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CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER Application Configuration Internal Construction Dielectric Fluid Accessories

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Page 1: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER

Application

Configuration

Internal Construction

Dielectric Fluid

Accessories

Page 2: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

APPLICATION

Distribution – Running lights, HVAC, Office

Motor Control Center

Dedicated Load – Pump, Crusher

Extreme Duty – Drag-line

Page 3: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Available ConfigurationsAvailable ConfigurationsPadmountPadmountStationStationSecondary Unit SubstationSecondary Unit SubstationSpecialtySpecialty– Grounding, Rectifier, Mine Duty

Page 4: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Shell vs. Core Form Transformers

Rectangular vs. Round Coil Construction

Disk Wound

INTERNAL CONSTRUCTION

Page 5: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Shell form & core form transformer constructionShell form & core form transformer construction

- 3 legged stacked core-Each phase shares a core bar. Harmonic

content can lead to tank heating if wye/wye connected.

-5 legged wound core-Each phase has a magnetic flux return path

independent from the other phases.

IEEE Std C57.12.80-2002 definitions:

Shell form: A transformer in which the laminationsconstituting the iron core surround the windings and usually enclose the greater part of them.

Core form: A transformer in which those parts of theMagnetic circuit surrounded by the windings have theForm of legs with 2 common yokes.

Page 6: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Shell & core transformersShell & core transformers

Page 7: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Rectangular coil & 5 legged core assemblyRectangular coil & 5 legged core assembly

Page 8: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Distributed gap core constructionDistributed gap core construction

Core after shear operation

“Distributed” gaps

Page 9: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Distributed gap core constructionDistributed gap core construction

Raw stock core material

Page 10: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Distributed gap core constructionDistributed gap core construction

Pressed cores queued for annealing

Loading the annealing oven

Page 11: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Annealed cores

Distributed gap core constructionDistributed gap core construction

Page 12: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Rectangular coilsRectangular coils

Cooling ducts

Core windows

HV taps

HV finish

HV start

LV winding

LV leads

Page 13: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

x x

x x2x 2x

2x 2x

Rectangular coils w/ distributed gap coresRectangular coils w/ distributed gap cores

Page 14: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Rectangular coils w/ distributed gap coresRectangular coils w/ distributed gap cores

Stacking the distributed gap cores

Annealed Laminations

Page 15: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

21 2 3 4 5

Application of core frame

Rectangular coils w/ distributed gap coresRectangular coils w/ distributed gap cores

Page 16: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Rectangular coils w/ distributed gap coresRectangular coils w/ distributed gap cores

Assembled 5 legged distributed gap core and coil assembly

Page 17: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Outer core legs and core frame

Rectangular coils w/ distributed gap coresRectangular coils w/ distributed gap cores

Page 18: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Shell & core transformersShell & core transformers

Page 19: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Round core and coil assemblyRound core and coil assembly

Top view, single core/coil

Page 20: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Cruciform core shearCruciform core shear

Page 21: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Cruciform stacked core constructionCruciform stacked core construction

Page 22: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Cruciform core constructionCruciform core construction

Top view

Yoke - leg interface

Page 23: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Cruciform stacked core constructionCruciform stacked core construction

Page 24: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Cruciform core

Page 25: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Round CoilsRound Coils

Page 26: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

360 degree cooling ducts

Round CoilsRound Coils

Radial forces are equalized during short circuits & overloads

Page 27: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Core Core –– Coil AssemblyCoil Assembly

Improved cooling

Page 28: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

core frame insulation

Core Core –– Coil AssemblyCoil Assembly

Page 29: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Round coils with cruciform coreRound coils with cruciform core

HV leads & taps

LV leads

Top yoke

Page 30: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Round coils with cruciform coreRound coils with cruciform core

Tanking assembled core & coil assembly

Page 31: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Disk-Type Coil Winding

Page 32: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Disk Coil Construction

Static Plate

Static Plate

PB Washer

Winding Tube Inner Diameter

Wound Diameter

Coil Inner Diameter

Coil section

Tube Extension

Winding Tube

Winding Space

Radial Spacers

Outside Vertical Spacer

Vertical Spacer

MDMCWD

RB

Radial Spacer

Outside Vertical Spacer

Vertical Spacer

Winding Tube

Continuous Disk Helical Disk

Page 33: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Stages of Disk Windings Assembly

Page 34: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Construction comparisonsConstruction comparisons

Page 35: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Rectangular coil Rectangular coil -- 5 legged core advantages5 legged core advantages

With strip conductor secondaries:

••HV electrically centered on the LV windingHV electrically centered on the LV winding

••Significant gain in mechanical strengthSignificant gain in mechanical strength

••Suitable for high volume productionSuitable for high volume production

••No tank heating from stray flux inductionNo tank heating from stray flux induction in tank in tank wall when connected wyewall when connected wye--wyewye

Page 36: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Round coil Round coil -- cruciform core usescruciform core uses

With wire / wire windings:

••Means of providing increased hoop strength Means of providing increased hoop strength

••Enables solid construction of higher kVA unitsEnables solid construction of higher kVA units

••Suitable for small power designs & dedicated loadsSuitable for small power designs & dedicated loads

••Reduction in width dimension for retrofit Reduction in width dimension for retrofit applications applications

Page 37: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Round Coil/Cruciform Core Advantages

•360 degree cooling•Increased insulation life•More efficient cooling during heavy duty cycles

•Top & bottom pressure plates•Containment of axial forces during short circuits

•Round coil construction•Maximum containment of radial forces during short circuits•Improved clearances between phases

Page 38: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Dielectric Fluids

Mineral Oil (Type II)Vegetable-Based Oil (Envirotemp FR3)– High Fire Point (300 degrees C)– Biodegradable

SiliconeVoltesso– Lower Temperature Pour Point

Page 39: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Standard Accessories

Oil Temperature GaugeLiquid Level GaugePressure/Vacuum GaugePressure Relief ValveDrain Valve w/ Sample PortUpper Fill PortAir Space filled with Dry Nitrogen

Page 40: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Optional Accessories Part 1

Dry Contacts on GaugesPressure Relief DeviceForced Air Cooling– 15% increased capacity 2499 kVA and smaller– 25% increased capacity 2500 kVA and larger

Winding Temperature GaugeSudden Pressure Rise Relay– Seal-In Relay

Page 41: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Optional Accessories Part 2

Removable RadiatorsPositive Pressure SystemStainless Steel – Auxiliary Wiring Cabinet – NEMA 4X– Hardware– Base– Tank– Radiators– Transitions

Page 42: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer
Page 43: CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER · CONSIDERATIONS WHEN SPECIFYING A TRANSFORMER zApplication zConfiguration zInternal Construction zDielectric Fluid ... A transformer

Thank you!