AEM

Unic

ore Innovation in

Transformer Coresand Manufacturing

October 2008

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Basic informationHistory of the Unicore technologyAEM Cores Pty Ltd began operations in 1958 as a manufacturer of arc welders. Shortly after it began production of cut cores (C cores). From the 1970’s AEM was the leader in specialist wound core manufacturing in Australia, producing single and three phase cut cores, toroidal cores in GOSS and Mumetal (NiFe) materials, and Distibuted Gap Cores. Today, AEM is the only specialist wound core manufacturer in South East Asia.

Because the market being served is small and very demanding of “special designs“, AEM has for many years developed its own specialist machin-ery. During the late 1980’s and early 1990’s the high cost of manufacturing the labour intensive cut cores forced AEM to look for methods of increased automation. The philosophy of AEM, driven by the founder and owner, Bill Jenkinson, has always been to strive for greater and greater transformer efficiency through innovative core design.

In the mid-1990’s engineers at AEM produced prototype machinery to produce Unicores. The Unicore Technol-ogy was successfully used for some time by AEM and its customers before large core manufactures visiting from overseas saw it. They immediately wanted to buy the Unicore machine so that they could provide the advantages of Unicore products to their markets.

More than 120 machines have been manufactured and Unicores are now being produced* or used in the follow-ing countries:

Detail of DUO3

Australia*BeneluxBrasil*Canada*Chile*Colombia*

Czech Republic*FranceIndia*Italy*Korea*Macedonia*

Malaysia*Mexico*New Zealand*NorwayPolandRussia*

South Africa*Spain*Turkey*United KingdomUSA*Venezuela*

The latest development is the DUO core. It is a low loss Unicore designed for easy assembly. This core is expected to slowly replace the use of large E&I, strip laminations and C cores.

We feel that ever tightening enviromental standards and efficiency requirements will drive the market towards high efficient Unicore poducts further in the future.

AdvantagesThe Unicore technology is very flexible, highly accurate, repeatable and reliable. Unlike production of toroidal and cut cores, it does not require any fixed tooling, such as various jigs and mandrils. Unicore laminations are fully formed when leaving the machine.

For General Purpose Transformers, Unicores have lower losses than cut cores or E&I and 90° Cut Lami-nations. Core assembly is very fast.

For Distribution Transformers, Unicore technol-ogy provides a highly flexible, accurate and reliable production system with all inherent advantages of wound core technology.

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UnicoresSimilarly as toroidal or cut cores, Unicores belong to the family of wound magnetic cores. Historically there are more than ten different types of Unicores. Some of them are not used any more as they were replaced by better types.

Unicores can be used for Distribution Transformers and General Purpose Transformers from less than 1000 VA to approx. 1500 kVA. According to latest knowledge a 10.000 kVA transformer has already been produced us-ing our cores.

Materials for UnicoresUnicores can be produced from any grade of Grain Oriented Silicon Steel (GOSS) with thickness from 0.2 to 0.35 and strip width from 20 to 300 mm. Two strips can be run simutaneously when using less than 140 mm strip.

It has been tested that some finer grades of GOSS can be also used for Unicores. For details please contact us.

Unicore geometry and sizesUnicores can weigh up to 1500 kg. A Unicore is defined by the following parameters:

Window Length (WL) Window Width (WW)Strip Width (SW) Build-up (BU)Strip Thickness (ST) Corner AngleTightness Factor (TF)

Unicore faces can be straight butt, DUO-core, Distributed Gap or Uncut. Unicores can be produced with 30°, 45° or 90° corners, depending on application. All these values can be easily specified and programmed.

New Unicore types are continuallydeveloped.

Adjustable assembly plate

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The Unicore machineAdvantagesThe Unicore machine is fully programmable computer controlled machinery. Therefore, it represents a very flexible production technology. Just by selecting a core type and entering core dimensions in the core defini-tion file, one can easily produce a single core or a big volume of cores. Just-in-time production results in low level of inventory. No tooling is needed.

AEM Australia

Power requirements• 3 phase and neutral, 415 V AC, 50/60 Hz electric

supply• 6 kPa compressed air to drive the folder bar and lift

the feed roller• SAE 32 hydraulic oil to drive the guillotine

Electric and air supply, PC connectionDetail of machine operation

DUO core definition file

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Zucchiatti Elettromeccanica, Italy

Our European installationsMore than 10 Unicore machines are operating in Europe now.

Vakar, Czech Republic

VP Technotron, Czech Republic

ALCE Elektrik, Turkey

INTEPS, RussiaElesa Transformadores, Spain

Makitel, Macedonia

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DUO coreApplicationDUO core is the newest type of Unicore. It is a low loss, price competitive core with very easy assembly. It is used for core-type, single-leg and shell-type, single and 3-phase General Purpose Transformers. Annealed DUO cores with one lamination per overlap may be used for Distribution Transformers.

After assembly into windings TIG welding of the last lamination and wedging is recommended.

DUO core typesTo reduce assembly time, the number of laminations per overlap may be increased from 1 up to 3. Increasing from 1 to 2 results in a 45 % decrease in assembly time, and 2 to 3 results in a further 25 % decrease. Note that losses and magnetizing VA will increase.

DUO sizesDimension Minimum (mm) Maximum (mm)Window Length (WL) 80 Unlimited*Window Width (WW) 40 Unlimited*Strip Width (SW) 20 (with two strips) 300 (with one strip)Build Up (BU) Material Thickness Unlimited*

* Not limited by the Unicore machine. Limited only by prac ti cal trans form er manufacturing considerations.

MaterialAny grade of GOSS, thickness 0.2 to 0.35 mm.

Optional annealingAnnealing reduces losses by 10 to 30 %, depending on the core size.

No bandingSimple TIG weld of final lamination only.

DUO3 core

DUO1 male half 3-ph DUO3 with corner holes

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Distributed Gap coresApplicationDG Unicores represent a family of cores with a single cut per lamination. They are used for single-leg and shell-type, single and 3-phase Distribution Transformers.

Unlike traditional technology of producing DG cores, no tooling is needed for production of DG Unicores.

DG Unicore typesThere are several different types of DG Unicores, namely a core with straight cut face, Diverging face (cascade of cut faces fans out) and End-Overlap (spirally wound laminations) face. The position and specification of the DG face can be easily programmed.

DG Unicore sizeDimension Minimum (mm) Maximum (mm)Window Length (WL) 60 Unlimited*Window Width (WW) 40 Unlimited*Strip Width (SW) 20 (with two strips) 300 (with one strip)Build Up (BU) Material Thickness Unlimited*

* Not limited by the Unicore machine. Limited only by prac ti cal trans form er manufacturing considerations.

MaterialAny grade of GOSS, thickness 0.2 to 0.35 mm.

Optional annealingAnnealing reduces losses by 10 to 30 % depending on the core size and is almost always desirable to achieve the highest efficiency.

3-ph DG core40 kg single-phase DG core

End-Overlap type of DG core

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Single Phase DUO Core AssemblyProcedure1. Insert the first full size inner lamination into the coils. 2. Insert the smallest male packet. 3. Insert the helper strips. 4. Insert the corresponding female packet and then remove the strips. 5. Now repeat the steps 2 to 4 until all packets including the last female half with the outer welding lamination have been inserted. 6. After welding the outer lamination an insulation material may be used to lightly wedge the remaining space between the core and the coil.

The disassembled core Female half of the core Male half of the core

Partly assembled core without bobbins

DUO3 detail

Example of a single phase DUO3 core assemblyCore size: WL 210, WW 60, SW 70, BU 60 mmCore weight: 21 kg Transformer power: 7.5 kVACore production time: 18 min Core assembly time: max 4 min

Assembly plates

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Taking a male packet Taking a female packet

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Three Phase DUO Core AssemblyProcedureAssembly of a three phase DUO core is very similar to the single phase DUO assembly. Start with assembly of the first inner core into the coils. After the second inner core is assembled insert an insulation material to wedge the inner cores apart so that the first outer male packet fits accurately. Last lamination of the inner cores may be welded. Now insert the outer core.

Example of a Cast Resin TransformerCore weight: 164 kg Transformer power: 50 kVACore production time: 41 min Core assembly time: approx. 50 min

First inner core assembled Inserting female packet

Wedging the inner cores

Source: EVPU, Slovakia

Inserting first lamination

Strapping the core Start of outer core assembly

An assembly table

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Example of a 50 kVA oil distribution transformerCore size (DUO3): WL 210, WW 105, SW 120, BU 84 mmCore weight: 110 kgCore production time: 38 min Core assembly time: approx. 40 min

Source: Cotrafo, Italy

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Cruciform Unicores 25 kVA dry distribution transformer with DDG1 coreCore size (DDG): WL 280, WW 128, SW 60/90/120, BU 116 mmCore weight: 152 kgCore production time: approx. 70 minCore assembly time: approx. 60 min

100 kVA distribution transformer with DUO2 coreCore size: WL 345, WW 120, SW 55/75/105/120/135/145, BUP 138Core weight: 284 kgCore assembly time: approx. 60 minutes

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Other types of UnicoresStep Butt coreThis type of Unicore is used for a shell type General Purpose Transformers only, up to approx. 1 kVA. Losses are much higher than DUO or DG cores but less than or comparable to a C core.

Butt-2 and Butt-3 coresThese cores have a gap of programmable size in 2 (single phase) or 3 (3-phase) legs. They are used in chokes and reactors.

Replacement of laminations, 1600 VA

Butt-2 core from eight different strips

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Gapped coreIt is a core with one gap of programmable size in one leg only.

Uncut coreIt is a core with no cuts. The Unicore machine is only feeding and folding steel.

Uncut cores are used for Current and Volt-age Transformers. They are always annealed to achieve the lowest loss and magnetizing current.

Straight laminationsThe Unicore machine can be programmed to produce rectangular 90° cut laminations which can be used for the manufacture of chokes and transformers.

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Demagnetizing ball bearings

Uncut core for Petersen coil

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Savings with UnicoreUnicore TransformerCore: Unicore DUO2 without annealingA Window: 155 × 60, Strip width: 90, Buildup: 50, Core weight: 20 kgB Window: 122 × 50, Strip width: 70, Buildup: 40, Core weight: 16,5 kg

Technical parameters:A Induction: 1.4 T, Current density: 3.3 A/mm², No-load loss: 70 W B Induction: 1.3 T, Current density: 3.0 A/mm²

Dimensions:A Width 210 × Depth 155 × Height 270B Width 260 × Depth 160 × Height 210

Total weight:A 31 kgB 26 kg

Classical Laminated TransformerDimensions:A Width 240 × Depth 153 × Height 310B Width 264 × Depth 132 × Height 228

Total Weight:A 39 kgB 31 kg

A Single Phase Transformer 5000 VA B Three Phase Transformer 3000 VA

Manual Magnetic

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Unicore production timesAs a guide a MS Excel spreadsheet is offered. By entering dimensions, production time and weight of single and 3-phase DUO and DG cores are calculated. Loading two strips less than 140 mm wide doubles capacity of the machine.

Annealing UnicoresUnicores are fully formed by the machine. It means they do not have to be annealed if higher losses can be ac-cepted. Depending on application, core size etc. one can decide that annealing is not necessary. With increasing size of a core the difference in losses between unannealled and annealed core is getting smaller.

Unicore Production TimesEnter Core Dimensions

WL 240 mmWW 80 mmSW 80 mm Strip Width is less than 130 mm, load two

strips and double productionBUP 80 mmST 0,30 mm

Note: The calculated cycle time is for one strip, loading two strips will halve the unit time and double production.Single Phase Cores min : sec Core Mass (Kg) Output (Kg/hr)DUO C core with 45deg corner 24:03 43 107

Distributed Gap (DGap, DDGap, EOLap) with 45deg corner 21:43 43 11930deg corner 27:54 44 95Three Phase Cores min : sec Core Mass (Kg) Output (Kg/hr)DUO E core with 45 deg corner 35:18 69 117

Distributed Gap (Ecore and Elap) with 45deg corner 35:05 69 11830deg corner 42:08 70 100Disclaimer: This spreadsheet is offered as a guide only, it’s accuracy cannot be guaranteed. Data is derived by graphical interpolation of empirical tests on actual cores made on a standard UCM2500 machine at AEM Cores Pty Ltd. Tightness Factor is assumed to be zero (default), increasing the TF will increase the core mass slightly. Dec03

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The manual magnetic test rig includes a variac connected to a power meter with either a single phase or three phase test leads around the test core.

Test results can be entered into the spreadsheet producing a graph showing interpolated core performance vs flux den-sity for both Power Loss (Watts) and Magnetising Force (A/m).

Test Rig for testing Single & Three Phase Unicores

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Examples of Unicore transformers

Shell-type DUO core transformer, Italy

Petersen coil with DG coresSingle-leg transformer Core type transformer

100 kVA transformer, Italy

230 kVA dry type transformer, SlovakiaShell type transformer with DUO cores, Russia

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3-phase choke, Italy 4-core 5-limb 3-ph transformer, Australia

10 MVA transformer, South Africa

Examples of instrument transformers

Example of frame

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Marine transformer, Norway

10 kVA transformer, Poland

6.3 kVA transformer, Russia

75 kVA oil distribution transformer, Macedonia

Three phase 100 kVA transformer, Poland

100 kVA transformer, Czech Republic

40 kVA transformer with NOSS core, Turkey

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2 kVA transformer with Stepbutt core

DUO transformer used for vacuum tube amplifier

20 kVA transformerwith DG core, Slovakia

EuropeALCE Elektrik, TurkeyElettromeccanica Zucchiatti, Pordenone, ItalyElesa Transformadores, SpainMAKITEL DOOEL, Ohrid, MacedoniaSuperfin, Berlin, Germany / INTEPS, Pskov, RussiaVakar, Dobrá, Czech RepublicVP Technotron, Frýdek-Místek, Czech Republic

Australia & New ZealandABB Australia, Darra, AustraliaAEM Cores Pty, Ltd, Gillman, AustraliaETEL Distribution Transformers, Auckland, New ZealandThycon, Coburg, AustraliaTyree Transformers, Mittagong, Australia

AsiaETAH SDN. BHD., Kuala Lumpur, MalaysiaJupiter Electricals, Vadodara, IndiaHan Chang Trans Co, Busan, KoreaKotsons, Agra, IndiaMangal Electrical Industries, Jaipur, IndiaManu Power Equipments Pvt, Ltd. Hyderabad, IndiaNeptune Stampings, Vadodara, IndiaPatson Transformers, Gujarat, IndiaStar Delta Transformers, Shopal, IndiaUttam Electricals Ltd., Jaipur, India

AfricaAlloy Magnetic Cores, Elsburg, South AfricaAreva, Johannesburg, South Africa

Some referencesNorth AmericaABB Inc, Jefferson City, Missouri, USAAmbar Electroingenieria, Ecatepec, MexicoBCL Magnetics, Burlington, Ontario, CanadaCarte International, Winnipeg, CanadaCondumex, Laredo, MexicoCorMag, Burlington, Ontario, CanadaEaton Electrical, Arden, North Carolina, USAEl-Met-Parts, Dundas, Ontario, CanadaElectromagnetic Ind., Clearwater, Florida, USAInstrument Transformers, Clearwater, Florida, USAKuhlman Electric Corp., Versailles, Kentucky, USALakeView Metals Inc., Winthrop Harbor, Illinois, USAMagnetic Metals, Anaheim, California, USAPauwels Transformers, Missouri, USAPower Magnetics, Gardena, California, USAProlec GE, Apodaca, MexicoTC Metals, City of Commerce, California, USA

South AmericaCaivet Transformadores, Caracas, VenezuelaCNS, Sao Paulo, BrazilINATRA, Guyaquil, EcuadorRhona S.A., Vina Del Mar, ChileRymel Engenieria Electrica, Itaqui-Autoquia, ColombiaSiemens, Bogota, Colombia

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AEM Cores Pty. Ltd.95 Bedford Street, GillmanSA 5013, AustraliaTel.: +61 8 8341 0086Fax: +61 8 8341 0225sales@aemcores.com.auwww.aemcores.com.au

Agent for Europe

Ruff s.r.o.Tyršova 1033, 744 01 Frenštát p. R.Czech RepublicTel.: +420 608 834 747Fax: +420 556 831 701info@ruff.czwww.ruff.cz

Austria, Germany & SwitzerlandSchäppi IndustrievertretungenGeissweidli 5CH-8846 WillerzellTel./Fax: ++41 55 422 00 40Tel.: ++41 79 620 35 47pschaeppi@bluewin.ch

Subagents in Europe

RussiaTC WindeqDomodedovskoe shosse, 1/3Moscow 142116Tel.: ++79 261 939 494Tel.: ++79 263 789 898info@windeq.com

SpainMP–TECNOIMPORT, S.L.Nord, 76 Local 2008950 Esplugues de LlobregatTel.: +34 93 473 7975Fax: +34 93 473 7992info@mptecnoimport.com

FranceMrs. Lydia Cayeux15, chemin des Beaudenons45220 St Germain des PrésTél.: ++33 2 38 94 63 32Fax: ++33 2 38 94 64 01cayeux.tct@wanadoo.fr

TurkeyUYGAR Teknoloji MühendislikElektrik MakineleriSan. ve Tic. Ltd. Sti.1420 Sokak No: 30/1-135220 Kahramanlar-IZMIRTel.: ++90 232 445 51 62Fax: ++90 232 445 51 63uygartekno@superonline.com la

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Cruciform 630 kVA DUO2 core from 8 strips