the design parameters along with CAD developed images of different transformer & core assembly parts dynamically. This CAD feature helps you to confirm and check the authenticity of computer generated design parameters. Design oil filled & dry type transformers with one software. More over this software can also be customized as per your requirements.

How does transformer design software work?1 - Just enter the KVA rating, Impedance, NLL (No Load Losses), LS (Load Losses), select the flux density and press the "Auto mode". Within seconds you get various design outputs just showing you the core and copper weights depending upon the entered impedance value. Select any set of values as per your preferred tolerance and you get the complete design data of the distribution or power transformer (clearances and certain other values are added as default values but you can change as per your requirements), 2 - Still you have the "Manual" mode to change and fine tune your design as per your requirement (if desired),

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3 - Change no. of HV coils/discs per limb, size of HV/LV conductor(s) - both round conductor and strip size, no. of parallel LV conductors, 4 - You can reset various clearances, change current density, conductor insulation as per your requirement and client specifications, 5 - Select HV winding type - Cross Over to Disc winding and vice -a - versa, 6 - Tapping details for OLTC and Off Load Tap Changer upto 25 steps. Enter any + step value through - step @ any % step value, 7 - You get values of Axial and radial forces developed in the windings during short circuits, temp gradients for HV and LV, Thermal Time Constant and ability to withstand shortcircuits with winding temperature rise, 8 - Pressed Steel Radiator (PSR) data calculation added you get automatic fixing dimensions of radiators - section width, CD and no. of fins. Options to select 226, 300 and 560 width sections. Tank drawing details are generated automatically. 9 - Feature added to get winding data for an old transformer 10 - GTP (Guaranteed Technical Particulars), Core details, core & winding assembly details, estimation and costing sheets are generated in the 'Word Format' for easy access, printing and sending the same via email to clients for approval, in house departments like design, QC, purchase, estimation, production, despatch. So this distribution and power transformer design software saves time, energy and revenue. A must key tool for transformer design and training professionals and engineering students.

Factors controlling and affecting the design of a transformerPrinciple of operation of a transformer

Theory of Transformer losses:-

Core losses are caused by two factors:  hysteresis and eddy current losses.  Hysteresis loss is that energy lost by reversing the magnetic field in the core as the magnetizing AC rises and falls and reverses direction.   Eddy current loss is a result of induced currents circulating in the core.

Efficiency of a transformer can be calculated as per equation (a),(b),(c)

Efficiency = power outut / power input

Efficiency = power outut / ( power output + core oss + copper loss)

Efficienct = VI*PF/(VI*PF + core loss + copper loss)

Where PF= power factor

Applications:

A key application of transformers is to increase voltage before transmitting electrical energy over long distances through wires. Wires have resistance and so dissipate electrical energy at a rate proportional to the square of the current through the wire. By transforming electrical power to a high-voltage (and therefore low-current) form for transmission and back again afterwards, transformers enable economic transmission of

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power over long distances. Consequently, transformers have shaped the electricity supply industry, permitting generation to be located remotely from points of demand.[3] All but a tiny fraction of the world's electrical power has passed through a series of transformers by the time it reaches the consumer.[4] Transformers are used extensively in electronic products to step down the supply voltage to a level suitable for the low voltage circuits they contain. The transformer also electrically isolates the end user from contact with the supply voltage.

Transformers: In a previous section (Switching Power Supplies), I touched on transformers. You should remember that a transformer has a primary winding and a secondary winding wrapped around a core. In car audio, the core is usually a donut shaped toroid. A transformer can be designed to step voltage up or down, and/or isolate. We discussed isolation in a previous section. This section will deal with stepping the voltage up or down.

Winding Ratio: Remember that the transformer windings are enamel coated magnet wire which is wrapped around the core (as seen below). The number of windings is determined by the number of times that a piece of wire makes a complete turn around the core. The primary winding is the winding which is driven (in car audio amplifiers, it's usually driven by transistors). The secondary winding is the output winding. The secondary is driven by the magnetic field that the primary induces in the core. A transformer with a ratio of 1:1 will not cause a voltage increase or decrease (disregarding small losses) from the primary to the secondary (as measured across each of the individual windings). If the ratio is 1:2 (primary:secondary), the voltage across the secondary will be twice the voltage across the primary. A ratio of 1:3 will result in a secondary voltage 3 times as high as the voltage on the primary. Of course all of this applies to a transformer which is very lightly or not loaded (minimal current flow). When current is drawn from the secondary winding, there may (will) be a voltage drop and therefore a primary to secondary voltage ratio which may not match the winding ratio exactly. This loss of voltage is primarily due to the less than 100% efficiency of the magnetic coupling of the primary and the secondary windings through the core and also some copper (resistance) losses. Remember that the primary and the secondary windings are not generally electrically connected together. This means that all of the power transfer between the primary and secondary is transferred (magnetically) through the core. The transformer below is similar to one that you would find in a small car audio amplifier. The winding ratio is 1:2. The different colors are each half of the center tapped primary and secondary. Notice that there are twice as many secondary windings as there are primary windings. The schematic symbol shows how the windings relate to each other. The center tap of the primary (red) is connected to the battery. The center tap of the secondary (black) is connected to ground.

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As a side note: The power driven into the primary will equal the power produced at the output of the secondary (if we ignore wire and core loss). If we have a 'step-up' transformer with a 1:2 ratio being driven with 24 volts A.C., the secondary output voltage (disregarding losses) will be 48 volts. If we load the secondary so that 5 amps of current is flowing through the secondary windings, the power output is P=I*E; P=5*48; P=240 watts. Since the power driven into the primary equals the power out of the secondary, we know that the power being driven into the primary is 240 watts. If we use the formula I=P/E, we see that the I=240/24; I=10 amps. If we were stepping the voltage down, the current flowing through the primary would be less than the current being drawn through the secondary windings

Advanced Info: When designing a transformer you have to calculate the number of primary windings so that the transformer will operate properly/efficiently. There are a few different variables that have to be taken into account.

Ac: Ac is the effective cross sectional core area. This number is supplied by the core manufacturer.

Primary Voltage: The primary voltage for a push-pull system is double the primary input voltage. For car amplifier switching power supplies, the input voltage is 12VDC. This means that the total primary voltage is 24 volts. If we use 13.5 volts as the input voltage, the primary voltage would be 27 volts.

Operating Frequency: The operating (oscillation) frequency is simply the frequency at which the primary is driven. Generally between 25,000hz and 100,000hz in car audio amplifiers.

Primary Turns: The number of primary turns returned by the calculator is the total number of turns on the primary side of the transformer. Of course, with a push pull system, the number of turns on each half of the primary must be equal. If the output says

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that you need 13 turns, you'd round up to 14 turns and each half of the primary would have 7 turns. From the previous diagram, you'd have 7 orange turns and 7 green turns on the core

Shell-Core Transformers

The most popular and efficient transformer core is the SHELL CORE, as illustrated in figure 5-4. As shown, each layer of the core consists of E- and I-shaped sections of metal. These sections are butted together to form the laminations. The laminations are insulated from each other and then pressed together to form the core.

TRANSFORMER WINDINGS

As stated above, the transformer consists of two coils called WINDINGS which are wrapped around a core. The transformer operates when a source of ac voltage is connected to one of the windings and a load device is connected to the other. The winding that is connected to the source is called the PRIMARY WINDING. The winding that is connected to the load is called the SECONDARY WINDING. (Note: In this chapter the terms "primary winding" and "primary" are used interchangeably; the term: "secondary winding" and "secondary" are also used interchangeably.)

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Figure 5-5 shows an exploded view of a shell-type transformer. The primary is wound in layers directly on a rectangular cardboard form.

Figure 5-5. - Exploded view of shell-type transformer construction.

In the transformer shown in the cutaway view in figure 5-6, the primary consists of many turns of relatively small wire. The wire is coated with varnish so that each turn of the winding is insulated from every other turn. In a transformer designed for high-voltage applications, sheets of insulating material, such as paper, are placed between the layers of windings to provide additional insulation.

Figure 5-6. - Cutaway view of shell-type core with windings.

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When the primary winding is completely wound, it is wrapped in insulating paper or cloth. The secondary winding is then wound on top of the primary winding. After the secondary winding is complete, it too is covered with insulating paper. Next, the E and I sections of the iron core are inserted into and around the windings as shown.

The leads from the windings are normally brought out through a hole in the enclosure of the transformer. Sometimes, terminals may be provided on the enclosure for connections to the windings. The figure shows four leads, two from the primary and two from the secondary. These leads are to be connected to the source and load, respectively.

SCHEMATIC SYMBOLS FOR TRANSFORMERS

Figure 5-7 shows typical schematic symbols for transformers. The symbol for an air-core transformer is shown in figure 5-7(A). Parts (B) and (C) show iron-core transformers. The bars between the coils are used to indicate an iron core. Frequently, additional connections are made to the transformer windings at points other than the ends of the windings. These additional connections are called TAPS. When a tap is connected to the center of the winding, it is called a CENTER TAP. Figure 5-7(C) shows the schematic representation of a center-tapped iron-core transformer.

HOW A TRANSFORMER WORKS

Up to this point the chapter has presented the basics of the transformer including transformer action, the transformer's physical characteristics, and how the transformer is

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constructed. Now you have the necessary knowledge to proceed into the theory of operation of a transformer.

NO-LOAD CONDITION

You have learned that a transformer is capable of supplying voltages which are usually higher or lower than the source voltage. This is accomplished through mutual induction, which takes place when the changing magnetic field produced by the primary voltage cuts the secondary winding. A no-load condition is said to exist when a voltage is applied to the primary, but no load is connected to the secondary, as illustrated by figure 5-8. Because of the open switch, there is no current flowing in the secondary winding. With the switch open and an ac voltage applied to the primary, there is, however, a very small amount of current called EXCITING CURRENT flowing in the primary. Essentially, what the exciting current does is "excite" the coil of the primary to create a magnetic field. The amount of exciting current is determined by three factors: (1) the amount of voltage applied (Ea), (2) the resistance (R) of the primary coil's wire and core losses, and (3) the XL which is dependent on the frequency of the exciting current. These last two factors are controlled by transformer design. Figure 5-8. - Transformer under no-load conditions.

This very small amount of exciting current serves two functions:

Most of the exciting energy is used to maintain the magnetic field of the primary. A small amount of energy is used to overcome the resistance of the wire and core

losses which are dissipated in the form of heat (power loss).

Exciting current will flow in the primary winding at all times to maintain this magnetic

Field.

MAGNETIC FIELD OF A COIL

Figure 1-3(A) illustrates that the magnetic field around a current-carrying wire exists at all points along the wire.

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Figure 1-5 illustrates that when a straight wire is wound around a core, it forms a coil and that the magnetic field about the core assumes a different shape. Figure 1-5(A) is actually a partial cutaway view showing the construction of a simple coil. Figure 1-5(B) shows a cross-sectional view of the same coil. Notice that the two ends of the coil are identified as X and Y.

Figure 1-5. - Magnetic field produced by a current-carrying coil.

When current is passed through the coil, the magnetic field about each turn of wire links with the fields of the adjacent turns. (See figure 1-4(A)). The combined influence of all the turns produces a two-pole field similar to that of a simple bar magnet. One end of the coil is a north pole and the other end is a south pole.

Strength of an Electromagnetic Field

The strength or intensity of a coil's magnetic field depends on a number of factors. The main ones are listed below and will be discussed again later.

The number of turns of wire in the coil. The amount of current flowing in the coil. The ratio of the coil length to the coil width. The type of material in the core.

Losses in an Electromagnetic Field

When current flows in a conductor, the atoms in the conductor all line up in a definite direction, producing a magnetic field. When the direction of the current changes, the direction of the atoms' alignment also changes, causing the magnetic field to change direction. To reverse all the atoms requires that power be expended, and this power is lost. This loss of power (in the form of heat) is called HYSTERESIS LOSS. Hysteresis

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loss is common to all ac equipment; however, it causes few problems except in motors, generators, and transformers. When these devices are discussed later in this module, hysteresis loss will be covered in more detail.

BASIC AC GENERATION

From the previous discussion you learned that a current-carrying conductor produces a magnetic field around itself. In module 1, under producing a voltage (emf) using magnetism, you learned how a changing magnetic field produces an emf in a conductor. That is, if a conductor is placed in a magnetic field, and either the field or the conductor moves, an emf is induced in the conductor. This effect is called electromagnetic induction.

Factors Affecting Coil Inductance There are several physical factors which affect the inductance of a coil. They include the number of turns in the coil, the diameter of the coil, the coil length, the type of material used in the core, and the number of layers of winding in the coils.

Inductance depends entirely upon the physical construction of the circuit, and can only be measured with special laboratory instruments. Of the factors mentioned, consider first how the number of turns affects the inductance of a coil. Figure 2-5 shows two coils. Coil (A) has two turns and coil (B) has four turns. In coil (A), the flux field set up by one loop cuts one other loop. In coil (B), the flux field set up by one loop cuts three other loops.

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Doubling the number of turns in the coil will produce a field twice as strong, if the same current is used. A field twice as strong, cutting twice the number of turns, will induce four times the voltage. Therefore, it can be said that the inductance varies as the square of the number of turns.

Figure 2-5. - Inductance factor (turns).

The second factor is the coil diameter. In figure 2-6you can see that the coil in view B has twice the diameter of coil view A. Physically, it requires more wire to construct a coil of large diameter than one of small diameter with an equal number of turns. Therefore, more lines of force exist to induce a counter emf in the coil with the larger diameter. Actually, the inductance of a coil increases directly as the cross-sectional area of the core increases. Recall the formula for the area of a circle: A = pr2. Doubling the radius of a coil increases the inductance by a factor of four.

Figure 2-6. - Inductance factor (diameter).

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The third factor that affects the inductance of a coil is the length of the coil. Figure 2-7 shows two examples of coil spacings. Coil (A) has three turns, rather widely spaced, making a relatively long coil. A coil of this type has few flux linkages, due to the greater distance between each turn. Therefore, coil (A) has a relatively low inductance. Coil (B) has closely spaced turns, making a relatively short coil. This close spacing increases the flux linkage, increasing the inductance of the coil. Doubling the length of a coil while keeping the same number of turns halves the value of inductance.

Figure 2 - 7. - Inductance factor (coil length). CLOSELY WOUND

The fourth physical factor is the type of core material used with the coil. Figure 2-8 shows two coils: Coil (A) with an air core, and coil (B) with a soft-iron core. The

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magnetic core of coil (B) is a better path for magnetic lines of force than is the nonmagnetic core of coil (A). The soft-iron magnetic core's high permeability has less reluctance to the magnetic flux, resulting in more magnetic lines of force. This increase in the magnetic lines of force increases the number of lines of force cutting each loop of the coil, thus increasing the inductance of the coil. It should now be apparent that the inductance of a coil increases directly as the permeability of the core material increases.

Figure 2-8. - Inductance factor (core material). SOFT-IRON CORE

Another way of increasing the inductance is to wind the coil in layers. Figure 2-9 shows three cores with different amounts of layering. The coil in figure 2-9(A) is a poor inductor compared to the others in the figure because its turns are widely spaced and there is no layering. The flux movement, indicated by the dashed arrows, does not link effectively because there is only one layer of turns. A more inductive coil is shown in figure 2-9(B). The turns are closely spaced and the wire has been wound in two layers. The two layers link each other with a greater number of flux loops during all flux movements. Note that nearly all the turns, such as X, are next to four other turns (shaded). This causes the flux linkage to be increased.

Figure 2-9. - Coils of various inductances.

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A coil can be made still more inductive by winding it in three layers, as shown in figure 2-9(C). The increased number of layers (cross-sectional area) improves flux linkage even more. Note that some turns, such as Y, lie directly next to six other turns (shaded). In actual practice, layering can continue on through many more layers. The important fact to remember, however, is that the inductance of the coil increases with each layer added.

As you have seen, several factors can affect the inductance of a coil, and all of these factors are variable. Many differently constructed coils can have the same inductance. The important information to remember, however, is that inductance is dependent upon the degree of linkage between the wire conductor(s) and the electromagnetic field. In a straight length of conductor, there is very little flux linkage between one part of the conductor and another. Therefore, its inductance is extremely small. It was shown that conductors become much more inductive when they are wound into coils. This is true because there is maximum flux linkage between the conductor turns, which lie side by side in the coil.

Conclusion:-

At the conclusion of my report of practical training, I wish to record my deep sense of satisfaction and pride for undergoing forty days of practical training at KOTSONS PVT. LTD., Alwar.

By this training I not only fulfilled the requirements of syllabus of my B.E. Degree but also had the opportunity of seeing how men and machines are at work at the cordial

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relation and proper understanding along with the sense of responsibility. Since of duty and discipline must prevail at all levels of hierarchy.

As a layman also as student of electrical engineering, huge & complicated structure of transformer always fascinated me. Now I know that at kotsons pvt. Ltd.alwar distribution transformers i.e. low rating (in kva) transformers are made and tested.It is one of the supplier for rajasthan’s all vidyut vitaran nigam limiteds. It also supplies to Haryana & Gujarat electricity boards.

Thus my training program was fairly planned and nicely executed to my entire satisfaction. It was a meaningful practical training in all respects.