transformadores de tipo seco

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CA08104001E For more information, visit: www.eaton.com/consultants

November 2013

Contents

Distribution Dry-Type Transformers—Low Voltage19

Sheet 19001

D i s t r i b u t i o n

D r y - T y p e

T r a n s f o r m e r s — L o w

V o l t a g e

Distribution Dry-Type Transformers—Low Voltage

Glossary of Transformer Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.0-2

The Energy Policy Act of 2005. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.0-5

General Description/Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-1

Ventilated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-5

General Purpose Encapsulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-8

K-Factor Rated for Nonlinear Loads (KT Type) TP-1 . . . . . . . . . . . . . . . . .

19.1-11

Harmonic Mitigating (HMT Type) TP-1. . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-12

NEMA TP-1 Energy Efficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-16

Energy Efficient (CSL-3 Type) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-17

Motor Drive Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-18

Hazardous Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-19

Mini–Power Centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-20

FAQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19.1-35

Specifications

See Eaton’s Product Specification Guide

, available on CD or on the Web.CSI Format: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1995 2010

Dry-Type Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16461 26 22 13

Mini–Power Centers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16463 26 27 00.11

Further Information

Volume 2—Commercial Distribution

2011, Tab 9 . . . . . . . . . . . . . . . .

CA08100003E

Eaton’s Family of Dry-Type Distribution Transformers


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Glossary of Transformer Terms

Air cooled:

A transformer that iscooled by the natural circulation of airaround, or through, the core and coils.

Ambient noise level:

The existing

or inherent sound level of the areasurrounding the transformer, prior toenergizing the transformer. Measuredin decibels.

Ambient temperature:

The temperature of the air surround-ing the transformer into which theheat of the transformer is dissipated.

Ampacity:

The current-carryingcapacity of an electrical conductorunder stated thermal conditions.Expressed in amperes.

Ampere:

The practical unitof electric current.

Attenuation:

A decrease in signalpower or voltage. Unit of measureis dB.

Autotransformer:

A transformer inwhich part of the winding is commonto both the primary and the secondarycircuits.

Banked:

Two or more single-phasetransformers wired together to supplya three-phase load. Three single-phasetransformers can be “banked” togetherto support a three-phase load. Forexample, three 10 kVA single-phasetransformers “banked” together will

have a 30 kVA three-phase capacity.

BIL:

Basic impulse level. The ability ofa transformer’s insulation system towithstand high voltage surges. AllEaton 600V-class transformers have a10 kV BIL rating.

BTU:

British thermal unit. In NorthAmerica, the term “BTU” is usedto describe the heat value (energycontent) of fuels, and also to describethe power of heating and coolingsystems, such as furnaces, stoves,barbecue grills and air conditioners.When used as a unit of power, BTU“per hour” (BTU/h) is understood,

though this is often abbreviated tojust “BTU.”

Buck-boost:

The name of astandard, single-phase, two-windingtransformer application with thelow voltage secondary windingsconnected as an autotransformerfor boosting (increasing) or bucking(decreasing) voltages in smallamounts. Applications can eitherbe single-phase or three-phase.

CE:

Mark to indicate third-partyapproved or self-certification tospecific requirements of theEuropean community.

Celsius (centigrade):

Metrictemperature measure.

°F = (1.8 x °C) + 32

°C = (°F-32) / 1.8

Center tap:

A reduced capacity tapat the mid-point of a winding. Thecenter tap on three-phase delta-deltatransformers is called a lighting tap.It provides 5% of the transformer’s kVAfor single-phase loads.

Certified tests:

Actual values takenduring production tests and certifiedas applying to a given unit shipped ona specific order. Certified tests areserial number–specific.

Common mode:

Electrical noiseor voltage fluctuation that occursbetween all of the line leads and thecommon ground, or between groundand line or neutral.

Compensated transformer:

A transformer with a turns ratiothat provides a higher than nameplateoutput (secondary) voltage at no load,and nameplate output (secondary)voltage at rated load. It is commonfor small transformers (2 kVA and less)to be compensated.

Conductor losses:

Losses (expressedin watts) in a transformer that areincidental to carrying a load: coilresistance, stray loss due to strayfluxes in the windings, core clamps,and the like, as well as circulatingcurrents (if any) in parallel windings.Also called load losses.

Continuous duty rating:

The load thata transformer can handle indefinitelywithout exceeding its specifiedtemperature rise.

Core losses:

Losses (expressed inwatts) caused by magnetization ofthe core and its resistance to magneticflux. Also called no-load losses or

excitation losses. Core losses arealways present when the transformeris energized.

CSA:

Canadian StandardsAssociation. The Canadian equivalentof Underwriters Laboratories (UL).

CSL3:

Candidate Standard Level 3(CSL3) design criteria developed bythe U.S. Department of Energy. Thisterm is used when considering themaximum, practical efficiency of atransformer.

cUL:

Mark to indicate UL Certificationto specific CSA Standards.

Decibel (dB):

Unit of measure used toexpress the magnitude of a change insignal or sound level.

Delta connection:

A standard three-phase connection with the ends ofeach phase winding connected inseries to form a closed loop with eachphase 120 degrees from the other.Sometimes referred to as three-wire.

Dielectric tests

: Tests that consist ofthe application of a voltage higherthan the rated voltage for a specified

time for the purpose of determiningthe adequacy against breakdowns ofinsulating materials and spacingsunder normal conditions.

Dry-type transformer:

A transformerin which the core and coils are in agaseous or dry compound insulatingmedium. A transformer that is cooledby a medium other than a liquid,normally by the circulation of air.

E3:

Eaton’s version of a CSL3transformer.

Eddy currents:

The currents that areinduced in the body of a conducting

mass by the time variation of magneticflux or varying magnetic field.

Efficiency:

The ratio of the poweroutput from a transformer to thetotal power input. Typically expressedas a %.

Electrostatic shield:

Copper or otherconducting sheet placed betweenprimary and secondary windings,and grounded to reduce electricalinterference and to provide additionalprotection from line-to-line or line-to-ground noise. Commonly referred toas “Faraday shield.”

Encapsulated transformer:

A transformer with its coils eitherdipped or cast in an epoxy resin orother encapsulating substance.

Enclosure:

A surrounding caseor housing used to protect thecontained equipment against externalconditions and prevent personnelfrom accidentally contacting live parts.


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Glossary

003

Environmentally preferable product:

A product that has a lesser or reducednegative effect on human health andthe environment when compared tocompeting products that serve thesame purpose. This comparison mayconsider raw materials acquisition,production, manufacturing, packaging,distribution, reuse, operation,maintenance and disposal of theproduct. This term includes recyclableproducts, recycled products andreusable products.

EPACT: The Energy Policy Act of1992 (EPAct) is an important piece oflegislation for efficiency because itestablished minimum efficiency levelsfor dry-type distribution transformersmanufactured or imported afterDecember 2006. EPAct, which wasbased on NEMA standards, defineda number of terms, including what

constitutes an energy-efficienttransformer. The DOE issued a rulethat defines these transformers andhow manufacturers must comply. DOEEPAct rule (PDF): Energy EfficiencyProgram for Certain Commercialand Industrial Equipment: TestProcedures, Labeling, and theCertification Requirements for ElectricMotors. Final Rule. 10-CFR Part 431.

Excitation current:

No load current.The current that flows in any windingused to excite the transformer whenall other windings are open-circuited.It is usually expressed in percent of the

rated current of a winding in which it ismeasured. Also called magnetizingcurrent.

FCAN:

“Full Capacity Above Nominal”taps. Designates the transformer willdeliver its rated kVA when connectedto a voltage source which is higherthan the rated primary voltage.

FCBN:

“Full Capacity Below Nominal”taps. Designates the transformer willdeliver its rated kVA when connectedto a voltage source which is lower thanthe rated primary voltage.

Frequency:

On AC circuits, designatesthe number of times that polarityalternates from positive to negativeand back again per second, such as60 cycles per second. Typicallymeasured in Hertz (Hz).

Ground:

Connecting one side ofa circuit to the earth through lowresistance or low impedance pathsto help prevent transmitting electricalshock to personnel.

Harmonic:

A sinusoidal waveform witha frequency that is an integral multipleof the fundamental frequency (60 Hz).

60 H

3

fundamental120 H

3

2nd harmonic180 H

3

3rd harmonic

240 H

3

4th harmonic

Harmonic distortion:

Nonlineardistortion of a system characterized by the appearance of harmonic(non-sinusoidal) currents in theoutput, when the input is sinusoidal.

Harmonic distortion, total (THD):

Thesquare root of the sum of the squaresof all harmonic currents present ina load, excluding the fundamental60 Hz current. Usually expressed asa percent of the fundamental.

High voltage windings:

In a two-winding transformer, the winding

intended to have the greatervoltage. Usually marked with“H” designations.

HMT:

Harmonic MitigatingTransformer (HMT) is better able tohandle the harmonic currents presentin today’s electrical power system.thereby increasing system capacity,reducing distortion throughout afacility, help to minimize downtimeand “mysterious” maintenance onequipment, and return the longevityof equipment life through reducedoperational energy losses, therebyrunning cooler.

Hp:

Horsepower. The energy requiredto raise 33,000 pounds a distance ofone foot in one minute. 1 hp is equalto 746 watts, or 0.746 kW.

Hi pot:

A standard test on dry-typetransformers consisting of extra-highpotentials (voltages) connected to thewindings. Used to check the integrityof insulation materials and clearances.

Hottest-spot temperature:

The highesttemperature inside the transformerwinding. Is greater than the measuredaverage temperature of the coilconductors, when using theresistance change method.

Hysteresis:

The tendency of amagnetic substance to persist inany state of magnetization.

Impedance:

The retarding forcesof current in an AC circuit; thecurrent-limiting characteristicsof a transformer. Symbol = Z

Inductance:

In electrical circuits, theopposition to a change in the flow ofelectrical current. Symbol = L

Inducted potential test:

A standarddielectric test of transformerinsulation. Verifies the integrity ofinsulating materials and electricalclearances.

Inrush current:

The initial high peak

of current that occurs in the first fewcycles of energization, which can be30 to 40 times the rated current.

Insulating transformer:

Another termfor an isolating transformer.

Insulation:

Material with a highelectrical resistance.

Insulation materials:

Those materialsused to insulate the transformer’selectrical windings from each otherand ground.

Integral TVSS or SPD: Major StandardChange for Surge Protective Devices

(formerly known as Transient VoltageSurge Suppressors). The primarysafety standard for transient voltagesurge suppressors (TVSS) has under-gone major revisions in the past threeyears with mandatory compliance bymanufacturers required by September29, 2009. Even the name of thestandard has changed from ULStandard for Safety for TransientVoltage Surge Suppressors, UL 1449to UL Standard for Safety for SurgeProtective Devices, UL 1449. Thismeans that TVSS listed to the UL 14492nd Edition standard will no longerbe able to be manufactured afterSeptember 29, 2009. All SurgeProtective Devices must be designed,tested, manufactured and listed tothe UL 1449 3rd Edition standard afterthis date.

Isolating transformer:

A transformerwhere the input (primary) windingsare not connected to the output(secondary) windings (i.e., electricallyisolated).

K-factor:

A common industry term forthe amount of harmonics produced bya given load. The larger the K-factor, themore harmonics that are present. Alsoused to define a transformer’s ability

to withstand the additional heatinggenerated by harmonic currents.

kVA:

Kilovolt-ampere. Designatesthe output that a transformer candeliver for a specified time at arated secondary voltage and ratedfrequency without exceeding thespecified temperature rise. Whenmultiplied by the power factor, willgive kilowatts or kW.

1000 VA = 1 kVA


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Lamination:

Thin sheets of electricalsteel used to construct the core of atransformer.

Limiting temperature: The maximumtemperature at which a componentor material may be operated

continuously with no sacrificein normal life expectancy.

Linear load:

A load where the currentwaveform conforms to that of theapplied voltage, or a load wherea change in current is directlyproportional to a change inapplied voltage.

Live part:

Any component consistingof an electrically conductive materialthat can be energized under conditionsof normal use.

Load losses:

I

2

R losses in windings.Also see conductor losses.

Low voltage winding:

In a two-winding transformer, the windingintended to have the lesser voltage.Usually marked with “X” designations.

Mid-tap:

See center tap.

Noise level:

The relative intensity ofsound, measured in decibels (dB).NEMA Standard ST-20 outlines themaximum allowable noise level fordry-type transformers.

Nonlinear load:

A load where thecurrent waveform does not conform tothat of the applied voltage, or where achange in current is not proportionalto a change in applied voltage.

Non-ventilated transformer:

A transformer where the core andcoil assembly is mounted insidean enclosure with no openings forventilation. Also referred to as totallyenclosed non-ventilated (TENV).

No load losses:

Losses in atransformer that is excited at ratedvoltage and frequency but that isnot supplying a load. No load lossesinclude core losses, dielectric lossesand conductor losses in the windingdue to the exciting current. Also

referred to as excitation losses.

Overload capability: Short-termoverload capacity is designed intotransformers as required by ANSI.Continuous overload capacity isnot deliberately designed into atransformer because the designobjective is to be within the allowedwinding temperature rise withnameplate loading.

Percent IR (% resistance): Voltage dropdue to resistance at rated current inpercent of rated voltage.

Percent IX (% reactance): Voltage dropdue to reactance at rated current inpercent of rated voltage.

Percent IZ (% impedance): Voltagedrop due to impedance at ratedcurrent in percent of rated voltage.

Phase: Type of AC electrical circuit;usually single-phase two- or three-wire,or three-phase three- or four-wire.

Polarity test: A standard teston transformers to determineinstantaneous direction of thevoltages in the primary compared to the secondary.

Primary taps: Taps added to theprimary (input) winding. See Tap.

Primary voltage: The input circuitvoltage.

Power factor: The cosine of the phaseangle between a voltage and a current.

Ratio test: A standard test oftransformers to determine the ratioof the input (primary) voltage to theoutput (secondary) voltage.

Reactance: The effect of inductiveand capacitive components of acircuit producing other than unitypower factor.

Reactor: A single winding device with

an air or iron core that produces aspecific amount of inductive reactanceinto a circuit. Normally used to reduceof control current.

Regulation: Usually expressed asthe percent change in output voltagewhen the load goes from full load tono load.

Scott T connection: Connection forthree-phase transformers. Instead ofusing three sets of coils for a three-phase load, the transformer uses onlytwo sets of coils.

Series/multiple winding: A windingconsisting of two or more sections thatcan be connected for series operationor multiple (parallel) operation. Alsocalled series-parallel winding.

Short circuit: A low resistanceconnection, usually accidental,across part of a circuit, resulting inexcessive current flow.

Sound levels: All transformers makesome sound mainly due to thevibration generated in its core byalternating flux. All Eaton general-purpose dry-type distributiontransformers are designed withsound levels lower than NEMA ST-20maximum levels.

Star connection: Same as a wyeconnection.

Step-down transformer: A transformerwhere the input voltage is greater thanthe output voltage.

Step-up transformer: A transformerwhere the input voltage is less thanthe output voltage.

T-T connection: See Scott Tconnection.

Tap: A connection brought out of

a winding at some point betweenits extremities, usually to permitchanging the voltage or current ratio.Taps are typically used to compensatefor above or below rated input voltage,in order to provide the rated outputvoltage. See FCAN and FCBN.

Temperature class: The maximumtemperature that the insulation systemof a transformer can continuouslywithstand. The common insulationclasses are 105, 150, 180 (also 185)and 220.

Temperature rise: The increase overambient temperature of the windings

due to energizing and loading thetransformer.

Total losses: The sum of the no-loadlosses and load losses.

Totally enclosed non-ventilatedenclosure: The core and coil assemblyis installed inside an enclosurethat has no ventilation to cool thetransformer. The transformer relieson heat to radiate from the enclosurefor cooling.

Transformer tests: Per NEMA ST-20,routine transformer production testsare performed on each transformer

prior to shipment. These tests are:Ratio tests on the rated voltageconnection; Polarity and PhaseRelation tests on the rated connection;No-Load and Excitation Current tests at rated voltage on the rated voltageconnection and Applied Potential andInduced Potential tests . Special testsinclude sound level testing.


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Glossary and The Energy Policy Act of 2005005

Transverse mode: Electrical noiseor voltage disturbance that occursbetween phase and neutral, or fromspurious signals across metallic hotline and the neutral conductor.

Turns ratio: The ratio of the number

of turns in the high voltage windingto that in the low voltage winding.

Typical test data: Tests that wereperformed on similar units that werepreviously manufactured and tested.

UL (Underwriters Laboratories): An independent safety testingorganization.

Universal taps: A combination of sixprimary voltage taps consisting of 2 at+2-1/2% FCAN and 4 at -2-1/2% FCBN.

Watt: A unit of electrical power whenthe current in a circuit is one ampere

and the voltage is one volt.Wye connection: A standard three-wire transformer connection withsimilar ends of single-phase coilsconnected together. The commonpoint forms the electrical neutral pointand may be grounded. Also referred toas three-phase four-wire. To obtain theline-to-neutral voltage, divide the linevoltage by .

The Energy Policy Act of 2005

The Energy Policy Act of 2005 and theresulting Federal Law 10 CFR Part 431require that efficiency of low voltagedry-type distribution transformers

manufactured after January 1, 2007shall be no less than the efficiencylevels listed in Table 4-2 of NEMAStandard TP-1-2002. Transformersspecifically excluded for the scope ofthis law include:

■ Transformers rated less than 15 kVA

■ Transformers with a primary orsecondary voltage greater than600V

■ Transformers rated for operation atother than 60 Hz

■ Transformers with a tap rangegreater than 20%

■ Motor drive isolation transformers

■ Rectifier transformers

■ Autotransformers

■ Transformers that supplyUninterruptible Power Supplies

■ Special impedance transformers

■ Regulating transformers

■ Sealed and non-ventilatedtransformers

■ Machine tool transformers

■ Welding transformers

■ Grounding transformers

■ Testing transformers

■ Repaired transformers

3 1.732( )


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Distribution Dry-Type Transformers

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Overview

General Description/Product Overview007

Energy-EfficientTransformers

NEMA TP-1 Energy-Efficient Ventilated Transformer

Eaton’s family of energy-efficienttransformers meet NEMA TP-1efficiency requirements and federalenergy efficiency laws mandatedby the Energy Policy Act of 2005.Distribution transformers installed in

the United States are required to meetthese energy efficiency requirements.Energy-efficient transformers areespecially designed to have low noload (core) losses. Minimum efficiencylevels have been established for thesetransformers when loaded at 35% oftheir full load capacity. Available 600V.Eaton offers a wide variety of energy-efficient transformers, including 150°C,115°C or 80°C; general purpose orK-factor rated; with aluminum orcopper windings. Eaton’s energy-efficient transformers are manufac-tured with a NEMA 2 enclosureas standard, and are suitable for

installation outdoors when a NEMA 3Rweathershield kit is installed. Eaton’senergy-efficient transformers use a220°C insulation system with 150°Ctemperature rise as standard.

Installation of energy-efficienttransformers may help facilitiesearn points toward LEED® certificationfrom the U.S. Green Building Council.

Refer to Page 19.1-16 for additionalinformation.

K-Factor Rated NonlinearTransformers

Ventilated Transformer

Eaton K-Factor nonlinear transformersare specifically designed to withstandthe harmful overheating effects causedby harmonics generated by nonlinear(non-sinusoidal) loads. These loadsinclude computers, laser printers,copiers and other office equipment,

as well as video monitors and otherelectronic equipment. The core andcoils of K-Factor transformers areespecially designed to have reducedinduction levels, which result in areduction in stray losses. Oversized(200% rated) neutrals and electrostaticshielding are provided as standard onK-Factor transformers. Eaton K-Factortransformers are available in ratingswith a K-factor of 4, 13, 20, 30, 40 and50. 600V-class single-phase modelsare available to 167 kVA; three-phaseratings to 1500 kVA. Eaton’s family ofK-Factor transformers are manufacturedwith the same high-quality construction

features as our ventilated transformerproducts, including NEMA 2 enclosuresand the 220°C (Class R) insulationsystem with 150°C temperature riseas standard.

Refer to Page 19.1-11 for additionalinformation. Eaton K-Factor–ratedtransformers comply with NEMATP-1 standards.

Harmonic MitigatingTransformers

Harmonic Mitigating Ventilated Transformer

Eaton’s harmonic mitigating trans-formers (HMTs) are specially designedtransformers that treat a wide varietyof harmonics. Also called “phase-shifting” transformers, their low zero-sequence impedance wye zig-zag

secondary windings prevent harmfultriplen (3rd, 9th, 15th, etc.) harmoniccurrents from coupling into the primarydelta, where they can progressupstream to the service entrance.Multiple HMTs with a variety of phase-shift configurations can be applied ina coordinated scheme to target 5th,7th, and higher order harmonics atthe common bus feeding all of thetransformers. HMTs are ideally suitedfor installations rich in harmonic loads,such as educational facilities (K-12and universities), government,commercial, medical and call-centerapplications. HMTs are manufactured

with the same high-quality featuresas Eaton’s ventilated transformers,including NEMA 2 enclosures and the220°C (Class R) insulation system with150°C temperature rise as standard.Additionally, Eaton’s HMTs aremanufactured with a 200% neutraland electrostatic shield as standard.


HMTs are available in fourconfigurations:

■ Type NON (0° phase-shift)

■ Type THR (30°)

■ Type POS (+15°)■ Type NEG (–15°)

Available in three-phase ratings to500 kVA and 600V. All Eaton HMTsmeet or exceed NEMA TP-1 efficiencylevels, when operated under eitherlinear or nonlinear load profiles EatonHMT transformers comply with NEMATP-1 standards.


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Overview


Motor Drive IsolationTransformers

Motor Drive Isolation Ventilated Transformer

Eaton’s motor drive isolation trans-formers are especially designed forthree-phase, SCR-controlled, variable-speed motor drive load profiles. Sizedby horsepower and common motorvoltages, motor drive isolation trans-

formers are braced to withstand themechanical stresses associated withAC adjustable frequency drives orDC drives. Available in three-phaseventilated designs to 1500 hp and600V. Epoxy encapsulated three-phasedesigns are available to 20 hp. Motordrive isolation transformers aremanufactured using the same high-quality construction features as ourventilated transformer products,including NEMA 2 enclosures and the220°C (Class R) insulation system with150°C temperature rise as standard.Epoxy encapsulated models haveNEMA 3R enclosures and 115°C

temperature rise as standard. All Eatonthree-phase motor drive isolationtransformers include a normallyopen dry contact temperature sensorinstalled in the coils. This sensor canbe connected to provide advance alertor warning of a potential overheatingof the transformer.


Read the text on Page 19.0-5 onthe Energy Policy Act of 2005 beforespecifying these units. These units areexempt from NEMA TP-1 requirements.

Hazardous LocationTransformers

Hazardous Location Transformers

Eaton’s hazardous location transformersare suitable for use in environmentsclassified by the National Electrical

Code® (NEC®) as Class I, Division 2,Groups A, B, C and D, as defined byNEC Article 501, when installed incompliance with NEC-recommendedprocedures for dry-type transformersrated 600V and below. As defined byNEC Article 500, Class I, Division 2locations include atmospheres thatmay contain volatile or ignitableconcentrations of flammable liquidsor gas vapors, or locations adjacent tosuch environments. Acetone, ammonia, benzene, gasoline, methane, propaneand natural gas are examples ofsuch substances.

Eaton’s hazardous location transformersare of the encapsulated design, and areavailable up to 600V ratings. Single-phase ratings 0.05 kVA through 25 kVA;three-phase ratings to 75 kVA.Hazardous location transformers usea 180°C insulation system with 115°Ctemperature rise.


Mini–Power Center

Mini–Power Center

An Eaton mini–power center replacesthree individual components:

■ Primary main breaker

■ Transformer

■ Distribution loadcenter.

The mini–power center combinesall three into a single unit. All inter-connecting wiring is performed at thefactory. Mini–power centers are ideallysuited for applications where 120Vis required at a remote location.Parking lots, workbenches andtemporary power on constructionsites are common applications formini–power centers. Available insingle-phase and three-phase ratingsto 600V, 100A, and 30 kVA withsecondary loadcenters withprovisions for up to 24 single-pole

branch breakers. Available withaluminum bus and plug-on branchbreakers, or with copper bus andbolt-on branch breakers.

Mini–power centers incorporate anencapsulated transformer in theirconstruction, and are NEMA 3Rrated for outdoor applications.



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Sheet 19

Overview


Shielded IsolationTransformers

Shielded Isolation Ventilated Transformer

Eaton’s shielded isolation transformersare typically installed where “sensitive”loads such as input circuits ofcomputers, medical equipment andmicroprocessors require additionalprotection from high-frequencyelectrical disturbances. Shielded

isolation transformers include anelectrostatic shield (Faraday shield)installed between the primary andsecondary windings. This shield isgrounded to the core of the transformerto attenuate high-frequency electricaldisturbances in the load from beingtransmitted to the line side of thetransformer. Shielded isolationtransformers are available in allsizes and ratings of encapsulated andventilated transformers. By design,all K Factor and harmonic mitigatingtransformers include an electrostaticshield as standard.

Read the text on Page 19.0-5 onthe Energy Policy Act of 2005 beforespecifying these units.

Marine DutyTransformers

Marine-Duty Ventilated Transformer

Eaton’s marine-duty transformers are“Type Approved” by the AmericanBureau of Shipping (ABS) for on-boarduse in steel vessels (not for propulsionsystems or combat vessels). Thesetransformers are typically installedbelow deck in electrical or mechanical

rooms where the ambient temperatureis greater than normal. Eaton’s marine-duty transformers are especiallydesigned for operation in 50°Cambient locations. Marine-duty ratedtransformers are manufacturedwith copper windings as standard.Encapsulated designs are available insingle-phase ratings 0.05 kVA through37.5 kVA; three-phase designs 15 kVAthrough 75 kVA. Ventilated designs areavailable in single-phase ratings of15 kVA through 100 kVA; three-phasedesigns 15 kVA through 300 kVA.Encapsulated and ventilated modelsare available up to 600V ratings. The

standard temperature rise of Eaton’smarine-duty transformers is 115°C.

Read the text on Page 19.0-5 onthe Energy Policy Act of 2005 beforespecifying these units.

“Buck-Boost” and Low Voltage Lighting Transformers

Buck-Boost Transformers

Eaton’s buck-boost transformers areideally suited to applications wherethe available voltage needs to beslightly increased (“boosted”) ordecreased (“bucked”) to be used in

a specific application. When buck-boost transformers are wired asautotransformers, they can be usedto accomplish this bucking or boostingof voltage. Buck-boost transformersare single-phase encapsulatedtransformers and are available inthree voltage combinations;

■ 120 x 240–12/24

■ 120 x 240–16/32

■ 240 x 480–24/48

...and are available in 0.05 kVA through7.5 kVA. These transformers can alsobe used at their nameplate voltages

for applications such as low voltageinterior or landscape lighting.


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Overview


CSL-3 Transformers

CSL-3 Transformer

Eaton CSL-3 transformers have thehighest efficiencies and the lowestlosses of any type of unit. Copper oraluminum windings are available in15 kVA through 300 kVA ratings. Unitsare available with temperature rise of150°C, 115°C or 80°C rise.

Eaton CSL-3 transformers are more

efficient than NEMA TP-1 by 34%–38%.

Using CSL-3 units lowers the carbonfootprint of a facility and assists withLEED certification.

Refer to Page 19.1-17 for additionalinformation on CSL-3 transformers.


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Sheet 19

General Purpose Ventilated Transformers

Description011

General ConstructionFeatures of General Purpose(TP-1, K-Factor TP-1 and HMTTP-1) Ventilated Transformers

Rated 600V and belowGeneral DescriptionEaton’s single-phase and three-phasegeneral purpose dry-type ventilatedtransformers are of the two-windingtype, self-cooled, and are available in awide variety of primary and secondaryvoltage combinations.

Eaton’s transformers are designed,manufactured and tested in accordancewith all of the latest applicable ANSI,NEMA and IEEE standards. All 600Vclass ventilated transformers withratings through 1500 kVA are UL®

listed and bear the UL label. Opencore and coil assemblies are URlabeled products.

These transformers are designed forcontinuous operation at rated kVA for24 hours a day, 365 days a year, withnormal life expectancy as defined inANSI C57.96.

Insulation SystemIndustry standards classify insulationsystems and temperature rise asshown below.

Table 19.1-1. Insulation System Classified

The design life of transformers havingdifferent insulation systems is thesame; the lower temperature systemsare designed for the same life as thehigher temperature systems.

Eaton’s ventilated transformers,regardless of their temperature rise,are manufactured using a 220°Cinsulation system. Required

performance is obtained withoutexceeding the insulation systemrating at rated temperature rise ina 40°C maximum ambient, with anaverage ambient temperature of 30°Cover a 24-hour period.

All insulation materials used areflame-retardant and do not supportcombustion as defined in ASTMStandard Test Method D635.

Core and Coil AssembliesThe transformer core is constructedusing high-grade, non-aging, siliconsteel with high magnetic permeability,and low hysteresis and eddy currentlosses. Maximum magnetic flux

densities are substantially belowthe saturation point. The transformercore volume allows for efficienttransformer operation at 10% abovethe nominal tap voltage. The corelaminations are tightly clamped andcompressed. Coils are wound ofelectrical grade aluminum or copper,and are of continuous woundconstruction. The BIL (basic impulselevel) for all 600V-class windings is10 kV. The core and coil assembly isinstalled on vibration-absorbing pads.

Ventilated transformers with wye-connected secondaries have the

neutral brought out to a separate XOterminal or bus bar.

The core and coil assembly isgrounded to the transformer enclosureby means of a visible flexible copperground strap. The copper groundstrap is sized per the NEC to be agrounding conductor.

AmbientTemperature

+ WindingRise

+ HotSpot

= Temp.Class

40°C40°C40°C

80°C115°C150°C

30°C30°C30°C

150°C185°C220°C


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Ventilated Transformers

Description012

TapsPrimary taps are available on mostEaton ventilated transformers toallow compensation for sourcevoltage variations.

Winding TerminationsPrimary and secondary windings areterminated in the wiring compartment.Encapsulated units have copper leadsor stabs brought out for connections.Ventilated transformers have leadsbrought out to aluminum or copperpads that are pre-drilled to acceptCu/Al lugs. Aluminum-wound trans-formers have aluminum pads; copper-wound transformers have copperpads. Lugs are not supplied with Eatontransformers; however, lug kits areavailable as a field-installed accessory.Eaton recommends external cables berated 90°C (sized at 75°C ampacity) forencapsulated designs and rated 75°Cfor ventilated designs.

Series-Multiple WindingsSeries-multiple windings consist oftwo similar coils in each winding thatcan be connected in series or parallel(multiple). Transformers with series-multiple windings are designated withan “x” or a “/” between the voltageratings, such as voltages of “240 x 480”or “120/240.” If the series-multiplewinding is designated by an “x,”the winding can be connected onlyin series or parallel. With a “/”

designation, a mid-point also becomesavailable in addition to the series orparallel connection. As an example, a240 x 480 winding can be connectedfor either 240 (parallel) or 480 (series).A 120/240 winding can be connectedfor either 120 (parallel) or 240 (series),or 240 with a 120 mid-point.

EnclosuresThe transformer enclosure is made ofheavy-gauge steel and is finished usinga continuous process of degreasing,cleaning and phosphatizing, followedby electrostatic deposition of a thermo-setting polyester powder coating and

subsequent baking. The coating coloris ANSI 61 and is UL recognized foroutdoor use. In compliance withNEMA ST-20, Eaton’s ventilatedtransformers are designed such thatthe maximum temperature on the topof the enclosure does not exceed 50°Crise above the ambient temperature.

For ventilated transformers, the enclo-sure construction is ventilated, drip-proof, NEMA 2, with lifting provisions.All ventilation openings are protectedagainst falling dirt. Proper installationof weathershields on ventilated trans-formers makes the enclosure NEMA3R rated and suitable for outdoor use.

To ensure proper ventilation and cool-ing of the transformer, follow manu-facturer’s recommended clearancesaround ventilation openings.

Installation Clearances

Eaton’s transformers should beinstalled with a minimum of 6 inchesof clearance around the transformerenclosure to prevent accidental contactwith flammable or combustible mate-rials. Most Eaton ventilated transform-ers require a minimum of 6 inches ofclearance in front and in back of the

transformer to allow for proper airflowthrough the transformer. Care shouldbe taken to avoid restricting theairflow through the bottom of thetransformer.

Transformers should be located inareas not accessible to the public.

Sound LevelsAll transformers emit some audiblesound due mainly to the vibrationgenerated in their core by alternatingflux. NEMA ST-20 defines themaximum average sound levelsfor transformers.

Table 19.1-2. NEMA ST-20 and IEEE C57.12.01Maximum Audible Sound Levels for 600VClass Transformers (dB 40)

All Eaton ventilated transformers aredesigned to have audible sound levelslower than those required by NEMAST-20. However, consideration shouldbe given to the specific location of atransformer and its installation tominimize the potential for soundtransmission to surroundingstructures and sound reflection.Installation and ambient conditionsat a specific location can result in field-measured audible sound levels asmuch as 15 dBA greater than thoselevels measured in a sound-proofchamber. The following installationmethods should be considered:

1. If possible, mount the transformeraway from corners of walls orceilings. For installations thatmust be near a corner, usesound-absorbing materials onthe walls and ceiling if necessary

to eliminate reflection.

2. Provide a solid foundation formounting the transformer anduse vibration dampening mountsif not already provided in thetransformer. Eaton’s ventilatedtransformers contain a built-invibration dampening system tominimize and isolate soundtransmission. However,supplemental vibrationdampening mounts installedbetween the floor and thetransformer may provideadditional sound dampening.

3. Make electrical connections to thetransformer using flexible conduit.

4. Locate the transformer in anarea where audible sound is notoffensive to building inhabitants.

5. If a transformer is going to beinstalled in a location wherethe audible sound could beobjectionable, consider installinga transformer specificallydesigned to have reducedsound levels. Eaton offersmany transformers with asound reduction up to 5 dBbelow NEMA ST-20 limits.

kVA VentilatedTransformers

EncapsulatedTransformers

0–9 10–50 51–150 151–300

40455055

45505557

301–500 501–700 701–10001001–1500

60626465

————


13/44


19November 2013


Sheet 19

Ventilated Transformers

Description013

Applicable Standards600V-class ventilated transformersare manufactured per the followingstandards:

■ UL 1561

■ NEMA ST-20■ ANSI C57.12.01

■ IEC 60726 for CE-marked ventilatedmodels

Seismic Qualification

Refer to Tab 1 for information onseismic qualification for this andother Eaton products.

Standard Production TestsThe following production tests areperformed as standard on all Eatontransformers, prior to shipment:

1. Ratio tests at the rated voltageconnection and at all tapconnections.

2. Polarity and phase relation testson the rated voltage connection.

3. Applied potential tests.

4. Induced potential tests.

5. No-load and excitation current at

rated voltage on the rated voltageconnection.

OperationEaton’s ventilated transformers aredesigned for continuous operation atrated kVA for 24 hours a day, 365 daysa year, with normal life expectancy asdefined in ANSI C57.96.

Short-term overload capacity isdesigned into transformers, as requiredby ANSI. Ventilated transformers willdeliver 200% of nameplate load for30 minutes; 150% of nameplate loadfor 1 hour; and 125% of nameplate load

for 4 hours without being damaged,provided that a constant 50% loadprecedes and follows the overload.Refer to ANSI C57.96-01.250 foradditional limitations.

Note: Continuous overload capacity is notdeliberately designed into transformers.The design objective is to be within theallowable winding temperature rise atnameplate full load capacity.

However, because Eaton’s ventilatedtransformers are manufactured using a220°C insulation system, 115°C and80°C low temperature rise transformerscan be operated as 150°C rise trans-formers. The excess thermal capacityof these low temperature rise trans-formers allows a 115°C transformer tobe operated as a 150°C rise transformer

and overloaded by 15% of its name-plate kVA without compromisingthe normal life of the transformer.Likewise, an 80°C rise transformeroperated as a 150°C rise transformeris capable of a constant 30% overloadwithout compromising the normal lifeexpectancy of the transformer.

Table 19.1-3. Rated Line Amperes for kVA and Voltages of Single-Phase Transformers

Note: Line Current = (kVA x 1000)/Line Voltage.

Table 19.1-4. Rated Line Amperes for kVA and Voltages of Three-Phase Transformers

Note: Three-Phase Line Current = (kVA x 1000)/(Line Voltage x 1.732).

kVARating

Rated Line Voltage

120 208 240 277 480 600 2400 4160 4800

1 1.5 2 3

8.3 12.5 16.7 25.0

4.8 7.2 9.6 14.4

4.2 6.3 8.3 12.5

3.6 5.4 7.2 10.8

2.1 3.1 4.2 6.3

1.7 2.5 3.3 5.0

0.4 0.6 0.8 1.3

0.2 0.4 0.5 0.7

0.2 0.3 0.4 0.6

5 7.5 10 15

41.7 62.5 83.3 125.0

24.0 36.6 48.1 72.1

20.8 31.3 41.7 62.5

18.0 27.1 36.1 54.2

10.4 15.6 20.8 31.3

8.3 12.5 16.7 25.0

2.1 3.1 4.2 6.3

1.2 1.8 2.4 3.6

1.0 1.6 2.1 3.1

25

37.5 50 75

208.3

312.5 416.7 625.0

120.2

180.3 240.4 360.6

104.2

156.3 208.3 312.5

90.3

135.4 180.5 270.8

52.1

78.1 104.2 156.3

41.7

62.5 83.3125.0

10.4

15.6 20.8 31.3

6.0

9.0 12.0 18.0

5.2

7.8 10.4 15.6

100167250333500

833.31391.72083.32775.04166.7

480.8 802.91201.91601.02403.8

416.7 695.81041.71387.52083.3

361.0 602.9 902.51202.21805.1

208.3 347.9 520.8 693.81041.7

166.7278.3416.7555.0833.3

41.7 69.6104.2138.8208.3

24.0 40.1 60.1 80.0120.2

20.8 34.8 52.1 69.4104.2

kVARating

Rated Line Voltage

208 240 480 600 2400 4160 4800

3 6 9

8.3 16.7 25.0

7.2 14.4 21.6

3.6 7.2 10.8

2.9 5.8 8.7

0.7 1.4 2.2

0.4 0.8 1.3

0.4 0.7 1.1

15 30 45

41.6 83.3 125.0

36.1 72.2 108.4

18.0 36.1 54.2

14.4 28.9 43.3

3.6 7.2 10.9

2.1 4.2 6.3

1.8 3.6 5.4

75 112.5 150

208.2 312.5 416.3

180.4 271.6 360.8

90.2 135.3 180.4

72.2108.2144.3

18.0 27.1 36.1

10.4 15.6 20.8

9.0 13.5 18.0

225 300 500

625.0 832.71387.8

541.9 721.71202.8

270.7 360.8 601.4

216.5288.7481.1

54.2 72.2120.3

31.3 41.6 69.4

27.1 36.1 60.1

7501000

2081.92775.8

1804.32405.7

902.11202.9

721.7962.3

180.4240.6

104.1138.8

90.2120.3


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General Purpose Encapsulated Transformers

Description014

General ConstructionFeatures of General PurposeEncapsulated TransformersRated 600V and Below

General DescriptionEaton’s single-phase and three-phasegeneral purpose encapsulated dry-typetransformers are of the two-windingtype, self-cooled, and are available in awide variety of primary and secondaryvoltage combinations.

Eaton’s transformers are designed,manufactured and tested in accordancewith all of the latest applicable ANSI,NEMA and IEEE standards. All 600V-class encapsulated transformers withratings through 75 kVA are UL listedand CSA certified, and bear the UL andCSA labels.

These transformers are designed forcontinuous operation at rated kVA for24 hours a day, 365 days a year, withnormal life expectancy as defined inANSI C57.96.

Insulation SystemsIndustry standards classify insulationsystems and temperature rise asshown below.

Table 19.1-5. Insulation System Classification

The design life of transformers havingdifferent insulation systems is thesame; the lower temperature systemsare designed for the same life asthe higher temperature systems.

Eaton’s encapsulated transformers aremanufactured using a 180°C insulation

system. Required performance isobtained without exceeding theinsulation system rating at ratedtemperature rise in a 40°C maximumambient, with an average ambienttemperature of 30°C over a 24-hourperiod.

All insulation materials are flame-retardant and do not supportcombustion as defined in ASTMStandard Test Method D635.

Core and Coil AssembliesThe transformer core is constructedusing high-grade, non-aging, siliconsteel with high-magnetic permeability,and low hysteresis and eddy currentlosses. Maximum magnetic flux

densities are substantially belowthe saturation point. The transformercore volume allows for efficienttransformer operation at 10% abovethe nominal tap voltage. The corelaminations are tightly clampedand compressed. Coils are woundof electrical grade aluminum orcopper, and are of continuous woundconstruction. The BIL (basic impulselevel) for all 600V-class windingsis 10 kV. In encapsulated transformers,the core and coil assembly iscompletely encased in a proportionedmixture of resin or epoxy, andaggregate to provide a moisture-

proof, shock-resistant seal. The coreand coil encapsulation system isdesigned to minimize the audiblesound level.

AmbientTemperature

+WindingRise

+HotSpot

=Temp.Class

40°C40°C25°C40°C40°C

55°C 80°C135°C115°C150°C

10°C30°C20°C30°C30°C

105°C150°C180°C185°C220°C


15/44


19November 2013


Sheet 19


Description015

TapsPrimary taps are available on manyEaton encapsulated transformersto allow compensation for sourcevoltage variations.

Winding TerminationsPrimary and secondary windings areterminated in the wiring compartment.Encapsulated units have copper leadsor stabs brought out for connections.Ventilated transformers have leadsbrought out to aluminum or copperpads that are pre-drilled to acceptCu/Al lugs. Aluminum-wound trans-formers have aluminum pads; copper-wound transformers have copperpads. Lugs are not supplied withEaton’s transformers; however, lugkits are available as a field-installedaccessory. Eaton recommends exter-nal cables be rated 90°C (sized at 75°Campacity) for encapsulated designsand rated 75°C for ventilated designs.

Series-Multiple WindingsSeries-multiple windings consistof two similar coils in each windingthat can be connected in series orparallel (multiple). Transformers withseries-multiple windings are desig-nated with an “x” or a “/” between thevoltage ratings, such as voltages of“240 x 480” or “120/240.” If the series-multiple winding is designated by an“x,” the winding can be connectedonly in series or parallel. With a “/”

designation, a mid-point also becomesavailable in addition to the series orparallel connection. As an example, a240 x 480 winding can be connectedfor either 240 (parallel) or 480 (series).A 120/240 winding can be connectedfor either 120 (parallel) or 240 (series),or 240 with a 120 mid-point.

EnclosuresThe transformer enclosure is made ofheavy-gauge steel and is finished usinga continuous process of degreasing,cleaning and phosphatizing, followedby electrostatic deposition of a thermo-

setting polyester powder coating andsubsequent baking. The coating coloris ANSI 61 and is UL recognized foroutdoor use. In compliance withNEMA ST-20, Eaton’s transformersare designed such that the maximumtemperature on the top of the enclosuredoes not exceed 50°C rise above theambient temperature.

For encapsulated transformers, theenclosure construction is totally-enclosed, non-ventilated NEMA 3R,with lifting provisions.

Wall mounting brackets are providedon many Eaton encapsulated trans-

formers. These mounting bracketsare designed to provide the properspacing between the mounting surfaceand the transformer enclosure.

To ensure proper ventilation andcooling of the transformer, followmanufacturer’s recommendedclearances around encapsulatedtransformers.

Sound LevelsAll transformers emit some audiblesound due mainly to the vibration gen-erated in their core by alternating flux.NEMA ST-20 defines the maximum

average sound levels for ventilatedtransformers, and IEEE C57.12.01defines the maximum average soundlevel for encapsulated transformers.

Table 19.1-6. NEMA ST-20 and IEEE C57.12.01Maximum Audible Sound Levels for 600VClass Transformers (dB 40)

All Eaton encapsulated transformersare designed to have audible soundlevels lower than those required byIEEE C57.12.01. However, consider-ation should be given to the specificlocation of a transformer and itsinstallation to minimize the potentialfor sound transmission to surroundingstructures and sound reflection.Installation and ambient conditions ata specific location can result in field-measured audible sound levels asmuch as 15 dBA greater than thoselevels measured in a sound-proofchamber. The following installationmethods should be considered:

1. If possible, mount the transformeraway from corners of walls orceilings. For installations thatmust be near a corner, use sound-absorbing materials on thewalls and ceiling if necessary

to eliminate reflection.

2. Provide a solid foundation formounting the transformer anduse vibration-dampening mountsif not already provided in thetransformer. Eaton’s encapsulatedtransformers use a specialencapsulation system to minimizeand isolate sound transmission.However, supplemental vibrationdampening mounts installedbetween the floor and thetransformer may provide foradditional sound dampening.

3. Make electrical connections to the

transformer using flexible conduit.

4. Locate the transformer in anarea where audible sound is notoffensive to building inhabitants.

5. If a transformer is going to beinstalled in a location where theaudible sound could be objection-able, consider installing a trans-former specifically designed tohave reduced sound levels. Eatonoffers many transformers with asound reduction up to 5 dB belowIEEE C57.12.01 limits.

kVA VentilatedTransformers

EncapsulatedTransformers

0–9 10–50 51–150 151–300

40455055

45505557

301–500 501–700

701–10001001–1500

6062

6465

——

——


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Description016

Applicable Standards600V-class encapsulated transformersare manufactured per the followingstandards:

■ UL 5085 up to 15 kVA

■ UL 1561 15 kVA and larger■ NEMA ST-20

■ ANSI C57.12.01

■ IEEE C57.12.01

■ IEC 61558 for single-phaseCE-marked models

■ CSA C22.2 No. 47-M90

Seismic Qualification

Refer to Tab 1 for information onseismic qualification for this andother Eaton products.

Standard Production TestsThe following production tests areperformed as standard on all Eaton transformers, prior to shipment:

1. Ratio tests at the rated voltageconnection and at all tap connections.

2. Polarity and phase relation testson the rated voltage connection.

3. Applied potential tests.

4. Induced potential tests.

5. No-load and excitation current atrated voltage on the rated voltageconnection.

OperationEaton’s encapsulated transformers aredesigned for continuous operation atrated kVA for 24 hours a day, 365 daysa year, with normal life expectancy asdefined in ANSI C57.96.

Short-term overload capacity isdesigned into transformers, as requiredby ANSI. Encapsulated transformerswill deliver 200% of nameplate load for30 minutes; 150% of nameplate loadfor 1 hour; and 125% of nameplate loadfor 4 hours without being damaged,provided that a constant 50% loadprecedes and follows the overload.Refer to ANSI C57.96-01.250 foradditional limitations.

Note: Continuous overload capacity is notdeliberately designed into transformersbecause the design objective is to be withinthe allowable winding temperature rise atnameplate full load capacity.

Table 19.1-7. Rated Line Amperes for kVA and Voltages of Single-Phase Transformers

Note: Line Current = (kVA x 1000)/Line Voltage.

Table 19.1-8. Rated Line Amperes for kVA and Voltages of Three-Phase Transformers

Note: Three-Phase Line Current = (kVA x 1000)/(Line Voltage x 1.732).

kVARating

Rated Line Voltage

120 208 240 277 480 600 2400 4160 4800

1 1.5 2

3

8.3 12.5 16.7

25.0

4.8 7.2 9.6

14.4

4.2 6.3 8.3

12.5

3.6 5.4 7.2

10.8

2.1 3.1 4.2

6.3

1.7 2.5 3.3

5.0

0.4 0.6 0.8

1.3

0.2 0.4 0.5

0.7

0.2 0.3 0.4

0 6

5 7.5 10 15

41.7 62.5 83.3 125.0

24.0 36.6 48.1 72.1

20.8 31.3 41.7 62.5

18.0 27.1 36.1 54.2

10.4 15.6 20.8 31.3

8.3 12.5 16.7 25.0

2.1 3.1 4.2 6.3

1.2 1.8 2.4 3.6

1.0 1.6 2.1 3.1

25 37.5 50 75

208.3 312.5 416.7 625.0

120.2 180.3 240.4 360.6

104.2 156.3 208.3 312.5

90.3 135.4 180.5 270.8

52.1 78.1 104.2 156.3

41.7 62.5 83.3125.0

10.4 15.6 20.8 31.3

6.0 9.0 12.0 18.0

5.2 7.8 10.4 15.6

100167250333500

833.31391.72083.32775.04166.7

480.8 802.91201.91601.02403.8

416.7 695.81041.71387.52083.3

361.0 602.9 902.51202.21805.1

208.3 347.9 520.8 693.81041.7

166.7278.3416.7555.0833.3

41.7 69.6104.2138.8208.3

24.0 40.1 60.1 80.0120.2

20.8 34.8 52.1 69.4104.2

kVARating

Rated Line Voltage

208 240 480 600 2400 4160 4800

3 6 9

8.3 16.7 25.0

7.2 14.4 21.6

3.6 7.2 10.8

2.9 5.8 8.7

0.7 1.4 2.2

0.4 0.8 1.3

0.4 0.7 1.1

15 30 45

41.6 83.3 125.0

36.1 72.2 108.4

18.0 36.1 54.2

14.4 28.9 43.3

3.6 7.2 10.9

2.1 4.2 6.3

1.8 3.6 5.4

75 112.5 150

208.2 312.5 416.3

180.4 271.6 360.8

90.2 135.3 180.4

72.2108.2144.3

18.0 27.1 36.1

10.4 15.6 20.8

9.0 13.5 18.0

225 300 500

625.0 832.71387.8

541.9 721.71202.8

270.7 360.8 601.4

216.5288.7481.1

54.2 72.2120.3

31.3 41.6 69.4

27.1 36.1 60.1

750

1000

2081.9

2775.8

1804.3

2405.7

902.1

1202.9

721.7

962.3

180.4

240.6

104.1

138.8

90.2

120.3


17/44


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Sheet 19

K-Factor Rated Nonlinear Transformers

Description017

K-Factor Rated NonlinearTransformers Rated 600Vand Below

ApplicationsEaton K-Factor transformers arespecifically designed to withstand theharmful overheating effects caused byharmonics generated by nonlinear(non-sinusoidal) loads. These loadsinclude computers, laser printers,copiers and other office equipment,as well as video monitors and otherelectronic equipment. Eaton K-Factortransformers are not simply over-sizedtransformers. The core and coils ofour K-Factor transformers are speciallydesigned to have reduced inductionlevels, which results in a reduction instray losses. Oversized (200% rated)neutrals and electrostatic shielding are

typical features found in our K-Factortransformers. Eaton K-Factor trans-formers are manufactured with thesame high-quality construction featuresas our other ventilated transformerproducts, including NEMA 2 enclosuresas standard.

Technical Data

Available Ratings

Eaton K-Factor transformers areavailable in a wide range of ratingsto meet specific voltage conversionrequirements. Eaton offers transformerswith K-factor ratings of 4, 13, 20, 30,

40 and 50.

kVA Capacity

Single-phase ventilated designs areavailable in ratings from 15 kVAthrough 167 kVA; three-phase ratings15 kVA through 1500 kVA.

Insulation System and Temperature Rise

Ventilated transformers are manufac-tured using a 220°C insulation systemwith 150°C temperature rise as stan-dard. Low temperature rise designs(115°C and 80°C temperature rise)are available as options.

Frequency

Most ventilated transformers aredesigned to operate in 60 Hz systems.50/60 Hz designs are available as anoption. Eaton’s ventilated transformerscan be designed to operate at a varietyof frequencies.

Winding Material

Aluminum conductor and terminationsare provided as standard on ventilatedtransformers. Copper winding conduc-tors and terminations are available asan option.


Eaton’s ventilated transformers shouldbe installed with a minimum of6.00 inches of clearance around thetransformer enclosure to preventaccidental contact with flammable or

combustible materials. Most Eatonventilated transformers require aminimum of 6.00 inches of clearancein front and in back of the transformerto allow for proper airflow through thetransformer. Care should be taken toavoid restricting the airflow throughthe bottom of the transformer. Trans-formers should be located in areas notaccessible to the public.

Wiring Compartment

Eaton’s ventilated transformers havewiring compartments sized to complywith NEMA and NEC standards.

The K-factor

A common industry term for theamount of harmonics produced by agiven load is the K-factor. The largerthe K-factor, the more harmonics arepresent. Linear loads, for example,have a K-factor of 1. Transformers maycarry a K-factor rating to define thetransformer’s ability to withstandthe additional heating generatedby harmonic currents.

Calculating the K-factor

All nonlinear waveforms can bebroken down mathematically intoa fundamental frequency and itsharmonics. IEEE C57.110 establishes

a direct relationship between theseharmonics and transformer heating.Underwriters Laboratories hasestablished a similar relationship, theK-factor, which is derived by summingthe square of the percentage current ata given harmonic level multiplied bythe square of the harmonic order.

K = ∑(Ih)2(h)2

Ih = Percent Current at Harmonic h

h = Harmonic Order, i.e., 3rd, 5th, 7th

For example, a load that is 90% of thefundamental, 30% of the third harmonic,and 20% of the fifth harmonic wouldyield (.9)2(1)2 + (.3)2(3)2 + (.2)2(5)2 ora K-factor of 2.62. This load wouldrequire a transformer with a K-factorrating of 4.

Transformers that carry a K-factorrating define the transformer’s ability towithstand a given harmonic load whileoperating within the transformer’sinsulation class.

An analysis of harmonic loads anda calculation of the K-factor must bemade to properly apply transformersin any building or facility. Note that

the calculated K-factor is not constantsince nonlinear loads changethroughout the day as equipment andlighting is turned off and on. Theseharmonic loads also change over thelife of the building or facility as equip-ment is added or removed.

Harmonic Currents

Harmonic currents are found in nonlin-ear loads. These currents are generatedby various types of equipment includingswitching mode power supplies thatabruptly switch current on and off duringeach line cycle. Switching mode powersupplies or diode capacitor powersupplies convert AC line voltage to lowvoltage DC. This process accomplishedby charging capacitors during each linecycle with narrow pulses of current thatare time-coincident with line voltagepeaks. Examples of this equipmentinclude electronic ballasts for fluorescentlighting, personal computers, printers,fax machines, electronic and medicaltest equipment uninterruptible powersupplies and solid-state motor drives.

Note: Nonlinear is synonymous with theterm non-sinusoidal.

Figure 19.1-1. Harmonic Currents Found in Nonlinear Loads Cause Wave Shape Distortion andCreate Added Stresses on Transformers


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Harmonic Mitigating Transformers

Description018

Harmonic MitigatingTransformers Rated 600Vand Below

ApplicationsEaton’s harmonic mitigating trans-formers (HMTs) are specially designedtransformers that treat a wide varietyof harmonics. Also called “phase-shifting” transformers, their low zero-sequence impedance wye zig-zagsecondary windings prevent harmfultriplen (3rd, 9th, 15th, etc.) harmoniccurrents from coupling into the pri-mary delta, where they can progressupstream to the service entrance.Multiple HMTs with a variety of phase-shift configurations can be applied ina coordinated scheme to target 5th,7th and higher-order harmonics at thecommon bus feeding all of the trans-

formers. HMTs are ideally suited forinstallations rich in harmonic loads,such as educational facilities (K–12 anduniversities), government, commercial,medical and call-center applications.HMTs are manufactured with thesame high-quality features as Eaton’sventilated transformers, includingNEMA 2 enclosures and the 220°C(Class R) insulation system with150°C temperature rise as standard.Additionally, Eaton’s HMTs aremanufactured with a 200% neutraland electrostatic shield as standard.Eaton’s harmonic mitigating ventilatedtransformers are designed primarily

for indoor installations. Ventilatedtransformers have NEMA 2 enclosuresas standard, and are suitable forinstallation outdoors when NEMA 3Rweathershield kits are installed.Ventilated transformers are typicallyfloor-mounted on an elevatedhousekeeping pad. When properlysupported, they are also suitable forwall mounting or trapeze-mountingfrom ceilings.

Technical Data

Available Ratings

Eaton’s harmonic mitigating trans-

formers are available in a wide rangeof ratings to meet specific voltageconversion requirements. Eaton’sHMTs accept a three-phase three-wireinput and have a three-phase four-wire(phases and neutral) output.

kVA Capacity

Three-phase ratings 15 kVA through500 kVA.

Insulation System and Temperature Rise

Eaton’s harmonic mitigating trans-

formers are manufactured using a220°C insulation system with 150°Ctemperature rise as standard. Lowtemperature rise designs (115°C and80°C temperature rise) are available asoptions.

Frequency

Eaton’s harmonic mitigating trans-formers are designed to operate in60 Hz systems. 50/60 Hz designs areavailable as an option. The transformerscan be designed to operate at a varietyof frequencies.

Winding Material

Copper conductor and terminationsare provided as standard on harmonicmitigating transformers. Aluminumwinding conductors and terminationsare available as an option.


Eaton’s harmonic mitigating trans-formers should be installed with aminimum of 6.00 inches of clearancearound the transformer enclosureto prevent accidental contact withflammable or combustible materials.Most Eaton ventilated transformersrequire a minimum of 6.00 inches ofclearance in front and in back of thetransformer to allow for proper airflow

through the transformer. Care shouldbe taken to avoid restricting theairflow through the bottom of thetransformer.

Transformers should be located inareas not accessible to the public.

Wiring Compartment

Eaton’s ventilated transformers havewiring compartments sized to complywith NEMA and NEC standards.

Thermal Sensors

Harmonic mitigating transformers areavailable with “warning” and/or “alarm”

thermal sensors imbedded in their coils.Thermal sensors are normally open drycontacts that can be wired to providea signal to remote locations to indicatea potential heating problem within thetransformer coils. Contacts are rated180°C (warning) and 200°C (alarm).

Application Considerations

Eaton offers harmonic mitigatingtransformers with four different phase-shift options:

■ Type NON (0° phase-shift)

■

Type POS (+15° phase-shift)■ Type NEG (–15° phase-shift)

■ Type THR (–30° phase-shift)

To select the proper HMT, thenonlinear load profile of a particularapplication must be known.

Type NON (0°) HMTs are ideallysuited for treating 3rd and other triplenharmonics that are the signature ofsingle-phase nonlinear loads. This isthe most common application encoun-tered. Type NON HMTs use electro-magnetic flux cancellation to canceltriplen harmonics. There, harmonicsare treated in the secondary windings

and prevented from coupling into theprimary delta windings, where theymay be transmitted upstream to theservice entrance location. Type NONHMTs can be deployed singly to treattriplen harmonics. As with most otherharmonic mitigating methods, thecloser the HMT can be installed to theload, the greater the benefit.

Type POS (+15°) and Type NEG (–15°)harmonic mitigating transformers aretypically used together in coordinatedpairs to treat 5th, 7th and otherharmonics that are generated by three-phase nonlinear loads. 5th, 7th and

higher order harmonics pass throughthe harmonic mitigating transformers,to a point of common coupling; thefirst common electrical point that isshared by the HMTs. At this commonpoint, balanced portions of the 5th,7th, etc., harmonic currents arecanceled and prevented from flowingfurther upstream in the distributionsystem. Type POS and Type NEGHMTs have nearly identical electricalcharacteristics, including zero-sequence and positive-sequenceimpedance and reactance. The moreclosely matched the coordinated pairsof transformers, the more thorough

the harmonic cancellation.Coordinated pairs of Type NON andType THR transformers, as well ascoordinated pairs of Type NON, TypeTHR, Type POS and Type NEG HMTsprovide treatment of 3rd and othertriplen harmonics within theirsecondary windings. This cancellationis achieved by virtue of their wyezig-zag winding configuration.


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Description019


As our world becomes even moredependent on electrical and electronicequipment, there is an increasedlikelihood that operations will

experience the negative effects ofharmonic distortion. The productivityand efficiency gains achieved fromincreasingly sophisticated piecesof equipment have a drawback:increased harmonic distortion in the

electrical distribution system.The difficult thing about harmonicdistortion is determining the source.Once this task has been completed,

the solution can be easy. Harmonicmitigating transformers (HMTs) areone of the many possible solutionsto help eliminate these harmfulharmonics.

Figure 19.1-2. Typical Waveform of Single-Phase Devices

Figure 19.1-3. Composite Waveform

Figure 19.1-4. Components of a Nonlinear Waveform

60 Hzfundamental

fundamental

7th

3rd5th

What are Harmonics?An understanding of how harmonicsare generated and what harmonicsreally are is necessary in order tounderstand how HMTs can provideharmonic mitigation. Electronic equip-

ment requires DC voltage to operate.Rectifiers and capacitors are used toconvert AC voltage to DC voltagewithin the equipment. These devicesare frequently referred to as switchmode power supplies. As the capaci-tors charge and discharge during thisconversion, the capacitor draws cur-rent in pulses, not at a continuous rate.This irregular current demand, asdepicted in Figure 19.1-2, distorts thelinear 60 Hz sine wave. As a result, thesetypes of loads are commonly referredto as non-sinusoidal, or nonlinear.

As shown in Figures 19.1-3 and 19.1-4,the waveform created by the nonlinear

source is actually the mathematicalsum of several sine waves, each witha different frequency and magnitude.Each of these individual waveforms iscalled a harmonic, and is identified byits frequency relative to the fundamentalfrequency, 60 Hz. In other words, eachindividual harmonic is identified by anumber, which is the number of com-plete cycles the specific harmonic goesthrough in a single 60 Hz cycle.

In Figure 19.1-4, the fundamentalfrequency is 60 Hz. The fundamentalfrequency is assigned the harmonicnumber of 1, and is the benchmark forall other harmonic numbering. The

fundamental, 60 Hz sine wave completes 60 full cycles in one second. The 3rdharmonic completes three full cyclesin the time it takes the fundamental tocomplete just one cycle, or 180 cyclesper second. Likewise, the 5th harmoniccompletes five full cycles in the timeit takes the fundamental harmonic tocomplete a single cycle, which equatesto 300 cycles per second. Odd multiplesof the 3rd harmonic (3rd, 9th,15th,21st, etc.) are commonly referred toas triplen harmonics.

The proliferation of electronic equipment(including computers, fax machines,copiers, electronic ballasts, office

equipment, cash registers, slot machines, electronic monitoring devices, video games, medical diagnostic equipmentand the like) is what makes single-phase devices the most common source ofharmonics. These devices generate a typ-ical waveform shown in Figure 19.1-2,and have a harmonic profile as shownin Table 19.1-9. As one can see, the pre-dominant harmonic is the 3rd harmonic.

Three-phase, nonlinear loads such asdrives, on the other hand, are typicallyrich in 5th and 7th harmonics.


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Description020

What Problems doHarmonics Cause?The distorted current waveform that iscreated by nonlinear loads can causemany problems in an electrical distri-bution system. Depending upon theseverity of the harmonic distortion,the negative effects of harmonics maybe tolerable, and the installation ofa K-factor–rated transformer may bean adequate solution. K-factor–ratedtransformers do not provide anyharmonic treatment. Rather, they aredesigned to withstand the destructiveeffects of the additional heat gener-ated by harmonic currents in thetransformer’s windings.

In many instances, the harmful effectsof harmonics are too severe, andsimply tolerating them is not anacceptable option. Harmonic currents

can cause excessive heating in distri-bution transformers. This additionalheat not only reduces the life expect-ancy of a transformer, it also reducesthe usable capacity of the transformer.Another side effect is that the audiblenoise of a transformer may be ampli-fied when installed in a system thatcontains harmonics.

An important characteristic ofharmonics is that they are transmittedupstream from the load, to the trans-former’s secondary windings, throughthe primary windings of the trans-former, back to the service entrance,

and eventually to the utility lines.

Harmonic currents flowing upstreamfrom nonlinear loads, through thesystem impedance of cables andtransformers, create harmonic voltagedistortion. When linear loads, likemotors, are subjected to harmonicvoltage distortion, they will draw anonlinear harmonic current. As withdistribution transformers, harmoniccurrents cause increased heating,due to iron and copper losses, inmotors and generators. This increasedheating can reduce the life of themotor, as well as the motor’s effi-ciency. In electrical cables, harmoniccurrents may also create increasedheating, which can lead to prematureaging of the electrical insulation.Nuisance tripping of the circuit break-ers protecting the cable may alsooccur. Communications equipmentand data processing equipment areespecially susceptible to the harmfuleffects of harmonics because they relyon a nearly perfect sinusoidal input.This equipment may malfunction, oreven fail, when installed in systemsthat are rich in harmonics.

The costs associated with downtimeresulting from the malfunction or fail-ure of electrical or electronic equip-ment can be staggering. These costscan easily surpass thousands, if notmillions, of dollars per hour in lostproduction or lost productivity. Inaddition to the well-defined costsassociated with the most catastrophicof harmonic effects, there are many

less quantitative costs that are oftenoverlooked when evaluating the needfor harmonic mitigation. The increasedheating caused by harmonics incables, motors and transformersincreases the cooling requirementsin air-conditioned areas. The sameincreases in heating result in increasedmaintenance costs and more frequentequipment replacement in order toavoid failures that could shut downa building for a period of time.

What do HMTs do?HMTs are an economical solution inthe battle against the harmful effectsof harmonics. HMTs are passivedevices: they don’t have any movingparts and they are typically energized

24 hours a day, 7 days a week, 365days a year. This means that they arealways “on the job” treating harmon-ics, regardless of the level of load theyare serving at a given point in time.Whenever the HMT is energized, it willprovide harmonic treatment.

Harmonic mitigating transformers arecommonly referred to as “phase-shift-ing” transformers. The HMT offeringfrom Eaton’s electrical business hasdelta-connected primary windingsand wye zig-zag connected secondarywindings. The use of wye zig-zag sec-ondary windings allows a transformer

to be designed in a wide variety ofdifferent phase-shifts (–30°, –15°,0°, +15°). In standard delta-wyetransformers, including K-factor–ratedtransformers, triplen harmonics arepassed from the secondary windingsinto the primary delta windings, wherethey are trapped and circulate. InHMTs, the electromagnetic fluxcancellation created by the wye zig-zagwinding configuration prevents 3rdand other triplen harmonics frombeing transmitted into the primarydelta winding. Harmonic treatment isprovided entirely by electromagneticflux cancellation; no filters, capacitors

or other such devices are used. Itis important to remember that theharmonic currents still flow in thesecondary windings.


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Description021

Benefits of Installing HMTsIn addition to improved systemreliability and reduced maintenancecosts, HMTs also have excellentenergy-saving characteristics. Withthe cost of electricity continuing to

increase around the world, there isan ever-increasing interest in energy-efficient products. In many facilities,the cost of electricity is the secondlargest expense, eclipsed only bysalaries and wages.

Transformers consume energyeven when they are lightly loaded ornot loaded at all. Significant energysavings may be attained if the no-loadlosses of a transformer are reduced.NEMA Standard TP-1 addressesthis issue by requiring high efficiencylevels when a transformer is loaded at35% of its full capacity. However, this

standard applies to linear load profilesonly, and tests to validate compliancewith NEMA TP-1 are performed usinglinear loads.

In actual applications, the growingpresence of electronic devices createsnonlinear load profiles. Nonlinearloads cause the losses in distributiontransformers to increase, therebyreducing their realized efficiency.Therefore, NEMA TP-1 efficiencycompliance may not be a true indica-tion of the efficiency of a transformerexposed to nonlinear loads. Thougha measure of linear load efficiency,Eaton’s family of HMTs meets theefficiency standards set forth inNEMA Standard TP-1. Because HMTsare intended to be installed in systemsthat contain high levels of nonlinearloads, Eaton’s family of HMTs isdesigned to meet the NEMA TP-1efficiency levels when applied tononlinear load profiles with 100%harmonic distortion, across a broadrange of load levels, not just the35% load level used in NEMA TP-1.These energy savings are realizedover the entire life of the transformer.

Table 19.1-9. Typical Harmonic Profile ofSingle-Phase Switched Mode Power Supply

Application InformationThe closer that an HMT can be locatedto the load, the greater the benefitsof harmonic treatment. Installationof a large capacity HMT at the serviceentrance of a large building would

certainly provide some harmonic treat-ment. However, installation of severalsmaller rated HMTs, perhaps oneor more on each floor of a building,provides greater benefits that will benoticed throughout the facility. For thisreason, the most popular HMTs will berated 75 kVA and less. This comple-ments the cost-efficiencies that can begained by distributing higher voltagesthrough smaller cables to the pointwhere a safer, lower v

transformadores de tipo seco

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