Training Module Manufacture Transformer

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SANJEEV KADIAN

Presents Presents

TRAINING MODULE

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1. UnderstandUnderstanding Transformersing Transformers 2. Core 2. Core 3. Conductor 3. Conductor 4. Bushings 4. Bushings 5. Buchholz Relay 5. Buchholz Relay 6. Hermatically Sealed T/fs 6. Hermatically Sealed T/fs 7. Magnetic Oil Level gauge 7. Magnetic Oil Level gauge 8. Silicagel Breather 8. Silicagel Breather 9. Sub-Assemblies 9. Sub-Assemblies 10. Tap Changer 10. Tap Changer 11. Temperature Indicator 11. Temperature Indicator 12. Transformer Oil 12. Transformer Oil 13. Repairing

13. Repairing Distribution TransformersDistribution Transformers 14. Sales & Marketing

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UNDERSTANDING TRANSFORMERS

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3 3 T R A N T R A N S FS FO RO RM E R B AM E R B A S I C SS I C S INTRODUCTION INTRODUCTION A transforme

A transformer ir is basically an electromas basically an electromagnegnetiticc statistatic equipmc equipment baseent based on the principal of Faraday’s law of d on the principal of Faraday’s law of electroma

electromagnegnetitic induction. A transformc induction. A transformer esseer essentintially consists of maally consists of magnegnetitic core, build-upc core, build-up of insulated siliof insulated siliconcon steel laminations, upon which are wound sets of coils suitably located with respect to each other and steel laminations, upon which are wound sets of coils suitably located with respect to each other and termed as primary and secondary windings. Such a combination may be used to derive a voltage higher termed as primary and secondary windings. Such a combination may be used to derive a voltage higher or lower than what is immediately available. In the former case, the transformer is termed as

or lower than what is immediately available. In the former case, the transformer is termed as step-upstep-up transformer, while in the later case, it is known as

transformer, while in the later case, it is known as step-downstep-down transformetransformer. r. The The primary wprimary winding is thatinding is that winding to which the supply voltage is applied, irrespective of whether it is higher or lower voltage winding, winding to which the supply voltage is applied, irrespective of whether it is higher or lower voltage winding, the other winding to which the load is connected is termed as secondary winding.

the other winding to which the load is connected is termed as secondary winding.

THE WORKING PRINCIPLE THE WORKING PRINCIPLE

If an alternating voltage is applied to the terminals of the primary winding of a transformer, with the If an alternating voltage is applied to the terminals of the primary winding of a transformer, with the secondary winding open-circuited, a very small current will flow in the primary circuit only, which serves to secondary winding open-circuited, a very small current will flow in the primary circuit only, which serves to magnetise the core and to supply the iron loss of the transformer. Thus, an alternating magnetic flux is magnetise the core and to supply the iron loss of the transformer. Thus, an alternating magnetic flux is established in t

established in the core whe core which induces an ehich induces an e.m.f. .m.f. in bothin both primary and seprimary and secondcondary windingsary windings. . As primAs primary andary and secondary windings are wound on the same core and as the magnetic flux is common to both windings, secondary windings are wound on the same core and as the magnetic flux is common to both windings, obviously, the voltage induced in the primary and secondary windings are, therefore, in direct proportion to obviously, the voltage induced in the primary and secondary windings are, therefore, in direct proportion to the number of turns in these windings.

the number of turns in these windings.

LAMINATED CORE LAMINATED CORE

Diagram

Diagram showing showing mamagneticgnetic

circuit

circuit and and windingwindings s of of aa

transformer transformer

TRANSFORMER LOSSES TRANSFORMER LOSSES

Transformer loss mainly has two components: no-load loss & load loss. Transformer loss mainly has two components: no-load loss & load loss.

No load loss results from steel materials, used for magnetizing core laminations. It includes hysteresis and No load loss results from steel materials, used for magnetizing core laminations. It includes hysteresis and eddy current loss, dielectric loss and copper loss due to no-load current.

eddy current loss, dielectric loss and copper loss due to no-load current. In order to print this document from Scribd, you'll first need to download it.

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Load loss arises from the resistive components, used for building the primary and secondary windings. It Load loss arises from the resistive components, used for building the primary and secondary windings. It comprises I

comprises I22_{R loss}_{R lossof windings, loss due to eddy cu}_{of windings, loss due to eddy current}_{rrent and stray loss in t}_{and stray loss in the tank an}_{he tank and core clam}_{d core clamp.}_p.

Diagram showing various components of losses Diagram showing various components of losses

EFFICIENCY EFFICIENCY

No-load loss of the transformer is constant and does not change with variation of load. However, load loss No-load loss of the transformer is constant and does not change with variation of load. However, load loss changes in respect of the loading pattern. The transformer will yield maximum efficiency at a load when changes in respect of the loading pattern. The transformer will yield maximum efficiency at a load when no-load loss and load loss are equal.

no-load loss and load loss are equal. REGULATION

REGULATION The reg

The regulatiulation ofon of a transformea transformer rr refers tefers to the chano the change of seconge of secondary terminal voltage betwdary terminal voltage between no load aeen no load andnd load conditions; it is usually quoted as a per cent or per unit value for full load at given power factor. load conditions; it is usually quoted as a per cent or per unit value for full load at given power factor.

G E

G EN E R A L N E R A L C OC ON S T R U C T IN S T R U C T I O NO N

Constructional Parts

The transformer is comparatively simple structure since there are no rotating parts, or bearings. The chief The transformer is comparatively simple structure since there are no rotating parts, or bearings. The chief

Hysteresis Hysteresis & eddy & eddy current current loss loss Di-electric Di-electric loss as a loss as a function of function of primary & primary & secondary secondary Copper Copper loss due to loss due to no-load no-load current current Stray loss Stray loss in tank & in tank & core core clamp clamp Loss due Loss due to eddy to eddy current current set-up in set-up in th thee II22_{R loss}_{R loss} for both for both primary & primary & secondary secondary windings windings N Noo--LLooaadd LLooaadd Total Total

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5 5 hysteresis losses. The silicon content of the iron and the nature of annealing are very important in hysteresis losses. The silicon content of the iron and the nature of annealing are very important in determining the hysteresis loss. Silicon makes the material brittle, thus making it difficult to process.

determining the hysteresis loss. Silicon makes the material brittle, thus making it difficult to process. Core C

Core Construconstruc tiontion

The core built up with high-grade non-aging cold rolled grain oriented silicon steel lamination having high The core built up with high-grade non-aging cold rolled grain oriented silicon steel lamination having high permeability and low hysteresis loss. A three legged, mitered and interleaved type core construction is permeability and low hysteresis loss. A three legged, mitered and interleaved type core construction is adopted. Main limbs are bound fiberglass types and clamp plates to ensure adequate mechanical adopted. Main limbs are bound fiberglass types and clamp plates to ensure adequate mechanical strength, and to prevent vibration during operation rigidly bolt yokes. The clamping structure and core strength, and to prevent vibration during operation rigidly bolt yokes. The clamping structure and core shee

sheet are speciallt are specially conny connected noected not tt to mo make onake one turn cire turn circuit & connecuit & connected to tcted to top of tank at oneop of tank at one point.point. Core construction of

Core construction of modern core type power Tramodern core type power Transformersnsformers

Cold rolled grain oriented steel laminations are used for cores of all modern power Transformers. This is Cold rolled grain oriented steel laminations are used for cores of all modern power Transformers. This is because it permits the use of flux densities between 1.6 to 1.8 wb/m

because it permits the use of flux densities between 1.6 to 1.8 wb/m22_{as compared with 1.3 wb/m}_{as compared with 1.3 wb/m}22_{for hot}_{for hot} rolled steel & consequently the weight of both core and windings is reduced.

rolled steel & consequently the weight of both core and windings is reduced. Cooling of cores

Cooling of cores

In transformers of medium and high capacity with diameter of circumscribing circle D>=0.35m the cores In transformers of medium and high capacity with diameter of circumscribing circle D>=0.35m the cores have the relatively small surface / volume ratio so that the temperature gradient in the core is excessive. In have the relatively small surface / volume ratio so that the temperature gradient in the core is excessive. In such cases the cooling must be augmented by dividing the core in to different stacks with longitudinal oil such cases the cooling must be augmented by dividing the core in to different stacks with longitudinal oil ducts (usually 6mm wide) running parallel to the lamination.

ducts (usually 6mm wide) running parallel to the lamination. Core-Clamping

Core-Clamping

All core-clamping bolts shall be effectively insulated with enamel or preferably varnish impregnated but not All core-clamping bolts shall be effectively insulated with enamel or preferably varnish impregnated but not insulated with paper. The joints must be of inter leaved type. Liberal axial ducts must be provided so as to insulated with paper. The joints must be of inter leaved type. Liberal axial ducts must be provided so as to ensure free circulation of oil and efficient cooling of the core, so that the maximum temperature at any ensure free circulation of oil and efficient cooling of the core, so that the maximum temperature at any point will be within permissible limits.

point will be within permissible limits. Earthing

Earthing

Positive earthing of the cabinet shall be ensured for providing two separate earthing pads. The earth wire Positive earthing of the cabinet shall be ensured for providing two separate earthing pads. The earth wire shall be t

shall be termerminated on to theinated on to the earthing pad aearthing pad and secund secured by the use of star of red by the use of star of self-etself-etching wching washeasher. r. UsUsing aing a separate earth wire shall do earthing of hinged door.

separate earth wire shall do earthing of hinged door. Core Earthing

Core Earthing

With the exception of individual laminations and core bolts, all internal metal parts of the transformer With the exception of individual laminations and core bolts, all internal metal parts of the transformer require earthing.

require earthing.

2. Electric Circuits

The windings of a transformer are made of copper or aluminium wire and / or strip. Heavy current capacity The windings of a transformer are made of copper or aluminium wire and / or strip. Heavy current capacity requires conductors of larger cross-section. To reduce eddy current losses within the conductors, several requires conductors of larger cross-section. To reduce eddy current losses within the conductors, several small wires or parallel strips are preferable than to use one large strip. This gives rise to unequal small wires or parallel strips are preferable than to use one large strip. This gives rise to unequal reactance components of the conductor, which can be reduced by transposing the conductors.

reactance components of the conductor, which can be reduced by transposing the conductors. Two

Two types of coil consttypes of coil constructructions are comions are commomonly used nly used –– ConceConcentrntric or Pancake ic or Pancake / int/ interlerleaved. Beaved. Between etween coilcoilss segments, spacers are provided to permit dissipation of heat from the windings either by ventilation or by segments, spacers are provided to permit dissipation of heat from the windings either by ventilation or by a liquid cooling medium.

a liquid cooling medium.

Double cotton, single cotton with an under layer of enamel or synthetics enamel, or double paper covering Double cotton, single cotton with an under layer of enamel or synthetics enamel, or double paper covering are m

are most comost commomonly being used nly being used for winding wires. Strfor winding wires. Strips are genips are generallerally covered y covered with layers of with layers of paperspapers known as DPC, TPC, QPC, MPC etc.

known as DPC, TPC, QPC, MPC etc.

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Winding Constructions Winding Constructions

The windings are arranged to ensure free circulation of oil and to reduce hot spots in the windings. All The windings are arranged to ensure free circulation of oil and to reduce hot spots in the windings. All m

materials aterials used in the asused in the assemsembly of windings are insoluble, nonbly of windings are insoluble, non-catalyt-catalytic and cheic and chemmicallically inactivey inactive in tin the hohe hott transformer oil. The windings are supported securely in axially as well as radially using radials spacers, transformer oil. The windings are supported securely in axially as well as radially using radials spacers, axial spacers, press board cylinders and clamp rings, so that they will not be displaced or deformed during axial spacers, press board cylinders and clamp rings, so that they will not be displaced or deformed during short cir

short circuits. cuits. The The coils coils are clamare clamped bped by adjustabley adjustable pressupressures bolts at are top end anres bolts at are top end and the face is uniformlyd the face is uniformly distributed to the windings using sturdy and to rings.

distributed to the windings using sturdy and to rings.

A transformer generally consists of LT & HT windings. The L.T. windings shall be circular and concentric A transformer generally consists of LT & HT windings. The L.T. windings shall be circular and concentric with HT

with HT windwindings on the outer side tings on the outer side the electrical he electrical and mand magnagnetic etic balancbalance unde under all er all condcondititions of operation.ions of operation. The arrangement shall permit free circulation of the oil to ensure the absence of hot spots. It is essential The arrangement shall permit free circulation of the oil to ensure the absence of hot spots. It is essential that the windings shall be subjected to through sinking occurring at site.

that the windings shall be subjected to through sinking occurring at site.

The general design and construction of the transformers and bracing’s of the windings shall be such that The general design and construction of the transformers and bracing’s of the windings shall be such that no mechanical movements of the coils will be possible with dead short on either side of the transformer. no mechanical movements of the coils will be possible with dead short on either side of the transformer. The short circuit ratings of the transformers shall be as per IS 2026 of latest issue. All clearance of The short circuit ratings of the transformers shall be as per IS 2026 of latest issue. All clearance of windings and other live parts shall be adequate for the maximum voltage operation plus 10 percent. There windings and other live parts shall be adequate for the maximum voltage operation plus 10 percent. There should be sufficient clearance between H.V. and L.V. windings yoke and the coils and between coil in HT should be sufficient clearance between H.V. and L.V. windings yoke and the coils and between coil in HT windings to have free oil circulation. Current density in the high voltage and low voltage windings together windings to have free oil circulation. Current density in the high voltage and low voltage windings together with the section of wire that will be used therein shall be clearly stated in the tender.

with the section of wire that will be used therein shall be clearly stated in the tender. High Voltage Conductor

High Voltage Conductor

For distribution transformers of medium capacity, the conductors being chosen for primary winding are For distribution transformers of medium capacity, the conductors being chosen for primary winding are mostly round in shape.

mostly round in shape. low

low VoltaVoltage Cge Conductor onductor

In case of low voltage conductors, since the current is generally high, a rectangular conductor is In case of low voltage conductors, since the current is generally high, a rectangular conductor is commonly used. Multiple strips in parallel are also selected for a higher rating transformer.

commonly used. Multiple strips in parallel are also selected for a higher rating transformer. Insulation

Insulation

The insulation material to be used for the windings shall be suitable for satisfactory service in tropical The insulation material to be used for the windings shall be suitable for satisfactory service in tropical climates in this country and full load operation as per ISS. DFC insulation shall be provided for high climates in this country and full load operation as per ISS. DFC insulation shall be provided for high voltage as well as low voltage windings.

voltage as well as low voltage windings. The insulation betwe

The insulation between the Hen the H.V. and L.V. windings and core, com.V. and L.V. windings and core, comprises Bakeprises Bakelilite –te – pappaper cyler cylinder or inder or elepha

elephantine wrap ntine wrap that is typicalthat is typical.. The The insulation of conduinsulation of conductors mactors may be oy be of papef paper, cottr, cottonon or glass tapeor glass tape, glass, glass tape be

tape being used ing used for air for air –– insulated transforminsulated transformers.ers.

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7 7 Terminal Arrangement

Terminal Arrangement

a) Bushing terminals shall be provided with suitable terminal connectors of approved type & size for a) Bushing terminals shall be provided with suitable terminal connectors of approved type & size for cable/overhead conductors’ termination of HV side & cable termination on LT side.

cable/overhead conductors’ termination of HV side & cable termination on LT side.

b) The neutral terminals of 433V winding shall be brought out on a bushing along with the 433V volt phase b) The neutral terminals of 433V winding shall be brought out on a bushing along with the 433V volt phase terminals to f

terminals to form 4orm 4wires system wires system for tfor the 43he 433V3V. Additi. Additionaonal neutral l neutral bushbushing shall be provided for earthing.ing shall be provided for earthing.

4. Transformer Tank

All the tanks are of double welded construction and are reinforced by stiffener of structural steel. All All the tanks are of double welded construction and are reinforced by stiffener of structural steel. All bottled connection to the tank is filled with the compressible oil tight gasket. The tank is provided with two bottled connection to the tank is filled with the compressible oil tight gasket. The tank is provided with two earthing terminals for the purpose of the grounding. The tank and accessories of the transformer can be earthing terminals for the purpose of the grounding. The tank and accessories of the transformer can be withst

withstanding full vacuum anding full vacuum of 0.1 Tore. And of 0.1 Tore. And a ma maximum aximum positpositive pressure of 1kg ive pressure of 1kg / sq.cm. / sq.cm. In order to relIn order to reliveive the excessive gaseous pressure which may build up by a fault or an arcing inside the tank, it is equipped the excessive gaseous pressure which may build up by a fault or an arcing inside the tank, it is equipped with a pressure relief device / explosion vent which is designed to operate when the maximum gaseous with a pressure relief device / explosion vent which is designed to operate when the maximum gaseous pressure in the tank exceeds 0.5 kg / 5q. cm.

pressure in the tank exceeds 0.5 kg / 5q. cm.

Tank bodies for most of the transformer are made from rolled steel plates, which are fabricated to from the Tank bodies for most of the transformer are made from rolled steel plates, which are fabricated to from the container. While designing tanks for transformer, a large number of factors include keeping the weight, container. While designing tanks for transformer, a large number of factors include keeping the weight, stray load losses and cost a minimum.

stray load losses and cost a minimum. The tanks sh

The tanks should beould be strong enostrong enough to withstand stresses produgh to withstand stresses produced buced by jacking and lify jacking and liftiting. The size of theng. The size of the tank must be large enough to accommodate cores, windings, internal connections and also must give the tank must be large enough to accommodate cores, windings, internal connections and also must give the require clearance between the windings and the walls.

require clearance between the windings and the walls.

The fittings include thermometer pockets, drain cock, rollers or wheels for moving the transformer in to The fittings include thermometer pockets, drain cock, rollers or wheels for moving the transformer in to position, eye –

position, eye – bolts, fbolts, for lior liftfting, conseing, conservators and brvators and breaths. Coreaths. Cooling tubes aoling tubes are were welded in, but seplded in, but separatearate radiators are individually welded and afterwards bolted on.

radiators are individually welded and afterwards bolted on. Radiators

Radiators

During service, the tank body can dissipate a total loss equivalent to 500 W/Sq m (maximum) of the tank During service, the tank body can dissipate a total loss equivalent to 500 W/Sq m (maximum) of the tank surface area. In case the total loss, i.e. (no-load + load loss) is more than the loss dissipated by tank surface area. In case the total loss, i.e. (no-load + load loss) is more than the loss dissipated by tank surface, the loss in excess is

surface, the loss in excess is required to be drequired to be dissipated with the help of adissipated with the help of additiditionaonal coolil cooling sung surface whrface which isich is commonly called radiator.

commonly called radiator. Classification of radiators Classification of radiators

Radiators commonly being used are of three different types: Radiators commonly being used are of three different types:

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1. EEllipticlliptical al tubtube e raradiadiator tor 2.

2. PPreressssed ed stesteel rael radiadiator tor 3.

3. CCorruorrugagated ted wwall all papanenell

Elliptical tube radiators and pressed steel radiators operate on then convection process of cooling, Elliptical tube radiators and pressed steel radiators operate on then convection process of cooling, whereas a corrugated wall panel performs cooling by radiation only.

whereas a corrugated wall panel performs cooling by radiation only.

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Corrugated wall panel radiators are commonly being used for sealed type transformers and also on such Corrugated wall panel radiators are commonly being used for sealed type transformers and also on such places where there are restrictions on overall dimensions. The radiators are widely used for transformers places where there are restrictions on overall dimensions. The radiators are widely used for transformers built for export, as corrugated wall panel transformers occupy less space and can accommodate more built for export, as corrugated wall panel transformers occupy less space and can accommodate more transformers in one container during transport.

transformers in one container during transport. Cooling Methods

Cooling Methods A

A SSiimmpplle e ccoooolliinngg 1

1 AANN NaNatuturaral cl coooolinling bg by ay atmtmoosspphheeriric cc cirircuculalatiotionn, w, withithoouut at anny sy sppeecciaial dl deevviciceess. T. Thhee transformer cores and coils are open all round to the air. This method is confined transformer cores and coils are open all round to the air. This method is confined to very small units of a few KV, at low voltages.

to very small units of a few KV, at low voltages. 2

2 AABB In In ththis is ccaasse te thhe e cocooolinling g is is imimpproroveved d bby ay an n aair bir blalasst, dt, direireccteted bd by sy suuitaitabble le trutrunnkkiningg and produced by a fan.

and produced by a fan. 3

3 OONN TThhe ge grereaat mt maajojoritrity oy of trf traannsfsfoormrmeers rs aare re ooil –il – imimmmeersrseed d wwith ith nnaatuturaral cl coooolinlingg, i.e, i.e. th. thee hea

heat developed in the corest developed in the cores and coand coilils is passed to the oil s is passed to the oil and theand thence to the tanknce to the tank walls, from which it is dissipated. The advantages over air cooling include freedom walls, from which it is dissipated. The advantages over air cooling include freedom from the possibility of dust clogging the cooling ducts, or of moisture affecting the from the possibility of dust clogging the cooling ducts, or of moisture affecting the insulation, and the design for higher voltages is greatly improved.

insulation, and the design for higher voltages is greatly improved. 4

4 OOBB In In ththis is mmeeththood d ththe e ccoooolinling g oof af an n OON N –– tytyppe e trtraannsfsfoormrmeers rs is is imimpprorovveed d bby y aair bir blalasstt over the outside of the tank.

over the outside of the tank. 5

5 OOFFNN TThhe e ooil iil is cs cirirccuulalateted d bby py puummp p to to nnaatuturaral al air ir –– ccooooleler.r. 6

6 OOFFBB FFoor lar largrge e tratrannsfsfoormrmeer ar artifirtificiciaal cl coooolinling g mmaay by be e uusesedd. T. Thhe e rerefrigfrigeeraratotor, wr, whheere re it isit is coo

cooled by aled by air –ir – blasblast.t. 7

7 OO AAn n ooil –il – imimmmeersrseed d trtraannssfoformrmeer or of thf this is tytyppe e is is ccooooleled d bby y ththe e ccirirccuulalatitioon n oof wf waateter inr in cooling tube

cooling tubes is sits is situated auated at tt the top ohe top of tf the tank he tank but below but below oil –oil – level.level. 8

8 OOFF SimSimilar, to Oilar, to OFBFB, ex, excecept thpt that that the ree refrigefrigeratorator emr emploploys wys wateater insr insteatead od of air bf air blaslast for t for cooling the oil, which is circulated by pump from the transformer to the cooler. cooling the oil, which is circulated by pump from the transformer to the cooler. bb.. MMiixxeed d ccoooolliinngg

ON/OFN, ON/OFB, ON/OFW, ON/OB/OFB, ON/OW/OFW, ONAN, ONAF, OFAF ON/OFN, ON/OFB, ON/OFW, ON/OB/OFB, ON/OW/OFW, ONAN, ONAF, OFAF Cooling ducts

Cooling ducts

In large transformers, the cooling surface of the cores must be augmented otherwise temperature rise will In large transformers, the cooling surface of the cores must be augmented otherwise temperature rise will be excessive owing to small surface/volume ratio of the cores. Cooling ducts provides the additional be excessive owing to small surface/volume ratio of the cores. Cooling ducts provides the additional surface. The cooling may be (I) horizontal or (ii) vertical. The vertical cooling ducts are along the direction surface. The cooling may be (I) horizontal or (ii) vertical. The vertical cooling ducts are along the direction of laminations and hence can be easily provided. The horizontal ducts are across the laminations and of laminations and hence can be easily provided. The horizontal ducts are across the laminations and therefore require special punching of core. The oil following through these ducts takes away the heat. therefore require special punching of core. The oil following through these ducts takes away the heat. Paintings

Paintings Tanks sho

Tanks should be sand uld be sand blastblasted or cleaned ed or cleaned by chemby chemical prical process before paintiocess before painting. In general ang. In general a priprimamary coatry coat In order to print this document from Scribd, you'll

first need to download it.

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9 9 SCHEDUL

SCHEDUL E OE OF TESTSF TESTS

ROUTINE TESTS

Following tests

Following tests are conducted on each and eveare conducted on each and every transformer.ry transformer.



 Measurement of Insulation ResistanceMeasurement of Insulation Resistance 

 Measurement of Voltage RatioMeasurement of Voltage Ratio 

 Separate Source Voltage Withstand TestSeparate Source Voltage Withstand Test 

 Induced Over-voltage Withstand TestInduced Over-voltage Withstand Test 

 MeMeasuremenasurementt of No Load Loof No Load Loss and Currentss and Current 

 Measurement of Impedance Voltage/Short Circuit Impedance and Load LossMeasurement of Impedance Voltage/Short Circuit Impedance and Load Loss 

 Measurement of Winding ResistanceMeasurement of Winding Resistance 

 Unbalance CurrentUnbalance Current

TYPE TESTS

Following tests are conducted on only

Following tests are conducted on only one transformer of eaone transformer of each rating for a particular design,ch rating for a particular design, subject to client’s requirement.

subject to client’s requirement.



 Impulse TImpulse Test -- est -- (Condu(Conducted by cted by recognized grecognized govt. testovt. testing laboratory)ing laboratory) 

 Short CShort Cirircuit cuit -- -- (Conducted (Conducted by by recognized recognized govt. Testing govt. Testing LaboLaboratorratory)y) 

 Check of Voltage Vector RelationshipCheck of Voltage Vector Relationship 

 Temperature Rise TestTemperature Rise Test 

 Oil Oil Dielectric TDielectric Testest 

 Air Pressure TestAir Pressure Test 

 Vacuum TestVacuum Test 

 Oil Leakage Test.Oil Leakage Test.

FINAL TEST

Following t

Following t ests are carried out on tests are carried out on t he Trahe Transformer as per sequence.nsformer as per sequence.



 Measurement of Insulation ResistanceMeasurement of Insulation Resistance 

 Measurement of Voltage Ratio and Check of Voltage Vector RelationshipMeasurement of Voltage Ratio and Check of Voltage Vector Relationship 

 Separate Source Voltage Withstand TestSeparate Source Voltage Withstand Test 

 Induced Over-voltage Withstand TestInduced Over-voltage Withstand Test 

 Measurement of No Load Loss and CurrentMeasurement of No Load Loss and Current 

 Measurement of Impedance Voltage/Short Circuit Impedance and Load LossMeasurement of Impedance Voltage/Short Circuit Impedance and Load Loss 

 Measurement of Winding ResistanceMeasurement of Winding Resistance 

 Unbalance CurrentUnbalance Current 

 Oil Oil Dielectric TDielectric Testest 

 Temperature Rise TestTemperature Rise Test 

 Air Pressure TestAir Pressure Test 

 Vacuum TestVacuum Test 

 Oil Leakage Test.Oil Leakage Test. 

 Magnetic balance testMagnetic balance test 

 Measurement of zero sequence impedanceMeasurement of zero sequence impedance 

 Measurement of noise levelMeasurement of noise level

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TESTI

TESTI NG PRONG PROCEDCEDUREURE INSULATION RESISTANCE:

INSULATION RESISTANCE:

The

The Oil/Oil/Air TemAir Temperature is measuperature is measured and red and recorded immrecorded immediatelediately prior to the test. y prior to the test. The The insulinsulatiation resistance of eachon resistance of each windings corresponding to other windings and to earth is measured and recorded.

windings corresponding to other windings and to earth is measured and recorded. I.R Value between

I.R Value between ::



 HV & E : : ConnHV & E Connect Poect Positsitive terminal of Insulatiive terminal of Insulation on Tester to HTester to HV V BushBushing and ing and NegaNegatitiveve

Term

Terminalinal to the to the Earth.Earth.



 LV & E : : ConnLV & E Connect Pect Positositive terminal of Insulatiive terminal of Insulation on Tester to LTester to LV V Bushing Bushing and and NegaNegatitiveve

Terminal to the Earth. Terminal to the Earth.



 HV & LV: : ConnHV & LV Connect ect PositiPositive ve terterminal minal of Insulatiof Insulation on Tester to Tester to HV HV Bushing Bushing and and NegaNegatitive ve toto

LVBushing. LVBushing.

VOLTAGE RATIO & VOLTAGE VECTOR RELATIONSHIP: VOLTAGE RATIO & VOLTAGE VECTOR RELATIONSHIP:

(A

(A) ) MeaMeasurement surement of of voltage voltage RatioRatio – –

To check the voltage ratio of Transformer Ratio Meter is used; To check the voltage ratio of Transformer Ratio Meter is used;

V1 N1 V1 N1 Voltage

Voltage RaRatio = tio = --- = --- = --- -- whwhere, ere, N1 N1 = = PrimaPrimary ry TurnTurn V2

V2 N2 N2 N2 N2 = = Secondary Secondary TurnTurn

(B

(B)) Voltage Vector RelationshipVoltage Vector Relationship (Dyn-11(Dyn-11))

Transformer’s A-phase of primary side and A-phase of secondary side are shorted, and in primary side Transformer’s A-phase of primary side and A-phase of secondary side are shorted, and in primary side 3-Phase

Phase supply (About balance supply (About balance voltvoltage age 400 V400 Voltolts) applied at rats) applied at rated frequency. ed frequency. Voltage is , tVoltage is , then, mhen, measuredeasured on following points on following points :-IV-2V = IV-2V = IV-2w = IV-2w = 1W-2W and !W-2V 1W-2W and !W-2V

In this test IV-2W and IV-2V may be same and 1W-2V may be more than 1W-2W In this test IV-2W and IV-2V may be same and 1W-2V may be more than 1W-2W

SEPARATE SOURCE VOLTAGE WITHSTAND TEST: SEPARATE SOURCE VOLTAGE WITHSTAND TEST:

In this test the full test voltage given below applied for 60 seconds between the winding under test and all terminals In this test the full test voltage given below applied for 60 seconds between the winding under test and all terminals of remaining windings, core, frame and tank of the transformer connected together to earth.

of remaining windings, core, frame and tank of the transformer connected together to earth. TESTS :

TESTS :

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11 11 NO LOAD LOSS AND CURRENT:

NO LOAD LOSS AND CURRENT:

The test i

The test is conducted by s conducted by a Three Wa Three Wattattmeter Mmeter Method. ethod. The NThe No Load Lo Load Loss and the no oss and the no load load currcurrent are meaent are measured atsured at rated

rated frequenfrequency at a cy at a rated voltage rated voltage while the while the other windother winding is to be ing is to be left open circuited. left open circuited. In this way aIn this way after applyingfter applying rated 3 Phase voltage at rated frequency from LV side, the current is measured in Ammeter. This current will be no rated 3 Phase voltage at rated frequency from LV side, the current is measured in Ammeter. This current will be no load current or magnetizing current, and the total reading of the watt meters will be the Total No Load Loss of the load current or magnetizing current, and the total reading of the watt meters will be the Total No Load Loss of the tested t

tested transformransformer.er. To me

To measure the No Load Loss and asure the No Load Loss and No Load current of No Load current of PowPower Transfer Transformer one Cormer one CT-PT set iT-PT set is connected s connected to an Autoto an Auto Transformer.

Transformer.

IMPEDANCE VOLTAGE/SHORT CIRCUIT IMPEDANCE & LOAD LOSS: IMPEDANCE VOLTAGE/SHORT CIRCUIT IMPEDANCE & LOAD LOSS:

The Impedance voltage/short circuit impedance and load loss are measured at rated frequency by applying an The Impedance voltage/short circuit impedance and load loss are measured at rated frequency by applying an approximately full load current to one winding with the other winding short circuited. The measurements may be approximately full load current to one winding with the other winding short circuited. The measurements may be made at any current between 25 percent and 100 percent, but preferably not less than 50 percent of the rated made at any current between 25 percent and 100 percent, but preferably not less than 50 percent of the rated current (principal tapping) or tapping current to the test current.

current (principal tapping) or tapping current to the test current. The m

The measured value of easured value of Load LLoad Loss maoss may be coy be corrrrected by the follected by the following formula :owing formula : 2

2 Rated Current Rated Current To

Total tal LoLoss ss = = --- ---Test Current Test Current

The measured value of the impedance voltage may be corrected by the following formula : The measured value of the impedance voltage may be corrected by the following formula :

Rated Current Rated Current Total

Total ImpeImpedandance ce voltage voltage = = --- ---Test Current Test Current

MEASUREMENT OF WINDING RESISTANCE: MEASUREMENT OF WINDING RESISTANCE:

To m

To measure the easure the resiresistance of stance of LV aLV and Hnd HV WV Windiinding ng , Kelvin and W, Kelvin and Wheatstone Bheatstone Briridge adge are respectire respectively used. vely used. TheThe resistance and temperature of each winding are recorded.

resistance and temperature of each winding are recorded.

UNBALANCE CURRENT: UNBALANCE CURRENT:

In this test of the Transformer, all three phases of secondary (Star Connected) are shorted and shorted point linked In this test of the Transformer, all three phases of secondary (Star Connected) are shorted and shorted point linked to the neutral point of transformer with an Ammeter.Then, full load current at rated frequency is applied to primary to the neutral point of transformer with an Ammeter.Then, full load current at rated frequency is applied to primary (Delta Connected) of the transformer. The current measured between the shorted secondary and the neutral point is (Delta Connected) of the transformer. The current measured between the shorted secondary and the neutral point is the unb

the unbalance cualance current. rrent. Circuit diCircuit diagraagram is respecm is respectitively samvely same as load loss test :-e as load loss test

:-In order to print this document from Scribd, you'll first need to download it.

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TEMPERATURE RISE TEST: TEMPERATURE RISE TEST:

In thi

In this test LV winding ofs test LV winding of the transformethe transformer ir is shorted ans shorted and from Hd from HV windV winding full ing full losses (Loalosses (Load loss at 75 Degd loss at 75 Deg. Cent. +. Cent. + No

No Load Load Loss) is fLoss) is fed. ed. One One thermomthermometer is pleter is placed in oil fiaced in oil filllled ed thermomthermometer pocket of treter pocket of transformer for oil ansformer for oil temp. andtemp. and other 3 N

other 3 Nos. thermoos. thermommeters in diffeters in different directions of the transformeerent directions of the transformer for r for amambient tembient temp. p. After feeding the total lAfter feeding the total loss atoss at tr

transformer, the voltansformer, the voltage current, top oiage current, top oil temp. and al temp. and ambient tempmbient temp. is measured. . is measured. These aThese all rll readings are taken eadings are taken one bone byy one after every hour. This process is continued till oil temperature rise of transformer remains constant. Keeping oil one after every hour. This process is continued till oil temperature rise of transformer remains constant. Keeping oil temp. rise constant, load is reduced at full rated current for one hour, after one hour supply shut-off. After shutting temp. rise constant, load is reduced at full rated current for one hour, after one hour supply shut-off. After shutting off

off the supthe supply hot resistances of ply hot resistances of winding are winding are immeimmediateldiately y memeasured. asured. Thus, aThus, aftfter plotter plotting the ing the graph graph between between titimeme and h

and hot resiot resistance, we can stance, we can fifind ond out the highest actual hot resiut the highest actual hot resistance at the zero time. stance at the zero time. In thiIn this way s way the mthe maximumaximum winding temperature rise can be calculated by the following formula :

winding temperature rise can be calculated by the following formula : (a) Hot R

(a) Hot Resistanceesistancex (225+x (225+RTRT)-225 ....)-225 ... For A. For Aluminiumluminium . . Cold Cold ResistanceResistance

(b) Hot Resistance x (235+RT)-235 ... For Copper (b) Hot Resistance x (235+RT)-235 ... For Copper

Cold Resistance Cold Resistance

where, RT = Ambient Temp. at the time of cold resistance : where, RT = Ambient Temp. at the time of cold resistance :

OIL DIELECTRIC STRENGTH TEST: OIL DIELECTRIC STRENGTH TEST:

To test the Dielectric strength of oil, a motorised oil testing set is used . Before using this instrument, the oil pot of To test the Dielectric strength of oil, a motorised oil testing set is used . Before using this instrument, the oil pot of thi

this instrs instrumeument washnt washed wed witith the samh the same oil, which te oil, which to be o be testtested. ed. After washing the pot, the gap betweeAfter washing the pot, the gap between the en the electlectrodesrodes is set at 2.5 m

is set at 2.5 mm m and and the oil is fthe oil is fililled in it. led in it. WWait for about 10 ait for about 10 minuminutes, so that the air bubtes, so that the air bubbles bles disappdisappear. ear. After this, After this, thethe instrumen

instrument it is switched ‘Os switched ‘ON’ and the N’ and the flflash pash point (ioint (in KVn KV) i) is noteds noted. . This proceThis process is rss is repeepeated for six tiated for six timemes and thes and the average of the six values is the Dielectric Strength of the oil.

average of the six values is the Dielectric Strength of the oil.

AIR

AIR PRESSURE TEST:PRESSURE TEST:

This is a type test which is conducted on the transformer tank. The tank may be fixed with a dummy cover with all This is a type test which is conducted on the transformer tank. The tank may be fixed with a dummy cover with all fifittittings including bngs including bushinushings in position and gs in position and subjected to a presubjected to a pressure of ssure of



 0.35 Kg/Cm0.35 Kg/Cm22(Hg) upto 1000 KVA Transformer Tank(Hg) upto 1000 KVA Transformer Tank 

 0.80 Kg/Cm0.80 Kg/Cm22(Hg) above 1000 KVA Transformer Tank(Hg) above 1000 KVA Transformer Tank

created insi

created inside the de the tank and tank and mamaintintained for one ained for one hour. hour. The The permanpermanent deflectient deflection oon of flf flat plate, afat plate, after pressurter pressure hae has bes beenen released should not exceed the values given below:

released should not exceed the values given below: Horizontal length of flat plate Horizontal length of flat plate

(in mm) (in mm) Permanent Deflection Permanent Deflection (in mm) (in mm) U

Upptto o aannd d iinncclluuddiinng g 775500 55 7

75511-- 11225500 66..55

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13 13 VACUUM TEST:

VACUUM TEST:

This is a type test , which is conducted on transformer tank. The transformer tank may be completed with all fittings This is a type test , which is conducted on transformer tank. The transformer tank may be completed with all fittings including bushings in position and shall be subjected to full vacuum corresponding to (-) 0.7 Kg/Cm.sq.(Hg) created including bushings in position and shall be subjected to full vacuum corresponding to (-) 0.7 Kg/Cm.sq.(Hg) created insi

inside the de the tank for one houtank for one hour. r. The The permanpermanent deflectent deflection of flion of flat plates aftat plates after the vacuum er the vacuum has behas been released en released shall notshall not exceed the value specified below without affecting the performance of the transformer.

exceed the value specified below without affecting the performance of the transformer.

Horizontal length of flat plate Horizontal length of flat plate

(in mm) (in mm) Permanent Deflection Permanent Deflection (in mm) (in mm) U

Upptto o aannd d iinncclluuddiinng g 775500 55 7 75511-- 11225500 66..55 1 1225511-- 11775500 88 1 177551 1 -- 22000000 99..55 2 2000011-- 22225500 1111 2 222551 1 -- 22550000 1122..55 2 2550011-- 33000000 1166 A Abboovve e 33000000 1199

OIL LEAKAGE TEST: OIL LEAKAGE TEST:

This is a type test, which is conducted on fully completed transformer. The transformer shall be oil filled and This is a type test, which is conducted on fully completed transformer. The transformer shall be oil filled and com

complete with all fplete with all fittittings. ings. TheThen following an following air pressure is applied:ir pressure is applied: 1) 0.35 Kg/Cm

1) 0.35 Kg/Cm22_{(Hg) pressure – For tr}_{(Hg) pressure –}_{For transformers upto 1000}_{ansformers upto 1000 KVA}_{KVA for one hour}_{for one hour}

2) 0.80 Kg/Cm

2) 0.80 Kg/Cm22_{(Hg) pressure – For tr}_{(Hg) pressure –}_{For transformers above 1}_{ansformers above 1000 K}_{000 KVA for 12 hou}_{VA for 12 hours}_rs

During this period no leakage should occur. During this period no leakage should occur.

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R A W

R A W M A T E RM A T E RI A L & I A L & A C CA C CE SE SS OS OR I ER I ESS

The following is the list of the major raw-material required for the manufacture and repair of transformers. The following is the list of the major raw-material required for the manufacture and repair of transformers.



 CORECORE  CORK SHEETCORK SHEET



 COPPERCOPPER  GASKET WASHERGASKET WASHER 

 OILOIL  BUSHINBUSHING CLAG CLA MPMP 

 STEEL (TANKS)STEEL (TANKS)  CLAMPING MEMBERCLAMPING MEMBER 

 RADIATORS / WALL PANELSRADIATORS / WALL PANELS  ARCING ARCING HORNHORNSS 

 TAP CHANGER OFF LOAD, ON LOADTAP CHANGER OFF LOAD, ON LOAD  BIMETALLIC CONNECTORBIMETALLIC CONNECTOR 

 BUSHINGS & FITTINGSBUSHINGS & FITTINGS  EARTHING LUGSEARTHING LUGS 

 COPPER SHEET & FLATCOPPER SHEET & FLAT  SRBP TUBESRBP TUBE 

 OIL CONSERVATOROIL CONSERVATOR  COTTON TAPECOTTON TAPE 

 BREATHERBREATHER  EMPIRE SLEEVINGEMPIRE SLEEVING 

 DIAL TYPE THERMOMETERDIAL TYPE THERMOMETER  PRESS BOARDPRESS BOARD 

 OIL LEVEL GAUGEOIL LEVEL GAUGE  INSULATING KRAFT PAPERINSULATING KRAFT PAPER 

 PRESSURE RELIEF DEVICEPRESSURE RELIEF DEVICE  INLINE INLINE CONNECTOCONNECTORR 

 BUCHHOBUCHHOLZ RELALZ RELAYY  BAKBAKELITE SHEEELITE SHEETT 

 OIL & WINDINOIL & WINDING G TEMP. TEMP. INDICATORINDICATOR  CI PLUGCI PLUG 

 RATING & DIAGRAM PLATERATING & DIAGRAM PLATE  BRIGHT RODBRIGHT ROD 

 BI-DIRECBI-DIRECTIONTIONAL AL ROLLERSROLLERS  BOLTS, NUTS, WASHERBOLTS, NUTS, WASHER 

 CABLE BOXCABLE BOX  PRIMER & FINISH PAINTPRIMER & FINISH PAINT 

 LIFTING LUGSLIFTING LUGS  INSLULATING VARNISHINSLULATING VARNISH 

 TERMITERMINAL MANAL MARKING PLATERKING PLATE  SOLDER WIRESOLDER WIRE 

 AIR RELEASE PLUG AIR RELEASE PLUG  LUGSLUGS 

 VALVESVALVES  GROUNDINGROUNDING TERMINALG TERMINALSS

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15 15

CORE

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CORE

The

The need for electrineed for electrical steel sheecal steel sheets of highest quats of highest quality has increlity has increased in recenased in recent yearst years due to rapid

due to rapid developmendevelopment of electricat of electricall machinery imachinery industry in mndustry in many countrieany countries. Grains. Grain Orien

Oriented steeted steel sheets naml sheets namely ORIEely ORIENTCONTCORE, ORIENRE, ORIENTCORTCORE H1-BE H1-B && ORIEORIENTCONTCORERE HI-B.LS are some of the finest quality of core.

HI-B.LS are some of the finest quality of core.

ORENTCORE.HI-B is a breakthrough in that it offers higher magnetic flux density, ORENTCORE.HI-B is a breakthrough in that it offers higher magnetic flux density, lower c

lower coreore loss and loss and lower lower magnetostrictimagnetostriction than on than any coany conventional nventional grain-oriegrain-orientednted electrical steel sheet.

electrical steel sheet.

ORIENT.HI-B.LS is a novel type with marked lower core losses, produced by laser ORIENT.HI-B.LS is a novel type with marked lower core losses, produced by laser irradiation of the

irradiation of the surface of ORIENTCORE.HI-B sheets.surface of ORIENTCORE.HI-B sheets.

Quality Quality



 Stable product qualityStable product quality 

 Core loss are extremely low in rolling directionCore loss are extremely low in rolling direction 

 PermeabiliPermeability is extremely hity is extremely high in gh in rolling direrolling directionction 

 Lamination factor is higher Lamination factor is higher 

 Excellent Insulation coatingsExcellent Insulation coatings

Standard Sizes Standard Sizes

O

ORRIIEENNTT..HHII--BB ORORIIEENNTT..HHII--BB..LLSS C

Cooiillss TThhiicckknneessss 00..2233mmm m & & 00..2277mmmm 0.30

0.30mmmm & 0.35& 0.35mmmm

0.23mm,0.27mm 0.23mm,0.27mm S

Sttaannddaarrd d WWiiddtthh 91914 4 mmm m & & 99550 0 mmmm A

Avvaaiillaabblle e WWiiddtthh FFrroom m 5500mmm m tto o 1100000 0 mmmm FFrroom m 5500mmm m tto o 99550 0 mmmm C

Cuut t lleennggtthh TThhiicchhnneessss SSaamme e aas s ffoor r ccooiillss L

Leennggtthh LLeennggtthhs s uupptto o 3311000 0 mmm m aarre e aavvaaiillaabblle e iin n 88440 0 mmm m aanndd 914 mm widths

914 mm widths

Core cut in customer specified sizes can also be provided Core cut in customer specified sizes can also be provided

Annealing

Annealing of stacof stacked elecked electrical strical sheetsheets

Though ORIENTCORE and ORIENTCORE.HI-B are grain orient steel sheets with Though ORIENTCORE and ORIENTCORE.HI-B are grain orient steel sheets with excellent magnetic properties, mechanical stress during such operations as cutting, excellent magnetic properties, mechanical stress during such operations as cutting,

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17 17 Following method is observed for

Following method is observed for stress relief annealingstress relief annealing 1.

1. Stacked eStacked electrical lectrical steel shsteel sheets are eets are heated heated thoroughly thoroughly in the in the edge-to-ededge-to-edgege direction rather than in the face-to-face direction, because heat transfer is far direction rather than in the face-to-face direction, because heat transfer is far faster in side heating.

faster in side heating. 2.

2. A cover A cover is put oveis put over sheets sr sheets stacked on tacked on a flat platea flat plate. Because . Because ORIENTCORE aORIENTCORE andnd ORIENTCORE.HI-B have extremely low carbon content and very easily ORIENTCORE.HI-B have extremely low carbon content and very easily decarburized at annealing temperatures, the base, cover and other accessories decarburized at annealing temperatures, the base, cover and other accessories used are of very low carbon content .

used are of very low carbon content . 3.

3. To prevenTo prevent oxidation t oxidation so as to so as to protect thprotect the coating e coating on the on the sheets, a nosheets, a nonoxidizingnoxidizing atmosphere free from carbon sources is used having less than 2%hydrogen or atmosphere free from carbon sources is used having less than 2%hydrogen or high-purity nitrogen gas. Due point of the atmosphere is maintained at 0ºC or high-purity nitrogen gas. Due point of the atmosphere is maintained at 0ºC or less.

less. 4.

4. Care is Care is taken to taken to the flatness the flatness of anneaof annealing baling base, because, because an se an uneven uneven basebase distorts cores, leadi

distorts cores, leading to possible ng to possible distortion durindistortion during assembly.g assembly. 5.

5. Annealing Annealing temperature temperature ranging ranging from 780ºC from 780ºC to 820ºC to 820ºC is maintaiis maintained for mned for moreore than 2 hours or more. Cooling is done upto 350ºC in about 15 hours or more. than 2 hours or more. Cooling is done upto 350ºC in about 15 hours or more. Available Grades Available Grades   ORIENTCOREORIENTCORE o o M1, M2, M3, M4, M5 & M6M1, M2, M3, M4, M5 & M6   ORIENTCORE.HI-BORIENTCORE.HI-B o o 23ZH90, 23ZH95, 27ZH95,27ZH100,30ZH10023ZH90, 23ZH95, 27ZH95,27ZH100,30ZH100 o o M-0H,M-1H,M-2H,M-3HM-0H,M-1H,M-2H,M-3H   ORIENTCORE.HI-B.LSORIENTCORE.HI-B.LS o o 23ZDKH90,27ZDKH9523ZDKH90,27ZDKH95

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Conductor

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19 19

CONDUCTOR

Conductors are one of the principal materials used in manufacturing of transformers. Conductors are one of the principal materials used in manufacturing of transformers. Best quality of copper rods are procured from indigenous as well as foreign sources. Best quality of copper rods are procured from indigenous as well as foreign sources. Normally 8

Normally 8 mmmm & 11 mm rods are & 11 mm rods are procured. For eaprocured. For each supply of inpch supply of input, test certificateut, test certificate from suppliers is obtained and at times, such input is got tested from reputed test labs. from suppliers is obtained and at times, such input is got tested from reputed test labs. Various sizes as specified by customers can be drawn. At each stage of drawing of Various sizes as specified by customers can be drawn. At each stage of drawing of copper

copper wireswires & strip& strips, the s, the dimension dimension is meais measured sured all all around around and and in cin case ase foundfound oversize particular die is replaced forthwith. During final stage of drawing smoothness oversize particular die is replaced forthwith. During final stage of drawing smoothness and brightn

and brightness is strictless is strictly y observed. Elobserved. Elongation, ongation, SpringinesSpringiness & Tensil ss & Tensil strength aretrength are thoroughly tested. While drawing, care is taken that the physical properties of the thoroughly tested. While drawing, care is taken that the physical properties of the conductors are

conductors are maintained.maintained.

After the wires & strips are drawn as per clients requirements they are moved on to After the wires & strips are drawn as per clients requirements they are moved on to paper covering process. To prevent the inclusion of copper dust or other extraneous paper covering process. To prevent the inclusion of copper dust or other extraneous matter under paper covering the conductor is fully cleaned by

matter under paper covering the conductor is fully cleaned by felt pads or other felt pads or other suitablesuitable means before entering the paper covering machine. As per the customers means before entering the paper covering machine. As per the customers requirements DPC

requirements DPC, TPC & , TPC & MPC conductors are produced. It is MPC conductors are produced. It is ensured that each layer ensured that each layer of paper is continuous, firmly applied and substantially free from creases. No bonding of paper is continuous, firmly applied and substantially free from creases. No bonding or adhesive material is used

or adhesive material is used except to anchor the except to anchor the ends of paper. ends of paper. Any such bondingAny such bonding materials used to anchor the ends do not have deleterious effect on transformer oil, materials used to anchor the ends do not have deleterious effect on transformer oil, insulating

insulating paper paper or the eleor the electric strengctric strength of the th of the covering. covering. It is ensureIt is ensured that thd that thee overlapping percentage is not less than 25% of the paper width.

overlapping percentage is not less than 25% of the paper width. Arrangem

Arrangement of ent of layerslayers

According to the number of layers

According to the number of layers used the paper is applied as fused the paper is applied as follows.ollows. Two

Two

layers:-Where there are two layers both of them are wound in opposite directions. Where there are two layers both of them are wound in opposite directions. More than two layers

More than two layers

Where there are more than two layers all the layers are applied in the same direction, Where there are more than two layers all the layers are applied in the same direction, all, except the outermost layer is butt wound, and the outermost layer is overlap all, except the outermost layer is butt wound, and the outermost layer is overlap wound. Within each group of papers the position of the butt joints of any layer relative wound. Within each group of papers the position of the butt joints of any layer relative to the layer below is progressively displaced by approximately 30 percent of the paper to the layer below is progressively displaced by approximately 30 percent of the paper width.

width.

Note: Overlapping can also be

Note: Overlapping can also be done as per customer done as per customer requirements.requirements.

Grade of paper Grade of paper

The paper, before application, is ensured to be free from metallic and other injurious The paper, before application, is ensured to be free from metallic and other injurious inclusions an

inclusions and d have no deleterihave no deleterious effect on insulous effect on insulating oil. The thickneating oil. The thickness of paper ss of paper used is between 0.025 mm to 0.075 mm.

used is between 0.025 mm to 0.075 mm. Enameled Conductor

Enameled Conductor

Apart from paper covered conductors, we have all the facilities of producing enameled Apart from paper covered conductors, we have all the facilities of producing enameled conductors as per

conductors as per customer specified requiremencustomer specified requirements.ts.

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BUSHINGS

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21 21

BUSHINGS

Insulators and Bushings are buil

Insulators and Bushings are built with thet with the best quality Porcelain shelbest quality Porcelain shells manufactured byls manufactured by wet process. The materials that go into the manufacture of these insulators offer best wet process. The materials that go into the manufacture of these insulators offer best quality mechanical and electrical characteristics. The standard colour of the glaze is quality mechanical and electrical characteristics. The standard colour of the glaze is brown, but white glazed insulators can also be made available on request.

brown, but white glazed insulators can also be made available on request. Manufacturing process

Manufacturing process

For manufacture of electro porcelain, high quality indigenous raw materials viz, China For manufacture of electro porcelain, high quality indigenous raw materials viz, China Clay, Ball Clay, Quartz and Feldspar is used. The raw materials in lots undergo Clay, Ball Clay, Quartz and Feldspar is used. The raw materials in lots undergo thorough test in quality control laboratory before being user for

thorough test in quality control laboratory before being user for manufacturemanufacture.. Quartz and feldspar are ground to required finesses and then

Quartz and feldspar are ground to required finesses and then intimately mixed with ballintimately mixed with ball and china clay in high speed blungers. They are then passed through electromagnetic and china clay in high speed blungers. They are then passed through electromagnetic separators, which remove iron and other magnetic impurities. The slip produced is separators, which remove iron and other magnetic impurities. The slip produced is passed to a filter

passed to a filter press where extra wpress where extra water is removed undater is removed under pressure and ther pressure and the resultinge resulting clay cakes are aged over a period. The aged cakes are extruded to required form viz., clay cakes are aged over a period. The aged cakes are extruded to required form viz., cylinders, on high vacuum de-airing pug mill. The extruded blanks or cylinders are cylinders, on high vacuum de-airing pug mill. The extruded blanks or cylinders are given shapes of Insulators / Bushings which are conditioned and are shaped on given shapes of Insulators / Bushings which are conditioned and are shaped on copying lathes as the case may be.

copying lathes as the case may be.

These shaped insulators / bushings are then dried under controlled conditioned and These shaped insulators / bushings are then dried under controlled conditioned and then they are glazed, Trade mark, month, year and country of

then they are glazed, Trade mark, month, year and country of manufacture are markedmanufacture are marked before firing. The glazed shells are fired in fuel efficient kilns having temperature before firing. The glazed shells are fired in fuel efficient kilns having temperature controls to ensure uniformity of f

controls to ensure uniformity of firing high strength in porcelain shells. Metal parts iring high strength in porcelain shells. Metal parts usedused in the assembly of Insulators, are of blackheart and malleable cast iron and are hot dip in the assembly of Insulators, are of blackheart and malleable cast iron and are hot dip galvanized to conform to

galvanized to conform to internationainternational standards.l standards. Testing, Assembly & packing

Testing, Assembly & packing

All insulators & bushings undergo routine electrical and mechanical tests. The tests All insulators & bushings undergo routine electrical and mechanical tests. The tests before and afte

before and after assembly are r assembly are carried out accocarried out according to IS Specrding to IS Specifications,ifications, to ensureto ensure their suitability for actual conditions of use. Porosity tests are also carried out regularly their suitability for actual conditions of use. Porosity tests are also carried out regularly on samples from every batch, to ensure that the insulators are completely vitrified. on samples from every batch, to ensure that the insulators are completely vitrified. These insulato

These insulators are then visuars are then visually checked and slly checked and sorted, before theyorted, before they are packed in sare packed in seaea worthy packing, to

worthy packing, to withstand transit conditions.withstand transit conditions.

Types

Types of

of Insula

Insulators

tors &

& Bushing

Bushings

s



 Bushing InsulatorsBushing Insulators o

o Hollow Porcelain Bushings upto 33 KVHollow Porcelain Bushings upto 33 KV o

o Application : Transformers, Capacitors, Circuit Breakers etc.Application : Transformers, Capacitors, Circuit Breakers etc. 

 Pin InsulatorsPin Insulators o

o Pin Insulators conforming to ISS, B.S., IEC and other internationalPin Insulators conforming to ISS, B.S., IEC and other international

standards upto 33 KV standards upto 33 KV

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

 Post type InsulatorsPost type Insulators o

o Post type insulators, complete with metal fittings, generally ISPost type insulators, complete with metal fittings, generally IS

Specification

Specifications and s and other International Standards upto 33 KVother International Standards upto 33 KV



 Solid Core InsulatorsSolid Core Insulators o

o Line PostLine Post o

o Long RodLong Rod o

o SupportSupport 

 Special Type InsulatorsSpecial Type Insulators o

o C.T. upto 66 KVC.T. upto 66 KV o

o P.T. toto 33 KVP.T. toto 33 KV o

o Weather CasingWeather Casing 

 L.T. InsulatorsL.T. Insulators o

o Shackel TypeShackel Type o

o Spool TypeSpool Type o

o Pin TypePin Type o

o Guy strainGuy strain

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Product Specification

1.

1. H.V. Bushings (IS:3347)H.V. Bushings (IS:3347) 11.. 1122--1177..5 5 KKV V / / 22550 0 aammppss 2 2.. 1122--1177..5 5 KKV V / / 66330 0 aammppss 3 3.. 1122--1177..5 K5 KV / V / 1100000 a0 ammppss 4. 4. 1212-1-177.5 .5 KKV / 2V / 200000-0-3315150 a0 ammppss 5 5.. 224 4 KKV V / / 22550 0 aammppss 6 6.. 224 4 KKV V / / 66330 0 aammppss 7 7.. 224 4 KKV V / / 1100000 0 aammppss 8 8.. 224 4 KKV V / / 2200000 0 –– 3311550 0 aammppss 9 9.. 336 6 KKV V / / 22550 0 aammppss 10 10.. 36 36 KV KV / 6/ 6330 a0 ammpsps 11 11.. 36 36 KV KV / 1/ 100000 0 amampsps 12 12.. 36 36 KV KV / 2/ 200000-0-313150 50 amampsps 2.

2. L.V. Bushings (IS:3347)L.V. Bushings (IS:3347) 11.. 1 1 KKV V / / 22550 0 aammppss 2 2.. 1 1 KKV V / / 66330 0 aammppss 3 3.. 1 1 KKV V / / 1100000 0 aammppss 4 4.. 1 1 KKV V / / 2200000 0 aammppss 5 5.. 1 1 KKV V / / 3311550 0 aammppss 3.

3. H.V. Bushings (IS:8603)H.V. Bushings (IS:8603) 11.. 112 2 KKV V / / 22550 0 aammppss 2 2.. 112 2 KKV V / / 66330 0 aammppss 3 3.. 112 2 KKV V / / 1100000 0 aammppss 4 4.. 112 2 KKVV / / 22000000--3311550 0 aammppss 5 5.. 336 6 KKV V / / 22550 0 aammppss 6 6.. 336 6 KKV V / / 66330 0 aammppss 7 7.. 336 6 KKV V / / 1100000 0 aammppss 8 8.. 336 6 KKV V / 2/ 2000000--3311550 0 aammppss 4.

4. C.T. Bushings (IS:5612)C.T. Bushings (IS:5612) 11.. 112 2 KKVV 2

2.. 224 4 KKVV 3

3.. 336 6 KKVV

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EPOXY BUSHINGS

All Epoxy Resin Cast Components are made from hot setting reins cured with All Epoxy Resin Cast Components are made from hot setting reins cured with anhydrides; hence these provide class-F Insulation to the system. In an oxidizing anhydrides; hence these provide class-F Insulation to the system. In an oxidizing atmosphere, certain amine cured Epoxy Resins can start to

atmosphere, certain amine cured Epoxy Resins can start to degrade at 150ºC whereasdegrade at 150ºC whereas the anhydride cured systems are stable at 200ºC therefore our epoxy components are the anhydride cured systems are stable at 200ºC therefore our epoxy components are cured with anhydrides which gives them a longer life.

cured with anhydrides which gives them a longer life.

Electrical & Mechanical Properties Electrical & Mechanical Properties

C

Coommpprreessssiivve e SSttrreennggtthh 11550000--2200000 0 KKgg//ccmm22 T

Teennssiil l SSttrreennggtthh 656500--88550 0 KKgg//ccmm22 D

Dii--eelleeccttrriic c SSttrreennggtthh 1188--222 2 KKVV//mmmm

Range

Range of products of products available in available in the marthe marketket

1.

1. AlAll del desisigngns of bs of busushihingngs fos for ser sealaled ted typype die diststriribubutition ton traransnsfoformrmererss 2.

2. All All dedesigsigns ns of of SpoSpoutsuts, T, Trolrolley ley bubushishingngs es etc tc for for 1.1 1.1 KV KV oil oil circircuicuit bt breareakerkerss 3.

3. ReResisin cn casast Ct CT’T’s & s & PTPT’s ’s fofor 1r 1.1 .1 KV KV InInststrurumement nt papanenelsls 4.

4. AnAny dy desesigign on of Bf Bus us BaBar sr supuppoportrts fs for or cocontntrorol pl pananelelss

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